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Highlights • Shear capacity of RC voided (V) slabs and TUBEDECK (TD) slabs is investigated. • Web-shear cracking did not affect the shear design of V and TD slabs. • Based on the real cross-sectional area, a shear strength prediction equation is proposed. • A moment–shear interaction design model for TD slabs is suggested. Abstract In order to improve structural efficiency, environmental performance, and constructability, a new type of one-way composite voided slab system (TUBEDECK) has been recently proposed which combines profiled steel decks with cast-in-situ RC slabs. Because eliminating concrete volume to optimize flexural strength can significantly reduce the shear strength of nonprestressed concrete or composite slabs without shear reinforcement, a clarification of the shear resistance capacity is required. In this study, shear tests on a total of 12 specimens were conducted with slab thickness, the presence or absence of voids and/or steel decks, and tension reinforcement ratio as variables. The results show that combined flexure and shear dominated the behavior of both voided (V) slabs and TUBEDECK (TD) slabs, and web-shear cracking did not affect strength. Predicted shear strength based on the minimum web width was too conservative. Conversely, the shear strength prediction equations, which were proposed on the basis of the real cross-sectional area of concrete, predicted the capacity of both V slabs and TD slabs from a reasonably conservative perspective. A discussion on the influence of moment–shear interaction is also included, and an interaction design model is proposed in a further investigation. [ABSTRACT FROM AUTHOR]

• A new type of CFS wall sheathed with paper straw board is proposed. • The characteristic values of the bearing capacity, lateral stiffness, ductility coefficient and energy dissipation coefficient of CFSSB wall are obtained. • Factors affecting the shear capacity of CFSSSB composite walls are investigated. • A design formula is proposed to predicting shear capacity of CFSSB walls. To explore the application of environmental protection material-paper straw board in cold-formed thin-walled steel (CFS) structures and further develop the sheathing system, an innovative CFS framing wall sheathed by paper straw board (CFSSB) is proposed. Eight CFSSB composite wall specimens and one CFS frame without sheathing were tested under monotonic and reversed cyclic horizontal loads to study the shear performance of the CFSSB composite wall. Also, the shear performance of the wall specimens can be obtained. The key parameters include the value of the vertical load and the form of the CFS frame in this experimental program. By analyzing the specimen's failure forms and failure process, the characteristic values of the bearing capacity, lateral stiffness, ductility coefficient and energy dissipation coefficient are obtained. The results show that the existence of paper straw board and adding diagonal braces to the CFS frame can significantly improve the shear capacity of CFSSB composite walls. The favorable seismic performance of the CFSSB composite wall was demonstrated in the experiment. In addition, a finite element model for CFSSB composite wall is developed using the software package ANSYS. The finite element analysis (FEA) results show a good agreement with the experiment results in terms of failure modes and skeleton curves, which verify the feasibility of the FEA model. Furthermore, extensive parametric analysis was carried out to analyze the factors affecting the shear capacity of the CFSSB composite wall. The FEA results show that the spacing of studs and self-tapping screws greatly influences the shear capacity of walls. Moreover, based on the failure of the screw connections, a formula for calculating the shear capacity of the CFSSB composite wall is proposed. The results of the formula calculation show good agreement with the experiment and FEA results, and it can provide a reference for engineering design. [ABSTRACT FROM AUTHOR]

Abstract: Measurement of short-term and long-term deflections is a necessary step towards understanding and evaluating the status of a bridge. In this paper, a novel non-contact weighted-stretched-wire (NCWSW) system is developed for measuring the deflection of a bridge. Also some factors related to the system are addressed. The proposed system is promising due to some attractive features such as high precision, low implementation cost and suitability for continuous monitoring. The efficiency and reliability of NCWSW system are investigated both analytically and experimentally. A realistic NCWSW system has been used in the monitoring of a real-world bridge. [Copyright &y& Elsevier]

• The design of the blower allows to use it in micro-jet module in the paper machine. • Control of the blower efficiency, fumes pressure and temperature was achieved. • High pressure of the medium with a high temperature of up to 500 °C was obtained. The article describes the project, strength calculations and construction optimization of a fan development, and its application in the blower, which was used for research of experimental, micro-jet blowing system, that regulates the moisture profile of the paper web. The blower was designed to compress to positive gauge pressure of 0.4 bar of fumes at a temperature of up to 500 °C with capacity of 1 m3/s. To meet these requirements, the blower was realized as an aggregate of four identical radial fans connected in series. Achieving the assumed pressure ratio for a single fan required the development of a specific rotor design and the use of steel with very good strength parameters at high operating temperatures. The fan was made in four copies and assembled into a prototype blower system for blowing fumes, which was successfully used in an experimental blower system for adjusting the cross profile of the web's moisture content in a paper machine. [ABSTRACT FROM AUTHOR]

This paper presented an innovative uplift-restraining friction pendulum bearing (UR-FPB) to address the limitations of traditional FPBs, which are unable to withstand vertical tensile loads. The UR-FPB is composed of a friction set acting as the horizontal sliding module and an anti-uplift set acting as the vertical uplift-restraining module. Based on this configuration, the study derived the theoretical force-displacement relationships of the UR-FPB, established three solid finite element models in Abaqus, and proposed a hybrid modeling method based on OpenSees. Then the practical effectiveness of this bearing and the credibility of the theoretical analysis models and hybrid numerical models were validated. The theoretical and numerical results demonstrate that the frictional behavior of the UR-FPB in horizontal sliding is characterized by multi-stage hysteresis relationships. The numerical results on the sliding characteristics and the corresponding hysteresis relationships are highly consistent with the theoretical results. The UR-FPB has a large horizontal sliding capacity similar to that of traditional FPBs, while the design of the anti-uplift configuration does not reduce or limit this sliding capacity. Significantly, the study investigated the uplift-restraining behavior of the UR-FPB and its effect on the horizontal responses. The analysis results suggest that the UR-FPB has a good uplift-prevention capacity and this paper recommends that the design value of tensile capacity should not exceed the yield force in tension. Therefore, this novel uplift-restraining friction bearing has an expected effectiveness, which can simultaneously resist vertical tensile loads and function as a horizontal seismic isolator. The proposed hybrid modeling method may provide a useful reference to model the behavior of the UR-FPB in software used for response-history analysis. • The study develops an innovative uplift‐restraining friction pendulum bearing (UR-FPB). • Three solid finite element models of the UR-FPB are established. • A hybrid modeling method for the UR-FPB is proposed based on OpenSees. • Theoretical analysis models and hybrid numerical models are validated. • This bearing exhibits excellent three-dimensional mechanical behaviors. [ABSTRACT FROM AUTHOR]

Shear wall structures are widely used in high-rise buildings. However, the design process of shear wall structures suffers from inefficiencies. This paper introduces StructDiffusion, an end-to-end intelligent system for shear wall layout generation and analysis. The proposed approach tackles the layout design task by employing a novel diffusion model architecture to generate conditional images. Key components of the proposed method include pretrained diffusion models, ControlNet for conditional control, and LoRA for efficient adaptation. Notably, the method allows for architectural plan images and basic textual design conditions as inputs, enabling manipulation of the generated layouts by adjusting attributes such as building height and seismic intensity. To evaluate the quality of the model's design swiftly, this paper presents a comprehensive evaluation framework that incorporates perceptual and structural validity metrics. Through experimental analyses, this paper demonstrates the effectiveness of the proposed model in generating layouts, surpassing the capabilities of GAN-based methods. Furthermore, our study investigates model-specific parameter configuration, text-guided capabilities, code compliance, and computational efficiency. StructDiffusion significantly enhances the automation and intelligence of structural engineering workflows. The framework effectively addresses challenges associated with instability, data scarcity, and limitations in assessment. This pioneering application of diffusion models opens up promising avenues for advancing data-driven structural design. • Pioneering stable diffusion models to replicate human structural design expertise. • Generating tailored layouts by aligning text-based design conditions and image-based architectural layouts. • Integrating LoRA, a low-rank decomposition technique, to optimize training efficiency with limited data. • Proposing an evaluation metric combining image quality and structural design considerations for robust model assessment. [ABSTRACT FROM AUTHOR]

Rammed earth is a traditional construction technique that has recently gained attention because of its benefits from an ecological perspective. The conservation of the existing valuable cultural heritage sites and the quality control of new constructions built with this material require the development and application of practical inspection techniques. This paper explores the application of sonic tests and sonic tomography as practical tools for monitoring the state of conservation of existing structures and the identification of heterogeneities or damaged areas. Two groups of 6 rammed earth specimens were manufactured and tested. The manufacturing process of each group allowed the application of compression loads and the identification of the Sonic Wave Propagation Velocities along directions parallel and perpendicular to the compaction forces during manufacturing. The SWPV were identified for the different paths between 9 measuring points located at two opposite sides of the specimens, leading to up to 6 different planes for each specimen. The SWPV are identified by identifying the Time-of-Flight of the elastic wave between each pair of excitation and receiver points. A discretized coloured map of the SWPV distribution for each plane defined by the measurement points array is obtained by the application of an algorithm already developed by the authors to obtain tomographic images for other materials and applications. The SWPV are identified after 2 different increasing values of a uniform compressive load is applied to each specimen. The results show that the analysis of the SWPV and tomographic images is sensitive to heterogeneities, such as compaction gradients from the manufacturing process, and also to the accumulated damage in the solid. The paper demonstrates that the proposed technique can be potentially used for a qualitative inspection of the state of conservation of specific rammed earth constructions. • Sonic wave propagation velocities (SWPV) are identified for different directions. • SWPV maps are obtained following a transmission tomography approach. • Estimated values of SWPV at 3 horizontal and 3 vertical planes are analysed. • SWPV are sensitive to progressive damage and compaction gradients. • No material anisotropy is found according to SWPV values. [ABSTRACT FROM AUTHOR]

The low-temperature brittle failure of materials could aggravate the brittle characteristics of shear failure of RC beams, which urgently needs scientific research. This paper aims to investigate the shear behavior and corresponding size effect of reinforced concrete (RC) beams at low temperature by numerical analysis. Firstly, a two-stage thermo-mechanical coupled mesoscale simulation method was developed, which considered the meso-structure characteristics of concrete as well as the ice-strengthening effect. Based on the mesoscale simulation method validated through a series of tests, the progressive shear failure process of RC beams at room and low temperatures was captured. The influences of temperature (T = 20, −30, −60 and −90 °C), structural size (cross-sectional height H = 300, 600, and 1200 mm) and shear span-to-depth ratio (a / h 0 = 1.0, 1.6, and 2.3) on key indexes of shear behavior were quantitatively analysed. The results indicate that compared to that at room temperature, the shear failure process of RC beams at low temperature is more rapid, exhibiting more obvious brittle characteristic. When the temperature drops from 20 °C to −90 °C, the nominal shear strength of RC beams is enhanced with a maximum increase of 57.0 % (for H = 300 mm) while the mid-span displacement is reduced with a maximum decrease of 46.8 % (for H = 300 mm). Compared to that at room temperature, the size effect on nominal shear strength of RC beams at low temperature is enhanced, with a maximum increase of 20.4 %. Finally, considering the influences of low temperature and shear span-to-depth ratio on the nominal shear strength, an improved size effect analytical model for was established, which can predict the shear capacity of different sized RC beams at low temperatures. This paper can provide a reference for the safe application of reinforced concrete structures in low temperature environments, and lay a foundation for the formulation of reinforced concrete structure design specifications at low temperature. • The shear behavior of RC beams at low temperature was modeled by 3D mesoscale model. • The meso-structure characteristics and ice-strengthening effect was considered in model. • The influences of low temperature and size characteristics of RC beams were investigated. • An improved size effect theoretical formula of RC beams at low temperature was established. [ABSTRACT FROM AUTHOR]

This paper aims to comprehensively discuss the latest research developments in the field of underwater structural defect detection and health assessment. The underwater robots can carry the non-contact detection equipment such as optical and acoustic devices, as well as the contact-based detection equipment like ultrasonic instruments, making them important platforms for underwater structural detection methods/tools. This paper first introduces the current progress of underwater robots in the underwater structural detection, elucidating the research progress in autonomous and intelligent path planning algorithms for underwater robots. It discusses the advantages and disadvantages of non-contact defect detection methods for underwater structures based on optics and acoustics, as well as their adaptability to different detection objects and requirements. The research also investigates contact-based underwater defect detection methods and points out the limitations of such methods. It summarizes methods for the three-dimensional (3D) reconstruction using underwater images or video data, laying the foundation for precise localization and quantitative analysis of underwater structural defects. It discusses the mainstream methods for assessing the health of underwater structures, highlighting the shortcomings of existing methods. Finally, it identifies the challenges and future trends facing current underwater structural defect detection methods, providing direction for future research in the intelligent underwater structural detection and assessment. • This paper investigates the research status in underwater structure detection, and proposes future development directions. • This paper provides a comprehensive review of non-contact and contact based underwater structure detection methods. • This paper provides a comprehensive summary of the assessment methods and research directions for underwater structures. [ABSTRACT FROM AUTHOR]

Full-depth precast deck panels hold the potential to enhance constructability and productivity, and reduce the costs associated with highway bridges. This paper investigates the influence of discontinuous shear connections between girders and panels on the flexural behaviour of composite beams. Experimental findings from precast composite beams and direct shear tests are presented, including L-shape push-off tests and double shear tests to determine resistance at rough concrete-to-concrete plain interfaces and shear pocket connections. Composite beams with a full-depth precast slab connected through a shear pocket with shear keys into the upper face of a precast beam exhibit equivalent flexural resistance to monolithic beams when shear pocket spacing remains below the effective depth of the composite beam. However, composite beams with shear pockets featuring plain interfaces show a reduction in flexural resistance of up to 30% compared to monolithic beams. Moreover, composite beams with shear keys demonstrate interface shear stiffness up to four times greater than those with plain interfaces, indicating full interaction. The paper proposes simplified equations to estimate flexural resistance for composite beams with full-depth precast slabs joined by shear pockets, showing a coefficient of variation of only 12% compared to experimental results, offering a reliable method for predicting flexural resistance in composite beams with discontinuous connections. • An empirical equation derived from direct shear tests is proposed for rough plane surfaces. • Two types and spacing of shear pockets in composite beam were analysed. • Composite beams with shear keys exhibit high interface shear stiffness. • Under cyclic loading, composite beams with shear keys demonstrate minimal stiffness loss. • Simplified equations for estimating the flexural resistance of composite beams are proposed. [ABSTRACT FROM AUTHOR]

This paper investigates the dynamic characteristics and Finite element model updating of two confined masonry buildings in Messina, constructed in the aftermath of the devastating 1908 earthquake. The study addresses the need for advanced research in this field to enhance the understanding of the dynamic behaviour of confined masonry structures. The authors identified the modal parameters of the buildings from ambient vibration tests. Finite element models have been developed and fine-tuned in a second step to optimize the agreement between the simulated and observed modal parameters. The optimized parameters are then compared with the outcomes of nondestructive tests on masonry and reinforced concrete. This research addresses the modelling issues when dealing with confined masonry structures, offering guidance to engineers to select the modelling parameters. The paper emphasizes the substantial stiffening effect introduced by confined masonry, as evidenced by the optimized Young's modulus of masonry, which is almost two and a half times higher than values obtained from flat jack tests. To accurately represent the interaction between reinforced concrete ties and masonry panels within equivalent frame models, it becomes crucial to adequately overstate the masonry stiffness to capture the mutual coupling between structural components. • Dynamic characterization of confined masonry buildings. • Intelligent Automated Operational Modal Analysis approach. • Predictive capabilities of simplified FE modelling for confined masonry. • Genetic optimization algorithm to fine-tune modelling parameters. • Insight to select model parameters for confined masonry. [ABSTRACT FROM AUTHOR]

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]

Knowledge of displacement responses of high-rise buildings under harsh wind excitations is essential for their wind-resistant structural design. This paper develops a machine learning model named long short-term memory (LSTM) to estimate the displacements of a 420-m-high building during Super Typhoon Mangkhut based on available field measurements. The developed model is trained and validated using the field measurements on the building during typhoon events, and the performance of the model is assessed against several evaluation criteria. Then, the trained LSTM model is employed to estimate the displacements of the skyscraper during Mangkhut. The accuracy of the estimated displacements is validated in time and frequency domains. Moreover, the background and resonant components of the estimated displacements during the extreme windstorm are analyzed. This paper aims to provide valuable reference for the wind-resistant design of high-rise buildings in tropical cyclone-prone regions. • Develop an LSTM model to estimate displacement responses of a 420-m-high building During Super Typhoon Mangkhut. • Examine effectiveness and accuracy of the developed LSTM model based on field measurements on the building during typhoons. • Estimate displacements of the skyscraper during Super Typhoon Mangkhut based on the LSTM model and available measurements. • Explore across-wind and along-wind responses, along with resonant and background components of the estimated displacements. [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 recent studies, deep learning methodologies have shown significant promise in crack detection. However, their practical implementation faces challenges due to the intricate diversity of structural surfaces and the inherent narrowness of cracks. To mitigate these problems, this paper introduces SegFormer, an efficient semantic segmentation model with hierarchical Transformer, for crack detection on concrete and asphalt surfaces in multiple scenarios. The combination of Cross-Entropy (CE) and Dice loss functions is employed to enhance the detection of fine cracks. Additionally, the paper presents an evaluation framework and discusses metrics for assessing crack segmentation results to provide a more precise and comprehensive analysis of model performance. Experimental results indicate that SegFormer outperforms Convolutional Neural Networks (CNNs) such as FCN, U-Net, and DeepLabV3 utilizing different backbones. Notably, the integration of multiple loss functions contributes to a more stable training process, expedites convergence, and yields enhanced results compared to models utilizing individual loss functions. • SegFormer is introduced for fine crack detection in various scenarios. • The combination of CE and Dice loss functions enhances crack detection. • A comprehensive model evaluation framework is presented. • Metrics for fine crack segmentation assessment are discussed. [ABSTRACT FROM AUTHOR]

Bonding strips is widely used for the strengthening of structures. This paper addresses the challenge of stress concentration in the strip-strengthened beams, where interfacial stresses at the end of the strip are usually large enough to causes premature brittle debonding failure. Lengthening bonded strips and thickening adhesive layer are effective solutions to decrease the stresses but sometimes difficult to implement. For example, obstacles under the beam may stop the strip from being lengthened with bonding. This paper proposes a feasible solution for this case that is extending the strip without bonding and then fixing it with additional anchors at the end. Analytical expressions are derived for interfacial stresses in strip-bonded beams with the end-anchored unbonded segment (EAUS). The deformation coordination relationship between EAUS and the beam is considered. The anchor bolts are analogous to elastic foundation beams to obtain their shear stiffness which will greatly influence the tension at the strip end. The theoretical results are then verified by finite element simulations. Moreover, parameter studies are performed to explore the effects of various strengthening configurations such as the length of the bonded and unbonded segments on interfacial stresses. The investigations show that the presence of the EAUS could substantially alleviate the concentration of interfacial stresses. The findings of this study provide a new approach on how to control stress concentration in the strip-strengthened beams. • Developed the analytical solution for the interfacial stresses in end-anchored unbonded segment. • Validated the analytical solutions via finite element simulations. • The interfacial stresses in strip-bonded beams were mitigated by appending end-anchored unbonded segment. • The anchor bolt was compared to an elastic foundation beam. [ABSTRACT FROM AUTHOR]

To improve the bearing and energy dissipation of the precast concrete (PC) shear wall, this paper proposes an angle-section and C-section steel embedded PC wall with external low-yield-point steel (LYP) energy dissipators (EDs). The wall is an energy-dissipation and load-bearing bi-functional system during the seismic and a design method for this wall is also presented in this paper. Two full-size precast shear walls with and without external EDs (PWE and PW, respectively), were designed based on the proposed method and tested under an axial compression ratio of 0.2. Seismic performance in terms of failure modes, hysteretic behavior, strength envelope, stiffness degradation, energy dissipation, and steel strains was investigated and discussed. According to the crack pattern observed during the test, the PW and PWE were found to be in flexural–shear failure mode, and the PWE exhibited better seismic behavior compared with the PW, The yield and peak loads of the PWE compared with those of the PW increased by 23% and 22%, respectively. The equivalent viscous damping ratios of the two walls exceeded 0.05. When the walls were under a large displacement, the equivalent viscous damping coefficient of the PWE was higher than that of the PW. Moreover, the cumulative energy dissipation of the PWE exceeded that of the PW by 15–55%. The strain in the embedded steel in the PWE was less than that in the PW, indicating that the PW suffered more nonlinear strain and concrete damage. Test results indicate that the supplementation of replaceable external EDs can improve lateral bearing and energy dissipation capacities as well as decrease the nonlinear strain to reduce the extent of damage to wall panels. Additionally, the analytical model of PWE based on the fiber model was proposed and the rationality of the model was verified by comparison of the numerical and tested results. Furthermore, a parameter analysis was conducted to investigate the seismic behavior of PWE considering various structural properties. • A precast concrete wall with angle and C-shaped steel embedded and low-yield-point steel energy dissipators is proposed. • The design method for PWE is also presented in this study and verified by test results. • Two full-scale wall panels are tested under lateral cyclic loading. • The use of supplemental external devices improve the bearing and energy dissipation capacities of the precast shear wall. [ABSTRACT FROM AUTHOR]

In this paper, seismic analyses of single-layer dome structures are carried out, with a particular emphasis on the incorporation of randomness in both geometrical imperfections and ground motions. First, the paper introduces models for random geometrical imperfections and stochastic ground motions, employing the Stochastic Imperfection Mode Superposition Method (SIMSM) for imperfections and utilizing the Spectral Representation Method (SRM) for ground motions. These models are designed to comprehensively account for the inherent uncertainties in real-world structural behavior. Subsequently, the Probability Density Evolution Method (PDEM) is applied to investigate the probabilistic response and seismic reliability of dome structures, which allows for a detailed examination of key performance indicators, such as displacement, plastic ratio, and strength damage, under the influence of random factors. Both deterministic and stochastic analyses are conducted to gain insights into the impact of randomness in geometrical imperfections and ground motions. The computational results unveil a crucial finding: an unfavorable distribution of imperfections can significantly compromise the dynamic performance and safety of single-layer dome structures. Furthermore, the paper delves into parametric analyses, with a specific focus on imperfection amplitude, the rise-span ratio and roof load as pivotal parameters. These analyses provide valuable insights into the sensitivity of the structural response to variations in these critical design factors. • Both the randomness in ground motions and geometrical imperfections is considered. • The randomness in ground motions has more significant impact. • Larger rise-span ratio can be detrimental to the dynamic reliability. • Excessive roof loads negatively impact the dynamic reliability of dome structures. [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]

The challenges of the substantial self-weight in prefabricated bridge deck slabs, the presence of numerous scattered steel beam components, and the low durability of bridge deck slabs have long been difficult issues to address in the context of traditional prefabricated steel-normal concrete (NC) composite girder bridges with flat steel webs. This paper proposes a solution through the optimization of structural forms and material properties by introducing a novel structural configuration as prefabricated steel-laminated concrete (LC) composite girder bridges with corrugated steel webs. The flat steel webs were substituted with corrugated steel webs, and the LC bridge deck slab was composed of a NC layer and an ultra-high performance concrete (UHPC) layer. This paper conducted three groups of experimental tests to comparatively analyze the effects of web forms and bridge deck materials on the flexural performance of composite beams. The results indicate that, under the conditions of consistent beam height and steel usage, composite beams with corrugated steel webs have fewer steel components, better stability, and smaller difference in bearing capacity compared to composite beams with flat steel webs. Compared with NC bridge deck slab, laminated bridge deck slab can increase the stiffness and bearing capacity of composite beam by about 13%, and the thickness of the bridge deck slab can be reduced by 20%. Furthermore, this paper presents a shear connection degree calculation method suitable for composite beams with corrugated steel webs, which effectively reduces the number of connectors. • I-beams with corrugated steel webs have similar load-carrying capacity and better stability to flat web beams. • The flexural contribution of the corrugated steel web cannot be ignored. • UHPC-NC laminated bridge deck slab increases the flexural capacity of composite beams by at least 13%. • The shear connection degree of steel-laminated concrete composite beams should be at least 0.85. [ABSTRACT FROM AUTHOR]

The paper presents an experimental program on a structural system, consisting of three long-span portal frames. The primary structural members, including columns and rafters, were constructed using cold-rolled aluminium back-to-back built-up channel sections. The system configuration featured two bays of single-span cold-rolled aluminium portal frames connected in parallel by a series of purlins spanning between the rafters to create a free-standing structure. A total of three full-scale tests (Frame Tests 1,2 & 3) were conducted with two loading scenarios. Frame Tests 1&2, which were identical to ensure accuracy, were subjected to vertical loads only, while Frame Test 3 underwent testing with combined horizontal and vertical loads. In all the tests, the columns were unbraced. The main objectives of this paper are, first, to describe the test setups and observe the structural behaviours of the portal frame systems. Consequently, the ultimate capacities were determined, and the predominant failure modes of the portal systems were identified as flexural-torsional buckling of the unbraced columns. The paper also provides information on the mechanical properties of the aluminium alloy 5052-H36 materials used to fabricate the structural members and frame components, obtained from compressive and tensile coupon tests. Further, the elastic buckling loads of the columns in the frame systems are reported in this paper, as determined from the measured load-deformation curves. While this paper primarily delves into the behaviour of the cold-rolled aluminium portal frames with a focus on flexural torsional buckling failures of unbraced columns, the authors have also conducted a separate study on the same system. In that separate study, the portal frames with the columns predominantly restrained against flexural-torsional buckling were investigated to enhance the ultimate capacities of the portal frame systems. • Three full-scale portal frames fabricated from cold-rolled aluminium back-to-back built-up channel sections are tested. • Aluminium alloy 5052-H36 materials are used to fabricate the cold-rolled aluminium structural members and frame components. • Portal frames are tested under two loading cases, including vertical loads only and combined horizontal and vertical loads. • Observed failure mode of the portal frames is flexural-torsional buckling of the unbraced columns. • Elastic critical loads of the columns of the portal frame tests are determined using the measured load-deformation curves. [ABSTRACT FROM AUTHOR]

Measuring a large grid structure is always based on the traditional total station, which requires a significant workforce. Aiming at the ring structure's characteristics, this paper fully uses multi-sensor advantages and proposes an automatic identification method of grid structure nodes. This method combines deep learning, panoramic camera, and laser scanning and improves the existing method of measuring the lifting process of the grid structure. The main contributions of this paper are as follows: (1) Aiming at the issue with existing measurement methods relying on complex multi-camera systems, a method based on a single panoramic camera and deep learning is proposed to quickly complete the full-field image target points detection, which provides a basis for the identification of target areas in the point clouds; (2) For the challenge posed by a large number of point clouds models and complex processing, a method of automatically capturing point clouds nodes by integrating panoramic camera and laser scanning was proposed. The projection points of the interest region of the image corresponding to the target region in the point clouds and precise identification of nodes were completed; (3) A node classification method and optimization method based on density peak clustering was proposed to solve the problem of node aliasing and processing node center in some areas of interest, for the classification and displacement calculation of grid structure nodes. The proposed method is validated on the scale frame model of a gymnasium, demonstrating the practicability of the proposed approach. • Aiming at the issue with existing measurement methods relying on complex multi-camera systems, a method based on a single panoramic camera and deep learning is proposed to complete image target detection, which provides a basis for the identification of target areas in the points cloud; • Aiming at the challenge posed by a large number of point clouds models and complex processing, a method of automatically capturing point clouds nodes by integrating panoramic camera and lidar was proposed. • A node classification method and optimization method based on density peak clustering was proposed to solve the problem of node aliasing and processing node center in some areas of interest, for the classification and displacement calculation of cable network structure nodes. [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]

This paper introduces a recursive formulation of blind modal identification as an alternative to conventional diagonalization methods based on multi-lagged covariance matrices. While traditional blind source separation methods are effective for modal identification in structural systems, dynamic systems experiencing sudden changes or rapidly changing environmental conditions require real-time algorithms for continuous health assessment. The proposed recursive eigenspace updates on output covariance estimates, using generalized eigen perturbation, show promise in identifying modal parameters for numerically simulated systems excited with white and colored noise spectra. The paper presents a detailed framework based on recursive simultaneous diagonalization, avoiding real-time diagonalization of multi-lagged covariance matrices by incorporating two auto-covariance matrices with different lags. To evaluate the performance of the new real-time algorithm, synthesized data from a five-degrees-of-freedom system is used. A comparison with traditional independent components demonstrates the effectiveness of the proposed approach in separating closely spaced modes with high damping in real-time. Experimental investigations conducted on controlled vibroimpact test beds confirm the robustness of the proposed approach. Furthermore, the paper shows that the modal parameters obtained using the proposed method for the benchmark ASCE-SHM structure are consistent with those obtained from state-of-the-art methods. The examples presented in the paper indicate that real-time mode separation for dynamic systems in operating conditions is feasible, which is a novel contribution in the field of recursive simultaneous diagonalization. [Display omitted] • Recursive simultaneous diagonalization achieved in a computationally efficient technique. • Online modal recovery performed on linear systems and practical benchmarks. • Comparison with traditional BSS based methods demonstrated and the effectiveness established using the proposed recursive method. • Error plots for eigenspace correlation indicates a steady convergence at from 20% sample population. • Development of recursive Mahalanobis distance as a new condition indicator for identifying online change of state. [ABSTRACT FROM AUTHOR]

This paper focuses on a reinforced concrete corbel strengthening method using post-tensioning cables, or just using the prestressing strands themselves, which are led through additionally drilled cable ducts. The text describes a highly efficient method that has also other advantages besides efficiency, which are: the character of the structure of concrete columns with corbels does not change, the prestressing reinforcement is protected by the concrete both mechanically and against elevated temperatures, and it is easy to apply. Firstly, the paper briefly describes some of the other available methods. However, these methods usually utilize the surface of the concrete, which is often impaired. Additionally, the alternative methods cannot be used or are considered in practice to be insufficiently reliable in specific situations. The paper then describes the design, the actual implementation, and verification of the post-tensioning by measuring the concrete deformation on real columns and full-scale corbels. It also discusses the preliminary design using Strut-and-Tie method Other sections of the text describe the measurements on full-scale corbel specimens and the subsequent numerical analysis performed using advanced methods. The concordance of the results confirms the correctness of the implementation and the design of the described strengthening method. • Strengthening of RC corbels by post-tensioning using substitute cable ducts method. • System validation via concrete deformation measured on real corbels and corbels models. • Verification of the strengthening system using advanced numerical analysis. [ABSTRACT FROM AUTHOR]

The use of external steel bracing systems (named exoskeletons) has recently emerged as a convenient technique for seismic upgrading of existing RC structures, as it possibly limits disturbance or interruption of building occupancy. However, although some conceptual formulations of the design problem can be found in the scientific literature, there are no universally accepted design criteria. The present paper highlights how alternative design choices can reverberate their effects on (i) the seismic performance of the upgraded structural system, (ii) its economic and ecological impact. For the sake of simplicity and consistency with the most common approach of practicing engineers, the present study adopted a force-based seismic design approach. The critical discussion proposed herein was obtained by varying the intensity of the seismic base shear force adopted for the exoskeleton design. Results of the design assessment show that the adoption of larger values of exoskeleton seismic design forces may not be the most suitable choice, especially if economic and ecological impacts are taken into account. • The paper deals with designing steel exoskeletons for seismic retrofitting of existing RC frames. • A comparison between three different upgrading solutions is reported. • A critical discussion about upgrading interventions is provided including member- and foundation-level interventions. • The adopted design procedures are consistent with the most common practice. • Economic and ecological impacts are determined with the aim to rate the alternative seismic retrofit options. [ABSTRACT FROM AUTHOR]

Quantifying the uncertainties of engineering systems modeled as nonlinear oscillators subject to random excitation is a theoretically complex and computationally demanding task. Consequently, finding an optimal design of such systems considering their life-cycle performance is prohibitive with Monte Carlo simulation methods. In this paper, an efficient performance-based design optimization approach is developed for finding the optimal parameters of engineering systems modeled as nonlinear/hysteretic oscillators subject to stationary and non-stationary excitation. This novel approach utilizes an arbitrary polynomial chaos expansion to estimate the expected cost of failure without performing a computationally expensive integration over the hazard levels. Moreover, we introduce a novel sequential heuristic optimization scheme based on simulated annealing to minimize the total expected cost over the structure life-cycle. Three examples are included in the paper to assess the developed optimization scheme. First, we use the developed framework to optimize a linear single-degree-of-freedom oscillator subject to broadband excitation. Second, a multi-degree-of-freedom oscillator with cubic nonlinearity in damping and stiffness, subject to stationary broadband excitation, is optimized to show the influence of the problem dimensionality in the optimization process. In the last example, a multi-story reinforced concrete shear building modeled as a multi-degree-of-freedom Bouc-Wen oscillator with stiffness and strength degradation and subject to multi-hazards modeled as stationary (wind excitation) and non-stationary (earthquake) stochastic processes, is optimized. • An efficient performance-based design optimization scheme is developed. • The best design of MDOF systems consider their life-cycle performance. • Statistical linearization is combined with time-variant reliability. • The monetary loss is estimated with an arbitrary polynomial chaos expansion. • A sequential simulated annealing optimization is employed in the framework. [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 presents an experimental investigation on web crippling behaviour of cold-formed stainless steel square and rectangular hollow sections (SHS and RHS) at elevated temperatures. A total of 21 web crippling tests were conducted under the Interior Two-Flange (ITF) loading condition as codified in ASCE/SEI 8–22 Specification at various temperatures up to 800 °C. Tensile flat and corner coupon tests were conducted to obtain the material properties of the cold-formed stainless steel SHS and RHS at various temperatures corresponding to those pre-set in the web crippling tests. Details of the test specimens, setups and procedures are comprehensively documented in this paper. Furthermore, the specimen temperatures together with the test results, including failure modes, web crippling strengths and load-deformation curves are fully reported. The obtained test results were used to evaluate the suitability of codified web crippling design provision as per ASCE/SEI 8–22, where reduced material properties were used in calculating the web crippling strengths at elevated temperatures. In addition, the test results were also compared with the predictions obtained from existing design rules in literatures for cold-formed stainless steel SHS and RHS at elevated temperatures. Moreover, reliability analyses were conducted to assess the reliability levels of these design provisions. It is demonstrated that the available web crippling design provisions can provide generally conservative and reliable strength predictions, and therefore are deemed suitable for predicting the web crippling strengths of cold-formed stainless steel SHS and RHS at elevated temperatures. • This investigation serves as the first test programme to study web crippling behaviour of CFSS sections at elevated temperatures. • Flat and corner coupon tests were conducted to obtain material properties at various temperatures. • A total of 21 web crippling tests were conducted under ITF loading condition with temperatures up to 800°C. • Test results are reported and existing web crippling design provisions are also assessed. [ABSTRACT FROM AUTHOR]

Friction Pendulum Bearing (FPB) with shearing keys will exhibit friction-coupling effect and collision phenomenon subjected to horizontal orthogonal ground motions. This paper establishes a numerical analysis model of FPB with four shear keys and viscous damping, considering the impact of the friction coupling effect and collision between the FPB and the shear keys on its displacement response. The influence of parameters of FPB on seismic displacement response with considering collision effect under horizontal orthogonal ground motions was studied. The results suggest that adjustments in damping and equivalent stiffness exclusively impact the amplitude of the displacement response, maintaining the response waveform. Conversely, variations in friction significantly alter the response waveform, as friction induces changes in the natural frequency of FPB. A heightened collision impact is noted with reduced spring stiffness. The displacement response is particularly amplified when the collision occurs at the vicinity of peak displacement in the time-history response of FPB. When the restoring stiffness and Peak Ground Acceleration (PGA) are low, the friction coupling effect significantly reduces the amplification of displacement response caused by collision effects. Viscous damping can considerably reduce the impact of collisions on the peak displacement of FPB and prevent the collision effects from noticeably amplifying or diminishing the peak displacement of FPB. • This paper proposes a numerical model of FPB considering shear key collisions. • Theoretical derivations and categorizations of collision and shearing scenarios involving shear keys are presented. • This model enables a decoupled analysis of the displacement response of FPB with shear keys under orthogonal horizontal seismic motions. [ABSTRACT FROM AUTHOR]

This paper proposes a novel structural analysis approach, the neural networks-based spring element (NNSE) method, to synergize machine learning (ML) techniques with the line finite element method (LFEM) for the second-order analysis method of pile-supported structures. Traditional LFEM, widely used in upper structure design, showcases limitations in efficiently modeling complex Soil-Structure Interaction (SSI) along piles since it requires dense element mesh for accuracy. Conversely, ML offers a mesh-free alternative for analyzing single piles but struggles in simulating pile-supported structures as the training sample collection for large-scale problems might be unbearable. This paper addresses these challenges by proposing a new analysis framework to utilize the neural network (NN) model, which only describes structural responses of single piles, for the simulation of entire pile-supported structures. In the proposed method, the NN model is not directly used for structural analysis but employed to formulate a new spring element named the NNSE to model single piles in pile-supported structures. This NNSE can be seamlessly implemented within the existing LFEM framework to analyze pile-supported structures, eliminating the dense mesh requirement for single piles and thereby significantly improving the computational efficiency. Extensive examples are provided to verify the effectiveness of the proposed method, indicating its potential in promoting the second-order analysis method to the design of pile-supported structures. • A novel NNSE method is proposed for analyzing pile-supported structures. • NNSE efficiently captures nonlinear SSI using one element per pile. • This method surpasses existing solutions in both efficiency and accuracy. • NNSE provides a novel integration of FEM and ML for structural analysis. [ABSTRACT FROM AUTHOR]

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

The collapse of the I-95 overpass in Philadelphia on June 11, 2023, due to a tanker-induced fire, caused significant traffic disruptions to an important transportation system on the East Coast of the United States. The increasing frequency of similar bridge fire events over the last few years has ignited a debate to re-visit the fire performance of bridges and to account for fire hazards in bridge structures. From this lens, this paper employs the established methodology of fire-based importance factors to assess the vulnerability of the I-95 overpass and then examines the causes and mechanisms for its collapse. To complement this methodology, the paper also presents mitigation strategies, if included, that could have mitigated the collapse of this overpass. More specifically, a finite element model is applied to trace the response of an I-95 girder section under combined effects of thermal and mechanical loading, considering three representative fire scenarios: standard, hydrocarbon, and design fire. Results from numerical simulations show that the bridge experienced rapid temperature rise as in the case of a hydrocarbon fire, leading to the failure of steel girders within 15 min of fire exposure. The developed model was also applied to evaluate strategies that could have minimized the collapse of the overpass under similar fire incidents: composite action and fire insulation. Both alternatives contributed to increasing the fire resistance of the steel girder, with the latter option proving to be significantly more effective. Overall, the increasing frequency of bridge fire incidents in recent years demostrates the need to integrate fire hazards into the design of critical infrastructure, particularly critical bridges, to enhance their resiliency under possible fire scenarios. • Vulnerability of bridges for fire induced collapse is highlighted. • The causes and failure modes in the fire induced collapse of I-95 bridge is analyzed. • The strategies that could have minimized the collapse of I-95 bridge is discussed. • An approach for enhancing resiliency of bridges against fire hazard is laid out. [ABSTRACT FROM AUTHOR]

This paper summarises current research findings related to the behaviour and simulation of a relatively new type of structural component: recycled aggregate concrete-filled steel tube columns (RACFST). The first part of the paper presents a review of the latest experimental campaigns on RACFST columns subjected to a variety of loading conditions. For each of loading condition, highlight observations about the behaviour of RACFST columns are presented. The second part of the paper provides a summary of numerical modelling approaches developed for simulating the structural behaviour of RACFST columns. Special attention is paid to the selection and calibration of material models for recycled aggregate concrete. Finally, directions for future investigations in this area are outlined and discussed. The review will benefit researchers and professionals seeking to gain an in-depth understanding of the behaviour of RACFST columns, and fills a gap in existing literature regarding a number of practical issues related to the numerical modelling of these components. • A state-of-the-art review of experiments on RACFST columns is presented. • The experimental behaviour of RACFST columns is summarised. • Different numerical modelling strategies for modelling RACFST columns are discussed. • Research gaps and directions for future investigations are highlighted. [ABSTRACT FROM AUTHOR]

This paper presents a novel developed Sprayed Ultra-High-Performance Cementitious Sandwich Panel (SUHPC-SP) for structural applications. The SUHPC-SP features sprayed UHPC outer layers making it suited for structural load bearing applications, and a foamed concrete core layer offering high thermal properties. With the development of enhanced material properties and novel production methods, the established SUHPC-SP can achieve optimal mechanical performance while minimising the volumes of material required. As such, this study assesses SUHPC-SP potential to increase sustainable outputs over reference Brick and Block (B&B) construction; by quantifying and comparing the whole life cycle environmental and economic impacts of the two methods. A comparative life cycle assessment (LCA) of these types of construction products is presented for the first time in this paper. The study found that integrating SUHPC-SP over typical B&B construction can reduce environmental impacts by as much as 500% and costs by up to 180%. This informs sustainable construction decisions, offering an effective alternative to conventional inefficient building methods and materials. • The study assesses the LCA of sprayed Ultra High-Performance Cementitious Sandwich Panels (SUHPC-SP). • A comparative LCA between SUHPC-SP and brick & block construction was assessed. • Sandwich panels have the potential to reduce costs and environmental impacts. • Using SUHPC-SP over typical brick & block reduces costs by up to 180%. • Using SUHPC-SP over typical brick & block reduces environmental impacts by up to 500%. [ABSTRACT FROM AUTHOR]

In the last two decades, mass timber structures have gained popularity in mid-rise or tall building applications worldwide. For timber buildings in seismic regions, it is critical to improve building seismic resilience. Conventional timber structures rely on connections for energy dissipation and system ductility. However, this dependence also carries the risk of damage, potentially resulting in structures that are irreparable in severe earthquakes. In this regard, as one of the low-damage seismic design technologies, self-centering (SC) techniques have been introduced to mass timber structures in 2005. The relevant research and applications have led to significant technological progress in the field. This paper provides an overview of recent research progress since 2019, encompassing experimental studies, analytical and numerical simulations, key design aspects, and practical applications of SC mass timber structures. It highlights recent technological advancements and identifies future research directions to address knowledge gaps identified in this review. • This paper reviews developments in SC mass timber structures, including experiments, simulations, design aspects, and applications. • In addition to the PT technique, experimental study on other SC technologies used in mass timber structures are also included. • Research that contributes to the design of SC mass timber structures is covered. [ABSTRACT FROM AUTHOR]

This paper explores static experiments and dynamic tests, along with structural analysis of certain glubam (glued laminated bamboo) dome models. A self-balancing lever system was employed for the static experiment, revealing mechanical performance details such as load-displacement relationships and internal axial forces in glubam dome structures. Dynamic behaviors were assessed through triaxial accelerometers on specific joints, employing the Bayesian FFT modal identification method to calculate structural modal parameters, including natural frequency and mode shape. Experimental outcomes closely aligned with results from the analytical approach using the finite element method. Overall, the paper contributes valuable insights into the static and dynamic characteristics of glubam dome structures, bridging experimental findings with analytical predictions. • An innovative glubam dome model was built by digital-twins parametrically. • A static experiment was conducted with a self-balancing lever system. • Dynamic properties of dome were investigated using Bayesian FFT modal ID method. • The finite element model was validated by static and dynamic test data. [ABSTRACT FROM AUTHOR]

Real-time hybrid simulation (RTHS) divides a structural system into an analytical and experimental substructure. The former is based on a well-established analytical model while the latter consists of a physical model in the laboratory, for which there is not a well-established analytical model. This paper extends real-time hybrid simulation to monopile-type Offshore Wind Turbines (OWTs) to enable the investigation of their behavior considering the response of pile foundations under operational and more severe conditions. The embedded foundation and surrounding soil of the OWT are modeled physically in a soil box in the laboratory while the remaining parts of the system and loading are modeled analytically. The program OpenFAST, developed by the National Renewable Energy Laboratory (NREL), is linked to the RTHS coordinator to determine the hydrodynamic and aerodynamic loads acting on the OWT, along with modeling the dynamics of the electric power generation equipment and associated controller for the OWT. The RTHS framework along with its initial implementation and validation are described in this paper. RTHSs of a 5 MW OWT subjected to operational and more severe conditions are performed to experimentally validate the framework. The framework offers a realistic approach to investigate the behavior of OWT structures supported on monopiles. This approach accounts for the coupled response of the OWT structure with its foundation, while experimentally capturing the nonlinearities of the soil-foundation interaction in real-time. • RTHS is extended to offshore wind turbine monopile structures. • OpenFAST software is modified and integrated into a RTHS framework. • Validated RTHS framework that incorporates the complete system into the simulation. • RTHS enables experimental assessment of offshore wind turbine foundation behavior. • RTHS computational challenges of offshore wind turbine structures are presented. [ABSTRACT FROM AUTHOR]

In recent decades, computer vision-based methods have been introduced into engineering structures to provide full-field, non-contact vibration measurement. However, the vision-based vibration measurement method is challenging to measure the targetless structures. This paper proposed a target-free out-of-plane vibration measurement method using projection speckle and camera self-calibration technology. In this method, the camera extrinsic parameter estimation result based on the direct method is used as the initial value in the proposed method. Then, a nonlinear inequality constraint on the extrinsic parameters is established regarding the epipolar condition to minimize the reprojection error. Furthermore, the projection relationship between the projection speckle displacement and the actual displacement of the structure is studied so that the deviation of the out-of-plane vibration displacement is corrected. In the experimental verification, 3D reconstruction and rigid translation experiments are designed, respectively. The results show that the self-calibration accuracy of the binocular camera proposed in this paper is notably improved compared with the existing methods. At the same time, the deviation correction effect of the vibration displacement is significant. Finally, the typical flat plate structure and composite wing structure are taken as vibration measurement cases to demonstrate that the proposed approach is reliable and accurate in measuring the dynamic responses of engineering structures. • A target-free vision-based method using projection speckle and camera self-calibration is proposed for structural vibration measurement. • To increase the accuracy of camera self-calibration, a nonlinear inequality constraint is implemented to minimize reprojection errors. • The correlation between speckle and actual displacement is established, correcting the out-of-plane deviation. [ABSTRACT FROM AUTHOR]

Steel-concrete-steel sandwich composite structures (SCSSCSs) have become popular and been used as the high-rise-building shear walls, immersed and shielding tunnels, bridge and offshore platform deck, nuclear shielding walls, protective structures, and bridge piers. This paper firstly made a review of 172 papers on developments of SCSSCSs and their different types of connectors. Followed, the compression behaviours of SCSSCS walls were reviewed, and theoretical models on predicting the ultimate compression resistance of SCSSCS walls were summarized. Thirdly, this study also summarized the previous investigations on behaviours of SCSSCS walls/slabs under out-of-plane (OP) loads and their key influencing parameters were also presented. Moreover, previous theoretical models on OP flexural bending and shear resistances were reviewed. Seismic behaviours of different types of SCSSCS walls have also been reviewed. Their failure modes, influencing parameters, and theoretical models on lateral shear resistances of SCSSCS walls were also reviewed. Finally, this paper reviewed the studies on behaviours of SCSSCS walls under OP patch loads. The review also revealed the key influencing parameters on the punching shear behaviours of SCSSCS walls. In addition, the general load-deflection behaviour and punching shear theoretical models were also summarized based on extensive test results. Finally, the useful conclusions were made based on this extensive review. • Different connectors used in steel-concrete-steel sandwich composite structures (SCSSCSs) were reviewed. • Flexural and shear behaviours and prediction models on bending and shear resistances of SCSSCSs were reviewed. • Compression behaviours and analytical models on compression capacity of SCSSCS walls were reviewed. • Cyclic behaviours of SCSSCS walls and their lateral shear capacity models were discussed. • Punching behaviours and prediction models of SCSSCS slabs/walls under OP patch loads were summarized. [ABSTRACT FROM AUTHOR]

Literature has recently provided the analytical model that predicts the shear strength of the anchor embedded into masonry. It is apparent that this model does not apply to the anchor embedded into concrete, as the ultimate contact pressures are different. A gap in the literature was hence filled, but there existed a remaining gap. In order to fill that last gap, further research was done. This paper is herein an account of that work. The paper deals with the anchor post-installed by drilling into an already compact concrete structure, used to transmit applied loads from an attachment to the concrete, subjected to a force acting at the end that emerges from the concrete and orthogonal to the anchor (shear force with no axial force), with large clearance from the edges, either alone or with large clearance from other anchors. Being post-installed, the embedded part of the anchor is a straight shaft with no hook at the embedded end, and with no nuts, washers, or plates attached to the shaft. The paper presents an analytical model absent in literature prior to this study that predicts the maximum shear force the anchor can carry, thus called "shear strength" of the anchor. The assumptions of the analytical model were established from the results of a non-linear numerical model specifically constructed by the author. The predictive capacity of the analytical model and accuracy of its results were assessed and verified by experimental tests of real anchorages specifically designed and performed by the author. This paper also presents the numerical model and the comparisons of the analytical predictions to those experimental results, as well as comparisons to experimental results borrowed from literature and code provisions. • Analytical formulation for the shear anchor post-installed into a hardened concrete member. • Existing analytical formulas are devoted to cast-in anchors for new structures. • Post-installation implies a straight shaft, without nuts, washers, or plates. • Anchor with adequate clearance from edges and other anchors, and without dowel or prying actions. • Shear strength of the post-installed anchor is dictated by the concrete in front of the anchor. [ABSTRACT FROM AUTHOR]

This paper describes a novel method for detecting bridge damage that uses a partially instrumented vehicle fleet, each vehicle being instrumented with just one accelerometer. Importantly, no prior knowledge of the bridge or individual vehicle properties is required. Firstly, a model simplification concept is proposed to calculate the displacement under the vehicle wheel from single acceleration measurements on a half-car model. Then, optimisation is used to find individual vehicle properties using simulated noisy measurements from a fleet of vehicles. Finally, accelerations from the fleet are used to find the 'apparent profile difference', which contains bridge deflection data. The difference is found to be independent of surface profile but dependent on vehicle axle weight differences and a moving reference influence function (MRIF). When the axle spacings and the relative axle weights are reasonably consistent in a subset of the fleet, the MRIF can be simplified into a compound MRIF. Even when the MRIF and individual axle weights are not available on-site, the shape of the compound MRIF can be determined through an iterative process and used to monitor bridge health condition. Bearing damage is represented in this paper as an increase of rotational resistance of the bearings. The numerical results show that the damage severity and location can be identified. • A new drive-by fleet monitoring concept is introduced using a partially instrumented vehicle fleet without knowing individual vehicle properties. • A new concept, vehicle model simplification, is introduced to enable monitoring bridges using partially instrumented vehicles. • Vehicle wheel displacement is successfully obtained from vehicle accelerations and used in structural health monitoring. • The relation between bridge deflection under the wheel and vehicle load is modelled as a moving reference influence function. This influence function is simplified to monitor bridges. [ABSTRACT FROM AUTHOR]

In prestressed concrete (PC) bridges, high-strength prestressing steel plays a key role in the flexural response of girders. In both pre-stressed and post-tensioned PC bridge girders, damage induced by corrosion or impact of under-passing high vehicles may led to rupture of one or more strands, significantly affecting the load-carrying capacity against dead and traffic loads. This paper presents an experimental study on the response of PC girders affected by strand rupture at different locations. Four reduced-scale post-tensioned concrete girders with different levels of initial prestressing force were tested under four-point bending. Two specimens with a different level of prestress were initially tested in undamaged configuration to provide a basis for the assessment of damage effects. The other pair of specimens were intentionally damaged - having the same initial prestressing level of their undamaged counterparts - in the lower tendon to investigate their limited flexural response under different performance levels including serviceability and collapse. Damage turned into a different critical cross section outside the loading region, i.e. both cracking and collapse were attained 1.1 m away from midspan. In the last section of the paper, a cross sectional analysis of the girder was developed at cracking and ultimate conditions for the prediction of damage impact on failure mechanisms, thus validating the experimental findings. • Experimental testing of four 1:5 scaled post-tensioned concrete bridge T-girders with parabolic tendons is presented. • The flexural responses of two damaged specimens are compared to their undamaged counterparts. • Influence of damage position on structural response of two girders having different pre-stressing levels is investigated. • The variation of girder response in terms of deflection and tendon internal stress is reported while cutting the strand. • An analytical study of the damaged cross-sections aided in the interpretation of the experimental findings. [ABSTRACT FROM AUTHOR]

The protection against seismic hazards for rigid block-like structures, commonly modeled as rigid blocks, is often achieved by coupling such structures with external protection devices. The most commonly used protection devices include dynamic mass absorbers, oscillating masses, base isolation systems, and hysteretic mass damper inerters. Additionally, several papers have studied the dynamic and seismic response of rigid blocks connected in series, with most of them focusing on the stacked rigid block system, where the blocks are placed one on top of the other. This paper investigates the seismic behavior of a system consisting of two rigid blocks connected in series through a linear visco-elastic Maxwell device. The aim is to understand the possibility of improving the seismic response of a rocking structure (modeled by one of the two rigid blocks) by connecting it with a rocking protection device (modeled by the additional rigid block). Each rigid block can exhibit three different types of motion: full contact, rocking motion around the left base vertex, and rocking motion around the right base vertex. Consequently, during the motion of the coupled system, nine different combinations can occur, each of which is described through a specific set of equations of motion. A parametric analysis is performed with the aim of investigating how the characteristics of the additional rigid block and connection device affect the seismic behavior of the main rigid block (the one modeling the rocking structure). The assessment is carried out through a comparison between the displacements of the coupled system and those of the stand-alone blocks. The results, organized in gain maps, show that there are several combinations of the characteristics of the additional rigid block and connection device that lead to an improvement in the seismic behavior of the main rigid block. • This paper investigates the seismic behavior of a system of two rigid blocks connected in series through a linear visco-elastic Maxwell device. • During the motion of the coupled system, nine different combinations can occur. • An extensive parametric analysis is performed with the aim to investigate how the characteristics of the additional rigid block and connection device affect the seismic behavior of the main rigid block. • The assessment is performed through a comparison between the displacements of the coupled system and those of the stand-alone blocks. • There are several combinations of the characteristics of the additional rigid block and connection device that lead to an improvement in the seismic behavior of the main rigid block. [ABSTRACT FROM AUTHOR]

This paper proposes a data-driven model for predicting the code-based seismic vulnerability index calibrated on a dataset comprising almost 300 buildings. The vulnerability index, estimated following the Italian Seismic Code, involved rigorous investigations, including geometric surveys, experimental tests, and numerical modelling. Leveraging data from these investigations, encompassing approximately 15 categorical and numerical explanatory variables, the authors developed several regression and classification predictive models, such as Logistic Regression and Artificial Neural Networks (ANN). The optimal models perform binary classification to determine the categorization into two macro-classes, defined by an arbitrary vulnerability threshold. The ANN model stands out as the best performer. When adjusting the vulnerability threshold to obtain a balanced dataset, such a model achieves an accuracy higher than 85%. The paper also discusses the importance of each feature by calculating the SHapley Additive exPlanations (SHAP) values. The proposed model can aid decision-makers in allocating resources effectively to mitigate seismic risks of built environments. • Data-driven model for code-based seismic vulnerability assessment. • 15 explanatory variables are considered. • Regression models perform poorly. • Binary classification is the only reliable approach. • The ANN model has an 85% accuracy on binary classification with balanced dataset. [ABSTRACT FROM AUTHOR]

Welding-induced residual stresses evolve under external loading and fatigue actions. This paper examines the effects of a variety of influencing factors on the residual stress evolution, such as the pre-tension, load ratio, variable amplitude loading, overloading, plate thickness, and crack depth, for which a comprehensive understanding is yet to be nurtured. The experimental and numerical findings demonstrate that the variable amplitude loading and overloading impose significant effects on the evolution of residual stresses during the cyclic loading test. Based on the experimental observations and numerical analysis, this paper presents four evolution forms of residual stresses and reveals their mechanical principles by the effective stress-strain curves in both the undamaged specimens and the fatigue-cracked specimens. The interaction between the positions with different incremental plastic strains changes the magnitude of residual stress and thus dominates the residual stress evolutions. • We investigate the effects of fatigue actions on the residual stress evolution. • We propose four residual stress evolution forms and reveal their mechanical principles. • Variable amplitude loading and overloading impose significant effects on residual stresses. • Interactions between materials with different Δε p dominates the residual stress evolutions. [ABSTRACT FROM AUTHOR]

This paper presents a novel unsupervised method for detecting progressive damage in bridge structures. Traditional supervised learning approaches require a large number of damaged samples to train a high-performing detection model, which poses challenges when applied to normal in-service bridges. Since in-service bridges usually lack data from damage scenarios and existing methods fail to achieve real-time detection, unsupervised learning has gained popularity due to its ability to work without damaged samples and offer better real-time performance. In light of this, this paper proposes a novel unsupervised damage detection method that utilizes an unsupervised attention-convolutional auto-encoder to reconstruct real-time vibration signals from bridge. Two damage indicators are employed to evaluate the effectiveness of the reconstruction process, aiming to capture potential changes in the progressive damage of bridges. The results demonstrate that: the attention-convolutional auto-encoder achieves excellent reconstruction performance for vibration signals from intact structures, which reconstruction error converging to 0 and structural similarity approaching 1. However, the reconstruction performance is less satisfactory for vibration signals in damage scenarios, deteriorating further as the damage level increases. By analyzing the variation patterns of vibration signals in attention-convolutional auto-encoders, it was confirmed that the reliability of the proposed evaluation effects by the two different types of damage indicators. Finally, the trend of progressive damage was extracted through these indicators, showcasing the effectiveness of the method in detecting progressive damage. This approach facilitates the identification of potential progressive changes in the normal operation process of bridges, thus enhancing real-time damage detection capabilities and contributing to the knowledge of bridge monitoring. • Self-attention mechanism was used to improve the performance of convolutional auto-encoder. • The consistency mechanism between two damage indicators and damage characteristics has been revealed. • The damage detection method was established through convolutional auto-encoder and tailored two damage indicators. [ABSTRACT FROM AUTHOR]