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This paper investigates comprehensively the resonance and cancellation conditions for the free vibration of elastically-supported (ES) beams subjected to successive moving loads. Focus is placed on application of the cancellation condition to minimize bridge vibrations, considering particularly the effect of elastic supports. In terms of the modal amplitude R of free vibration of the ES beam, both resonance and cancellation conditions are identified. This paper is featured by the fact that the cancellations are classified into two types as the external (load-related) and internal (structure-related) ones. Through the (internal) cancellation function, the criterion for selecting the optimal support stiffness ratio (SSR) is derived for the first time for suppressing the resonance of short to medium-span railway bridges. It depends solely on the bridge/vehicle length ratio L / d , and can be utilized to achieve near-perfect cancellation. The theoretical findings are validated by the finite element method (FEM) for various parameters. The results reveal that for beams with lengths in the ranges of (0.5 d , d ] and (1.5 d , 2 d ], an SSR closer to the lower bound of the acceptable range should be selected to achieve the best effect. And for beams with lengths in the range of (d , 1.5 d ], the SSR should be selected as close to the optimal value as possible. Besides, it was found that damping in the beam and supports contributes to further suppression of vibration for bridges designed with optimal SSR. • Derive new resonance and cancellation conditions for elastically supported beams. • Classify cancellations as external (load-related) and internal (structure-related) ones. • Optimal support stiffness ratio (SSR) for near-perfect cancellation of resonance. • Optimal SSR relies solely on the bridge/vehicle length ratio and is easy to use. • Verify the effectiveness of SSR criterion for various factors. [ABSTRACT FROM AUTHOR]

Currently, progressive collapse studies are mostly conducted based on an event-independent assumption. With studies employing an event-dependent premise mainly concerning explosion or fire events, the aftermath of impact loading is seldom reported. Meanwhile, interactions between reinforced concrete (RC) members and superstructures under impact loading need further evaluation. In this paper, finite element models of RC structures subjected to impact loading and progressive collapse are established and validated utilizing LS-DYNA. A valuing methodology of erosion parameters for the continuous surface cap model (CSCM) considering element size is proposed in this process. The influence of impact column removal (ICR) on the progressive collapse performance of RC frame structures is studied at sub-assemblage and structure levels. The parametric study indicates that the ICR process can be described by an impact loading stage and a gravity load stage. It is also found that structures experiencing ICR are exposed to a higher risk of progressive collapse, with the downward force exerted by the impacted columns being a significant contributing factor. Dynamic analyses demonstrate that the acceleration of the column removal point (CRP) can be used to validate and quantify the downward force. The hybrid force-displacement boundary conditions of frame columns give rise to the development of downward force. Recommendations for resisting progressive collapse considering ICR are proposed based on the analytical results of the paper. • A new threat-dependent perspective to progressive collapse research is elucidated, focusing on impact column removal (ICR). • Interactions between impacted columns and superstructures are illuminated, emphasising the influence of downward force. • The boundary conditions of frame columns suggest a new research roadmap for impact response of structural members. • The study on the effects of ICR indicates higher progressive collapse risk due to downward forces and initial damage. • Recommendations of resisting progressive collapse considering ICR are proposed. [ABSTRACT FROM AUTHOR]

In this paper, a novel equilibrium-based form-finding approach for a mega-latticed structure is presented based on vector-based 3D graphic statics and the Combinatorial Equilibrium Modelling (CEM). This approach can be effectively applied to the conceptual design phase of the structures with various design objectives under conservative loads. It allows us to adjust the design parameters in real time during the design phase and to obtain the resultant forms immediately. Based on a certain selection strategy, the forms have a better state of internal membrane forces compared to the original spherical structure. An ANSYS Parameter Design Language (APDL)-based automatic geometric modelling method for mega-latticed structures with various surface forms is developed. The proposed method solves the problem that the existing modelling methods are only available for spherical structures. It is highly applicable for modelling mega-latticed structures with spherical, cylindrical, and other heterogeneous surfaces. Furthermore, a complete design workflow that combines the proposed form-finding approach (for conceptual design), the automatic geometric modelling method (for transformation), and the finite element method (for deepening design and analysis), is discussed. This paper provides a reference for the design of mega-latticed structures and similar truss-based spatial structures. • A new equilibrium-based form-finding approach for a mega-latticed structure is proposed. • An automatic geometric modelling method for mega-latticed structures is improved. • A design workflow combining the form-finding approach and finite element method is discussed. • A case study is performed to verify the validity of the whole structural design process. [ABSTRACT FROM AUTHOR]

Hybrid reinforced concrete steel (RCS) frames consisting of reinforced concrete (RC) column and steel (S) are used frequently in practice for mid-to-high-rise buildings. RCS frames possess several advantages from structural, economical and construction view points compared to either traditional RC or steel frames. One of the key elements in RCS frames is the beam-to-column joint. This paper suggests a design method to evaluate the mechanical behaviour of a novel type of exterior RCS beam-column connection in which a steel profile totally encased into a RC column is used to connect the beam through the steelwork part of composite section. The proposed design model is developed considering experimental test results and finite element (FE) analyses. In the first part of the paper, an experimental investigation on the static behaviour of the hybrid joint is presented. Four full-scale specimens were tested under monotonic loading. The primary differences between the specimens are the concrete class and the anchorage length of the embedded steel profile in the RC column. The experimental results indicated that the overall behaviour of the specimens was significantly affected by the shear panel deformations of the embedded profile. Next, a finite element model was created. The FE model predictions compared favourably against experimental tests and confirmed the order of yielding/cracking of joint components. Finally a design method based on Eurocodes 2, 3 and 4 is proposed to determine the initial rotational stiffness and the bending resistance of the joint. • Experimental tests on hybrid steel beam to RC column joints with encased steel profile. • Limited impact of long encased steel profile on mechanical characteristics. • Order of yielding/cracking of components evaluated experimentally and by finite elements. • An Eurocode model for the initial rotational stiffness and bending resistance. [ABSTRACT FROM AUTHOR]

The most common and practical connection between CLT walls can be realized with inclined screws. This choice avoids the realization of more elaborated half-lap or spline joints. The failure mechanism of CLT-to-CLT screwed connections is highly ductile. However, the epistemic and aleatoric uncertainties associated with the capacity estimation of the connection might lead to an undesired overstrength, compromising the expected hierarchy between failure mechanisms. This paper presents the results of an extended experimental campaign to estimate the overstrength of CLT-to-CLT screwed connections. However, the overstrength directly obtained from the experimental tests could be underestimated. In the experimental campaign, the same wood and screw stock is used, which might not represent the actual scatter of the material properties and construction uncertainties of the as-built connection (e.g., the screw inclination). Therefore, this paper attempts to provide a model-driven assessment of the overstrength factor, assuming more realistic values for the parameter uncertainties. The authors propose a method for removing the contribution of epistemic uncertainty to the model-driven estimation of the overstrength based on experimental tests with two Montecarlo simulations. Following the proposed method, the paper compares the overstrength estimations from the experimental tests to the predictions of analytical and nonlinear finite element models. This study has proven that an overstrength factor between 1.8 and 2 can represent the actual uncertainties in as-built CLT-to-CLT screwed connections. • Overstrength assessment of CLT-to-CLT screwed connections. • Proposal of a novel formulation for overstrength. • Experimental tests on CLT-to-CLT screw connections. • Epistemic and aleatoric uncertainties in the overstrength estimate. • Uncertainty propagation in analytical and FE models. [ABSTRACT FROM AUTHOR]

This paper is concerned with the behaviour of square concrete-filled dual-stiffened steel tubular (CFDSST) slender columns with a concentrically-placed inner circular steel tube. Previous studies have illustrated that these columns have greater structural performance in terms of load-carrying capacity compared with conventional concrete-filled stiffened steel tubular (CFSST) columns. However, the behaviour of CFDSST slender columns filled with ultra-high strength concrete (UHSC) has not been investigated and current design codes do not include provisions for UHSC, although it is increasingly popular owing to demands for structures to be lighter and more sustainable. Accordingly, the current paper fills that gap in existing knowledge and explores the behaviour of CFDSST slender columns using finite element (FE) analysis. The available test results from previous studies were collated and are employed to validate the numerical model. The validated FE model is then employed to investigate the axial load versus deflection responses for a wide variety of UHS-CFDSST slender columns. The behaviour of both intermediate-length and long columns is assessed through parametric analyses. The results of these studies show that the strength of the concrete sandwiched between the two steel sections, the yield strength of outer steel tube, and the outer tube slenderness ratio have a significant effect on the axial resistance of UHS-CFDSST intermediate-length columns, while the capacity of long columns is most affected by the sandwiched concrete strength. The ultimate resistances are compared with different available design methods, and AISC 360–16 code is recommended for predicting the ultimate resistance of UHS-CFDSST slender columns with modifications proposed to account for the different components forming this innovative cross-section. • New research is presented on the behaviour of square concrete-filled dual-stiffened steel tubular (CFDSST) slender columns. • Ultra high strength concrete is employed for the infill, for the first time. • An advanced finite element model is developed and validated. • The behaviour of intermediate-length and long columns is assessed by parametric analyses and reliable design is proposed. • The results show the potential of these sections to offer innovative structural solution for heavily loaded scenarios. [ABSTRACT FROM AUTHOR]

• 15 tests of bolted joints between Fe-SMA and steel plates are carried out. • The reliability of reinforcing steel structures with bolted Fe-SMA is verified. • The key influencing parameters of the bolted joints are obtained. • Some design suggestions on bolted joints between Fe-SMA and steel plates are proposed. The new intelligent material Iron-based Shape Memory Alloy (Fe-SMA) brings novel solutions for the performance rehabilitation of existing steel structures. To fully utilize the potential of the Fe-SMA active prestressed reinforcement, the systematic study of reliable joint is significant. Therefore, the bolted joints between Fe-SMA and steel plates was experimentally studied in this paper, whose reliability and convenience in metal structures have been generally accepted. Firstly, a series of 15 mechanical performance tests of bolted joints between Fe-SMA and steel plates were carried out. The key influencing parameters of the bolted joints were obtained, and different failure modes were observed, which can provide experimental verification for further finite element modelling and theoretical study. Furthermore, the effects of end distance e , edge distance s , bolt diameter d , thickness of Fe-SMA plate t and bolt layout on the ultimate load-bearing capacity, initial stiffness and failure modes of the bolted joints between Fe-SMA and steel plates were discussed, and some specified design suggestions on bolted joints between Fe-SMA and steel plates were proposed. This paper mainly aims to provide the experimental basis and design recommendations for compilation of the relevant specifications, which is expected to advance the scientific application of Fe-SMA in the performance rehabilitation of steel structures. [ABSTRACT FROM AUTHOR]

• Paper describes a methodology that was successfully applied for the development of a temporary road traffic steel barrier in compliance with T1/W1 level according to EN 1317; • A simplified theoretical analysis of 178 barrier, laboratory test of three types of barrier connectors (for two types of barrier), explicit FEM modeling of four chosen barrier, and a full-scale crash test for final barrier are presented; • The stiffness of barrier connector was established based by laboratory barrier test (the FEM model was validated based on laboratory tests); • The chosen final barrier alternative passed the crash test for T1/W1 (TB21) containment level, performed by certified laboratory [35] , which proves that the presented procedure could be used successfully for traffic barrier development. Over a million people die in road crashes and tens of millions result injured or disabled each year, globally. Hence, there is a constant concern for improving the safety of the roads to protect road users, and those at the most risk, the road workers. Construction, maintenance, and utility work are constantly needed to ensure safety and functionality of roads and highways. Temporary road traffic barriers are used to separate passing traffic from the workspace and protect the workspace from an errant vehicle intrusion. Steel barriers are light, and their major advantage is rapid installation. These barriers are not anchored to the ground, and their behavior relies on the base-pavement friction, mass inertia, and stiffness of the system. The paper describes a methodology that was successfully applied for the development of a temporary road traffic steel barrier in compliance with the European specification EN 1317. The study included a simplified theoretical analysis of 178 barriers, static laboratory tests of three types of barrier connectors, development of explicit finite element models (EFEMs) of four selected barrier designs, and a full-scale crash test of the final barrier design. It is shown that static laboratory tests of complex connector systems can help to improve the design process and reduce the cost. The analysis and use of EFEMs was enough so that just a single full-scale crash test was sufficient for certification of the barrier design for use in Europe. The final barrier is compliant with the EN 1317–2 requirements for T1/W1 (TB21) containment level, which was confirmed by a full-scale crash test. [ABSTRACT FROM AUTHOR]

• This paper applied the lightweight aggregate concrete (LWAC) into partially encased steel-concrete composite (PEC) stub columns. • The axial compression test was conducted to explore the work properties of partially encased steel-concrete composite stub columns with LWAC. • The finite element models of the PEC-LC column were established to conduct a systemic parametric investigation. • The axial strength calculation method of PEC-LC columns was proposed considering the flange strength reduction and core concrete enhancement. This paper applied lightweight aggregate concrete (LWAC) in the partially encased steel-concrete composite (PEC) stub columns to achieve the advantages of lightweight and easy assembly. A total of 8 axial-loaded specimens were tested to explore the effect of concrete type, concrete strength, link spacing, longitudinal rebars, and height-to-width ratio on the compressive behavior of the partially encased steel-concrete composite stub columns with lightweight aggregate concrete (PEC-LC). Then, the finite element models of PEC-LC columns were established to conduct a systemic parametric investigation. The results demonstrated that the PEC-LC column experienced failure due to concrete crushing and local buckling of flanges, similar to the PEC column. Compared to the PEC column, the PEC-LC column exhibited a similar load-bearing capacity but poorer post-peak compressive performance, which could be improved by closer link spacing. Consequently, applying LWAC to reduce the self-weight of prefabricated members is a feasible option. Besides, the contact stress and the stress distribution at typical cross-sections were analyzed to reveal the confinement effect of H-shaped steel and links on the filled LWAC. Finally, A calculation method for estimating the axial compression capacity of the PEC-LC column was proposed, taking into account the reduction in flange strength and enhancement of core concrete. The accuracy of the calculation method was verified by comparison with experimental and numerical data. Overall, this research serves as a valuable reference for promoting the adoption of the PEC-LC column in assembled structures. [ABSTRACT FROM AUTHOR]

• Cut-and-cover shallow metro and railway stations are seismically vulnerable. • This is due to the internal hyperstaticity of its rigid transverse box section. • This paper proposes an alternative solution with low lateral stiffness. • The proposed technology is applied to a relevant actual case study. • This case is deeply analyzed, and the offered solution proofs feasible. Underground cut-and-cover structures are commonly designed as rigid box sections; however, in practical applications, connections between walls and slabs are frequently rather hinged (because of ease of construction). The abovementioned rigid configurations are highly sensitive to seismic ground motions, due to their important lateral stiffness and internal hyperstaticity; conversely, structures with articulated (or sliding) members have a smaller lateral stiffness, and would be significantly less affected by seismic waves, as would simply accommodate the imposed strains. This flexible solution has been widely considered in practice, but has received little attention from the academic community; this paper tries to close this gap by investigating preliminarily the seismic performance of box-section underground structures with hinged or sliding members. The well-known Daikai Station, damaged by the 1995 Kobe earthquake is analyzed in this paper as a highly relevant case study. An alternative solution is proposed for that station; both simplified and precise calculations have been performed. The simplified calculations are linear static analyses of the station-soil system; the soil-structure interaction is represented by a simple classical model. The precise calculations are nonlinear time-history analyses of an integrated finite element model of the station and the surrounding soil. Both types of analyses refer to the traditional and the proposed solutions of the station. The results of the static and dynamic analyses are satisfactorily compared; they prove that the proposed flexible solution is fully feasible and provides better seismic performance. Finally, another paper by the same authors presented a supplementary case study on a 2-story 3-bay subway station; the outcomes of these two studies could contribute to ground this constructive solution for shallow underground rectangular cut-and-cover structures in seismic areas (both for new construction and retrofit). Noticeably, this approach can be utilized for both cast-in-place and precast structures. [ABSTRACT FROM AUTHOR]

• This paper presents a real-time Topology Optimization (TO) algorithm based on the Moving Morphable Component (MMC) method using a Convolutional Neural Network (CNN). • A new data pre-processing method is proposed, which can preserve the numerical characteristics of the structure boundary, hence it can help CNN to capture data features with a limited sample set. • The boundary information of the optimized result is used as the model label. It can avoid the component dislocation phenomenon and improve model prediction accuracy. Classical optimization methods require finite element analysis in iterations, which increase the computing time and decrease the algorithmic efficiency. The deep learning model can potentially realize real-time topology optimization design, but it normally requires large training set. This paper presents a real-time topology optimization algorithm based on the Moving Morphable Component (MMC) method using a Convolutional Neural Network (CNN). The optimization algorithm uses a new data pre-processing method, which can preserve the numerical characteristics and smoothness of the structure boundary, hence it can help CNN to capture data features with a limited sample set. The topology optimization boundary information of the optimized result is used as the sample set label to avoid the components dislocation phenomenon. The new algorithm effectiveness has been verified with several examples. The trained model can significantly improve the optimization efficiency of the MMC method and offer accurate results with a clear structure boundary. [ABSTRACT FROM AUTHOR]

Highlights • Development and validation of ABAQUS material models for steel headed studs and UHPC. • Experimentally-supported finite element simulations for model validation. • Assessment of in-plane torsion and direct shear interaction for an eccentrically loaded stud group. • Identification of failure mechanisms for stud diameter-to-base plate thickness ratios. Abstract A novel bridge repair method has been developed to strengthen steel bridge girders with section loss due to end corrosion. The repair comprises of welding headed shear studs to the non-corroded portion of the web plate and encasing them in ultra-high performance concrete (UHPC) to create an alternate bearing load path. The interaction between the headed studs and the UHPC panels is crucial in the force transfer. Therefore, a careful study is needed through high-fidelity finite element analysis to complement the experimental results. This paper presents the development of a model in Abaqus finite element software that enables capturing the behavior of studs embedded in UHPC. The model was validated using a series of experimental results from push-out tests with headed shear studs welded onto a thin web plate. Experimental results from push-out tests performed on stud diameters of 12, 16 and 19 mm and two levels of eccentric loadings were used to calibrate the modeling methodology. The model explicitly considers effects of material damage, contact between the studs and UHPC, and the precise geometry of the weld collar of studs. After validation, design parameters such as interaction of in-plane torsion and direct shear, and limits for web thickness-to-stud diameter ratio were studied to compliment the experimental data. The results are expected to inform engineers about the design of this novel repair method. In addition, this paper may enable future finite element studies on the performance of studs in UHPC. [ABSTRACT FROM AUTHOR]

• A novel bridge weigh-in-motion method is presented using parametric dynamic bridge-vehicle interaction formulation. • Modal parameters extracted from ambient vibration tests are used to accurately simulate the bridge structures. • The formulation offers superior computational efficiency since it eliminates the need for calibrated finite element models. • The proposed method resulted in accurate estimations even when the vehicle travel path differs from calibrations. • The Proposed method was validated using a full-scale case-study arterial highway bridge in Canada. Dynamic bridge weigh in motion systems use models that can simulate the dynamic behaviour of a bridge subjected to moving traffic. Currently available models use complex and computationally expensive Moving Force Identification (MFI) methods that utilize finite element models to estimate the bridge torsional and transverse dynamic behaviour. This paper presents a novel dynamic parametric BWIM method that utilizes the experimentally estimated modal parameters for simulating the response of a bridge structure to moving loads. The estimated modes of an in-situ structure inherently capture the true bridge behaviour for any generalized geometry, boundary conditions and load position. Therefore, it enables the complex torsional and transverse bending behaviour of the bridge to be captured. In this paper, the mathematical derivation of the analytical model is presented in detail, then model calibration and weighing procedures are outlined, followed by the validation of the proposed method using a full-scale case study arterial highway bridge in the Canadian Province of New Brunswick. The proposed dynamic BWIM method offers a novel solution for the development of real-time BWIM systems that is efficient to calibrate and accurate in vehicle identification. [ABSTRACT FROM AUTHOR]

Full-field measurements of the continuous spatiotemporal response of the physical processes such as structural vibration or fluid flow generate large datasets. In many scientific fields, such continuous spatiotemporal dynamic models are represented by partial differential equations (PDEs). In the past, attempts have been made to identify the PDE models from the measured response by inferring its parameters by the use of either regression or deep learning-based techniques. But the previously presented regression-based methods fail to estimate the parameters of the higher-order PDE models in the presence of moderate noise. Likewise, the deep learning-based methods lack the much-needed property of repeatability and robustness in the identification of PDE models from the measured response. The authors introduced the method of S imulta N eous Basis Function A pproximation and P arameter E stimation (SNAPE) in a recent paper which addresses such drawbacks by fitting basis functions to the measured response and simultaneously infer the parameters of the PDE model. In this paper the theory and formulation of SNAPE is presented to perform physics-guided identification of the Euler–Bernoulli beam PDE model which is widely applied in the modeling of large scale infrastructures to nanoscale structures.The domain knowledge of the physics is used as a constraint in the formulation of the optimization framework. The alternating direction method of multipliers (ADMM) algorithm is used to simultaneously optimize the loss function over the parameter space of the PDE model and coefficient space of the basis functions. The proposed method not only infers the parameters but also estimates a continuous function that approximates the solution to the PDE model. The efficacy of the method is both numerically and experimentally validated on noise corrupted full-field vibration response. The method neither requires the knowledge of the initial or boundary conditions of the beam nor comprises of model discretization error as in the case of finite element model updating. SNAPE demonstrates its applicability on various homogeneous and time-varying nonhomogeneous boundary conditions. • Application of SimultaNeous basis function Approximation and Parameter Estimation (SNAPE). • B-Spline functions to fit measured data and simultaneously satisfy the PDE model. • Estimates PDE model parameters and approximate analytical solution of the PDE model. • Demonstrated on a wide variety of beam support conditions and support excitations. • Constrained optimization to systematically combine physics and data science. [ABSTRACT FROM AUTHOR]

This paper presents a new approach to the analysis of thin-walled beams. The proposed model is developed by utilizing the eXtended Finite Element Method (XFEM). Global enrichment functions are added to a standard 3D Finite Element (FE) coarse mesh to enhance its performance and reduce the number of degrees of freedom. These analytical functions provide an approximate solution in the longitudinal direction of the beam. The resulting model bridges the gap between the Finite Prism Method (FPM), which provides an efficient approximation to beam bending with analytical functions but has also well-known limitations, and a detailed 3D FE model, which can accurately resolve thin-walled structures but is computationally demanding. Our method can be easily extended for beams with non-prismatic cross-sections (e.g., tapered beams) or with perforations, which makes it more general than other semi-analytical methods, such as the FPM. However, these extensions are not in the scope of this paper. Additionally, one can improve the solution by sectional and/or longitudinal mesh refinements. The performance of the model is investigated on two benchmark problems. The results show that the proposed method captures different global and sectional deformation modes of thin-walled beams when subjected to torsion, including shear-lag and distortion cross-section. Furthermore, convergence studies demonstrate the superior performance of the proposed method as compared to the FPM, and a 3D FE model with a coarse mesh. • A new model is proposed for the analysis of thin-walled beams. • The model is developed based on the extended finite element method. • Global enrichment functions are added based on the free-vibration modes of continuous beams. • An explicit stiffness matrix is formulated for a 3D eight-node brick element with enrichment functions. • The model captures different modes of deformation including shear-lag and distortion of the cross-section. [ABSTRACT FROM AUTHOR]

• A 3D finite element model is developed for the two-step corbel. • A database with 126 corbels is made by parametric analysis. • An analytical model is proposed for the design of two-step corbels. • The proposed analytical model has strength reduction factors calculated. Corbels are a common element in the beam–column connections of precast concrete structures. This paper analyses the failure of a two-step corbels system using computational modeling. A finite element model is developed and calibrated using the test results for two-step corbels without secondary reinforcement but with steel fiber–reinforced concrete. A database is developed from the parametric analyses of two-step corbels, varying the a/d ratio (0.34–0.76), the rate of the main reinforcement (0.19–0.50%), the compressive strength of the concrete (30–70 MPa) and the amount of steel fibers (1.0% and 1.5%). An improved analytical model, using the developed database, is proposed to design the two-step corbels. The reliability of the proposed analytical model is evaluated using a second database, developed in this paper, and a strength reduction factor of 0.66 for failure by yielding of the main reinforcement and 0.56 for failure by crushing of the concrete strut, were obtained. Therefore, the improved analytical model obtained for the design of two-step corbels represents an advance, in terms of structural safety and economy, when compared to the previous analytical models recommended in the literature. [ABSTRACT FROM AUTHOR]

Deconstructable structures offer great flexibility and reduce material waste. Fiber Reinforced-Polymer (FRP) decks resting on steel girders combine high durability, lightweight, fast construction, and deconstructablility. Composite action between the decks and girders is achieved using shear connectors. Until now, most shear connectors use adhesives or grouts, limiting their maintenance, reuse, or recycling. This paper presents a closed-form solution to analyze the behavior of an FRP deck connected to multi-girders using variable sequential stiffness shear connectors considering partial Degree of Composite Action (DCA). The analytical model, which is verified using Finite Element model and prior experimental studies, is further used to study stress and deflection for various multigirder configurations. Finally, the DCA considering variable stiffness shear connectors is presented and linked to effective width ratios, paving the way for adopting variable stiffness in bridge standards. • The analytical model accounts for multi-girder configurations. • Closed-form solution for deconstructable variable stiffness shear connectors. • A design guideline linking effective width for different degrees of composite action. [ABSTRACT FROM AUTHOR]

This paper presents an approach to investigate the effect of temperature on the transmission and distribution of vibration energy for train-track-bridge coupled systems. The vibration of the coupled system can be simulated by integrating the multi-body dynamics model of the train with the finite element models of the track and bridge. The transmission and distribution of vibration energy can be evaluated using a structural intensity method. This approach was implemented to investigate the vibration characteristics of a coupled system under extreme temperature conditions. The system consisted of a CRH2 high-speed train, a CRTS I double-block ballastless track, and an arch bridge. The results show that extreme temperature not only impacts the characteristics of vibration energy transmission in the coupled system but also affects vibration energy distribution. This research provides new insights into vibration control and optimization design for bridges in regions with significant temperature variations. • A vibration energy quantification and visualization method for train-track-bridge coupled systems is proposed. • Hybrid modelling integrating multi-body dynamics and finite element models is performed. • Thermal effect as well as track irregularity are considered. • Vibration energy transmission characteristics of each substructure of the coupled system are analyzed. • The distribution law of vibration energy under various thermal conditions is analyzed for a high-speed railway arch bridge. [ABSTRACT FROM AUTHOR]

Conventional cold-formed steel wall systems suffer from low lateral loading-carrying capacities and stiffnesses, which represent the main barrier to their use in multi-story buildings. To address it, a cold-formed steel center-sheathed shear wall (CFSCSSW) system with higher lateral load-carrying capacity and better lateral structural performance is proposed. This paper presents experimental, numerical, and analytical studies on the behavior of the proposed CFSCSSW subjected to combined vertical and horizontal loads. Firstly, a full-scale test was conducted, with the test setup, loading procedures and measuring instrument reported in detail. The obtained test results, including the load-carrying capacity, failure mode and strains, were fully analyzed. Then, finite element modeling was conducted to simulate the experimental observations, and parametric studies were carried out to investigate the influences of different geometric and loading parameters on the behavior of CFSCSSWs. Finally, a three-strip model with a variable position on end studs (TSM-VPC) was proposed for CFSCSSWs and shown to accurately simulate the direction of the tensile field within the sheathing and also resulted in high accuracy in calculating the load-carrying capacities, followed by a design example. ● An innovative cold-formed steel center-sheathed shear wall (CFSCSSW) system is proposed. ● A full-scale test on CFSCSSW under combined loading is conducted, with test results fully analysed. ● The influences of key geometric and loading parameters are investigated through parametric studies. ● A three-strip model is proposed for calculating the load-carrying capacity of CFSCSSW. [ABSTRACT FROM AUTHOR]

Constructing an interpretable model for the long-term deformation Structural Health Monitoring (SHM) of earth-rock dams is of great significance for improving the safety state evaluation and monitoring effect. In this paper, a physics-data-driven model for the deformation SHM of earth-rock dams is proposed based on deep mechanism knowledge distillation. Firstly, the deterministic model is established based on the Finite Element Model (FEM) and outputs the hydraulic load component curve and aging component curve. Then a regression prediction model (HTSGAN) between influencing factors and deformation measurements at multiple measurement points is established based on the Graph Convolutional Network (GCN) and attention mechanism. Finally, the Teacher-Hydraulic-Time-Seepage Graph Attention Networks (T-HTSGAN) model is established based on the feature-based multi-teacher knowledge distillation using the knowledge of hydraulic loading physics and soil-rock creep physics of the FEM for mechanism constraints. The model effectively solves the problems of poor model interpretability and lack of physics knowledge constraints in previous earth-rock dam SHM models. The research results are applied to a project of a 185.5-meter-high concrete-faced rockfill dam, and the predictive performance of the model is more effective and stable through the comparison of six baseline models. The comparative analysis of the component curves proves the effectiveness of the proposed knowledge distillation method for mechanism constraints and improves the interpretability of the neural network model. Therefore, the model is more suitable for engineering applications. • A new physics-data-driven deformation monitoring model for earth-rock dams is proposed. • Mechanical constraints of dam SHM model is further improved by a new neural network model mechanism constraint method. • The application results of a high CFRD show that the model has high accuracy and good engineering applicability. [ABSTRACT FROM AUTHOR]

Traditionally, uncertainty quantification in the context of liquid storage tanks has primarily focused on ground motion record-to-record variability, along with partial consideration of material randomness. This paper presents a comprehensive framework for addressing "modeling uncertainty" in the seismic analysis of rectangular tanks, including the influence of foundation interactions. The framework encompasses uncertainties inherent in both general finite element and mathematical modeling techniques, as well as uncertainty in modeling parameters (e.g., hydrodynamic mass and concrete constitutive model). This is achieved through the implementation of an efficient design of experiments. By employing an innovative intensifying artificial acceleration, over 26,000 transient simulations are conducted, spanning the full spectrum of structural behavior from linear to nonlinear regimes. Through a series of uncertainty quantification and sensitivity analyses, this study assesses bias and dispersion arising from diverse model assumptions. Furthermore, fragility analysis and machine learning post-processing techniques are employed to extract latent insights from the generated data. The outcomes underscore that numerical and mathematical modeling uncertainties can bear comparable significance to ground motion record-to-record variability. The adoption of distinct modeling strategies introduces biases in fragility curves, particularly within higher damage states. Consequently, it is advised to account for modeling randomness directly (via simulation) or approximately (leveraging the insights from this study) in any uncertainty quantification related to storage tanks. • A unified framework is proposed for epistemic uncertainty quantification. • The modeling variability is quantified in the liquid storage tanks for the first time. • An innovative intensifying artificial acceleration is used for uncertainty quantification. • The significance of β m o d e l i n g for coupled tank–foundation system is demonstrated. • A detailed machine learning-based sensitivity analysis is performed. [ABSTRACT FROM AUTHOR]

Given that the stiffness of joints has an important influence on the global behavior of steel structures, considerable efforts have been made to develop methods to characterize their behavior. In the component method, that is adopted by Eurocode 3, one of the most relevant components is the column web panel in shear; however, this component has never been the subject of research when additional plates are welded between the column flanges to attach the secondary beams to the minor axis of the column. This paper proposes a stiffness formulation for the component column web panel in shear with additional plates, taking into account the stiffening contribution of these additional plates. To archive this, four experimental tests of beam-to-column joints were carried out, a finite element model was calibrated with the experimental data by comparing moment-rotation and moment-deformation curves, a parametric study of sixty different configurations was performed with the calibrated finite element models to obtain the stiffness of the component column web panel in shear and the initial stiffness of the joint. Then, the proposed stiffness formulation for the component was validated with the results of the parametric study, obtaining a very good agreement. Finally, a compilation of the stiffness formulation of all the components of the joint type extended end plate with additional plates was made and validated, when comparing this analytical stiffness with the initial stiffness of the joints of the parametric study, satisfactory concordance was found. [Display omitted] • Study of end plate bolted steel joint with additional plates welded between column flanges to attach secondary beams. • Experimental work to validate finite element models. • Development of a parametric study with finite element models. • Proposal of a formulation for the component column web panel in shear with additional plates welded between column flanges. • Compilation and validation of the stiffness formulation for all the components of the studied joint. [ABSTRACT FROM AUTHOR]

Semi-oval hollow section is an innovative cross-section profile, including one semi-circular flange, one flat flange and two flat webs. While the semi-circular flange (exposed to fluid or wind) offers a low level of hydrodynamic or aerodynamic drag, the flat elements facilitate connections with other members. This paper presents experimental and numerical investigations into the local buckling behaviour and resistances of austenitic stainless steel semi-oval hollow sections under combined compression and bending. A testing programme was firstly conducted and included initial local geometric imperfection measurements and ten eccentric compression tests. In conjunction with the testing programme, a numerical modelling programme was performed, where finite element models were developed to validate against the test results and conduct parametric studies for expanding the test data pool over a wider range of cross-section dimensions and loading combinations. The obtained test and numerical data were used to evaluate the applicability of the relevant design interaction curves for austenitic stainless steel rectangular hollow sections, as prescribed in the European code and American specification, to austenitic stainless steel semi-oval hollow sections. On the basis of the evaluation results, the codified design interaction curves were found to provide conservative resistance predictions. Finally, an improved design interaction curve, with more accurate end points and suitable shape, was developed and led to more accurate and consistent resistance predictions for austenitic stainless steel semi-oval hollow sections under combined compression and bending. • The local buckling of austenitic stainless steel semi-oval hollow sections under combined loading was studied. • Ten eccentric compression tests were conducted. • FE models were developed to simulate the test results and then used to perform parametric studies. • The applicability of relevant codified design interaction curves was assessed, showing conservatism. • A new design interaction curve was proposed and provided improved design accuracy and consistency. [ABSTRACT FROM AUTHOR]

In large-span bridges or high-rise buildings, CFST columns with large width-to-thickness ratio are often adopted, which require proper stiffening measures to improve the mechanical behaviors. This paper presents a comparative study of circular CFST stub columns with different stiffening methods, including longitudinal stiffeners (cross-shaped, T-shaped and ordinary type), additional reinforcement and headed studs. Axial compression tests have been conducted to investigate the effects of different stiffening methods on the failure mode, ultimate strength and ductility of the circular CFST stub columns. Finite element models are established to simulate the columns' behaviors and conduct parametric studies. Based on test and simulation results, an axial bearing capacity prediction model for circular CFST stub columns stiffened by longitudinal stiffeners is proposed. It is demonstrated that the failure modes of the steel tube and core concrete are changed by the longitudinal stiffeners. The longitudinal steel stiffeners as well as reinforcing cage can effectively improve the axial bearing capacity and ductility of the columns. The latter is more efficient in promoting the bearing capacity while the former is more efficient in improving the ductility and residual strength. A combination of the additional stirrups and the ordinary stiffeners will be a more economical choice. In addition, the proposed formula gives better prediction accuracy compared to the equations in various design codes. • Axial compression tests are conducted on circular CFST stub columns with different stiffening methods. • Longitudinal stiffeners with different shapes, additional rebar and headed studs are studied. • Finite element models are established to simulate the columns' behaviors and conduct parametric studies. • An axial capacity model for circular CFST columns stiffened by longitudinal stiffeners is proposed. • Longitudinal stiffeners and reinforcing cage can improve the axial capacity and ductility of the columns. [ABSTRACT FROM AUTHOR]

The seismic response is a critical aspect of structural engineering, as it directly influences the design and safety evaluation of such systems. Structural seismic response becomes more complicated when unavoidable uncertainties in the structure are considered. Therefore, solving and analyzing the stochastic dynamic response of structures efficiently and accurately is of great significance. Various uncertainty quantification methods such as the stochastic finite element method, Monte Carlo method, and polynomial chaos expansion method have made significant progress in this field. However, these methods do not provide a comprehensive study of the seismic response of stochastic structures and efficiency problems rapidly emerge as the number of random variables increases. This paper delivers a comprehensive study of the seismic dynamic response of space truss and reticulated shell structure considering uncertainties in material properties, geometry, and loading. To this end, the finite element model of the structure was first modeled and the deterministic solutions were obtained. Then, polynomial surrogates are modeled for the natural frequency, mode participation factor, mode superposition response, and transient response of the structure under stochastic uncertainties. The sparse grid technique is used to select sparse quadrature points, which overcomes the curse of dimensionality caused by full grid integration. The results demonstrate that the sparse grid-based polynomial chaos expansion is more efficient. Uncertainty quantification reveals the uncertainty of modal analysis, response spectrum analysis, and transient response analysis of space truss and reticulated shell under seismic excitation. In summary, this study provides valuable insights and an efficient and accurate uncertainty quantification tool for the seismic dynamic analysis of stochastic structures, ultimately contributing to safer and more robust structural designs. • Analyzing the seismic dynamic response of stochastic structures comprehensively. • Sparse grid-based PCE for quantifying uncertainty in stochastic dynamics. • Addressing the dimensional catastrophe of traditional non-intrusive PCE. • Sparse grid-based PCE metamodel for post-processing is more efficient and accurate. [ABSTRACT FROM AUTHOR]

Concrete dams are prone to cracks during construction and operation process. Cracks on the upstream surface may induce the risk of hydraulic fracturing, thereby significantly reducing the safety of dam structure. Nevertheless, image processing technology, non-destructive testing technology and structural performance analysis technology with cracks are in a relatively independent state, leading to difficulties in analysis of actual cracks combined with numerical simulations. This paper proposes a novel approach for combination of intelligent identification technology and refined finite element method (FEM) for modeling and simulating the hydraulic fracturing resistance of the actual crack in concrete dams. With image processing technology and non-destructive testing technology, direction and depth of actual cracks are identified and extracted, then the 3D geometric model of actual cracks is generated. The refined model with the identified actual crack is constructed by the node projection strategy. This approach is used to assess the hydraulic fracturing resistance of the concrete dam with actual cracks in the alpine region. The results demonstrate that the critical crack depth of hydraulic fracturing is 12.93 m, and the opening width is 1.01 mm, which is 2.53 times the limit value for Class D cracks in the code (DL/T5251–2010). The refined modelling method based on actual crack detected on site can accurately evaluate the crack state compared to the conservative code. • A novel approach for generation and simulation of the 3D actual crack is proposed. • Refined FEM model with the identified actual crack is established by node projection strategy. • Hydraulic fracturing resistance of the actual crack in the concrete dam is evaluated. • Refined simulation method based on actual crack can accurately evaluate crack state compared to the conservative code. [ABSTRACT FROM AUTHOR]

Climate change exacerbates the structural deterioration of concrete highway bridges, posing a threat for them to resist vehicle collisions. However, the investigation into the safety of highway bridges under the joint effects of climate change, deterioration, and collisions caused by heavy vehicles is lacking. This paper presents a practical framework for assessing the lifetime fragility of concrete highway bridges exposed to both heavy vehicle collisions and climate change-accelerated corrosion. The main challenge of applying fragility-based approach in this framework lies in developing surrogate demand models, which traditionally requires extensive time-consuming simulations of vehicle-bridge collisions using finite element methods. To overcome this, an impact force time history model is proposed as an efficient alternative to represent collision demands on bridge piers by heavy vehicles. Implementation of this model has demonstrated a remarkable reduction of approximate 90% in computational time requirements compared to the collision analysis. The framework enables the generation of fragility surfaces at any given time throughout the bridge's service life. The effectiveness of the framework is demonstrated using an example highway bridge, and fragility surfaces are generated for various climate scenarios. The results indicate a rise in the probability of collapse, from 0.4% for a structurally sound bridge to 87.2% after 80 years of chloride exposure when subjected to a heavy vehicle collision with an impact velocity of 100 kph and a truck weight of 36 t. Additionally, the impact of climate change is evident, further increasing this probability to 97.4%. These findings underscore the significant roles that both corrosion and climate change play in influencing the vulnerability of concrete bridges to heavy vehicle collisions. Addressing these factors in collision design and lifetime assessment is essential for ensuring the structural resilience and safety of bridges over time. • Evaluation of bridges' vulnerability under the combined impacts of heavy vehicle collisions, corrosion, and climate change. • Development of an impact force time history model as a substitute for dynamic collision simulations. • Characterization of bridges' collision resistance, incorporating site-specific chloride exposure and climatic conditions. • Analysis of bridges' time-dependent failure probabilities during collision events throughout its lifespan. [ABSTRACT FROM AUTHOR]

Prestressing is a viable and effective technique used in concrete structures that allows the improvement of their performance. Its efficiency depends on the layout of the tendons, understood as the number of strands, their profile, curvature, and eccentricities. Layout design is a laborious and usually iterative trial-and-error process that aims to ensure that stress limits are not exceeded while, on the other hand, to minimize the total weight of prestressing steel. To automate the process, this research presents a novel genetic algorithm and a machine learning-based approach with a parametrically defined geometry of a tendon consisting of straight lines and circular arcs. The paper describes assumptions, implementation, and validation of the methods using a two-span two-girder bridge structure as an example. The genetic algorithm was incorporated to minimize the total weight of prestressing steel and ensure a correct design with no limit state exceedances. Since prestress evaluation in statically indeterminate structures requires repetitive and time-consuming numerical simulations, usually finite element analysis (FEA), a neural network was used to predict numerical output based on the layout parameters. The introduction of the neural network significantly reduced the total computation time. The results show the usability of the proposed approach in further studies and in engineering practice. • Genetic algorithm and neural network combined establish an effective optimization framework for prestressed concrete design. • Genetic algorithm is able to find optimal solutions even when all candidates in initial generations exceed the constraints. • Neural network can successfully replace time-consuming Finite Element Analysis (FEA) in design process. • The profile geometry of a tendon can be easily parametrized using linear segments and circular arcs. [ABSTRACT FROM AUTHOR]

In this paper, the boundary-based finite element method (BFEM) is developed for the bending-extension coupling analysis of shear deformable laminated composite curved beams with non-uniform thickness. The curved beams are discretized into a series of uniform straight segments. Based upon the first order shear deformation theory and the reciprocal theorem of Betti and Rayleigh, the boundary integral equations (BIEs) associated with each beam segment are derived and expressed in explicit form. The fundamental solutions required in the BIEs are obtained explicitly from the associated Green's function. Since no singular integrals, numerical integrations and function interpolations are involved in the BIEs, our proposed BFEM provides an exact solution for a straight beam with uniform thickness, and only one single element with two end nodes is required for our analysis. Even only an approximate solution is provided for a curved beam with non-uniform thickness, BFEM converges faster than the conventional finite element method, and the results are in well agreement with those obtained by the commercial finite element software. Through the illustrated numerical examples, its generality is shown by: (1) stacking sequence of laminates: symmetric or unsymmetric; (2) beam geometries: straight, stepped, or curvilinear with uniform or non-uniform thickness; (3) loading types: axial force, transverse force and/or bending moment; distributed or concentrated; and (4) supporting conditions: clamped, simply supported, or free; with or without internal supports. • Incorporate with bending-extensional coupling and transverse shear deformations. • Develop BFEM for composite laminated curved beams with non-uniform thickness. • Solve all involved integrals and construct element stiffness matrices explicitly. • Derive explicit-form analytical solutions for straight uniform laminated beams. • Provide more efficient and accurate results than conventional finite element method. [ABSTRACT FROM AUTHOR]

Light weight steel-based panels are largely used for the envelope (walls, roofs) of different kind of buildings. They are typically designed from the weather-related conditions of the site (climatic actions, thermal comfort). Despite their low weight, they have adequate load carrying capacities under transverse loads. However, under extreme loading conditions, like the high intensity pressures associated with external explosions, the panels can be heavily damaged or detached from the structure. The study presented in the paper describes the results obtained on liner tray walls tested for transverse loading until complete failure. The test program included also shear tests on end fastenings. The liner trays were arranged as single span systems supported on side beams and loaded at the mid-span. After a quasi-linear response, the maximum flexural strength is reached. Then, due to a local instability, there is a drop in capacity, followed by an increase in response capacity due to development of catenary forces. If the end fasteners have adequate resistance, the ultimate capacity in the catenary stage can be significantly higher than the peak flexural capacity. The ultimate capacity depends also on the in-plane stiffness of the support columns. • Experimental assessment of liner tray wall panels in case of transverse loads. • 2 types of end support conditions, one with low in-plane stiffness and one with high in-plane stiffness were considered. • Increasing the number of end fasteners allows development of catenary forces. • Tests on liner trays confirmed the results on individual fasteners. • Easy to use Finite element models calibrated against test data. [ABSTRACT FROM AUTHOR]

Glued-laminated timber (GLT) is an efficient and renewable material with potential to enhance sustainability in construction, but its potential has been partly hindered by relatively large uncertainty related to its strength. Previous research indicate that by linking information from the grading process to the GLT fabrication more reliable GLT beams could be made. To this end, this paper represents a finite element based modelling approach combining a continuum damage model with sequentially linear analysis that is suitable for simulation of the bending stiffness and strength of GLT beams. The model has been implemented in Matlab and can be easily integrated into different parametric simulation workflows. Based on validation against 36 experimentally tested GLT beams, the model can predict bending stiffness with high accuracy and provides reasonably accurate predictions for bending strength. The model is also capable of producing qualitatively realistic fracture patterns of GLT beams. The mesh-size study suggests that the best agreement for bending strength with test data is obtained with a sparse mesh, which is discussed in detail. The model is considered suitable for follow-up studies involving the optimization of GLT beam layups. • A novel simulation approach for glued-laminated timber beams is presented. • The model has been validated against experimental data with good agreement. • The model can also qualitatively predict post-peak fracture behaviour. • Mesh-size effects are evaluated and suggestions based on findings are given. [ABSTRACT FROM AUTHOR]

Operational Modal Analysis (OMA) is a powerful approach to be used in structural performance assessment of historical masonry buildings during their service life. OMA is effective for detecting global damage to masonry buildings, although in some conditions it may exhibit poor sensitivity in detecting local/slight structural damage. Additionally, establishing robust correlations between changes in modal features and the residual load-bearing capacity of monitored buildings is an unresolved task in most of real-world applications. To deepen into these aspects, this paper presents an experimental and numerical program involving two full-scale masonry wall specimens tested under controlled laboratory conditions. Progressive damage was induced in diverse structural settings, and OMA was used to identify the modal features of the wall systems at increasing damage levels. Damage-induced decays in modal features were correlated with performance limit states related to the structures' residual load-bearing capacity, while non-linear Finite Element (FE) models were defined to replicate the tests. The obtained results contribute to filling current research gaps by demonstrating that natural frequencies and mode shapes can be sensitive to local and slight structural damage, also proposing correlations between damage-induced decays in modal features and performance limit states, hence corroborating the use of FE models for replicating damage-induced decays in both vibration frequencies and mode shapes. • Full-scale masonry walls are progressively damaged in diverse structural settings. • OMA is used to detect localized/small damage to the tested masonry buildings. • Modal features are found to be sensitive to the increasing damage entity. • Correlations are made between structures' modal features and load-bearing capacity. • FE models can accurately replicate damage-induced modifications in modal features. [ABSTRACT FROM AUTHOR]

Shear walls are widely used as lateral load-resisting systems in high-rise building structures. The design and nonlinear analysis of shear walls under seismic loads for recoverability are complicated and challenging, which demands nonlinear computer modeling procedures. This paper presents a novel finite element named Double Vertical Beam-column with Shell Element (DVBSE) for the nonlinear analysis of complex reinforced concrete shear walls with columns. The DVBSE is implemented in the open-source finite element program OpenSees. The theoretical formulations of DVBSE are described in detail. The accuracy of the developed DVBSE is established by comparing the finite element analysis results with existing experimental data on recoverable steel-GFRP composite bar reinforced concrete shear walls. The comparative study demonstrates that the proposed DVBSE is superior to the commonly used finite element model in simulating the responses of recoverable complex shear walls under seismic loads. These research findings contribute to further advancements in the development of new shear wall elements and lay a solid foundation for the nonlinear numerical simulation of innovative shear walls. • A new finite element DVBSE is developed for modeling shear walls under seismic loads. • The DVBSE incorporates vertical fiber-based beam-column elements and shell elements. • The DVBSE is implemented in the open-source finite element program OpenSees. • The accuracy of the DVBSE is verified by test results of recoverable complex shear walls. • The DVBSE offers an efficient approach to simulate the seismic behavior of shear walls. [ABSTRACT FROM AUTHOR]

This paper presents the application of a thick-shell nonlinear finite element analysis procedure to estimate the punching shear resisting performance of reinforced concrete slab-column connections under variable connection shear stress conditions. In the analyses performed, varied connection shear stress conditions stem from slabs being supported by columns with different cross-section aspect ratios, being subjected to different distributions of gravity loading, being constructed with different planar reinforcement ratios in orthogonal directions, as well as the application of unbalanced bending moments. Forty-eight isolated slab-column connection specimens presented in the literature were modelled and analyzed using a thick-shell finite analysis procedure. All numerical results were developed using a predefined set of material models and analysis parameters, a consistent meshing procedure, and are shown to provide meaningful agreement with experimental data without the need for case-specific model calibration or the adoption of specialised failure criteria. The results show that thick-shell modelling methods can be suitable for estimating the punching shear response of slabs subjected to non-uniform shear stress development in connection regions, and can provide similar levels of precision to that obtained for the analysis of idealised slab-column connections typically used for design procedure and model development. • Low-cost shell FEA for punching shear assessment of reinforced concrete flat plates. • Analysis of 45 non-idealised connection specimens representative of real-world construction. • Good agreement between FEA simulations and reported results without model calibration. • Result accuracy comparable to that obtained for more typical idealised connection specimens. [ABSTRACT FROM AUTHOR]

This paper presents a finite element (FE)-based reliability analysis of reinforced concrete masonry walls under eccentric axial loading, considering the slenderness effect. The main purpose is to (1) examine the importance of model error and (2) investigate the effect of different failure criteria on the reliability assessment of masonry walls. To achieve this goal, three representative walls with different slenderness ratios, designed in accordance with CSA S304–14 provisions, are selected for the reliability analysis. Finite element models of masonry walls are used to formulate the limit-state function for the reliability problems considered. A subset simulation algorithm in conjunction with Polynomial- Chaos-Kriging (PCK) surrogate models is used to address the computational cost involved in FE-based reliability analysis. It is found that the reliability assessment results are highly dependent on the model error. In addition, it is found that the local failure criteria are not always more conservative compared to global (wall) failure criteria due to stability failure, particularly for slender walls or walls designed with vertical loads at low eccentricities. Furthermore, it is found that other factors are found to influence the reliability assessment, including the slenderness ratio, load ratio, and eccentricity-to-thickness ratio, leading to reliability-inconsistent designs according to the current codes. • A macro finite element model is developed for the simulation of reinforced concrete masonry walls under eccentric axial loading considering slenderness effects. • Model error associated with the finite element model is quantified by compiling an experimental database. • Incorporation of model error is crucial for reliability analysis. • The influence of load eccentricity-to-thickness ratio, slenderness ratio, and load ratio on the reliability assessment is investigated. • The effects of different failure criteria (i.e., limit states) on the reliability assessment are studied. [ABSTRACT FROM AUTHOR]

This paper presents experimental and numerical investigations into the web crippling behaviour and load-carrying capacity of stainless steel built-up I-section members under End-Two-Flange (ETF) concentrated transverse loading. An experimental programme was conducted on 23 austenitic and duplex stainless steel built-up I-section specimens, with each consisting of two identical press-braked channel sections assembled back-to-back by means of self-tapping screws. Following the experimental programme, a numerical modelling programme was performed, where finite element models were firstly developed to replicate the tests and then used to conduct parametric studies. Based on the test and numerical data, the existing design rules for stainless steel built-up I-section members failing by web crippling, as set out in the current European, American and Australian/New Zealand design standards, were assessed. The comparisons indicated that the European and Australian/New Zealand design standards resulted in overly conservative and rather scattered failure load predictions, while the American design standard led to less scattered failure load predictions, but with many predictions on the unsafe side. Therefore, an improved design approach was proposed and shown to provide substantially improved failure load predictions for stainless steel built-up I-section members under End-Two-Flange loading. • The web crippling behaviour of stainless steel built-up I-sections under ETF loading was studied. • Tests were conducted on 23 stainless steel built-up I-section specimens. • FE models were developed and validated against test results and then used for parametric studies. • The existing codified design rules were assessed and a new design approach was proposed. [ABSTRACT FROM AUTHOR]

This paper presents an investigation into the free vibration and nonlinear dynamic analyses of new complex edge contour plate structures, known as single-variable-edge (SVE) plates. Cracks emerge at the center of the plate's surface, and the effects of edge crack orientation and depth on the dynamical characteristics of the laminated nanocomposite SVE plates have been considered in this study. The functionally graded graphene nanoplatelet reinforced composite (FG-GPLRC) material was utilized for the edge-cracked plate that rests on a Winker-Pasternak elastic foundation. The Halpin-Tsai micromechanical model is used to predict the material characteristics, which are presumptively temperature-dependent. The rule of mixtures is employed to determine Poisson's ratio, density mass, and thermal expansion. The governing equations are established based on the theory of elasticity, and Von Karman-Donnell geometric nonlinearity assumption. To confirm the reliability and accuracy of this approach, the acquired findings are validated with those produced using Finite Element Analysis (FEA). Furthermore, the geometrical and material parameters, fracture properties, and environmental (temperature and elastic foundation) factors are also investigated in the study. The research findings hold significant implications for applications in aerospace and aeronautical, civil, and mechanical engineering. • The crack orientation and depth have been built in laminated nanocomposite structure. • The dynamics of cracked complex plates have been scrutinized in two aspects: linear and nonlinear responses. • The periodic and chaotic status of the complex structure in critical points have been investigated. [ABSTRACT FROM AUTHOR]

This paper studies the novel vibration control of an inerter-enhanced mega sub-controlled structure system (MSCSS). The seismic response of MSCSS is investigated using a tuned viscous mass damper inerter (TVMDI) and compared with existing control methods. This novel strategy evaluates two kinds of TVMDIs on MSCSS, including the inter-story TVMDI, where the TVMDIs are installed inter-story, and the outrigger-based TVMDI, where the TVMDIs are vertically connected between the outrigger and the perimeter of the MSCSS's column to achieve significant energy dissipation. First, a finite element model of MSCSS is established and validated with the experimental model of MSCSS. The governing equation of the enhanced MSCSS is derived from the uncontrolled model. Subsequently, the MSCSS equipped with TVMDIs is thoroughly examined and compared to the existing methods. The effectiveness of the proposed strategy subject to ground motion records via the numerical analysis method is also demonstrated. Finally, the reliability analysis of the enhanced MSCSS based on the probability density function is presented. Results from the numerical investigation of the MSCSS enhanced strategies have revealed that the inter-story and outrigger TVMDI system generally improved the response effectiveness of MSCSS better than the viscous damper (VD) and middle story isolation (MSI) systems. However, the outrigger TVMDI enhanced mega frames control effectiveness more effectively than the story-based TVMDI, whereas the latter is more suitable for substructures. ● The novel vibration control of an inerter-based enhanced MSCSS is studied. ● An uncontrolled FEM of MSCS is presented and validated with the experimental model. ● The dynamic equation of MSCS equipped with TVMD is derived from uncontrolled model. ● The proposed strategies is examined and compared to the existing control methods. ● The reliability analysis of the TVMD-enhanced MSCSS based on the PDF is presented. [ABSTRACT FROM AUTHOR]

Headed stud shear connectors are commonly implemented in steel-concrete composite floors for connecting the concrete slab to the steel beam and providing composite action between those two elements. The orientation of profiled sheeting is usually transverse or parallel to the supporting beam, and for those cases, design codes provide specific detailing requests and relations for obtaining headed stud resistance. Nevertheless, design codes do not recognise specific configurations when the angle between profiled sheeting ribs and the beam is in the range between 0° and 90°, which is characteristic of irregular-shaped floor structures. Due to the lack of design recommendations for headed stud resistance in these cases, investigations of the effect of the rib-to-beam angle on headed stud shear performance were conducted and presented in this paper. Experimental work included push-out tests conducted on specimens with rib-to-beam angles of 45° and 60°, as well as control specimens with ribs transverse to the beam. The influence of varied rib-to-beam angles on shear connector properties such as shear resistance, stiffness, ductility, and failure mode was discussed. According to experimental research, finite element models of push-out tests were created and verified. The parametric numerical analysis covered key parameters such as concrete class, headed stud height and diameter, and rib-to-beam angle. According to the results, an analytical relation for obtaining headed stud resistance in profiled steel sheeting with a rib-to-beam angle between 30° and 90° was proposed. • Rib-to-beam angles between 0° and 90° in steel-concrete composite beams. • Experimental push-out tests on headed studs with rib-to-beam angles of 45° and 60°. • Development of finite element numerical models. • Parametric study for different rib-to-beam angles, concrete classes and stud geometry. • Analytical relation for stud resistance for varied rib-to-beam angles. [ABSTRACT FROM AUTHOR]

This paper presents the experimental and numerical results of an ongoing research project on the use of thermal break systems (TBSs) in internally insulated reinforced concrete (RC) structures. A new TBS, which combines steel profiles and U-shaped steel bars, is introduced and tested under monotonic loading to determine its horizontal and vertical shear capacities. The test results confirmed the appropriateness of SLABE-TBS for use in exterior wall–slab joints that demand high ductility or energy absorption despite the failure mode by concrete punching. The tested joints exhibited load-carrying capacities of 190.2 and 120.5 kN/m under horizontal and vertical loading, respectively. On the other hand, the finite element analysis performed using LS-DYNA software confirmed the significance of the U-shaped steel bars of the SLABE-TBS in improving the joint's shear capacity. However, incorporating the steel bars in the SLABE unit can reduce the equivalent stresses in the adjacent steel profiles by 33 %. • A new thermal break system (SLABE-ZN) for exterior wall–slab joints was proposed. • The tested exterior joints equipped with SLABE-ZN exhibited stable behavior under horizontal and vertical loading. • Incorporating steel bars in the SLABE unit can reduce the equivalent stresses in adjacent steel profiles by 33 %. • The contribution of the U-steel bars was approximately 30 % and 21 % under horizontal and vertical loading, respectively. • Decreasing the insulation thickness by 10 mm accounts for a 7 % increase in the load-carrying capacity of the SLABE system. [ABSTRACT FROM AUTHOR]

The development of a bonded glass-steel element that is capable to i) transfer out-of-plane loads due to wind loads in transverse direction, ii) in-plane shear loads, due to wind in longitudinal direction and iii) in-plane compression due to self-weight implies that the structural continuous adhesive glass-metal connection becomes an integral part of the entire bonded glass-steel unit. The frame members are restrained by the joint-glass system due to the glass bonded to the steel frame. To assess the capability of continuous adhesive glass-steel connections to transfer the abovementioned loads, research is indispensable. The available knowledge on the capacity of glass panes used as structural bracing element in steel frames is limited. This paper reports about the structural performance of welded steel corners, both not bonded and bonded with glass panes, to assess the in-plane load-bearing capacity of these connections. In a first experimental phase tests on welded steel corners with different configurations are conducted, whilst during the second phase specimens bonded with glass panes on both sides are tested. Numerical models are developed and validated based on the experimental results, which are then used for parametric studies. As such, the rotational stiffness of semi-rigid welded steel corner configurations and the additional stiffness obtained by bonded glass panes can be determined. The results demonstrated that the specimens with adhesively bonded glass panes on both sides using the structural silicones Sikasil® SG-500 and DowSil™ 993, and the hybrid polymer adhesive Soudaseal 2 K, significantly increased the initial rotational stiffness of the welded steel corners. Specimens bonded with the hybrid polymer adhesive behave significantly stiffer than specimens bonded with the structural silicones. Parametric studies on validated finite element models reveal that the effect of the glass thickness is important for low values of the adhesive thickness. The width-to-thickness ratio of the adhesive layer largely influences the value of the rotational stiffness of the connection. The generated data by the numerical models can now be implemented in analytical models for the calculation of steel structures with semi-rigid joints. • Continuous adhesive glass-metal connections using three adhesives are investigated. • The rotational in-plane stiffness is experimentally determined for (un)bonded specimens. • Analytical analyses allowed the validation of the experimental results. • Finite element models were validated and used for parametric studies. • The results can be used for the calculation of (bonded) steel structures with semi-rigid joints. [ABSTRACT FROM AUTHOR]

This paper studied the axial compression behavior of the steel tube reinforced concrete (STRC) column, which consisted of inner CFST and outer RC components. Ten specimens, including seven STRC columns, two RC columns, and one CFST column were tested. The test parameters included the CFST area ratio (inner CFST to the whole section), longitudinal rebar ratio and stirrup space. The test results showed that the compressive behavior of STRC column with a CFST area ratio of 0.04 was close to that of the RC column, and the compressive behavior of the STRC column with a CFST area ratio of 0.13 was between that of the RC column and CFST column. The finite element (FE) models were developed and verified by test results to investigate the effects of longitudinal rebar ratio and stirrup space on the axial compression behavior of STRC column with various CFST area ratios. The load distribution between inner CFST and outer RC components was analyzed. The FE results showed that the effects of the longitudinal rebar ratio on the ultimate load of STRC column were related to the CFST area ratio. The accuracy and applicability of the five methods suggested by codes for predicting the ultimate load of STRC column were discussed based on the test and FE results. • The compression test of steel tube reinforced concrete (STRC) column with low CFST area ratio was firstly carried out. • The influences of both CFST area ratio and longitudinal rebar ratio on ultimate strength of STRC column were discussed. • The refined finite element model of STRC column for parameter analysis is established. • The five methods of codes for ultimate strength of STRC column was calculated and discussed. [ABSTRACT FROM AUTHOR]

Despite the extensive investigations on the shear strengthening of reinforced concrete (RC) beams using externally bonded fiber-reinforced polymer (EB-FRP) composites, the critical problem of how the skew angle (angle between FRP and crack opening direction) influences the bond capacity of FRP has drawn little concern and remains unsolved. This paper presents the first three-dimensional (3D) finite element (FE) model for studying the failure of skew FRP-bonded concrete joints. The concrete was simulated using the concrete damaged plasticity model, and the FRP was modeled as an orthotropic material equipped with the LARC05 model as the damage criterion. The FRP-to-concrete interface was described using a linear elastic cohesive law. The 3D FE model, which provided a relatively large convergent mesh size of 2.5 mm, was calibrated and validated using the bond tests of aligned and skew FRPs. Both the tests and FE results revealed a notable decrease in the bond capacity of FRP at the skew angle of 45°. The parametric analysis demonstrated that the adverse skew effect was reduced when the FRP width increased or FRP thickness decreased, by delaying the onset of the stable peeling-off of concrete along the FRP fiber axis. Compared with FRP, steel plate suffered less from the skew effect, due to its isotropic nature. This study can provide valuable implications for more effective shear-strengthening methods of RC beams and facilitate novel insights for the development of more robust design models. The 3D FE framework can also serve as a versatile tool for analyzing the complicated failure modes of various FRP-strengthened concrete systems. • A three-dimensional FE model was developed for skew FRP-bonded concrete joints. • Non-zero skew angles could reduce notably the peak axial load of FRP during pullout. • The FRP bond width and FRP thickness have a significant impact on the skew effect. • Steel plates suffered less from the adverse skew effect due to its isotropic nature. • Regularized compressive stress-strain law is vital in CDPM for tension-shear failure. [ABSTRACT FROM AUTHOR]

This paper presents a study on the axial compression performance of trussed concrete-filled steel tubular (CFST) hybrid structures. A total of 26 specimens were tested, including 15 circular and 11 square cross-sectional specimens. The effects of cross-sectional types, yield strength of steel of CFST chord, web types, number of chords, and equivalent slenderness ratio were investigated to clarify the mechanical behavior of trussed structure. The analyses of the full-range response, the typical failure mode, and the distribution of the transverse deflection and strain of the structures were carried out. A finite element analysis (FEA) modelling of trussed CFST structure was established and validated against the experimental results. Through the numerical simulation, the analysis of the internal force and stress was conducted, and the hybrid effect between the web and CFST chord was revealed. Based on parameter analysis, the design calculation was proposed, and the trussed CFST hybrid structure was equivalent to a single CFST to calculate its load-bearing capacity by introducing equivalent slenderness ratio proposed. ● A total of 26 specimens were tested, including 15 circular and 11 square cross-sectional specimens. ● The influences of critical factors of trussed CFST hybrid structure were investigated. ● A FEA modelling for trussed CFST hybrid structure subjected to axial compression was established and validated. ● Design calculation for trussed CFST hybrid structure were proposed and carefully verified. [ABSTRACT FROM AUTHOR]

This paper presents a stochastic methodology to perform time-dependent seismic fragility analysis for reinforced concrete (RC) columns subjected to chloride attacks. Numerical modelling methods considering the increasing variability of reinforcement mechanical properties were proposed based on the stochastic constitutive model for corroded steel bars. Depending on the finite element model validated by test data for uncorroded and corroded RC columns, two novel stochastic cases and a traditional deterministic case were introduced and then applied to pushover analysis, incremental dynamic analysis and seismic fragility analysis. The results of damage limit states (DLSs) determined by stochastic pushover curves indicated that the seismic capacity/DLSs for columns along the service life were time-dependent and followed lognormal distributions. The incremental dynamic analysis curves and seismic fragility curves implied that chloride-induced corrosion typically led to a substantial increase in the failure probability of columns. In comparison with the correlated stochastic method, considerable underestimations of component level fragility across different damage limit states were obtained using the deterministic approach, which highlighted the importance of accounting for the variability of mechanical properties of corroded steel bars in the time-dependent seismic fragility analysis. • The increasing variability of reinforcement mechanical properties was considered. • The distributions of time-dependent damage limit state were developed. • Stochastic methods were presented in time-dependent seismic fragility analysis. [ABSTRACT FROM AUTHOR]

In this paper, a composite column using carbon fibre reinforced plastics and polyvinyl chloride composite tube (CFRP-PVC) to constrain coral aggregate seawater sea-sand concrete (CSSC) was proposed, and CFRP was pasted on the inner and outer walls of the PVC tube. To investigate the effects of the number of CFRP layers and void defects on the axial compression performance of PVC tubes, six specimens were made for axial compression loading tests and finite element parameter analysis. The results indicate that due to PVC improving the integrity of CFRP, PVC tube provide a stress transfer path for CFRP, placing CSSC in a triaxial compression state. When both the inner and outer walls of the tube are pasted with CFRP, brittle failure of CFRP-PVC tube can be effectively avoided and have relatively superior mechanical properties. In the same situation, when one layer of CFRP is pasted on the inner wall of the tube, it has better ductility and bearing capacity. When two layers of CFRP are pasted on the outer wall of the tube, the coefficient of constraint stress increase is as high as 121.5%, and the void defect only has a significant impact on ductility. A finite element model of CFRP-PVC confined CSSC columns considering Hashin damage criterion was established based on ABAQUS, accurately predicting the failure process and CFRP damage morphology of test columns under axial load. Parameter analysis shows that when the confinement coefficient of CFRP-PVC confined CSSC columns is less than 0.3 and the height-diameter ratio is greater than 15, the load-displacement curve will lose the strengthening stage, and increasing the number of outer CFRP layers will slightly increase the stiffness of the strengthening stage. A bearing capacity calculation method suitable for CFRP-PVC confined CSSC was proposed based on the model of steel tube confined concrete, with an error of 1.2%. ● CFRP-PVC tube confined coral aggregate seawater sea-sand concrete (CSSC) column was proposed. ● The axial compression test was conducted to explore the mechanical properties of CFRP-PVC confined CSSC columns. ● The finite element models of the CFRP-PVC confined CSSC column were established to conduct parametric investigation. ● The axial strength calculation method of CFRP-PVC confined CSSC columns was proposed considering the CFRP-PVC tube restraint efficiency. [ABSTRACT FROM AUTHOR]

Duplex stainless steel (DSS) is an emerging construction material for structural engineering, which is featured with high mechanical strength and superior corrosion resistance. Compared with considerable research on DSS structural members, available research is relatively limited for structural joints/connections between these members. In line with this concern, this paper presents a comprehensive experimental and numerical study of duplex stainless steel bolted connections (DSSBCs), focusing on the behaviour and design related to block shear failure. Eleven specimens are tested to investigate the effect of different bolt arrangements on the block shear behaviour. Furthermore, a detailed numerical study was performed as a supplement to the experimental tests, where the anisotropic mechanical properties of DSS are considered in the finite element modelling. Based on the test and analysis results, it is found that the block shear failure mode of DSSBCs resembles that of carbon steel bolted connections, which can be characterised as necking of the tensile section and yielding of the shear sections. Using the experimental and numerical data obtained in this and previous studies, the applicability of various block shear design methods to stainless steel bolted connections is assessed. An updated design method is proposed for predicting the block shear capacity of duplex and austenitic stainless steel bolted connections. A proper partial safety factor/resistance factor is suggested for the proposed method based on the results of reliability analyses. • Block shear of duplex stainless steel bolted connections (DSSBCs) are studied. • DSSBCs exhibit similar block shear mode to carbon steel bolted connections. • Existing design methods are evaluated for stainless steel bolted connections. • A modified method is proposed for stainless steel bolted connections. • A reliability analysis is performed to provide suggestion of partial factor. [ABSTRACT FROM AUTHOR]

The cable-strut structures have the features of low stiffness and weak damping, resulting in large vibration response under dynamic excitation. The vibration response of the cable-strut structures can be reduced by active control methods. However, many traditional active control methods need to build a state-space model (SSM) based on finite element model (FEM), and solving the active control force for the high-dimensional SSM is time-consuming. In this paper, the dynamic mode decomposition with control (DMDc) method is proposed to achieve a data-driven reduced-order SSM for active vibration control of cable-strut structures. This proposed method only uses the data of structural response and control force input to build reduced-order SSM and does not rely on the FEM. Linear quadratic regulator (LQR) design using the DMDc-based reduced-order SSM (DMDc-LQR) is more computationally efficient than that using the FEM-based SSM (FEM-LQR). The relationship between the design parameters of the DMDc-LQR controller and the FEM-LQR controller is established, which ensures that the control performance indexes of the DMDc-LQR controller and the FEM-LQR controller are equal. The effectiveness of the proposed DMDc-LQR method is validated using numerical Kiewitt cable dome and tensegrity grid under wind and seismic loads. The results show that the DMDc-LQR controller maintains similar control effect to that of the FEM-LQR controller and has advantage of high computing efficiency as well. In addition, the influence of critical parameters (i.e., data noise and model order) on vibration control effect is comprehensively explored. It is found that increasing the model order is effective to mitigate the noise influence on the DMDc-based reduced-order SSM and ensures the effectiveness of the DMDc-LQR controller. • A data-driven reduced-order state-space model (SSM) method is proposed. • The linear quadratic regulator (LQR) is designed based on reduced-order SSM. • The control effect and design efficiency of two LQR controllers are discussed. • The influence of noise and model order on the vibration control effect is explored. [ABSTRACT FROM AUTHOR]

This paper presents experimental and numerical investigations into the post-fire cross-section compressive behaviour and resistances of circular recycled aggregate concrete-filled stainless steel tube (RACFSST) stub columns. Twelve stub column specimens, fabricated from concretes with three recycled coarse aggregate replacement ratios (0%, 35% and 70%), were tested after exposure to the ISO-834 standard fire for 0 min (i.e. at ambient temperature), 15 min, 30 min and 45 min. The experimental investigation included heating and cooling of specimens, cylinder tests and post-fire tensile coupon tests and stub column tests. The test results, including load–end shortening curves, failure loads and failure modes, were fully reported and the initial compressive stiffnesses and confinement effect were discussed. The numerical investigation was subsequently conducted, where thermal and mechanical finite element models were developed and validated against the test results and then used to perform parametric studies to generate further numerical data. Given the absence of design codes for stainless steel–recycled aggregate concrete composite structures after exposure to fire, the relevant design rules for circular natural aggregate concrete-filled carbon steel tube stub columns at ambient temperature, as set out in the European code, Australia/New Zealand standard and American specification, were assessed, using post-fire material properties, for their applicability to circular RACFSST stub columns after exposure to fire, based on the test and numerical data. The assessment results generally revealed that the European code and the Australian/New Zealand standard led to an acceptable level of design accuracy and consistency, while the American specification resulted in rather conservative and scattered post-fire cross-section compression resistance predictions. • The compressive behaviour of circular RACFSST stub columns after exposure to fire is investigated. • Post-fire compression tests on twelve circular RACFSST stub column specimens are conducted. • The influences of heating durations and RCA replacement ratios are analysed. • Thermal and mechanical FE models are validated against test results and then used to conduct parametric studies. • The relevant design codes are assessed against the test and FE data. [ABSTRACT FROM AUTHOR]

The use of cold-formed steel (CFS) built-up sections in engineering practice is widely gaining popularity due to their ability to provide sustainable solutions and optimised section design opportunities. This paper presents an experimental and numerical investigation conducted on CFS built-up stiffened box section columns under axial compression. A total of 13 new experimental tests were conducted with specimens having an overall web depth up to 550 mm. Detailed nonlinear elasto-plastic finite element (FE) models were then developed and verified against the test results. Upon verification, a parametric study involving 144 FE models was carried out to investigate the effects of section thickness, column length, and screw spacing on the buckling resistance of CFS built-up stiffened box sections. The test and finite element analysis (FEA) results were compared with the buckling resistances determined by the American Iron and Steel Institute (AISI S100) and Australian and New Zealand Standards (AS/NZS 4600). It was found that the buckling resistances determined by the AISI S100 and AS/NZS 4600 for CFS built-up stiffened box sections were conservative by 9.3% on average, compared to experimental and FEA results. Modified Direct Strength Method (DSM) design equations for predicting the buckling resistances of CFS built-up stiffened box sections were then proposed, and a reliability analysis was conducted to assess the feasibility of the proposed equations. • Buckling resistance of axially loaded CFS built-up stiffened box sections was studied experimentally and numerically. • A nonlinear finite element model was developed and validated against the test results. • A parametric study was conducted to investigate the effects of different parameters. • Assessment of the current design guidelines was conducted. • New design equations for predicting the buckling resistance were proposed. [ABSTRACT FROM AUTHOR]