In order to improve the seismic performance of traditional HDR(high-damping seismic isolation rubber bearings)bearings and their adaptability in simply supported beam bridges in high-intensity seismic zones, a new type of composite seismic bearing was developed based on the rational integration of steel bar dampers and HDR bearings, and its structural construction and mechanical behavior were described. Taking a specific specification product as an example, the vertical compression performance and horizontal hysteresis performance were demonstrated through finite element numerical simulation and experimental research. Then, a 5~20 m concrete simply supported beam bridge in an 8-degree seismic zone was taken as the object, and a finite element model was established using SAP2000 to study its seismic performance. The results showed that the vertical compression performance of the bearing met the standard requirements, and the horizontal hysteresis curve was more full than that of the HDR bearings. The finite element numerical analysis and experimental results were in good agreement with the theoretical skeleton model. Compared with the HDR bearings seismic system, the internal force response of the bridge pier increased to a certain extent after the use of the composite bearing, but it is still within the capacity range, and the displacement of the bridge beam end and the relative displacement of the pier-beam are significantly reduced, which can effectively avoid the occurrence of seismic damage such as beam-falling and collision of adjacent beams.

In order to investigate the effectiveness of treatment measures for silt subgrade in high seismic fortification areas, vibration table model tests were conducted on pure silt subgrade and reinforced silt subgrade. Based on a comparative analysis of the failure characteristics and dynamic response laws of the two models, the influence mechanism of reinforcement on the seismic performance of silt subgrade was explored. The experiment shows that after the peak acceleration of seismic load reaches 0.25 g, the experimental pure silt subgrade gradually experiences cracking, fragmentation, and sinking failure. After adding four layers of geogrids on the slope side of the subgrade, the seismic resistance of the silt subgrade can be effectively improved. When the peak acceleration of the seismic load is loaded to 0.35 g, although cracks also appear on the reinforced silt subgrade, the subgrade can still maintain good integrity. Under seismic loads, reinforced silt subgrade and pure silt subgrade have basically the same acceleration and dynamic soil pressure response rules. The acceleration amplification factor increases nonlinearly with the increase of subgrade height, and decreases with the increase of seismic load. Under the same load, the amplification factor on the slope side of the subgrade is larger than that on the centerline side, but the difference between reinforced silt subgrade is smaller. The dynamic soil pressure of both models shows a pattern of “larger on both sides and smaller in the middle” in the height direction of the subgrade. In the direction of the subgrade cross-section, the dynamic soil pressure on the centerline side of the subgrade is greater than that on the slope side. Due to the influence of subgrade structure, the potential fracture surface of reinforced silt subgrade under seismic loads will form at the end of the reinforced body and within the low pressure compaction zone. Reinforcement is an effective measure to improve the seismic performance of silt subgrades. In practical engineering applications, the length of the reinforcement should not be less than 0.65H, and there should also be sufficient anchoring length.

In the current context of increasingly constructed urban built environments, the disaster impacts of functional disruptions in urban buildings hit by earthquakes can quickly propagate and intensify through the social chain. To quantify the functional disruption of earthquake-damaged building complexes, this paper focuses on assessing the functional recovery time of urban building complexes after an earthquake and develops a comprehensive assessment framework. The framework employs a fuzzy hierarchical analysis to quantify the impact of key factors, such as building renovation class, regional economy, climate, and topography, on the recovery process. Additionally, the study divides the rehabilitation process of the urban complex into a preparation phase and a repair and reconstruction phase, and develops a systematic assessment model for each phase. In the preparation stage, the assessment model especially considered the impact of the earthquake emergency period and systematically sorted out the time required for five key recovery preparations under different intensities of effects according to the expected intensity of earthquake effects; the assessment model for the repair and reconstruction stage was constructed based on the damaged area of the earthquake-damaged houses as well as the time required for repairing or reconstructing per square meter. The model preliminarily estimates the reconstruction time per unit area of houses of different building structure types in China through in-depth analysis of the quota data, and takes into account the uncertainties in the construction process by using the Monte Carlo simulation method. And the repair time per unit area of a house is derived by reasonably discounting the reconstruction time based on its damage degree. The research results not only provide new perspectives for the theory of urban disaster management, but also provide good data support for the resilience building of the government and enterprises and the rapid development of recovery decisions after disasters.

A large number of seismic investigations have shown that the damage caused by nonstructural components could not be ignored, and with the increasing maturity of the response spectrum method, it has become an important method for the seismic response analysis of nonstructural components. However, the current method of generating response spectrum was mostly used for multi-story structures, and the method of generating response spectrum for large-span structures was still not clear. Therefore, this article establishes nine types of single-layer cylindrical reticulated shell structural models on the basis of ABAQUS and Python. Through numerical analysis, the representative nodes of the single-layer cylindrical reticulated shell were identified by comparison, and the spectral characteristics of the three-way acceleration response spectrum were investigated and analyzed, and the fitting form of the node response spectrum was established, and the fitting formula of the three-way acceleration response spectrum of the single-layer cylindrical reticulated shell nodes was proposed. In addition, this article further determined the calculation formula of each characteristic parameter through the fitting analysis, and investigated the relationship between the peak acceleration amplification factor, the peak spectral acceleration amplification factor and the effective distance of the nodes, the structural rise-to-span ratio and the roof mass based on the representative nodes. The research results in this article could be used to approximate the seismic response of the single-layer cylindrical reticulated shell non-structural components, and could provide a valuable reference for the generation of response spectrum for other large-span structures.

To enhance the protection of masonry pagodas and improve the damping performance of suspension pendulum damper (SPD), a novel SMA composite pendulum damping system is proposed, integrating shape memory alloy (SMA) into SPD. This system enhances the inertia force generated by the pendulum within SPD by leveraging the super elasticity and high damping characteristics of SMA, thereby improving the overall energy dissipation capability of the damping system. Initially, the study outlines the process of obtaining the equivalent restoring force of SMA through stochastic equivalent linearization. Subsequently, it establishes the SDOF computational model of the SMA composite pendulum damping system by drawing parallels with the SDOF computational model of SPD. The paper elucidates the structure and operational principles of the damping system, followed by an exploration of the effects of two control parameters on its performance. Further, the study applies both SPD and the new composite pendulum damping system to a masonry pagoda. The structural vibration response is analyzed under three distinct seismic excitations following the implementation of the damping system using ABAQUS software. The findings reveal that the SMA composite pendulum damping system outperforms SPD in vibration control under various seismic excitations, demonstrating its superior applicability.

In order to expand the application of perfobond leiste (PBL) shear connectors, the low-cycle reciprocating loading tests were conducted on one steel reinforced concrete composite shear wall and four steel plate concrete composite shear walls with PBL shear connectors. The failure mechanism and seismic performance of the specimens were studied. The results show that the failure modes of shear walls under horizontal loads can be divided into two types including bending failure and bending-shear failure. The aspect ratio of the walls, the configuration of steel core plates and the arrangement of the PBL shear connectors are important factors affecting failure modes. PBL shear connectors can facilitate steel core plates working well with the concrete. Besides, the configuration of steel core plates can improve the bearing capacity of the walls. The bearing capacity of shear walls decreases with the increase of aspect ratios, and the vertical arrangement of PBL shear connectors is better than the horizontal arrangement of PBL shear connectors. Based on the design of compression-bending capacity of steel reinforced concrete columns recommended in EN 1994-1-1:2004, a design formula of compression-bending capacity for steel plate concrete composite shear walls with PBL shear connectors is proposed. It is verified that the design formula can accurately calculate the compression-bending capacity of the shear walls with large aspect ratios by comparison.

A simplified method for calculating the longitudinal movement and cumulative displacement of the stiffening girder in long-span suspension bridges under random traffic flow is proposed. In this method, the suspended stiffening girder system is equivalent to a single-degree-of-freedom (SDOF) vibration system. Based on this SDOF system, the longitudinal vibration equations of the suspension bridge’s stiffening girder under moving loads and random traffic flow are derived. A rapid calculation method for the stiffening girder’s longitudinal vibration response under random traffic flow is proposed. Taking an example of a long-span suspension bridge and using existing traffic measurement data, random traffic flow samples are generated based on the Monte Carlo method. These samples are then treated as random loads on the SDOF system. The SDOF vibration equation is solved, and the results are compared with ANSYS dynamic analysis results. The findings reveal that under random traffic flow, the stiffening girder undergoes longitudinal movement and accumulates a significant displacement. This cumulative displacement consists of both static and dynamic components, with the latter contributing more significantly. Compared to the finite element transient dynamic analysis, the displacement response results obtained from the simplified SDOF system show minimal differences in extreme values and root mean square(RMS) values (less than 5%), although there is a slightly larger difference in cumulative displacement (approximately 13% ~ 19%). This indicates that the simplified vibration model can capture the stiffening girder’s longitudinal movement characteristics under random traffic flow. The proposed simplified method greatly simplifies the analysis of the stiffening girder’s longitudinal movement under random traffic flow, enabling response evaluation and parameter optimization in the preliminary design stage.

In order to improve the seismic performance of reinforced concrete (RC) frames, carbon fiber-reinforced polymer (CFRP) was used to retrofit reinforced concrete frame structures. The effects of CFRP on the failure mode, the energy dissipation characteristics, the lateral stiffness degradation patterns, the ultimate bearing capacity degradation and the ductility of RC columns were investigated by the pseudo-static tests. The results show that the peak bearing capacity, initial stiffness and ductility of the CFRP reinforced model are increased by 43.89%, 39.27% and 30.10%, respectively. Based on the parametric study of the finite element model, the contribution of CFRP to the seismic upgrading effect of RC columns was quantitatively revealed, and the optimized design of CFRP retrofitted was proposed. The results indicated that the peak load, ductility and energy dissipation capacity of the whole structure are improved by using CFRP full-wrap reinforcement and strip reinforcement models with different coverage areas. The damage degree of column decreases, the damage degree of beam increases, and the failure mode changes from “column hinge” to “beam hinge”. Simultaneously, different CFRP reinforcement areas and the distance between strip-shaped CFRP have different reinforcement effects on concrete structures. Based on the investigation results, the recommended ratio of the width of CFRP strip to its spacing is 1.00 to 1.25.

The damping of the primary structure has a certain impact on the dynamic characteristics of the system. However, the damping of the primary structure is often neglected when optimizing the design of DVAs using analytical methods to simplify calculations. This paper employs the perturbation method to derive an analytical solution for the optimized design parameters in negative stiffness-inerter dampers considering the damping of the primary structure under random excitation. Firstly, the governing equation of the vibration system under base acceleration excitation is established to obtain the absolute acceleration response transfer function and the corresponding mean square value. Secondly, the perturbation method is introduced to obtain the analytical solution of the optimal design parameters of the negative stiffness-inerter damper considering the primary structure damping under the H₂ criterion, and the validity of these analytical solutions is verified. Subsequently, through comparative case studies, it is demonstrated that neglecting the primary structure damping can cause significant deviations between the optimal design parameters of the negative stiffness-inerter damper and the actual values when the primary structure damping radio is relatively large highlighting the necessity of considering primary structure damping in parameter analytical optimization design. Finally, the optimal mean square value of absolute acceleration in the frequency domain and the peak value of the time history response in the time domain are compared after installing negative stiffness-inerter dampers and inerter dampers for the primary structure with damping, respectively. The result indicates that reducing the damping ratio of the main structure allows negative stiffness to increasingly improve the damper’s effectiveness. Furthermore, it demonstrates that the negative stiffness-inertance damper is more efficient in controlling the peak time-history response of the main structure.

The main building structure in a thermal power plant houses a large number of mechanical and electrical equipment, which is an essential component of the entire building. In this study, a calculation model for the main building structure considering the interaction between equipment and structure was established. A separate structural model of the main building structure was used as a comparison. Through static push-over analysis, the seismic performance of the structure was evaluated. The seismic fragility analysis based on SPO2IDA was conducted for both models. It was found that the structure-equipment interaction system in the elastic-plastic stage has a higher stiffness. The coal bunker has a significant damping effect on the coal bunker layer and adjacent layers, but it slightly increases the inter-story drift angle on the floor with the maximum inter-story displacement angle. The seismic fragility curve of the structure-equipment interaction system in the main power plant is obtained based on the SPO2IDA method.