The mechanical properties of large-span space structures are complicated and change greatly during its construction. So it is necessary to monitor the real time status of the structure to ensure the safety of the construction process. However, the number of monitoring points is often very large due to the space structure's large number of members and three-dimensional forcing characteristics. An optimization method for reducing monitoring points is proposed based on the characteristics of certain correlation between different members' mechanical responses during construction in this paper. Firstly, the comprehensive correlation matrix of structural response was established by using correlation coefficient method and grey correlation degree method, and the cluster correlation matrix with block characteristics was calculated by the bond energy algorithm, so as to construct the classification and optimization principle of reducing measuring points. Then, LSTM neural network was used to build a response prediction model, and the in-situ monitoring data was used to train and verify the prediction model. The results show that Pearson correlation coefficient and B-type grey correlation can effectively explore the similarity between the change size and trend of spatial structural responses. At the same time, LSTM neural network can learn to optimize the response correlation between the measuring points and its related measuring points, realizing the global monitoring of the structure.
Accurate measurement of fatigue crack length is essential for routine maintenance of steel bridges, and automated technologies have already been applied in maintenance operations. However, conventional image processing strategies suffer from complex and multi-source interference in steel box girders. This study proposed a two-stage method combining region recognition and morphological processing to diminish noise in fatigue crack images, thereby improving the accuracy of crack recognition and length measurement. The object-recognition-former (OBFormer) model was built to detect and isolate the fatigue crack regions, leveraging the advanced feature extraction module and localization capabilities. Optimized Canny algorithm was utilized to suppress noise and extract the skeletal line of the fatigue crack from detected regions. The length of the crack was calculated by modifying the coordinate system of the crack plane and quantifying the number of pixels along the skeletal line. Experimental results showed that the OBFormer model effectively handled complex background interference and accurately detected the fatigue crack regions, with a mean average precision (mAP) of 91%. After morphological processing, the length of the crack skeleton was accurately calculated with a relative error of less than 5%. The proposed methodology provides a reliable and efficient solution for fatigue crack measurement, offering significant potential for real-world applications in structural health monitoring and bridge maintenance.
The unique band gap characteristics of periodic structures result in varying degrees of attenuation of elastic wave propagation across different frequency ranges. With the increasing demand for periodic grid structures, particularly long-span grids, in various sectors of industry and daily life, the issues of vibration reduction and isolation in such structures have become increasingly prominent. Inspired by the periodic properties of phononic crystals, this study conducts a mechanical analysis of grid rod elements, derives the corresponding periodic equations, and investigates their underlying periodic mechanisms. Numerical simulations confirm the existence of band gaps in steel and aluminum hybrid grid rods and examine the effects of the rod's Elastic modulus, density, and inner radius on these band gap characteristics. Finally, the impact attenuation performance of the steel-aluminum hybrid grid rod is compared with that of pure steel and pure aluminum grid rods. The results show that: (1) with increasing Elastic modulus, the starting frequency, end frequency, and width of the widest band gap all increase, while the starting frequency, end frequency, and width of the 13th-order band gap first increase and then disappear; (2) with increasing density, the width of the widest band gap decreases, and the starting frequency, end frequency, and width of the 16th-order band gap all decrease until it disappears; (3) with increasing inner radius, the width of the widest band gap increases, and the starting frequency, end frequency, and width of the 19th-order band gap all increase, with low-frequency band gaps gradually emerging; and (4) compared to steel and aluminum grid rods, the steel and aluminum hybrid grid rod exhibits superior impact wave attenuation performance, with the band gap characteristics of single-rod elements playing a critical role in suppressing vibrations throughout the entire grid structure. Copyright (c) 2026 by The Hong Kong Institute of Steel Construction. All rights reserved.
To investigate the effect of openings on the flexural performance of large-section partially encased composite beams (referred to as large-section PEC beams), static tests were conducted on five large-section PEC beams with different configurations. The study focused on the influence of web openings in the primary and secondary beams on the flexural performance, ductility, and failure modes of the specimens under four-point bending. The results indicate that under static loading, all specimens exhibited good ductility, with strength-to-yield ratios ranging from 1.18 to 1.30, and retained some strength reserves after reaching the yield load. Web openings slightly reduced the load-bearing capacity and sectional stiffness of the specimens. The strain in the main steel component and the concrete strain along the section height approximately exhibited a linear distribution, conforming to the plane section assumption. A finite element model was developed based on the test results. The load-deflection curves and stress contours matched well with the experimental results, and the error between the simulated and experimental ultimate load-bearing capacities was within 10%. The flexural load-bearing capacity calculated using the proposed method for large-section PEC beams with web openings showed minor deviations from the experimental values, with minimal influence from size effects, confirming the safety and reliability of the adopted formulas.
Existing theoretical rotational curve calculation methods for end plate-bolted joints often overlook component-level load transfer mechanisms and full deformation processes. This paper introduces a full-process subcomponent analysis method, which systematically evaluates the force-deformation behavior of joint domains, bolts, end plates, and stiffeners at critical failure stages. Simplified models and formulas are developed to calculate the load-bearing capacity and rotation angles of each component. The proposed method was validated through experiments, numerical simulations, and a practical engineering case. The results show that the proposed method accurately predicts joint rotational behavior, with the end plate thickness and bolt configuration significantly influencing load distribution. By revealing the load transfer mechanisms and clarifying the physical meaning of each component's role in joint rotation, the findings of this study provide a robust theoretical foundation for holistic structural analysis and large-scale computation of steel structures.
Prefabricated foundations offer numerous advantages such as convenient construction, high bearing capacity, energy efficiency, environmental friendliness, and less wet work on-site. Accordingly, this study introduces a novel structural system based on an assembled beam-slab foundation. To further explore the mechanical properties of the precast beam slab units in the modular beam-slab foundation, experimental research and numerical simulation were conducted. Test findings indicate that the structure primarily undergoes bending-type failure. From the yielding of the specimen to the attainment of the ultimate load, the specimen undergoes significant displacement changes, indicating that the structure possesses good bending resistance and ductility. Based on the experimental results, an accurate finite element model was established for parametric analysis. The findings indicate that the bearing capacity of the foundation slab is significantly influenced by parameters such as reinforcement ratio and slab thickness, with the reinforcement ratio having the most pronounced effect. The ultimate load-carrying capacity increases with the reinforcement ratio, composite slab thickness, and concrete strength. In contrast, the thickness of the C-section steel has the least effect on the bearing capacity, with the foundation slab's bearing capacity remaining virtually unchanged. Copyright (c) 2026 by The Hong Kong Institute of Steel Construction. All rights reserved.
This paper introduces a novel double-skin composite wall (DSCW) system reinforced with horizontal rebar trusses. The seismic performance of five double-skin composite wall specimens with rebar trusses and one specimen without rebar trusses was investigated under low cyclic lateral loading. The test results demonstrate that all specimens reached a flexure-dominated ultimate state, accompanied by local buckling of the faceplates in the shear wall and the boundary columns of the concrete-filled steel tube (CFST). The five specimens reinforced with rebar trusses exhibited excellent ductile behavior, with ductility coefficients ranging from 1.86 to 2.78. Comparative analysis among the specimens revealed that the inclusion of rebar trusses effectively stabilized the faceplates and improved the overall performance of the composite walls. Closer spacing of the rebar trusses, such as 100 mm, proved to be more effective. Specimens with vertical and horizontal rebar trusses demonstrated similar peak load capacities; however, the specimen with vertical rebar trusses achieved a 6.0% higher ductility coefficient, indicating improved deformation capacity. Furthermore, the use of a discontinuous inner steel plate in the CFST boundary column was found to reduce both lateral load-carrying capacity and ductility, rendering it an unsuitable design choice for this system. Copyright (c) 2026 by The Hong Kong Institute of Steel Construction. All rights reserved.
By utilizing intelligent construction technology, the production process of the steel fabric for simply-supported box girders in high-speed railways has been upgraded from manual binding to automatic welding. However, welding can affect the fatigue performance of steel bars. To evaluate this impact, fatigue tests were conducted on five groups of specimens as well as the base metal. The test results indicate that fatigue failure occurred at the welded spot, presenting as a brittle failure. As the stress amplitude decreases, the fatigue life of the specimens increases significantly. The fatigue life is more sensitive to stress changes at low-stress amplitudes. When the stress ratio increases, both the fatigue life and the stress amplitude decrease, and the sensitivity of the fatigue life and stress amplitude to the stress ratio gradually increases. On the overall fatigue S-N curve, the stress amplitude corresponding to a fatigue life of 2 million cycles for the welded steel bar was approximately 128.72 MPa. Compared with the base metal, the stress amplitude decreased by 45.75%. The stress amplitude under ultra-high cyclic loading was predicted. The coupling relationship of stress-amplitude stress-ratio fatigue-cycle was fitted and analyzed, relevant equations were derived, and a safety line for the values of stress amplitude and stress ratio was determined.
Exploring high-performance structures suitable for high corrosion marine environment is one of the research priorities engineering. In order to meet the requirements of the marine environment and reduce costs, thin-walled stainless-steel was used to design a high-performance component. Two stainless-steel lipped channels were welded to form a new stainless steel tubular column, with concrete filled inside, a high-performance concrete-filled stainless-steel tubular column was designed. Axial compression short column test, finite element analysis of axial compression short columns, axial compression and compression-bending intermediate-length columns were carried in the paper. Six groups of axial compression tests were conducted, results shown that both rectangular stiffening ribs and V-shaped stiffening ribs could enhance the restraint capacity of the external stainless-steel tube. The ultimate capacity of the axial compression short column with bidirectional ribs was 15.04% higher than that of the short column with unidirectional ribs. The axial compression mechanization of short columns, axial compression and compression-bending mechanization of median long column were analyzed by FEM. For axial compression short columns, the main parameters were the size of the V-shaped stiffeners and the compressive strength of the concrete. When the width-to-thickness ratio of the V-shaped stiffener was 8.33 and the angle was 90 degrees, the cross-sectional performance was the best. When the concrete was C80, the peak load was increased by 17.20% compared with C60. For axial compression and compression-bending intermediate-length columns, the main parameters were the slenderness ratio and eccentricity. When the slenderness ratio was in the range of 15.17-91.02, the larger the slenderness ratio, the faster the stiffness degradation. When the eccentricity was in the range of 0.56-3.75, the deformation capacity of intermediate-length columns was better, and the ductility was also better. The recommendation compression-bending capacity calculation formula was proposed, with high accuracy.
Nowadays, more research has been done to investigate the behaviour of concrete filled double steel tube (CFDT) columns owing to the numerous advantages over concrete-filled steel tube (CFST) columns. Very few studies have focused on the behaviour of stiffened CFDT columns. This research gap is aimed to be covered in this paper, by studying the behaviour of CFDT columns under axial loads using different stiffener profiles that are welded to the inner and outer tubes. The performance of square-stiffened CFDT columns is investigated using the finite element (FE) method. Three types of stiffeners were studied: rectangular, inclined, and tie stiffeners. The verified FE model is used to study the effect of different parameters on the behaviour of stiffened CFDT columns. The results show that using tie stiffeners give the most increase in the ultimate axial load capacity by more than 15%. A simplified analytical model is presented to predict the axial load capacity of stiffened CFDT columns using tie stiffeners.
Prestress optimization is a critical step in the structural design of suspen-dome, often requiring extensive and timeconsuming iterative computations. This study proposes a hybrid framework that integrates the NSGA-III algorithm with machine learning-based surrogate models to address the prestress multi-objective optimization problem of suspen-dome. A comparative analysis of three machine learning algorithms-Deep Belief Network (DBN), Sequence-to-Sequence (Seq2Seq), and Backpropagation Neural Network (BPNN)-is conducted to evaluate surrogate modeling performance. The multi-objective optimization considers four objective functions, and the NSGA-III algorithm is employed to effectively obtain the Pareto front. The optimal solution is selected using multi-criteria decision-making, and a case study is presented to validate the accuracy and efficiency of the proposed method. Results show that the BPNN-based surrogate-assisted optimization achieves the best overall efficiency. The introduction of surrogate models reduces computation time by 95% while maintaining optimization performance comparable to traditional finite element analysis (FEA)-based methods.
Transmission towers serve as critical carriers for electric energy transmission, making health monitoring research highly significant. Horizontal dynamic displacement is a key indicator in health monitoring; however, estimating the horizontal displacement of transmission towers using conventional equipment or methods remains challenging. Therefore, this paper proposes a reconstruction method for horizontal two-directional dynamic displacement based on measured strain data. Firstly, the simplified mechanical model of the transmission tower and the strain decoupling formula for main members are established. Then, the two-directional modal superposition method is developed by integrating the stochastic subspace identification (SSI) theory to realize the transformation from strain to displacement. Subsequently, the two-directional vibration simulations of the transmission tower show that the reconstruction error at the 27 m high measuring point is only 2.07%, and the method maintains high precision even under high noise conditions. Finally, a scaled model test of the transmission tower confirms that the reconstructed horizontal two-directional dynamic displacement matches the measured values closely in both time and frequency domains.
This research introduces an efficient cross-sectional analysis algorithm utilizing innovative Gaussian segmental elements for arbitrary-shaped steel sections. Steel members with arbitrary-shaped sections are gradually widely employed in engineering due to their mechanical benefits. Achieving accuracy in cross-sectional analysis remains crucial for the understanding of their comprehensive structural behavior and enhancing design optimization. Traditional fiber-based crosssectional analysis methods prioritize accuracy but often compromise computational efficiency. The proposed algorithm leverages the Gaussian quadrature method, renowned for its precise approximation of definite integrals, to address complex cross-sectional geometries. In addition, a refined line-segment model is introduced to solve the overlapping problem by configuring eccentricities at the ends of segments. The paper elaborates on the derivation of the novel Gaussian segmental element designed for modeling the arbitrary-shaped section, determining the section properties, generating full yield surfaces, and calculating the moment-thrust-curvature relationships. Notably, the algorithm balances accuracy and computational efficiency by strategically selecting integration Gauss points and weights across thicknesses. Three groups of examples are provided to demonstrate the accuracy and efficiency of the proposed method for the cross-sectional analysis of arbitrary-shaped steel sections. Copyright (c) 2026 by The Hong Kong Institute of Steel Construction. All rights reserved.
This paper proposes a novel steel-timber hybrid beam-column joint suitable for the "timber above and steel below" lowrise hybrid structural system. Sleeves and L-shaped connectors are set up at the joints. Sleeves are set up to prevent the wood from cracking, while L-shaped connectors prevent the steel column from twisting when connecting the upper wood column to the lower I-beam. In order to investigate the impact resistance, the deformation characteristics, damage mechanism and energy dissipation capacity were investigated through tests and numerical simulations. The effects of key parameters such as impact mass, velocity, position, impactor shape, and beam end constraints on the impact resistance of the joints were also analyzed. The results show that the joint's performance overall was excellent, in which the L-shaped connector served as the primary deformation zone. The joint's deformation and displacement under the same impact conditions were reduced significantly by reinforcing the connector's thickness. Furthermore, the spring support replaced the crossbeam's restraint function effectively during the tests. The parametric analysis revealed that an increase in the hammer's velocity at impact leads directly to a significant increase in the impact's peak force and a prolonged impact platform. In contrast, an increase in the hammer's mass had a limited effect on the impact's peak force, and merely extended its decay process. Based upon the experimental results and parametric analysis, the vulnerabilities of the steel-timber hybrid joint in the "timber above and steel below" structural system were identified, and corresponding improvement measures are proposed. Copyright (c) 2026 by The Hong Kong Institute of Steel Construction. All rights reserved.
This study presents an analytical and numerical investigation of ultra-high-performance concrete-filled double-skin tubular (UHPC-CFDST) columns with circular cross-sections under fire conditions. An automated algorithm was employed to develop and verify a finite element (FE) model capable of accurately simulating CFDST columns incorporating different concrete types (normal concrete, ultra-high-performance concrete (UHPC), and lightweight concrete) in both core and ring regions. The validated model was used to examine the influence of key parameters, offering deeper insight into the behavior of such columns under fire. Three temperature-dependent material models were developed to represent UHPC, lightweight concrete, and high-strength steel at elevated temperatures. Additionally, a finite difference-based thermal model was proposed to simulate the temperature distribution across the column cross-section and to predict fire resistance (FR) time. To the best of the authors' knowledge, existing fire design standards do not provide specific models for CFDST columns under fire, and available research in this area is limited. This study addresses this gap by evaluating the applicability of Eurocode 4 (EC4) and proposing a simplified modification that improves the prediction accuracy of fire resistance for UHPC-CFDST columns. Copyright (c) 2026 by The Hong Kong Institute of Steel Construction. All rights reserved.
With the advantages of simple form, beautiful appearance, uniform force and strong span ability, grid structure has been widely used in long-span space structure. The traditional design often relies on the experience of engineers with low efficiency and using heuristic algorithms to drive design is a very good way. Simple genetic algorithm is a typical heuristic algorithm, the concept is clear, but easy to "precocious" or even not convergence. Based on the idea of "dual-population evolution", this paper introduces a series of strategies, and constructs an improved dual-population genetic algorithm (IDPGA). Two subpopulations evolve independently and exchange some individuals to prevent falling into local optima and expand searching capabilities. Then, combined with ABAQUS script, two acceleration strategies are adopted to form an intelligent optimization framework for solving the grid structure design problems, including static and dynamic optimization problems. The results show that the algorithm is effective, reliable, robust and accurate. In addition, in practical application, a satisfactory engineering solution can be found without fully exerting the optimization ability of the algorithm. Copyright (c) 2026 by The Hong Kong Institute of Steel Construction. All rights reserved.
Traditional seismic design method of steel canopy structures usually assumes that the lower support structure to be rigid. However, in practical engineering, the steel canopy and the lower support structure interact as an integrated system. With the innovation in design method of steel canopy structures, the seismic design of traditional large cantilever steel structure faces higher requirements. In this study, the integrated model of a large stadium steel canopy and its lower support structure is used as a reference. To consider the influence of the lower support structure, two simplified preliminary analysis models are established separately. Time history analysis is performed on all three models to evaluate simplified calculation methods for the lower support structure under seismic excitation. A series of studies are conducted to identify the causes of the discrepancies in the dynamic response among models. The study examines the effects of stiffness in-homogeneity in the lower support structure, revealing significant directional variations in stiffness across three axes. Furthermore, by analyzing peak acceleration and frequency variations between input and output for ground motion in the lower support structure, the results demonstrate that the structure's amplification and filtering effects of the lower support structure on ground motion are key contributors to in dynamic response variability. Results indicated that the seismic performance of large cantilever steel canopy structures should be evaluated using an integrated model to ensure more reliable seismic design outcomes. Copyright (c) 2026 by The Hong Kong Institute of Steel Construction. All rights reserved.
To enhance the weak-axis performance of double corrugated steel plate shear walls (DCSPSWs), this study introduces an innovative orthogonal-installed double corrugated steel plate shear wall (OD-CSPSW). The proposed system comprises two orthogonally interlocked corrugated plates connected via through-bolts and integrated into a steel frame using fish-tail plate connections. A large-scale general-purpose finite element (FE) software, ABAQUS 6.14, was employed. Following validation against experimental benchmarks, 15 OD-CSPSW models were analyzed, and the effects of the corrugation angle and arrangement method on the hysteretic behavior of OD-CSPSWs were investigated. Additionally, two specimens of the co-directional DCSPSWs were designed as the control group. The results indicate that the OD-CSPSW demonstrates better hysteretic behavior compared to the co-directional DCSPSW. Specifically, the OD-CSPSW with a corrugation angle of 45 degrees demonstrates the best overall stiffness and resistance to out-of-plane buckling, while also possessing a high energy dissipation capacity. According to the coverage method, the shear wall exhibits the highest initial stiffness when fully coverage, though its load-bearing capacity degrades more rapidly. For non-fully coverage, the energy dissipation capability of a vertically-centered shear wall outperforms a horizontally-centered one. It is recommended that when designing the OD-CSPSW, the corrugation angle should be set to 45 degrees with full coverage, and if non-fully coverage is necessary, a vertically-centered arrangement should be selected. Copyright (c) 2026 by The Hong Kong Institute of Steel Construction. All rights reserved.
This study investigates the single-layer cable-net roof structure of the Xiatian Cultural Park Stadium by conducting a 1:10 scale model experiment to systematically examine the internal forces and deformations under various static loading conditions. The experiment incorporates full-span loading scenarios, and in conjunction with finite element simulations, analyzes and compares the force and deformation responses of the load-bearing cables, ring cables, diagonal cables, anti-wind cables, and back cables. The results demonstrate that, during loading, the cable forces and node displacements in all groups exhibit a linear relationship with the applied load. Among these, the ring cables sustain the highest internal forces, indicating their role as the primary load-bearing elements of the structure. Moreover, the finite element analysis results for static performance show close agreement with the experimental data, with discrepancies remaining within an acceptable range. This consistency verifies the accuracy of the numerical simulation method and confirms the reliability of the experimental results. The findings offer valuable reference data for the structural design and optimization of similar systems.
In prefabricated support and hanger, the study of corner strength in cold-formed thin-walled steel (CFTWS) is crucial. Corners are prone to stress concentration, increasing local buckling and connection failure risks. This study analyzes the stress in the corner parts and derives the yield strength using the linear hardening model and the Von-Mises yield criterion. Based on the Prandtl-Reuss flow rule and strain superposition principle in plastic mechanics, a theoretical analysis of corner material hardening during the cold-bending process is conducted. Experiments and ABAQUS simulations are carried out to prove the effectiveness of the theoretical model. The findings reveal that the cold bending effect is relatively significant. The yield strength of the corner parts is about 79-86 MPa higher than that of the flat parts, which is equivalent to an increase of 23% to 25%. Due to the relatively low degree of anisotropy and smaller thickness measurement errors in thicker CFTWS, the theoretical formula has higher calculation accuracy for steel plates with greater thickness. In addition, in the same batch of steel produced by the same cold bending process, the yield strength of CFTWS slightly decreases with the increase of thickness. Copyright (c) 2026 by The Hong Kong Institute of Steel Construction. All rights reserved.
