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This study investigates the load-carrying mechanism and proposes precise strength prediction methods for hole threads in Thread-fixed One-side Bolts bolted curved T-stubs to circular steel tube connections. A series of parametric analysis was performed with an advanced 3D finite element model considering critical parameters including tube wall thickness, bolt angle and bolt size. The axial load distribution along the hole threads and the shear stress distribution at the thread root were analyzed in detail. It was found that there were three typical load distribution patterns along hole threads, which were (1) linear pattern; (2) concave parabola pattern; and (3) convex parabola pattern, and the ratio of bolt stiffness to tube wall stiffness was identified as the pivotal factor affecting the axial load distribution. Meanwhile, the analysis results indicated that the bending moment on the TOBs did not affect the load distribution along hole threads, but led to a non-uniform stress distribution along the thread in the same turn. In the end, the prediction formulas for the carrying capacity of hole threads are presented by modifying Yamamoto's equation based on the analysis findings. The formulas are validated against the finite element analysis results and previous test results. The prediction can reach the highest accuracy when adopting the proposed failure criterion 2, with average errors of − 0.001 and − 0.002, respectively, demonstrating the accuracy and reliability. • An advanced 3D finite element model for bolted connections was developed. • The load distribution along hole threads were analyzed in detail. • Three typical load distribution patterns along hole threads were found. • Proposing methods to predict the load-carrying capacity of hole threads. [ABSTRACT FROM AUTHOR]

This study provides a thorough comparative analysis of structural design strategies across different ductility classes and seismic action levels, as outlined in Eurocode 8 provisions. The analysis is carried out for 5- and 10-storey building examples. The research highlights key findings regarding base shear demand, storey displacements, sensitivity coefficients, and other crucial structural performance parameters. Those findings indicate that while buildings designed for DCM and DC3 ductility classes generally exhibit similar base shear values and roof displacements, exceptions arise, particularly in the lower-storey buildings where DC2 demonstrates significantly lower roof displacements. The influence of strut inclination on design bending moments is also noted, underscoring its significance in structural behaviour. Moreover, the study delves into interstorey drift ratio (IDR) demands from analysis, revealing consistent displacement patterns across various structures with notable implications for deflection and stability. Additionally, insights into chord rotation control, sensitivity coefficients, and reinforcement quantities shed light on their behaviour under diverse seismic conditions, aiding in optimising structural design strategies. • The study compares the design demands of buildings for some ductility classes and seismic action based on the Eurocode 8. • Analysis shows similarities in base shear values and roof displacements for buildings designed for DCM and DC3. • Structures like DC2.W.50.5 and DC3.W.50.5 exhibit higher resistance to deformations compared to others. • Torsional rotation varies by height, with DC3.W.75.5 showing the highest average torsional angle in 5-story buildings. • The sensitivity coefficients highlight structural behavior, indicating minor to significant impacts on internal forces. [ABSTRACT FROM AUTHOR]

The seismic behaviour of hybrid coupled walls (HCWs) made of a single reinforced concrete (RC) wall connected to two steel side columns through steel links, named as single-pier HCWs (SP-HCWs), is studied through nonlinear finite element simulations. The design concept is that the steel links are intended to work as dissipative elements while the steel side columns and the RC wall should remain elastic. Given that previous studies highlighted difficulties in avoiding damage at the base of the RC wall due to the concentration of bending moment, this study focuses on a special configuration providing very limited damage at the base of the RC wall that could be rapidly and economically repaired. The original scheme of SP-HCW with fixed base is modified introducing a hinged connection combined with vertical steel elements, called corner components. A ductile design methodology is proposed and applied for proportioning 54 case studies with different building heights, coupling ratios, height-to-length ratios of the RC wall, in addition to different base conditions (fixed base, hinged base with corner components designed as non-dissipative elements, hinged base with corner components designed as dissipative elements). Results of nonlinear finite element analyses validate the design methodology and highlight the potentialities of the proposed solutions, showing the benefits of a hinged base with corner components. • The seismic performance of single-pier steel and concrete hybrid coupled walls is studied. • Focus is made on alternative hinged base solutions to protect the wall from damage. • A seismic ductile design procedure is proposed and applied to a wide set of case studies. • Results provide insights into the benefits of the developed base configurations. [ABSTRACT FROM AUTHOR]

Six T-shaped welded multi-partition composite members were tested under eccentric compression loading by considering the influence of eccentricity and eccentric angle. The test results showed that no weld tearing occurred when the specimen was damaged, indicating that the two vertical welds could ensure the overall working performance of the specimen. The specimens exhibited the smallest bearing capacity when failing along the asymmetric axis, which was the most dangerous situation. The parametric analysis is conducted by a verified finite element model considering the influence of the slenderness ratio, section height-to-width ratio, section depth-to-width ratio, concrete and steel grade, steel ratio, and eccentric angle. If concrete contributes a larger proportion to the bearing capacity, the interaction curve of axial force and bending moment tends to protrude. Conversely, the interaction curve of axial force and bending moment gradually shrinks as the slenderness ratio increases. Based on this observation, a calculation method of T-shaped welded multi-partition composite members under eccentric compressive loading along the asymmetric axis is proposed by considering the effect of the slenderness ratio. Formulas for bearing capacity under biaxial eccentric compression are proposed based on the results of the parametric analysis. • Eccentric compression of T-shaped welded multi-partition composite members was studied through experiments and FE analysis. • The measured torsion angle confirms the good torsional capacity of T-shaped composite members. • The effects of the slenderness ratio and biaxial eccentricity on the bearing capacity of the specimen are studied. • The N - M curve of T-shaped composite members under eccentric compression loading along the asymmetric axis is proposed. [ABSTRACT FROM AUTHOR]

3D concrete printing (3DCP) is an innovative technology for constructing complex freeform structures that are difficult or expensive to build using conventional construction methods. The printing of double-curved shells and aesthetically pleasing geometries for façade panels and roof elements requires a detailed investigation of the load-carrying capacity and failure mode during complex loading. Moreover, integrating reinforcement into printed elements is one of the major challenges in 3DCP for manufacturing structural components. Textile reinforcement has high formability and tensile strength and can be used as an in-process reinforcing method during printing. In this study, one layer of alkali-resistant glass textile was used to reinforce the 3D printed and mould-cast high-performance concrete curved members. The commonly used concrete printing nozzle was modified to allow ease in textile placement along the printing path. Further, the feasibility of the modified nozzle was evaluated by printing two different curved structures and was validated. In addition, two different curvatures of curved elements, with and without textile reinforcement were printed to study the effect of textile reinforcement and geometry when subjected to a point load in the middle. The deformation behaviour, crack development, and propagation were monitored using digital image correlation. It was observed that the textile reinforcement enhances the interlayer bonding leading to slower crack propagation and enhanced load-carrying capacity. An increase of about 10 % in the peak load-carrying capacity of 3D printed specimens was observed with the addition of textile reinforcement when compared to their mould-cast. Also, 3D printed specimens was observed to have larger deformation ductility compared to mould-cast specimens. Further, the textile aligns better with increasing curvature which enhances the resistance of membrane forces more uniformly resulting in a 15.5 % increase in the ultimate moment capacity. In addition, the first crack load and the ultimate load were predicted based on the arch equations and the results showed that the current method predicts the capacity with reasonable accuracy. • In-process reinforcement with textiles during printing is a potential reinforcing method. • Modified nozzle aligns textile reinforcement easily along any desired printing path. • Textile reinforcement improves interlayer bridging and orients better for higher curvatures. • Ultimate moment capacity and crack propagation are improved significantly with textile reinforcement. [ABSTRACT FROM AUTHOR]

Seismic-designed reinforced concrete (RC) structures could be subjected to asymmetrical low-velocity impact loads, e.g., vehicle/barge collisions and rockfall impacts, while existing studies mainly focus on the dynamic responses of symmetrical impacted scenarios. This study experimentally and numerically examined the influence of stirrup ratio and impact location on failure modes and impact behaviors of RC beams. Firstly, symmetrical and asymmetrical drop-weight tests were conducted on six RC beams, and digital image correlation technique was applied to capture the damage evolution process and dynamic responses. Then, the above test was reproduced to validate the applicability of the finite element analyses approach, and numerical simulations were further performed to explore the transformation mechanism of the failure mode of asymmetrical impacted beams. The results showed that, (i) the shear-bending capacity ratio of the beam decreased with the stirrup ratio increasing or the impact location moving towards the mid-span, causing its failure mode to transform from shear to flexural under asymmetrical impact loads; (ii) the shear bearing capacity mainly controlled the occurrence of concrete cracking of asymmetrical impacted beams, and moment bending capacity influenced the post-cracked performance; (iii) increasing the stirrup ratio improved the joint action between longitudinal bars and stirrups and enhance the confinement effect on concrete, reducing the damage degree and deformation of asymmetrical impacted beam; (iv) under the effect of shear wave propagation, asymmetrical impacted beams completed the global impact process faster than symmetrical impacted ones. Finally, a two-degree-of freedom model was established to quickly calculate the displacement-time history at the impact location of asymmetrical impacted beams. The current work could provide a helpful reference for the impact-resistant design of RC structures against asymmetrical impact loads. ● Symmetrical and asymmetrical impact tests on seismic-designed RC beams are conducted. ● Influence of stirrup ratio on symmetrical and asymmetrical impacted beams are compared. ● Transformation mechanism of failure modes in asymmetrical impacted beams are analyzed. ● A two-degree-of freedom model was proposed to quickly calculate the displacement of asymmetrical impacted beams. [ABSTRACT FROM AUTHOR]

Buckling-restrained braces (BRBs) featuring flat steel core plates can be susceptible to local bulging failures when the restrainer lacks the necessary stiffness and strength. These failures arise from outward forces generated by high-mode buckling waves within the steel core. However, the methods for evaluating these high-mode buckling waves and the associated outward forces have remained elusive. This study addresses this gap by conducting cyclic loading tests on five BRB specimens with all-steel restrainers. These tests allow for direct observation of high-mode buckling waves during loading. Among the specimens, three have core segment lengths of 300 mm, each with varying debonding layer thicknesses (0.6 mm, 2 mm, and 4 mm). The remaining two specimens have approximately 900 mm core segments with a 2 mm thick debonding layer. All five specimens displayed stable hysteretic responses until the steel core fractured. Load cells were used to directly measure the outward forces induced by the steel core plate during testing. Strain gauges attached to the steel core surface provided insights into the distribution of strain variations at the high-mode buckling waves. The results indicate that adopting the tangent modulus theorem is a suitable method for estimating high-mode buckling wavelengths. Furthermore, this study establishes relationships between the outward forces and gap dimensions, including their growth over time. This research proposes a method to estimate outward forces, accounting for bending moments developed at the crests of high-mode buckling waves and considering restrainer stiffness. This method can serve as a valuable tool for assessing the risk of local bulging failure in BRBs. [ABSTRACT FROM AUTHOR]

This paper presents the results from two full-scale transversally stiffened plate girder's load tests in shear and bending. The plate girder's internal stiffener forces and shear buckling resistance are estimated using the web and stiffener measured strains. These results show that the reported axial compression and bending moment of the intermediate transverse stiffeners for the tested plate girder are 70% of the FprEN 1993–1-5: 2022 [1] design force. The two full-scale plate girders fail due to buckling shear. Nonlinear FEM analyses based on the test girder geometry, measured initial geometric imperfections, and the material properties from the tensile tests, show excellent agreement with the test results, with less than 5% on the maximum applied forces and related displacements. The principal membrane stresses path that triggers the failure of the web plate are investigated based on numerical results and compared with the test measurements. Contrary to the assumption of a rotated stress field model, the principal compression stress obtained in the experimental test was higher than shear buckling stress in the vicinity of the intermediate transverse stiffener. • Experimental shear behaviour of full-scale thin-walled plate girders in what concerns shear loading past ultimate loading. • Focus on intermediate transverse stiffener behaviour and shear load path. • Data acquisition techniques are resumed regarding measurements using optical extensometer and laser scanning. • Finite Element Model and Analysis were performed for the simulation of the experimental tests reported. • Obtained experimental and numerical outcomes are compared to current recommendations provided by EN1993-1-5. [ABSTRACT FROM AUTHOR]

To enable secondary energy-dissipation components to actively attract and dissipate seismic energy, a new type of sacrificial-energy dissipation beam-column joint (SEDJ) was proposed. This study validates the performance of the proposed SEDJ through full-scale quasi-static loading tests. The rotation angle of the proposed SEDJ at the beam end, corresponding to the peak strength F u , can be controlled within 1/250 - 1/50. In addition, the beam and column components remain elastic, thereby achieving the seismic performance objectives of "no damage, sacrificial-energy dissipation, and no collapse under service-level (SLE), design-basis (DBE), and maximum-considered (MCE) earthquakes", respectively. This study enhances the design of the SEDJ by adopting a built-in sleeve connection scheme to significantly reduce the free-stroke displacement, and a double-coupling block scheme to solve the issue of stress concentration in friction plates that leads to cracking. Furthermore, the efficiency of the installation and disassembly of friction plates is improved, thus enabling the rapid replacement of bolts and friction plates after strong earthquakes. Finally, a practical engineering design methodology is proposed that decouples the bending moments of the sacrificial M R and energy-dissipation M S stages, this methodology activates the sacrificial mechanism under DBEs or MCEs to protect primary beam and column components, and will provide potential insights for the development and application of innovative structural components based on the sacrificial mechanism design philosophy. • Sacrificial-energy dissipation beam-column joint (SEDJ) was improved and tested. • Working mechanism of SEDJ was identified through full-scale tests and theoretical analysis. • Engineering design methodology was proposed for SEDJ. [ABSTRACT FROM AUTHOR]

This paper proposes a design methodology to derive an analytical bilinear moment‒curvature diagram ( M ana – χ ana ) for the cross-section of fibre reinforced concrete (FRC) elements that also includes conventional steel flexural reinforcement (R/FRC). This bilinear diagram is obtained by determining the post-cracking tensile capacity of FRC (N tc FRC), which integrates not only the tensile stiffening capacity of the FRC surrounding the conventional flexural reinforcement due to the bond stress transference between this reinforcement and FRC, but also the tensile softening of the cracked FRC out of this zone. This M ana – χ ana is defined by two points, the first corresponding to the cracking moment and its corresponding curvature ( M cr ana , χ cr ana ), while the bending moment of the second point of this diagram (M u ana) is a multiple of the analytical cracking moment ( C u M cr ana), where C u is dependent on the fibre volume percentage (V f). The curvature corresponding to M u ana , χ u ana , is obtained by assuming the flexural stiffness of a fully cracked RC section. Therefore, the M ana – χ ana is determined by geometric and material properties of directly assessed by a designer. For demonstrating the applicability of the proposed design methodology, a database of beams of distinct cross-section aspect ratios and compressive strength classes, reinforced with different percentages of steel fibres and reinforcement ratios of conventional steel bars was established. By using the bilinear M ana – χ ana , and applying the principle of virtual work, the deflection of these beams was estimated with sufficient accuracy for design purposes, when compared to experimental records. Although the formulation has been applied to beams made by steel fibre reinforced concrete (SFRC), it is conceptually general and applicable to elements of concrete reinforced with other types of fibres. [Display omitted] • A general inverse strategy is proposed to predict moment-curvature for R/FRC members. • By using this bilinear moment-curvature, deflection of R/SFRC beams can be predicted. • Despite the simplicity, the model accurately predicts deflections for R/SFRC members. • The model was applied to SFRC but can be conceptually extended to other FRC. [ABSTRACT FROM AUTHOR]

Steel-concrete composite box girders with corrugated steel webs (CSWs) are broadly used in bridge engineering, in which the joints between top RC slabs and steel girders with CSWs are usually subjected to transverse bending moments caused by off-center vehicle loads. Stud connectors arranged in the joints usually bear repeated pull-out forces in this case and are prone to fatigue failure. Therefore, two reduced scale joints between top slabs and weathering steel girders with CSWs were designed and tested, on which variable amplitude fatigue loads were applied to investigate the fatigue performance of studs incorporated in the joints. The two joints presented similar fatigue behavior, i.e., cracks of not more than 0.26 mm in width appeared on the surface of the top slab during the fatigue loading, and the separation of the top RC slabs and the top girder flanges was observed; meanwhile, minute cracks developed along the welds connecting the CSW with the bottom girder flange, and the stiffness of the joints gradually decreased due to the accumulation of fatigue damage. The two joints underwent 2,650,000 and 2,103,600 load cycles respectively before fatigue failure occurred. After partially demolishing the RC slabs, several welded head studs in the joints were observed fractured at the roots and detached from the top girder flange. Whereafter, finite element (FE) models referring to the test joints were developed and analyzed, and the effect of the wave height (WH) of the CSW and the transverse row spacing (TRS) of studs on the distribution of pull-out forces among studs was investigated. It showed that the pull-out force bore by each stud in the joint was distributed unevenly even in the same row. Then, a modification factor α was introduced to revise the pull-out forces of studs calculated in the theoretical method. An equation to determine the factor was fitted, considering the effect of the WH of the CSW and the TRS of studs. Finally, the detail category for studs bearing pull-out forces in the joints was discussed based on the experimental results and the collected test data, and it was preliminarily recommended studs subjected to pull-out forces can be classified into detail category 45 specified by Eurocode 3 in fatigue design. • Fatigue tests on the joint between the top slab and the steel girder with corrugated steel web (CSW). • Numerical analyses on the stress distribution of group studs in the joints between top slabs and steel girders with CSWs. • Fatigue detail category of studs subjected to pull-out forces caused by transverse bending moments. [ABSTRACT FROM AUTHOR]

The integration of box girders with corrugated steel webs (CSWs) and an extradosed cable-stayed design gives rise to an innovative and distinctive bridge design, recognized as the extradosed cable-stayed bridge with CSWs. The synergistic integration of the technical benefits facilitates expanding the maximum span and enhancing the adaptability of this structural configuration. Subjected to cable forces, the main bridge superstructure featuring a box girder with CSWs experiences vertical shear, substantial axial force, and bending moments. Shear buckling on the CSWs emerges as a prominent issue influencing design considerations. In response to heightened internal forces near support, the main girder is typically configured with variable height. The Resal effect in the tapered girder leads to additional shear stresses from axial forces and bending moments, consequently modifying the effective shear stress on the CSWs. Therefore, traditional basic calculation assumptions that solely account for the vertical component of cable forces in shear stress calculations are frequently inaccurate. This study presents a modified theoretical method for calculating shear stress in tapered box girders with CSWs subjected to cable forces by considering the Resal effect. The proposed modified method incorporates not only the vertical shear but also considers bending moments and axial forces. The finite element simulation and experimental results showcase its remarkable accuracy, concurrently validating the presence of the Resal effect in tapered box girders with CSWs under cable forces. Additionally, this study quantitatively analyzes the shear force redistribution phenomenon induced by vertical shear, axial force, and bending moments considering the Resal effect. This reveals the shear performance of tapered box girders with CSWs under cable forces. The study is expected to provide a strategy and theoretical guideline for rapidly and efficiently obtaining the shear stresses of tapered box girders with CSWs in extradosed cable-stayed bridges under cable forces. • The inclined stay cables in extradosed cable-stayed bridges with CSWs have a narrow angle, resulting in a larger horizontal cable force than vertical component. • Additional shear stresses induced by axial forces and bending moments in the tapered girder due to the Resal effect. • A modified theoretical method for calculating shear stress in tapered box girders with CSWs subjected to cable forces by considering the Resal effect is proposed. • The phenomenon of shear redistribution on the CSWs due to vertical shear, axial forces and bending moments is quantitatively analyzed considering the Resal effect. [ABSTRACT FROM AUTHOR]

Built-up radially battened columns (RBCs), comprising several identical circular steel tubes interconnected by multiple radial-shaped battens, represent an innovative column design that combines aesthetic appeal with exceptional load-bearing capacity. This makes them well-suited for architectural applications in large public buildings such as stations and airports. The axial compressive strength design methods for the built-up RBC have been extensively explored in the authors' prior studies. However, in real-world engineering applications, built-up RBCs may experience simultaneous axial compression and varying directional bending moments, particularly when considering potential eccentric compression or wind and earthquake loads in public buildings. Currently, strength design methods for this loading condition are still lacking. To address this deficiency, this paper primarily delves into the failure mechanism and strength design methods for built-up RBCs experiencing combined axial compression and arbitrary directional bending moments. Initially, the sectional strength of the built-up RBC is investigated by using a shell finite element model (FEM) for the built-up RBC. It is revealed that the compression-bending sectional strength of the built-up RBC exhibits significant differences with varying bending directions and tube numbers. Moreover, in some bending directions, the M - N sectional strength curve of the built-up RBC exhibits convexity. By integrating theoretically derived equations grounded in the principles of materials mechanics with FEM numerical calculations, concise and practical design equations are proposed for accurately predicting the sectional strength of the built-up RBC under combined axial compression and arbitrary directional bending moments. Subsequently, The buckling strength of the built-up RBC is studied using the FEM, considering initial geometrical imperfections consistent with first-order flexural buckling and accounting for geometric nonlinearity. It is noted that the bending direction of the built-up RBC may deviate during loading. Besides, the M - N buckling strength curve of the built-up RBC is not as convex as its M - N sectional strength curve. Based on calculations from numerous examples, practical design equations for predicting the buckling strength for the built-up RBC under axial compression and any directional bending moments are introduced. The key findings of this paper contribute to the compression-bending strength design of RBCs, enriching RBC design theory and promoting the widespread application of built-up RBCs in actual engineering projects. [Display omitted] • The M - N strength of RBCs varies with different bending directions and tube numbers. • The M - N sectional strength curve of the built-up RBC is convex. • The built-up RBC's bending direction may deviate during loading. • The M - N buckling strength curve of RBCs is less convex compared to its M - N sectional strength. • The M - N strength of RBCs can be predicted by a quadratic function. [ABSTRACT FROM AUTHOR]

This paper develops a fiber-based model for rectangular/square concrete-filled steel tube (CFST) columns under arbitrary end moments considering the member imperfection. The accuracy of the proposed model regarding the prediction of capacity, deflection curves and full range curves is verified using a collected test database. The verified model is further used to investigate the behaviour of rectangular/square CFST columns under arbitrary end moments. It was found that the varying trends of strength and deformation capacity of rectangular/square CFST columns under arbitrary end moments are opposite while increasing the end moment ratio β , L/r ratio and f c , whereas those are the same if increasing b/t ratio and f y. Higher f y and/or smaller b/t ratio may be adopted in order to achieve larger strength and deformation capacity simultaneously. The location of maximum deflection at peak state h kp / L is only significantly affected by end moment ratio β , whereas the location of critical section at peak state h cp / L is significantly affected by end moment ratio β , L / r ratio and yield strength f y. Moreover, current design codes, i.e., EC4, AISC 360 and GB50936–2014, were found to poorly predict the resistance to axial load and bending moment of rectangular/square CFST columns under arbitrary end moments. • FBE model for rectangular/square CFST columns under arbitrary end moment considering member imperfection was developed. • Higher f y and/or smaller b/t ratio may be adopted to achieve larger strength and deformation capacity simultaneously. • The location of critical section at peak state is significantly affected by β , L / r ratio and f y. • Current design codes poorly predict the capacities of rectangular/square CFST columns under arbitrary end moments. [ABSTRACT FROM AUTHOR]

Concrete-filled tubular flange (CFTF) girders offer superior torsional stiffness compared to traditional I-shaped plate girders, providing enhanced flexural performance. To accurately assess the flexural capacity of CFTF girders, both flexural tests and theoretical analyses were conducted on specimens with and without concrete decks. The experimental data were meticulously analyzed to understand the flexural mechanism, yielding sequence, interface slip, strain distribution, and confinement effect of CFTF girders. Subsequently, finite element models were then utilized to analyze the influence of cross-section dimensions and material optimization on the flexural behavior of CFTF girders. Comparative analyses with I-shaped girders were also performed to highlight the structural advantages of CFTF girders. The proposed flexural calculation formulas were validated against both experimental and analytical results, demonstrating a fitting accuracy between 95 % and 98 % for the yield moment and between 96 % and 98 % for the ultimate moment. The method proposed in this paper provides a reliable and accurate approach for evaluating the flexural capacity of CFTF girders, significantly contributing to the advancement of design and analysis practices in structural engineering. • The flexural tests and theoretical analyses on concrete-filled tubular flange (CFTF) girders were conducted. • The flexural mechanism, interface slip, strain distribution, and the confinement effect are analyzed. • Finite element models are utilized to analyze the influence of cross-section dimensions and material optimization. • A calculation method for the elastic and plastic flexural behavior of CFTF girders is proposed. [ABSTRACT FROM AUTHOR]

Two models for time-domain simulation of vertical dynamic vehicle–track interaction and prediction of differential settlement in a transition zone between a ballasted track and a Moulded Modular Multi-Blocks (3MB) slab track are calibrated and verified using field measurements from a test site on the Swedish iron ore line. The dynamic analysis is performed using two-dimensional (2D) and three-dimensional (3D) track models in MATLAB and ANSYS, respectively. A seven-parameter representation of the ballast and subgrade is applied in the 2D model. It considers sleeper coupling through the ground via a discretised mass-spring-damper system. The more extensive 3D model includes a solid finite element (FE) model of the layered soil foundation with properties determined from a multichannel analysis of surface waves (MASW) carried out at the test site, and with perfectly matching layers (PML) added at the boundaries. The measured responses include rail receptance functions from both track forms on either side of the transition, as well as transient responses in terms of sleeper displacements and rail bending moments generated by the passing heavy-haul traffic. Both models are employed to simulate the passage of an iron ore freight vehicle through the transition zone. The accumulated settlement for one year of traffic is predicted using an iterative approach and compared with the measured long-term sleeper settlement. Good agreement is observed between the measurements and the settlements forecasted by both models, with the simulation time being approximately 25 times shorter for the 2D model. • Calibrating and modelling a transition zone between ballasted track and slab track using 2D and 3D models. • Using iterative approaches to simulate long-term differential track settlement at a transition between two track forms. • Calibrating empirical settlement models versus measured data and using those models to predict long-term settlement at a transition zone. • Comparing long-term sleeper settlement versus measured sleeper settlement. • The distribution of forces transmitted to the ballast varies considerably along a transition zone, and this is studied by including ballast masses in a 2D model and considering sleeper interaction via the ground [ABSTRACT FROM AUTHOR]

Civil structures and buildings may be subjected to accidental impact load scenarios to which the response is still a research subject. Impact failure mode and resistance of concrete structures have shown to be rather different from those under quasi-static loading, due to the influence of strain-rate modification of material properties, development of inertia forces leading to variable sectional forces' distributions and local damage mechanisms. A high sensitivity to develop shear-related failures of reinforced concrete beams under impact loading has been observed experimentally, with a complex shear-bending interaction difficult to be modelled numerical and analytically. Shear force-bending moment (M-V) interaction diagrams have been traditionally employed to provide the combination of sectional forces leading to failure. Thus, the availability of such diagrams for impact scenarios would be very useful for the engineering practice. In the present paper, an experimental investigation is presented to analyze the impact resistance of reinforced concrete beams with different span-to-depth ratios in order to determine possible envelope M-V interaction curves in impact regime. Sectional forces are tracked with the help of Digital Image Correlation (DIC) supported with High-Speed Video (HSV). Impact tests have covered beam specimens with and without shear reinforcement to understand the different failure modes. Envelope interaction diagrams are proposed taking into account the curvature rate from the experiments, which allows considering the particular strain-rate conditions of the tests. • Fully-instrumented impact experiments on RC beams have been completed. • Envelope dynamic shear force-bending moment interaction diagrams have been derived. • Analytical formulation including the curvature rate and M-V interaction is proposed. [ABSTRACT FROM AUTHOR]

In this study, the Fire Dynamics Simulator (FDS) is used to simulate the scene of the prestressed concrete (PC) girders with corrugated steel webs (CSWs) exposed to automobile traffic fire. The temperature field coupling between the FDS and Finite element (FE) model is accomplished via the sub-program fds2ascii, and the validation of the coupling methodology is confirmed through experimental validation. Subsequently, the shear performance of the prismatic and tapered PC girders with CSWs at ambient temperature is analyzed using the ABAQUS program, and the theoretical calculation formula for predicting the shear stresses in these girders is derived. The numerical results indicate that the proposed shear stress calculation formula accurately predicts the shear stress on CSWs of the PC girders at ambient temperature. Furthermore, the mechanical properties and failure modes of the PC girders with CSWs under fire conditions are analyzed by thermodynamic coupling. Unlike at ambient conditions, the temperature self-stresses induced by the non-uniform temperature gradient complicates the internal forces of the PC girders with CSWs under fire conditions. As the temperature rises, the initial prestress within the external prestressed tendons experiences a gradual reduction. Following a 25-minute fire exposure, the prestress diminishes significantly, nearly reaching zero, resulting in a rapid escalation of deflection in the PC girders with CSWs. For prismatic girders, the out-of-plane stiffness of the CSWs decreases due to high temperature, resulting in significant lateral deflection and buckling. For tapered counterparts, the temperature-induced self-stress amplifies the negative Resal effect, which leads to an increase in the shear stress on the CSWs near the inclined bottom slab. Consequently, this heightened stress level leads to shear yielding in the CSWs. • An effective FDS-FE coupling methodology is confirmed through experimental validation. • Considering the additional shear stress caused by bending moment and axial force, a comprehensive theoretical shear stress formula has been developed. • Under the vehicle fire, the PC girders with CSWs occur premature buckling failure and local web yielding. [ABSTRACT FROM AUTHOR]

The response assessment of bridges crossing navigable waterways under vessel collisions is commonly conducted assuming intact bridge models. However, local scour may occur at bridge foundations, which has been identified as one of the major hydraulic causes of bridge failures. Therefore, it is imperative to consider local scour in the design and analysis of bridges against vessel collisions. Many previous studies have focused on the bridge response under vessel collisions assuming deterministic scour depths with incremental values, without integrating a scour prediction modeling in the analysis. This work investigates the barge-bridge collisions in the presence of scour at pile foundations, by using empirical scour prediction models. The accuracy of each prediction model is evaluated using relevant laboratory test and field measurement records. Finite element (FE) models of a four-span continuous reinforced concrete (RC) bridge and a jumbo hopper barge are developed in LS-DYNA. The current study identifies the correlation between the upstream flow depth and the barge collision location in the analyses. Numerical results illustrate that both scour depth and collision location influence the displacement, shear force, and bending moment response of bridge piles. The struck bridge pier accommodates a considerably increased displacement with an increased scour depth, while the shear force and bending moment are primarily influenced by the collision location. The influence of scour on the barge-pier collision force is marginal. The maximum axial force in soil springs increases considerably with scour depth. The choice of scour prediction model shows a significant impact on the displacement, shear force, bending moment of piles, the displacement of struck pier, and the axial force of soil springs. • Different empirical scour prediction models exhibit prediction discrepancies for different scour conditions. • Both the scour depth and barge collision location affect the bridge response. • Increased scour depth results in a significant increase in the maximum horizontal displacement of the bridge pier and group piles. • The selection of scour prediction models has great influences on the predicted collision-induced bridge response. [ABSTRACT FROM AUTHOR]

The safety and reliability of wind turbines subjected to multiple loads has recently attracted great attention. To investigate how soil-structure interaction (SSI) affects the seismic performance of operating wind turbines, a wind tunnel-shaking table test platform has been built which can realize applying wind load and seismic load simultaneously. A 1:100-scaled wind turbine model with two different kinds of foundations (soil-structure interactive foundation and rigid foundation) has been tested under four seismic excitations (El-Centro and Taft, input in two directions) when it keeps operating in wind excitations. Nacelle displacement with the soil-structure interactive foundation was significantly larger than that of the rigid foundation, reaching 3–5 times at a peak ground acceleration (PGA) of 0.8 g. The maximum nacelle displacement of the scaled model with soil-structure interactive foundation always occurs in the direction of incoming wind, unlike the rigid one occurring in the direction of seismic input direction. The rigid foundation model presents a strong whipping effect with an acceleration amplification factor of the tower top (APF = 3). In contrast, the model with soil-structure interactive foundation shows mild whipping effect due to smaller foundation stiffness (APF of the tower top = 1.5). The study demonstrates SSI could weaken dynamic responses, reducing bending moments but inducing excessive nacelle displacement, risking structural damage. This study underscores the importance of SSI in evaluating the safety and reliability of wind turbines subjected to the wind and seismic loads and provides experimental results for future designs. • A joint wind tunnel and shaking table test system is developed for testing scaled wind turbine in operation. • Various soil-structure interactions, wind loads, seismic loads and operation loads are considered in the tests. • Dynamic characteristics and displacement, acceleration and bending moment are measured and analysed. • Compared to rigid foundation, soil-structure interaction leads to greater displacement but less acceleration and bending moment. [ABSTRACT FROM AUTHOR]

This study presents enhancements made to traditional aluminum alloy gusset (AAG) joints, including the integration of a central stiffening (CS) system, an inter-panel stiffening (IS) system, and a peripheral stiffening (PS) system. Three sets of tests on a full-scale specimen are conducted to investigate the improved AAG joint's axial stiffness, in-plane and out-of-plane bending stiffness, as well as ultimate load-bearing capacity. Nonlinear refined finite element models (FEMs) are established and validated through experimental results. Theoretical mechanical models are developed by integrating experiments and FEMs. These models elucidate the contribution of the stiffening systems to the joint's mechanical performance. The CS system is proven to significantly assist in load transfer, particularly in out-of-plane bending conditions. The IS system enhances overall inter-panel integrity, especially during the plastic deformation phase under out-of-plane bending moments. The PS system improves joint stiffness by participating in load transmission under both axial load and in-plane bending moments. Compared to traditional AAG joints, the combined effects of the three stiffening systems enhance overall structural integrity, stiffness, and load-bearing capacity. This enables the full utilization of component material properties and provides excellent ductility before failure occurs. • A theoretical model of an improved aluminum alloy gusset joint was developed. • FEM and mechanical model alignment were achieved, validated by full-scale tests. • Three loading phases in directions confirmed joint enhancements in mechanical model. • Stiffening systems optimized load transfer, increasing joint stiffness and capacity. [ABSTRACT FROM AUTHOR]

Understanding the contribution of the vibration modes to the response of a tower-like structure subjected to base excitations is crucial for a safe and optimized design. The modal contributions to the structural response are generally assessed through modal participation factors and effective masses; however, relatively recent studies pointed out the variability of the modal contributions depending on the response effect (e.g., top displacement, base shear force, base bending moment). The formulation proposed here derives the shear force and the bending moment at the base of a tower-like structure by combining the influence function technique with the quasi-static equivalent forces technique. The resulting formulation of the tower response relies on the concept of modal contribution factors, which provides a straightforward indication of the modal contributions associated with a given response effect. The proposed methodology is applied to the case of wind turbine towers erected on temporary foundations at the port quayside without rotor nacelle assembly to assess the forces on the foundations due to the seismic loading on the towers. This technique may be of great relevance for assessing the tower integrity during installation and for the design of the temporary foundations at the quayside of harbors in seismic area, also considering the quick expansion of the offshore wind energy in countries prone to earthquakes. • Modal contributions to the response of tower-like structures to base excitations. • Variability of the modal contributions depending on the response effect. • Influence effective functions and quasi-static dynamic-equivalent forces techniques. • Seismic response of an offshore wind turbine tower without RNA at the port quayside. • Time-frequency analyses of non-stationary seismic excitations. [ABSTRACT FROM AUTHOR]

The study aims to assess the impact of RuC on twelve concrete-filled double-skin steel tube (CFDST) specimens. The research explores key variables, including outer tube slenderness ratio, hollow ratio, and rubber replacement ratio. Rubber particles replace natural aggregates at replacement ratios (ρνr) of 0%, 15%, and 30% by mass. The experimental findings are comprehensively discussed, encompassing member flexural capacity, confinement effects, ductility, energy dissipation, and failure mechanisms. The findings reveal that replacing normal concrete (NC) with RuC leads to a reduction in beam flexural strength ranging from 5.0% to 18.1%, depending on ρ νr and outer tube diameter. In contrast, RuC members exhibit an increase of up to 70% in ductility and 27.7% in energy dissipation compared to members with NC, depending on rubber content. Increasing the outer tube thickness proves to be an effective method for mitigating strength reduction due to rubber replacement. Specifically, elevating the outer tube thickness from 3.6 mm to 4.5 mm results in strength enhancements of 17.0%, 19.0%, and 23.7% for beams with NC, 15%RuC, and 30%RuC, respectively. Furthermore, the results are applied to assess existing design models and to suggest modifications that offer improved strength estimations for a broad spectrum of rubber replacement ratios. • Experimental studies of circular rubberized concrete-filled double-skin steel tubes under four-point bending. • The effect of outer tube slenderness ratio, hollow ratio, and rubber replacement ratio on flexural behaviour. • Analysis on member flexural capacity, confinement effects, ductility, energy dissipation, and failure mechanisms. • Assessment of existing design models and new proposed design equation for predicting bending moment capacity. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study into the structural behaviour and strength of concrete-filled stainless steel tubular stub columns with circular and square cross-sections subjected to combined compression and bending moment. A total of sixteen concrete-filled stainless steel tubular (CFSST) stub columns were tested, including two section types (circular and square hollow sections), two grades of concrete infill (C30 and C60), two thicknesses of tube wall for each cross-section (6 and 10 mm), and five loading eccentricity ratios (0, 0.2, 0.3, 0.4 and 0.5). The CFSST stub column specimens were loaded in compression, with different loading eccentricities applied to achieve a wide range of axial load-to-bending moment ratios. This research provides a comprehensive report on the experimental methodology and subsequent observations, including the failure modes, load-deformation curves, axial load-bending moment curves, strain development at the key locations and values of ductility index. It can be observed that for circular CFSST columns, ultimate load decreased by roughly 70% with an increase in loading eccentricity ratios from 0 to 0.5, while for square columns, the reduction was about 50% under same conditions. The experimental results were used to evaluate if the existing design provisions for carbon steel-concrete composite structures is capable of designing the investigated CFSST stub columns. It was found that the mean ultimate load to predicted failure load ratios are 1.25, 1.32, and 1.36, with coefficients of variations (COV) equal to 0.08, 0.09 and 0.11, for the European, American, and Chinese codes, respectively. Consequently, the design approach specified in the Chinese code led to the most conservative and scattered strength predictions among the three codified design approaches. In contrast, the European code provides the most precise predictions of the test results, though there still remains scope for improvements in the ultimate resistance predictions of CFSST stub columns subjected to combined compression and bending. • Stub column tests on concrete-filled stainless steel circular and square cross-sections subjected to combined compression and bending moment were conducted. • The structural responses of eccentrically loaded stub columns were discussed. • Strain developments were analyzed to elucidate the interaction between stainless steel outer tubes and concrete infill. • The design provisions in EN 1994-1-1, ANSI/AISC 360-16 and GB 50936-2014 were assessed. [ABSTRACT FROM AUTHOR]

The mechanism and reasonable values of the dynamic amplification effect of highway continuous beam bridges under the action of vehicle fleets are quite complex and very unclear at present. This study, using 23 highway continuous beam bridges with the main span lengths from 32 m to 165 m as research objects, investigates the mechanism and influencing factors of the dynamic amplification factors (DAFs) of highway continuous beam bridges under the action of vehicle fleets based on the vehicle-bridge coupled vibration analyses. The results show that the travelling speeds and vehicle intervals (VIs) exert an important influence on the DAFs of continuous beam bridges. The maximum dynamic response at different travelling speeds and VIs is searched in this study, the maximum static response at different VIs is also searched, and their ratio is regarded as the effective DAFs. Based on the calculation results, it is concluded that when the roughness surface condition (RSC) is 'good' (or 'average'), the effective DAFs for the vertical displacement and vertical bending moment at the mid-spans can safely take a value of 1.15 (or 1.30); those for the vertical bending moment at the inner supports and shear force can safely take a value of 1.10 (or 1.20); and when the bridge fundamental frequency is less than 1.0 Hz, all DAF values can take a value of 1.05 (or 1.10). Meanwhile, the relevant provisions in AASHTO LRFD (2017) and CEN (2003) are considered on the safe side when RSC is 'good' or 'average'. ● The mechanism and factors of DAFs of continuous beam bridges are investigated. ● The idea of effective DAFs is proposed, which is more of practical significance. ● Based on 23 example bridges, the DAF spectra of continuous beam bridges are given. ● The research fills the gap of similar studies in the past. [ABSTRACT FROM AUTHOR]

A controllable plastic hinge with bending moment-shear separation was developed according to the design concept of an earthquake-resilient structure using replaceable multi-slit energy dissipation devices. Furthermore, a novel precast concrete beam-column joint was proposed to achieve repair of the post-earthquake damage in prefabricated structures. Pseudo-static cyclic loading tests were conducted on three precast concrete exterior beam-column joints and one conventional monolithic joint specimen to investigate the seismic performance and validate the effectiveness of the proposed joint. The results revealed that when the maximum flexural capacity of the precast joint was close to that of the monolithic joint, the precast joints exhibited better seismic performance in terms of ductility, deformation, and energy dissipation capacity than that of the monolithic joint. Furthermore, the damage and failure of the precast joints were mainly concentrated in the multi-slit energy dissipation device. In contrast, the precast concrete beam and column components remained elastic, allowing for the control of damage locations at the precast joint and facilitating efficient post-earthquake repair. Finally, a theoretical relationship was established between the flexural capacity and deformation of the connection zone in the precast joint, serving as a theoretical reference for the design of multi-slit energy dissipation devices and shear connection keys. • A new type of earthquake resilient precast joint is presented and investigated. • A connection form of plastic hinge with bending moment-shear separation is developed. • The theoretical method of the proposed bending moment-shear separation hinge is established. [ABSTRACT FROM AUTHOR]

Recent developments have demonstrated that the behaviour of segmental grey cast iron (GCI) tunnel linings can be simulated accurately with sophisticated 3D numerical models where the geometry of the segments and joints is considered explicitly. Such a 3D model is, however, impractical for geotechnical numerical analyses where the tunnel lining is usually simulated with simpler, structural elements. In this paper, a novel tunnel joint model specifically developed for simulating the behaviour of GCI longitudinal joints with beam elements in geotechnical finite element analysis is introduced. Unlike existing models, the model considers the contribution of the bolts to the joint response and the nonlinear decay of the rotational stiffness after joint opening as well as the dependency on the compression level. After calibration of the model parameters, the model was utilised in a series of parametric analyses replicating the elastic continuum model using 2D beam elements. The response of the segmental GCI lining was essentially equivalent to that predicted by an advanced 3D model which validated the new modelling approach. The development of the joint beam model enables the nonlinear behaviour of segmental GCI tunnel linings to be accounted for in routine geotechnical numerical analyses. • A new model is proposed to represent the bending moment-rotation behaviour of tunnel joints. • The bending moment-rotation relationship is dependent on the axial force and characterised by a hyperbolic expression. • The joint model captures the bending moment-rotation behaviour as predicted with 3D modelling. • The behaviour of segmental grey cast iron tunnel linings can successfully be simulated with beam elements. [ABSTRACT FROM AUTHOR]

To enhance the shear buckling resistance of girder bridges with corrugated steel webs (CSWs), especially near the intermediate support where maximum shear force and negative bending moment are experienced, it is common practice to encase the CSWs with concrete. This paper analyses the mechanical performance of concrete-encased prismatic girders with CSWs based on finite element (FE) simulations, theoretical analysis and existing experiments. The concrete encasement restricts the axial free deformation of the concrete-encased CSWs (CCSWs), thereby diminishing the accordion effect of the CSWs. As a result, the normal strains in both the CCSWs and the concrete encasement become nearly identical, demonstrating a linear distribution that aligns with the plane section assumption. The study reveals that the concrete encasement assists the CCSWs in shouldering a portion of the shear force, and shear stress in the CCSWs is no longer uniformly distributed. In addition, a stiffness-based shear carrying calculation method for CCSWs and concrete encasement is theoretically derived. It is observed that due to the constraint of concrete encasement, the actual shear modulus of CCSWs surpasses that of CSWs without encased concrete, rendering it more similar to that of a flat steel plate. Lastly, this study firstly proposes a shear stress calculation formula for CCSWs, which theoretically explains the parabolic shear stress distribution in CCSWs. Error analysis reveals that traditional basic shear method, which assumes uniform shear stress distribution in CSWs, significantly underestimates the actual shear stress in CCSWs. Remarkably, the modified shear method proposed in this study accurately predicts shear stresses in CCSWs. • The normal strain in the CCSWs demonstrates a linear distribution that aligns with the plane section assumption. • The shear modulus of CCSWs surpasses that of CSWs without encased concrete. • The shear stress along the depth of CCSWs is no longer uniformly distributed. • A theoretical formula for predicting the shear stress distribution of CCSWs is proposed. [ABSTRACT FROM AUTHOR]

Shear design and verification of bridge deck slabs subjected to concentrated loads (as those of wheels from traffic) is a topic subjected to scientific and engineering debate, where several questions remain open. Several design procedures have been proposed in the past to determine suitable values of the internal forces for design, such as the so-called load-spreading rule or considering a smoothing length for redistribution of the internal forces calculated based on linear elastic approaches. Despite these previous efforts, several instrumental aspects governing the response of bridge deck slabs still need to be clarified and subjected to scientific discussion. An important one relates to the location of the governing control section. Typically, for the case of cantilever bridge deck slabs, two control sections are checked: one close to the webs (acting as linear support) and another near the concentrated loads. While there is no debate about the shear check performed at the section close to the linear support (similar to a one-way slab response), how the check has to be done at the section close to the load introduction zone remains unclear (which can be interpreted as punching or as a one-way shear phenomenon). Another aspect under discussion is the determination of the internal forces considering the redistributions related to the non-linear behavior of the slab, avoiding too simplistic and overly conservative rules. To better understand the phenomenon and to lead to more comprehensive and consistent design approaches, the behavior of cantilever bridge deck slabs subjected to concentrated loads is thoroughly investigated in this paper. The study starts with several phenomenological observations on shear failures in cantilever bridge deck slabs obtained from previous experimental programs. Then, a refined analysis is presented considering a realistic out-of-plane shear response of reinforced concrete slabs. From these analyses, the internal forces can be evaluated in a sound manner accounting for a gradual reduction of the out-of-plane shear stiffness as a function of bending moments and shear forces. This new feature allows tracking the location of the potential shear-critical regions and examining the forces redistributions related to non-linear behavior. Unlike traditional approaches (like the "load-spreading rule" or smoothing lengths), the presented numerical analyses can consider shear failures at any location. The main findings from the physical observations and refined analysis are eventually used to propose a simple but phenomenologically consistent design methodology aimed at practical applications. • Observation on bridge deck tests collected from the literature indicates significant internal forces redistribution. • The geometry and kinematics of the failure cracks of such bridge decks are more similar to the shear cracking of beams without shear reinforcement. • A novel numerical modeling strategy was developed based on a smeared approach to account for the presence of shear redistribution. • A parametric (numerical) study on full-size bridge decks confirmed the influence of direct strutting and flexural reinforcement curtailment. • A phenomenologically consistent design methodology aimed at practical applications was ultimately proposed. [ABSTRACT FROM AUTHOR]

In this paper, the structural behaviour of timber precast concrete composite (TCC) beam-to-column subassemblies subjected to hogging bending moments is investigated. Full-scale testing and analytical modelling are undertaken on timber precast concrete composite joints and beams. The composite actions were transferred via coach (lag) screw shear connectors embedded in the small grout pockets. The laboratory tests were designed to determine the influence of the size and type of timber beams (i.e., laminated veneer lumber (LVL) or glued laminated timber (GLT)), size of screw shear connectors and amount of reinforcement (in the slabs) on the structural behaviour (i.e., load-displacement, stiffness, capacity, and ductility) of the TCC beam-to-column connections. The hogging moment capacity and stiffness of the TCC floors with nominal slab thickness of 80 mm and reinforcing ratio (in the range of 0.9–1.8%) were up to 24% and 17% higher than that of the bare timber beam, respectively. The size of coach screw shear connectors (in the range of 8–16 mm) had less than 13% effect on the capacity and stiffness. An analytical model for calculating the peak load and stiffness of the TCC beams under hogging bending moment is developed. The model is shown to perform well when compared to the collected test data. • Behaviour of TCC beam-to-column connections under hogging moment is studied. • Slab reinforcing ratio had less than 24% effect on the hogging moment capacity. • Slab reinforcing ratio had less than 17% effect on the stiffness of the TCC beam. • A model for estimating stiffness & strength of TCC under hogging moment is proposed. • Full composite action increased the capacity & stiffness of the TCC by 56% and 38%. [ABSTRACT FROM AUTHOR]

The current Eurocode 3 rules for buckling of welded I-section members are based on the assumption of hot-rolled flanges. However, flame-cut flanges are widely used in practice and induce significantly different residual stress distributions, affecting the lateral-torsional buckling resistance. Experimental tests and finite element analyses considering residual stress distributions clearly highlighted the beneficial effect of flame-cut flanges compared with hot-rolled flanges on the lateral-torsional buckling resistance of welded I-beams. To complete these preliminary results, a large number of non-linear finite element analyses are performed considering welded beams made of hot-rolled or flame-cut flanges. The beams are composed of steel grades S275 and S355. Numerical results confirm the influence of the flange fabrication process on the buckling behaviour. Eurocode 3 rules are found to be overly conservative for welded beams made of flame-cut flanges. Consequently, proposals are made that are more suitable for estimates of the lateral-torsional buckling resistance of welded beams made of flame-cut flanges. The code rules are also very conservative for welded beams made of hot-rolled flanges with a medium-to-high slenderness. A design method is thus proposed to improve the prediction accuracy of the lateral-torsional buckling resistance of slender welded beams made of hot-rolled flanges. The novel design method from prEurocode 3 provides acceptable values of the buckling resistance for welded beams made of flame-cut flanges but is restricted to uniform doubly symmetric beams. An extension of its scope to mono-symmetric uniform beams as well as tapered beams is thus suggested. An enhanced imperfection factor is proposed, adapted to welded beams made of flame-cut flanges. • Design method to compute the LTB resistance of welded beams with flame-cut flanges using the Eurocode 3 buckling curves. • Design method to compute the LTB resistance of welded beams depending on their geometry, flange fabrication process and bending moment distribution. • Adaptation of the new verification format of prEN 1993–1-1 for lateral-torsional buckling to tapered and/or mono-symmetric beams. [ABSTRACT FROM AUTHOR]

Among the different methods of strengthening glulam bolted joints, the reinforcement method that utilizes steel straps offers the advantages of low cost, convenient installation and satisfactory reinforcing effect. This research presents the results of a series of tests on glulam bolted joints with prestressed steel straps under combined bending moment and axial force, including a theoretical derivation of moment-rotation curves. The findings indicated that the existence of steel straps led to a delay in glulam splitting with a pronounced increase in bearing capacity compared with ordinary glulam bolted joints, i.e. by 46.85 %, 63.17 %, and 53.65 %, respectively. A three-line moment-rotation model was established to predict its mechanical behavior. This research provides valuable insights for the reinforcement of glulam connections under combined load and serves as a reference for future research in this field. • A novel type of reliable glulam connections was proposed. • The proposed joints were tested under moment and axial load. • The calculation method of ultimate load and stiffness were derived. • Moment-rotation curves could be obtained according to the proposed equations. [ABSTRACT FROM AUTHOR]

FRP-concrete-steel double-tube columns (i.e., double-tube concrete columns or DTCCs) are a novel type of structural members composed of two concentrically-placed tubes (i.e., an outer FRP tube and an inner steel tube) with all the space inside the two tubes filled with concrete. Shear studs on the inner steel tube are recommended to increase the composite action when DTCCs are subjected to large bending moments. The optimized section configuration of DTCCs allow the three constituent materials in the columns to deliver their respective advantages and to avoid their respective shortcomings. The limited existing studies on DTCCs have been focused on their compressive behavior. These studies have demonstrated the excellent ductility of DTCCs, an important advantage for their potential applications in regions with seismic risk. However, the seismic behaviour of DTCCs has not been systematically investigated. Against this background, this paper presents a combined experimental and numerical study on the seismic behaivour of DTCCs, where the experimental part included a series of large-scale DTCCs tested under combined cyclic lateral loading and constant vertical compression, while the numerical part included the development of a finite element model incorporating beam-column elements and specific stress-strain models to consider the unique behaivour of the two parts of concrete in DTCCs (i.e., the concrete core inside the inner steel tube and the concrete ring between the two tubes). The experimental results revealed that: (1) the increase of FRP thickness had a positive effect on their hysteretic behavior; (2) when the steel ratio was constant, the peak lateral load of DTCCs increased with the steel tube diameter; (3) the concrete core not only enhanced the lateral load capacity and the ductility of DTCCs, but also provided efficient suppression on the buckling of the steel tube. The numerical model, established using the OpenSees platform, is able to provide reasonably accurate predictions of the hysteretic behaviour of all specimens. • The seismic behavior of FRP-concrete-steel double-tube columns (DTCCs) was investigated experimentally and numerically. • DTCCs generally have rounded hysteretic curves with ample energy dissipation capacity. • The concrete core of DTCCs can effectively suppress the local buckling of the inner steel tube. • A numerical model was established for DTCCs, which was able to provide predictions with reasonable accuracy. [ABSTRACT FROM AUTHOR]

Round-ended concrete-filled steel tubular (RECFST) columns are gaining increasing usage in bridge structures. During their service life, RECFST columns under eccentric compression may suffer from impact loading. This study conducted test and numerical investigations to assess the performance of RECFST columns under the coupled actions of compression, bending and lateral impact loads. Fourteen columns were fabricated and tested, considering the influences of axial-load ratio, bending moment and impact energy. The damage mode and the time histories of impact force and displacement were accessed and analyzed. The experimental findings revealed that the initial bending moment negatively affected the impact resistance of RECFSTs. In addition, finite element model was established in ABAQUS and calibrated against the test results. The calibrated model was then employed to conduct the failure mechanism analysis and parametric study. Finally, a single-degree-of-freedom (SDOF) analysis was conducted to predict the mid-height deflection of RECFST columns under combined action of compression, bending and lateral impact loads, by incorporating the influences of pre-axial load and initial bending moment. • Drop-hammer impact tests on RECFST columns with varying eccentric compression. • Coupling influence of compression, bending and lateral impact loads. • Prediction of mid-height deflection response using the SDOF method. [ABSTRACT FROM AUTHOR]

The study presented the results of the experimental and numerical study on the rotational behavior of the bolted glulam beam-to-column connections reinforced by double U-shaped welded steel sections. To demonstrate the enhancement efficiency of double U-shaped steel sections on the performance of bolted glulam beam-to-column connections, both unreinforced and reinforced bolted glulam connections were tested under the monotonic pure bending scenario and the cyclic loading scenario with combined shear and bending, respectively. Besides, detailed finite element (FE) models of the reinforced bolted glulam beam-to-column connections were developed and then validated by the experimental results. The rotational behavior of the unreinforced connections and that of the reinforced connections were compared in terms of damage modes, performance parameters, stiffness degradation, and cumulative energy dissipation, respectively. The effects of two configurational parameters on the rotational behavior of the reinforced connections were analyzed, which were the diameter of the holes predrilled in the beams and the width-to-thickness ratio of the top plates of the U-shaped steel sections. In the monotonic pure bending tests, the rotational stiffness of the reinforced connections is 1.20–2.22 times that of the unreinforced connections. The rotational stiffness of the reinforced connections is enhanced as the width-to-thickness ratio of the top plates is reduced. Furthermore, when the diameter of the holes predrilled in the beams is enlarged from 22 mm to 30 mm, the rotational stiffness and the ultimate moment resisting capacity of the reinforced connections are reduced by 27.8% and 16.6%, respectively. As for the cyclic loading tests, when reinforced with U-shaped steel sections, the ultimate moment resisting capacity and the rotational stiffness of the bolted glulam connections are enhanced by 26.7% and 17.0%, respectively. The degradation of the secant stiffness of the unreinforced connection is more severe, indicating that the reinforcement with double U-shaped steel sections is an efficient damage-resistant technique for both new and existing bolted glulam connections. based on the developed FE models, both the failure modes and the moment-rotation curves of the reinforced connections under the monotonic pure bending scenario can be predicted. • Bolted glulam beam-to-column connections reinforced by different U-shaped welded steel sections were tested. • 3D detailed finite element (FE) models were developed and then validated by the experimental results. • The influences of configurational parameters on the rotational behavior of the reinforced connections were analyzed. [ABSTRACT FROM AUTHOR]

This article proposes a methodology to design and execute multiaxial fatigue tests for wind turbine blades without the need to use sensitive design data, such as blade cross-sectional geometry. An approach based on bending moments is used, which matches the actual strain behavior of the material in all regions of beam-like structures under cyclic loading. To facilitate the implementation of the proposed methodology, a numerical validation of the equality between damage indices obtained from bending moments and strains is carried out using a commercial blade of fully known design. Then, an experimental demonstration of how to obtain the proposed bending-moment-based damage indices during real fatigue tests is performed using a large commercial blade with unknown design. It is expected that with the application of the proposed methodology, better fatigue tests can be carried out for these structures than those designed following current standards. • Multiaxial fatigue tests for wind turbine blades without sensitive design data. • Only applied bending moments and cross-section stiffness ratio needed as input. • Match between bending-moment-based and strain-based fatigue damage indices.. • Numerical validation and experimental demonstration using commercial blades. [ABSTRACT FROM AUTHOR]

Large-amplitude cable vibrations are remarkably common in cable-stayed bridges subjected to wind and mechanical loading due to low inherent damping of these structures. Although the high slenderness ratio of cables means that bending moments are not normally significant over their free length, local effects near the cable anchorage induce non-negligible bending stress variation under dynamic loading, which could lead to fatigue failure of stay cables. In modern parallel strand stay cables, the fatigue performance depends on the fatigue properties of the individual seven-wire monostrands which together make up the cable. We introduce a new bending fatigue testing device for seven-wire monostrand which can control the fatigue loading in the axial and transverse directions of the cable independently. The fatigue endurance of monostrand with guide deviators is significantly longer than without guide deviators present, especially for smaller bending fatigue amplitudes. We found that bending fatigue life of monostrand is also reduced by increased constant or dynamic axial stress, but over-tensioning of the monostrand (e.g. during construction) had no consistently adverse effect on fatigue life. For monostrand loaded in severe bending, fatigue occurs due to the bending stress variation caused by the combination of bending moments and axial forces at the extreme edges of the monostrand cross-section, rather than due to relative movement and fretting between adjacent wires within the monostrand. • Bending fatigue performance of stay cables near the anchorage is studied experimentally. • The fatigue endurance presents a negative relationship with angular deviation. • Guide deviators can significantly extend the fatigue endurance of monostrands. • Fatigue life of monostrands is reduced by increased constant or dynamic axial stress. • Fatigue occurs due to the bending stress variation rather than fretting between adjacent wires. [ABSTRACT FROM AUTHOR]

Implementing section curvilinearization (SC) by curving flat sides into curved sides before fiber-reinforced polymer (FRP) jacketing has been proposed to enhance the FRP confinement effectiveness of FRP-confined rectangular concrete columns. In this paper, ultra-high performance engineered cementitious composite (UHP-ECC) is proposed as the added concrete for SC, with an aim to enhance both bending and axial strengths of concrete columns given that the UHP-ECC can contribute to resisting tensile stresses for columns. Thirteen large-scale FRP-confined square reinforced concrete (RC) columns with SC using UHP-ECC were tested under eccentric compression loading to explore their eccentric compressive behavior. The test parameters included the rise-to-span ratio, the FRP thickness, the eccentricity and the surface roughness of the old concrete. The test results show that FRP confinement with SC using UHP-ECC can substantially enhance the peak axial load and the bending moment than those without SC, while the ultimate lateral displacement is marginally increased. An increase in the rise-to-span ratio leads to an increase in the peak axial load. • UHP-ECC is proposed as the added concrete for section curvilinearization before FRP strengthening. • Thirteen large-scale FRP-confined square RC columns with SC using UHP-ECC were tested under eccentric compression. • FRP confinement with SC using UHP-ECC can substantially enhance the peak axial load and the bending moment than those without SC. • The ultimate lateral displacement of the strengthened columns is marginally increased. • An increase in the rise-to-span ratio leads to an increase in the peak axial load. [ABSTRACT FROM AUTHOR]

With the development of the high-rise buildings, the columns with special cross-sectional shapes are frequently adopted for architectural and aesthetic purposes. The concrete filled steel tube (CFST) is a reasonable choice for such requirement due to the characteristics of excellent seismic performances, construction efficiency and strong adaptability to special shapes. This paper focuses on the seismic performance of a special-shaped hexagonal CFST column with an inner diaphragm plate and shear studs adopted in a super high-rise building. Experiments were conducted on five column specimens under axial compressive force and lateral cyclic loading to investigate the influence of various parameters including loading angle, axial compression ratio, shear studs and the type of in-filled concrete. In one of the specimens, the ultra-high performance concrete (UHPC) was used as the in-filled concrete to substitute the conventional normal strength concrete, and the effects on the capacity and ductility of the column were revealed. Then the failure mode, the load-deflection curves, seismic performance indexes and the strain distribution were analyzed. The flexural capacities of the columns were evaluated by the fiber section model, where the failure criterion considering the buckling of steel tube was proposed and the effects of studs were included. Finally, the contribution to axial force and bending moment from outer steel tubes, inner diaphragm plate and in-filled concrete were calculated and compared based on the proposed model. It is found that the fiber section model considering the steel plate buckling and strengthening effects of studs precisely predicted the moment-curvature curves and the flexural capacity of the test specimens. The contribution of the inner diaphragm plate was considerable which could not be neglected. • A special-shaped hexagonal CFST column with an inner diaphragm and shear studs are proposed. • Tests were conducted on five column specimens under axial compressive and lateral cyclic loading. • The configuration of studs and UHPC can significantly increase the strength and deformation capacity. • The proposed fiber model considering the buckling of steel tubes and effects of studs gives good prediction. • The inner diaphragm plate shows considerable contribution which can not be neglected. [ABSTRACT FROM AUTHOR]

Prestressed high-strength concrete piles reinforced with non-prestressed steel reinforcement (PRHC piles) have been developed to improve their seismic performance. In this study, the seismic response and failure mechanism of PRHC piles was investigated using a shaking table test. The dynamic characteristics, dynamic soil pressure, superstructure response, acceleration magnification factors, maximum curvature ductility demand, bending moment response, and failure mode identification of the PRHC piles were determined. The performance of PRHC piles was compared with that of prestressed high-strength concrete pipe (PHC) piles, which showed that the PRHC piles experienced higher energy dissipation and lower maximum curvature ductility demands than PHC piles. In addition, the PRHC piles suffered bending failure at the upper-middle positions, and the plastic zones were higher than those of the PHC piles. The adverse effects of long-period and pulse-type ground motions on pipe piles should be considered in designing for strong seismic events. The addition of non-prestressed reinforcement to a pipe pile allows longer segments of the pipe pile to be involved in providing resistance. • The seismic response characteristics of PRHC piles are studied. • The performance of PRHC piles is compared to that of PHC piles based on two shaking table tests. • The influence of non-prestressed reinforcement and the seismic failure mechanism of PRHC piles are investigated. [ABSTRACT FROM AUTHOR]

Large investments in the implementation of wind turbines were made in the last decades, which increased the importance of this source in the national electricity systems. The management of this asset can strongly benefit from the development of cost effective monitoring strategies. These may contribute to the extension of the lifespan of existing wind turbines, to the reduction of insurance costs by reducing the operation risk and to the optimization of the design, leading to an increase in the competitiveness of this energy source. This paper is dedicated to the implementation and validation of tools to assess the fatigue condition of wind turbine blades from strains measurements with a set of fiber optic strain gages installed at the blade roots. It describes the data processing needed to obtain accurate experimental estimations of the bending moments applied to the blade roots and the procedure to obtain the accumulated fatigue damage. The instrumentation of two wind turbine rotors aligned with the most frequent wind direction allowed quantifying the interaction between neighboring wind turbines and its effect on fatigue life consumption. The paper presents unique experimental data simultaneously collected in two 1.8 MW wind turbines of an onshore wind farm during 14 months that permitted a very clear illustration of wake effects on fatigue consumption. • Calculation of the blade-root moments based on strain measurements after careful pre-processing and calibration. • Quantification of the wind loads and characterization of the blades dynamic response considering different loading scenarios. • Damage assessment approach using FBG sensor data, studying WTs loaded by winds with different speed and turbulence intensity. • Characterization of the interaction between neighbouring WTs based on blade fatigue life consumption and energy production. [ABSTRACT FROM AUTHOR]

• This study proposed a novel kind of wet joint with UHPC shear keys to connect prefabricated composite beams. • The effects of different parameters for UHPC shear key on strengthening shear performances of wet joints were investigated. • The failure mechanism of novel UHPC shear key joints was clarified in detail. • The calculation formulas considering different factors were established to design and optimize the prefabricated composite beams. Ultra-high-performance concrete (UHPC) has excellent mechanical properties, which could be used in the connecting region between different prefabricated members to improve the continuity and integrity of prefabricated composite structures. In this paper, a novel kind of wet joint with UHPC shear key was proposed to connect different prefabricated components for assembled steel–concrete composite beams, and the effects of different parameters for UHPC shear key on strengthening shear performances of wet joints were evaluated via a series of push-out tests. Results indicated that the specimens with wet joints mainly failed and slipped in the precast and post-cast concrete interface under the longitudinal force. The application of the UHPC shear key could significantly increase the ultimate shear strength of the interface compared to the single layer of extended reinforcements, and the UHPC shear key with embedded short reinforcements could further improve the shear resistance and ductility to ensure the composite action between the precast slab and wet joint. Compared with the dual layers of extended reinforcements, the combination of the UHPC shear key and short straight steel bar presented a better performance in strength under a relatively lower slip level. In addition, the increase in width was helpful for enhancing the shear strength of the UHPC shear key, but the shear keys with the larger width might cause the failure of the precast part between two UHPC shear keys prior to the UHPC shear keys so limiting the strength development of interface, thus the reasonable design size of the shear key should be selected depending on the precast and post-cast concrete strength. Furthermore, an equation for the wet joint with UHPC shear key was proposed, which considered the proportion of effects of different factors such as the interface bonding strength, interface friction, extended reinforcement, negative bending moment, UHPC shear key and embedded short straight steel bar on the longitudinal shear behavior of UHPC wet joints. [ABSTRACT FROM AUTHOR]

• Iron-based Shape Memory Alloy rebars are available in the construction sector. • They can generate recovery stresses easily due to the shape memory effect. • Hollow Core Slabs structural floors improve their behaviour with continuity. • An active continuity of these structural floors can be achieved with Fe-SMA. • The experimental results ensure an improvement in Service Limit State. Despite the relatively recent introduction of Iron-based Shape-Memory Alloys (Fe-SMA) into structural engineering, more than 150 real applications have been performed to date in Central Europe, especially in retrofitting projects. Thanks to the Shape-Memory Effect, a prestrained and correctly anchored Fe-SMA bar can generate recovery stresses when heated up to 160 °C (activation) or more, and then cooled down. This paper presents research results about using Fe-SMA reinforcing bars as active (prestressed) continuity reinforcement in the hogging bending moment region of Hollow Core Slabs structural floors (HCS-sf). An experimental campaign was designed and carried out on eight HCS-sf specimens, four with concrete topping and four without, and two different slab heights. Using the HCS-sf specimens with the activated Fe-SMA bars resulted in better behaviour in the Service Limit State, which preliminarily proved the effectiveness of the proposed methodology for the specimens with concrete topping, although construction problems arose with the specimens without concrete topping. [ABSTRACT FROM AUTHOR]

• This study investigated fatigue behavior of CWGs using CWTs to lower the cost of fatigue tests. • The comparative tests demonstrated that it was reasonable to investigate the fatigue behavior of a CWG using a CWT. • Fatigue tests were carried out on CWT specimens with two different waveform radii of R30 and R60. • Fatigue behaviour of CWT specimens were investigated based on hot spot stress concept to consider the stress concentration. • S-N curve was recommended for calculating the fatigue strength of the CWG based on the hot spot stress range. Fatigue of steel corrugated-web girders (CWGs) is a new research topic. This study uses trapezoidal corrugated-web T-section members (CWTs) to lower the cost of fatigue tests when investigating the fatigue behavior of a trapezoidal CWG. First, static tests were conducted, and the CWG under a bending moment and CWT under an axial force were compared, which verified that the flanges had the same stress distribution characteristics under equivalent loads. This demonstrates that it is suitable to investigate the fatigue behavior of a CWG using a CWT. Second, fatigue tests were performed on trapezoidal CWT specimens with two different waveform radii, R30 and R60, and their hot spot stress concentration factors at the fatigue critical location of CWG (the intersection between a parallel fold and an inclined fold of a web) were obtained, which reached 1.63 and 1.54, respectively. Of the 18 CWT specimens that experienced fatigue failure, 72 % of the initial cracks occurred at point S, indicating that this location was the most susceptible to fatigue cracking. The same S-N curve (log 10 N = 12.928-3log 10 Δ σ hs) could be applied in calculating the fatigue strengths of CWTs with different wave radii (R30 and R60) when the hot spot stress range that considered the stress concentration factor (SCF) was used. [ABSTRACT FROM AUTHOR]

• Experimental investigation of CFS profiles coupled to trusses (construction phase). • Experimental investigation of full-scale composite ribbed slabs. • Trusses provided a maximum increase of flexural stiffness and strength of 708% and 357%, respectively during construction phase. • Proposal of a design approach to analytically determine the flexural strength of the slabs during serviceability. • Proposed formulation presented 95% accuracy in determining the flexural behavior of the prototypes. • Experimental results and semi-empirical equations indicate that the area of the steel formwork can be fully considered as steel reinforcement for sagging bending moment. By means of a series of full-scale laboratory tests, this research studied the flexural behavior of a composite ribbed slab employing cold-formed steel profiles as formwork before and after concrete casting. An experimental program was devised and separated in two sets of tests. The first set consisted of the execution of four-point bending tests on eight specimens to represent the system during construction, featuring three specimen types; isolated profile, profile with plastic spacers along the channel and a full assembly including the profile, the plastic spacers and a rebar truss. Displacement and strain as a function of load were measured and the data was used to analyze the influence of the different components on the flexural strength and stiffness of the system. On the second set of tests, three ribbed composite slab specimens featuring steel profiles were subjected to four-point bending. Displacement was registered along with strain on the concrete layer. A formulation to determine the flexural strength of the slabs based on Eurocode is presented and compared to experimental observations. The first phase indicates significant increases of flexural strength and stiffness by coupling a truss to the profile and varying the height of the former, namely a maximum increase of 708% in stiffness and 357% in strength. Isolated profiles and profiles with plastic spacers all failed by distortional buckling, while the full assembly specimens failed by instability of the top chord on the trusses. Second phase results show that the analytical prediction is adequate to determine the flexural strength of the prototype slabs, with approximately 95% accuracy for this sample size. All slab specimens failed by plastic hinge formation within the pure moment span. Furthermore, strain measurements on the concrete indicate that the formulae chosen to determine the effective width of the concrete "tee" section is also adequate. [ABSTRACT FROM AUTHOR]

• The proposed design model guides the selection of required liner thicknesses. • Bending moments induced by earth loading govern liner design. • Nonlinear response of concrete may influence design. • Numerical models updated with nonlinear concrete and soil response. Buried reinforced concrete pipes (including sewers, stormwater pipes and other gravity flow structures) that experience unsafe levels of deterioration are commonly rehabilitated using trenchless solutions, such as the application of cementitious liners. Cementitious liners are centrifugally cast onto the inner surface of the damaged pipes with a spinning head that travels along the length of the pipe. Once cured, the liner increases the strength of the damaged pipe to resist applied earth and surface loads. A design method previously proposed by the authors provides guidance for selecting the required liner thickness to rehabilitate deteriorated concrete pipes situated at deep burials. However, this design method considers the linear elastic behaviour of the soil and pipe materials. Neglecting the nonlinear effects of crushing concrete within the host pipe may impact the predicted liner thicknesses for repair. Thus, the current study evaluates the impact of incorporating nonlinear compressive material behaviour on the required liner thicknesses to repair damaged concrete pipes. The required liner thicknesses obtained from the nonlinear version of the design method for rehabilitations of several pipes selected from the ASTM C76-11 Standard experiencing varying levels of deterioration are compared to thicknesses obtained using the authors' linear elastic solutions. The comparisons indicated that considering the nonlinear material response of the concrete generates slightly larger estimates of required liner thickness. The discrepancies between the estimated liner thicknesses were observed to be insignificant for pipes experiencing cracking and losses of concrete cover, demonstrating that the linear elastic model is suitable for design purposes. However, for damaged pipes situated at deep burials experiencing losses of tensile reinforcement, the discrepancies between the liner and nonlinear calculations become more significant. It is recommended that the results of the linear elastic model be checked with the nonlinear model for the repair of pipes experiencing loss of tensile reinforcement, or for deeply buried pipes. [ABSTRACT FROM AUTHOR]

The AISC 360-16 Specification recommends that the design shear force between parts of a composite column in the load introduction area shall be calculated based on the force allocation at ultimate limit state. Applicability of this straightforward method to the load levels that usually arise in slender composite columns is questionable, as this capacity-based force allocation is only true when the axial force is equal to the plastic resistance of the composite cross-section. Next, the number of required shear connectors is calculated as a quotient of the design shear force and the strength of a single shear connector. We demonstrate that: first, for the lower load levels, the stiffness-based force allocation gives a more accurate estimate of the shear force; second, the number of shear connectors satisfying the strength requirement can lead to insufficient force transfer between parts of the composite cross-section. To investigate the shear transfer mechanism in composite columns, we derive an analytical model with linear elastic constitutive relations both for steel and concrete and three types of shear force slip laws: elastic, elastic plastic, and rigid plastic. The case studies carried out for different shear transfer scenarios demonstrate the importance of the shear connection stiffness on the effectiveness of the load introduction. The remaining portion of the shear force is transferred outside the load introduction area, which hampers the column's ability to withstand shearing from varying bending moments or incipient buckling. To control the shear force transfer efficiency by enhancing the shear connection stiffness, we propose an original Stiffness Method and provide design charts as an aid in the design process. • Force allocation in composite columns revisited. • The axial stiffness of column parts drives force distribution for typical columns. • Closed-form solutions for shear transfer between cross-section parts. • Shear connection stiffness affects the effectiveness of load introduction. • Proposed stiffness method allows controlling the force transfer effectiveness. [ABSTRACT FROM AUTHOR]

• Blade root bending moments of an onshore wind turbine are monitored based on a load monitoring system and verified by simulation model. • Load characteristics and fatigue load of blade root bending moments with different operational conditions are analyzed. • A thrust estimation method of wind turbine based on measured blade loads is presented. • Equivalent fatigue load of blade root bending moment based on measured loads is obtained. Bending moment is an important parameter in structural design of the wind turbine blades. The purpose of the present study is to accurately determine the actual bending moments on the blades of wind turbine in service and study the characteristics. It can be helpful to provide supports for the design load of wind turbine blades. For this purpose, a blade load monitoring system was developed and installed on a 2 MW onshore wind turbine to measure bending moments at the blade root. A simulation model which is consistent with the monitoring wind turbine was used to verify the availability of the system. Based on the monitored bending moments and operational conditions of the wind turbine, the characteristics and fatigue load of blade root bending moments were analyzed. Meanwhile, the relationship between bending moments of blade root and operational parameters was discussed. A thrust estimation method based on monitored bending moments of blade root was presented which will help to assess the loads on the tower and foundation of the wind turbine. At last, a calculation method of equivalent fatigue load based on wind speed-rotor speed joint distribution was established which will contribute to the fatigue design of blades. [ABSTRACT FROM AUTHOR]

• Statistical approach for assessment of probability of rail break due to wheel–rail impact loading. • Multi-dimensional stochastic parameter space including detector and field test data. • Meta-models based on poly-harmonic splines to reduce computational cost of analysis. A simulation procedure to predict the probability of rail break due to a measured wheel load spectrum is presented. The load distribution includes a representative proportion of high-magnitude dynamic loads generated by out-of-round wheels. Linear elastic fracture mechanics is applied to determine the stress intensities of pre-existing rail head cracks in a continuously welded rail subjected to combined bending and temperature loading. Rail bending moments are evaluated using a validated time-domain model of dynamic vehicle–track interaction. The considered multi-dimensional stochastic parameter space includes field test data of dynamic loads from a wheel impact load detector and crack depths from eddy current data. Meta-models based on poly-harmonic splines are applied to reduce the computational cost of the analysis. Supported by the extensive field test data, the simulation procedure is demonstrated by investigating the influences of freight traffic type, track support stiffness and rail temperature on the probability of a rail break initiated at a pre-existing rail head crack. [ABSTRACT FROM AUTHOR]

• Double-headed bar overlap connection has been proposed for steel bar connection between precast reinforced concrete members. • Based on 21-specimen tests, working mechanism of double-headed bar overlap connection has been discussed. • Special size and spacing for stirrup reinforcement in the proposed rebar splice are suggested. • Tensile capacity prediction of double-headed bar overlap connection is presented. The superiorities in construction time, cost, and quality of precast RC structures are accompanied by the challenges in connection, particularly in steel bars connections between RC components. The extensively used steel bar connections for either grouted sleeve splice connection or grouted spiral-confined lap connection requires on-site grouting, which is a concealed construction process with increased the risk of grouting defects, thereby impairing connection reliability. The confined headed bar connection (CHBC) with visible on-site construction has been proposed to address the unseen grouting defects concerns. However, modern structures that use large-diameter or high-strength rebars present higher demands for steel bar connection capacity. For CHBC, it is suggested to use either a long connection length or a large-size head to satisfy the capacity demand. However, the long connection length can increase field wet operation, which is disadvantage in precast concrete construction. The large-size head can help reduce the connection length, but it can cause inconvenience including construction congestion and the increased eccentric bending moment under tension. This paper presents the CHBC with double-head configuration, which can reduce the single head size. The proposed CHBC consists of confinement stirrups and two overlapped headed bars and the stirrup confining the core concrete can also improve the CHBC capacity. Experimental investigation on 21 CHBC specimens has been carried out. The failure modes, bearing capacity, and stirrup strain development have been studied. Effects of the double-head configuration and confinement stirrup ratio have been analyzed through experimental and numerical investigation. Results show that the double-head configuration has a minor impact on the tensile capacity of CHBC while the increase of confined stirrup ratio can improve the tensile capacity of CHBC. Configuration details of size and spacing for stirrup reinforcement in CHBC are proposed. Based on the test results, CHBC tensile capacity prediction method is suggested, which can take the head configuration into account. [ABSTRACT FROM AUTHOR]