The quantitative calculation and evaluation of seismic damage play a crucial role in ensuring structural safety, conducting performance-based structural analysis, and implementing seismic strengthening measures. However, there is limited research on the damage performance of blind-bolted T-stub steel connections used extensively in prefabricated buildings. In this study, the tensile sub model of a blind-bolted T-stub steel connection in a beam–column joint is investigated. The influence of the flange and web thickness of the T-stub connector, as well as the shear-loaded connecting bolts on the web of the T-stub, on the tensile performance of the sub model are considered. Four tensile destructive tests are conducted on a T-stub connector connected to a hollow section column using blind bolts. The experimental results, including failure modes, force–displacement curves, and strain development in the hollow section column and T-stub, are discussed and analyzed in this study. The test results reveal three main failure modes for this tensile substructure: the plastic deformation of the hollow section column, the bending fracture of the T-stub flange, and the fracture of the T-stub web bolt holes due to compression. Furthermore, a ductile damage finite element analysis method is employed to simulate the fracture damage process of the substructure, and the corresponding damage index is calculated using the typical Park–Ang damage model for evaluation, showing good agreement with the damage classification levels specified in FEMA.

To investigate the dynamic performance and seismic response of Ming dynasty masonry pagodas in the Jiangnan region of China, the Great Wenfeng Pagoda in Taizhou, Zhejiang Province, was selected as the study object. Based on on-site inspection and maintenance records, the in situ compressive strength of masonry at each level was measured using a rebound hammer, considering that the pagoda was immovable and no destructive testing was permitted. A numerical model of the pagoda was established using the finite element software ABAQUS 2016 with a hierarchical modeling approach. The seismic response of the pagoda was computed by applying the El Centro wave, Taft wave, and artificial Ludian wave, and the seismic damage mechanism, the distribution of principal tensile stress, and seismic weak zones were analyzed. The results showed that the horizontal acceleration increased progressively along the height of the pagoda. Under minor earthquakes, the pagoda remained largely elastic, whereas under moderate and strong earthquakes, the acceleration at the top and bottom and the story drifts increased markedly, with the effects being most pronounced under the Taft wave. The damage was primarily concentrated in the first and second stories at the lower part of the pagoda and around the doorway. Tensile stress analysis indicated that the masonry blocks in the first and second stories were at risk of tensile failure under strong seismic action, whereas the lower-level stone blocks in the first story remained relatively safe due to their higher material strength. This study not only reveals the seismic weak points of Ming dynasty masonry pagodas in the Jiangnan region but also provides a scientific basis for seismic performance assessment, retrofitting design, and sustainable preservation of traditional historic buildings.

Steel traditional Chinese buildings (STCBs) are constructed using modern materials, replicating the esthetics of ancient Chinese buildings, but their irregular joints differ significantly from those in conventional steel structures. To investigate the influence of beam section shape and axial compression ratio on the failure mode and shear resistance of all-welded irregular joints (WIJs) in STCBs, the size proportion relationships in the traditional Chinese modular construction system for such joints in existing practical projects are analyzed. Four exterior joint specimens were designed and fabricated for pseudo-static loading tests. The failure mode, hysteresis curve, and skeleton curve of the specimens were obtained. The test results indicate that the failure mode of the specimens involves shear deformation in the lower core area, with final failure due to crack formation in the weld at the junction between the column wall and the beam flange. As the axial compression ratio increases, the bearing capacity of the joint decreases. Based on the test results, the numerical model was established by using finite element software Abaqus2016, and parameter analysis was performed by varying the axial compression ratio of the column. After analyzing the force transfer mechanism of the core area in the WIJs of STCBs, a simplified calculation formula for the shear bearing capacity of the core area was derived based on the proportional relationship outlined in the construction manual from the Song Dynasty. The calculated results show good agreement with the experimental results, providing a basis for the structural design of WIJs in STCBs.

To investigate the influence of isolation-layer eccentricity on the torsional response of step-terrace mountain (STM) structures, a 1:10 scaled reinforced concrete model was designed and tested using shaking table experiments. Both isolated and non-isolated configurations were considered, and different eccentricity levels were achieved by adjusting the bearing layouts in the upper and lower isolation layers. The torsional response was evaluated in terms of torsional angle, torsional displacement ratio, and relative torsional effect. The results indicate that the non-isolated STM structure exhibits pronounced torsional amplification and progressive damage accumulation. Deformation and damage are concentrated in the upper stories and dropped-story region, eventually leading to a stiffness–degradation–dominated failure pattern. In contrast, the STM isolated structure effectively suppresses torsional response, and inter-story rotations remain small and relatively uniform along the height, indicating that seismic deformation is primarily redistributed within the isolation layers rather than amplified in the superstructure. The experimental results further demonstrate that torsional behavior is governed by the coupling effect between isolation-layer eccentricity and seismic input direction. The eccentricity in the upper isolation layer plays the dominant role in triggering torsional amplification, while simultaneous eccentricities in both isolation layers produce a cumulative torsional effect. When the eccentricity of the isolation layers is controlled within 5%, the torsional displacement ratio remains below 1.2, while the non-isolated structure reaches values exceeding the code limit of 1.5. In addition, slope-direction excitation intensifies absolute torsional deformation due to overturning effects induced by elevation differences. These findings highlight that torsional response in STM isolated systems is controlled by the interaction between vertical irregularity and isolation-system asymmetry.

Four full-scale exterior beam-to-column connections comprising H-section beams and square hollow-section (SHS) columns were tested under low-cycle reversed loading to investigate two engineering-oriented T-stub section configurations and the effects of the presence or absence of triangular stiffeners. Failure modes, moment–rotation response, stiffness degradation, energy dissipation, and cumulative damage were evaluated, together with nonlinear finite element simulations and a modified Park–Ang damage assessment. All specimens progressed from bolt-hole slip through plastic deformation to localized fracture. In the unstiffened connections, damage concentrated near the T-stub flange-to-web junction; stiffeners redistributed critical demand toward the stiffener welds, adjacent T-stub webs, and SHS column walls. The maximum differences in initial rotational stiffness relative to J1A were 15.69% and 15.07% in the positive and negative loading directions, indicating that the elastic-stage response reflected the combined deformability of the T-stub, blind-bolt assembly, and column wall. The maximum increases in yield moment, peak-resistance moment, and ductility coefficient were 20.59%, 43.71%, and 45.91%, respectively. Complete-history energy dissipation varied non-monotonically across the tested configurations. The finite element model reproduced the global and local responses, while the damage-index results showed overall correspondence with the observed failure progression. The findings emphasize stiffness compatibility and rational distribution of plastic demand rather than maximum local stiffness.

Modern Chinese traditional-style buildings (MCTBs) preserve the beam–column –construction of historical architecture, but the irregularity of joints continues to constrain their seismic performance. To enhance the energy-dissipation capacity of these joints, viscous dampers were installed at the Que-Ti braces (cantilever corbels beneath beam ends) of beam–column joints. Six 1/2.6-scale specimens were designed and tested under periodic dynamic loading. The experimental results indicate that the installation of viscous dampers significantly improved the failure modes by delaying the formation of plastic hinges at beam ends, as well as the initiation of base material cracking and weld fracture. After damper installation, the joint strength increased by 18–46%, and the improvement was more pronounced in double beam–column joints. A finite element model was established in ABAQUS to investigate the effects of axial load ratio, damping coefficient and damper length on joint strength, hysteretic energy dissipation, and damper mechanical response. The results revealed that the axial load ratio has a limited influence on the overall joint strength and damper contribution. Increasing the damping coefficient significantly enhances the joint hysteretic energy dissipation and peak damper force, exhibiting an approximately linear relationship. The damper length has a minor influence on joint strength, but a longer damper slightly increases the hysteretic energy dissipation and equivalent viscous damping, while the maximum damper displacement is mainly governed by the damper length. Similar damper contributions are observed in single beam–column and double beam–column joints, indicating stable and reliable energy-dissipation behavior. The proposed numerical approach can predict the axial deformation, velocity, and force demands of dampers under various loading conditions. In addition, preliminary design recommendations for irregular steel joints with supplemental viscous dampers in MCTBs were developed based on ancient Chinese architectural literature and refined through combined experimental observations and finite element analyses (FEA).