Grouted sleeve connections are widely used in precast structures due to their excellent connectivity and ease of construction. However, variations in local stiffness within the grouted sleeve region and the relatively weak integrity of the concrete interface at the joint have negatively impacted the seismic performance of precast structures. This paper systematically summarizes the seismic performance tests, theoretical calculations, and numerical analysis of grouting sleeve connection joints, precast assembled components, and precast overall structures. Firstly, this paper elucidates the basic structure and force transmission mechanisms of grouted sleeves while summarizing the critical factors that influence the mechanical performance of sleeve grouted connections. Secondly, the influence laws of the strengthening effect of grouted sleeves on the mechanical properties of precast assembled structures are analyzed. Additionally, the impacts of the arrangement patterns of grouted sleeves and grout defects on the seismic performance of precast structures are investigated. Meanwhile, the calculation methods for the bearing capacities (bending, shear, and torsion) of precast assembled structures connected by grouted sleeves are summarized. Finally, the modeling methods of numerical analysis models for grout sleeve splice and precast assembled components connection with grouted sleeves are analyzed. Based on these, the following researches directions need to be explored: stiffness compatibility between sleeves, steels, and concrete; grouting quality assurance and detection methods; unified constitutive model for grouting material; calculation method for the bearing capacity of precast structure with grouted sleeve connections considering grouted sleeves, concrete, and steels factors.

This paper proposes a nonlinear spring restraint structure to overcome the limitations of the static thrust test method in evaluating underground structure systems. Considering the difficulties of soil-structure interaction, high costs, and limited observability of test phenomena, the proposed approach integrates basic principle of the reaction displacement method for underground structures. It recognizes that the traditional elastic spring fails to capture soil state changes during loading, thus prompting the introduction of a more dynamic spring-structure system. It suggests using nonlinear springs instead of soils for analyzing seismic performance. Through Pushover analysis on a single-span underground structure model, the influence of factors such as the axial compression ratio and spring-structure interaction on mechanical performance is investigated. Comparing bending moment capacity curves of key sections shows that the static thrust overlay model for spring-underground structures is suitable for seismic analysis of underground structures. Up to an inter-story displacement angle of 1/200, both the linear and nonlinear spring models are highly accurate, but beyond this threshold, the nonlinear spring model is significantly superior. The simplified analysis method for seismic performance of nonlinear spring-underground structure systems provides insights into the complex force behaviors of underground structures.

To characterize the mechanical properties of 7075 high-strength aluminum alloy, three specimens for the monotonic tensile test and five specimens for cyclic loading were designed and fabricated. Based on the Ramberg-Osgood model, numerical fitting was carried out separately for the monotonic tensile stress-strain curves and cyclic loading skeleton curves of aluminum alloy bars. A comparative analysis was conducted on the tensile mechanical properties and hysteresis mechanical properties of 7075 high-strength aluminum alloy. The combined hardening parameters for high-strength aluminum alloy were calibrated, and a combined hardening hysteresis constitutive model was established. Using the software ABAQUS, a numerical analysis model of high-strength aluminum alloy was created, and the simulation results were compared with and validated against experimental results. The results indicate that 7075 high-strength aluminum alloy exhibits excellent hysteresis performance, and the Ramberg-Osgood model shows good applicability to the monotonic mechanical properties of high-strength aluminum alloy. The finite element simulation results based on the combined hardening model are in good agreement with the test results. The calibrated combined hardening model can be used for the seismic behavior analysis of structures reinforced with high-strength aluminum alloy.

The isolation structure is equipped with isolation devices to extend the natural vibration period and reduce the seismic response. However, improper construction causes the infill wall to be built around the isolation device, which restricted the free movement of the superstructure, thus affecting the actual isolation performance of the structure. In order to quantify the impact of the above unfavorable factors on the seismic isolation performance of the structure, this paper takes a certain reinforced concrete(RC) frame as the research object, uses a method of combining in-situ testing and numerical simulation, and compares and analyzes in the OpenSees considering whether the constraint effect of the infill wall is taken into account. Seismic response of isolation structures under different types of earthquake motions. The research results show that compared with unconstrained seismic isolation structure, the maximum acceleration of the upper floors, the maximum inter-story drift and the maximum base shear force of structures with seismic isolation layers constrained by peripheral infill walls increase by 20.4%, 38.7%, 35.7% under frequent earthquakes. The displacement of the isolation layer is reduced by 79.4%. Under the action of seismic precautionary earthquakes, they increase by 21.6%, 59.8%, 86.5%, respectively, and the displacement of the isolation layer is reduced by 37.8%. Under the action of rare earthquakes they increased by 17.7%, 19.4%, and 14.9% respectively, and the displacement of the isolation layer decreased by 10.3%. As the peak acceleration of the input ground motion increases, the lead rubber bearing will play a greater role only after the infill wall is damaged. Under rarely occurred earthquake, the seismic isolation layer breaks through the constraints of the surrounding filling walls and can basically achieve the seismic isolation effect.

In this paper, a kind of embedded bolt connector was proposed. The utilization of embedded steel blocks and bolt taper sleeves can reduce the damage to concrete and steel beams under load, and enable the removal and replacement of the composite beam. Eight groups of specimens were designed and manufactured. After the push-out test, the specimens were removed and reassembled. Subsequently, a reloading test was conducted and the demountable ability were analyzed. The influence of bolt diameter, bolt strength, T-shaped steel block and external diameter of the embedded steel block were discussed. The results showed that when the specimen was damaged, the bolt was cut or the concrete was crushed. Eight groups of specimens could be quickly disassembled after loading. The dismantled steel beam and T-shaped steel block could be reused for many times. After loading, the concrete slab in undamaged and slightly damaged state could be reused for more than twice, and the shear performance of the specimen remained basically unchanged. The concrete slab in a damaged condition can be reused once, but its shear resistance will be reduced. The concrete slab in a severely damaged condition is not to be reused. In addition, the embedded bolt connector has good anti-lift performance. With an increase of bolt diameter or strength, the bearing capacity of specimen and the damage of concrete slab increased. With an increase in the outer diameter of the embedded rigid block, the bearing capacity of the specimen remained unchanged, while the damage to the concrete slab decreased. The presence or absence of T-shaped rigid block had little impact on the bearing capacity of the specimen, but could enhance the demountable performance. Finally, the local damage coefficient η of concrete slab was proposed as the control index for demountable performance, and when η is about 0.5, it is in a good demountable state.

The substation is the core link in the transmission and distribution of electricity. Post-electrical equipment holds an important position in substations. They are not only numerous but also diverse, and are very likely to be damage in earthquakes. This paper takes the 500 kV voltage transformer as the research object, installs a new type of steel wire rope seismic isolation bearing on it, and compares and analyzes the response characteristics of the prototype structure and the seismic isolation structure under seismic action through the seismic simulation shaker test. The test results show that the fundamental frequency of the isolation structure has been significantly reduced compared with the prototype structure, confirming the effectiveness of the new wire rope seismic isolation support in reducing the seismic response of post-electrical equipment. Meanwhile, the seismic isolation structure shows high isolation efficiency in reducing acceleration and stress response, but the isolation effect for displacement response is relatively limited. Under strong seismic effects, the seismic isolation structure can effectively reduce the acceleration and stress response of the equipment, which reduces the risk of breakage of porcelain insulators of transformers due to vibration. At the same time, the seismic isolation bearings will not have significantly reduced the top displacement response of the equipment. Therefore, in the subsequent improvement of the new wire rope seismic isolation support, it is necessary to comprehensively consider the various responses caused by seismic forces to ensure the overall safety of the equipment.

Hybrid simulation with model updating utilizes the test data to identify the parameters of the experimental substructure and updates the model of the numerical substructure, effectively avoiding the errors induced by the inaccurate parameters of the numerical substructure in traditional hybrid simulation. To ensure the accuracy of parameter identification, the selected constitutive parameters must be observable and highly sensitive. The existing local parameter sensitivity analysis method belongs to qualitative analysis and cannot specifically and quantitatively evaluate the sensitivity of the parameters. Therefore a parameter sensitivity analysis method based on correlation analysis is put forward. This method quantitatively evaluates the parameter sensitivity of constitutive parameters by calculating the correlation coefficient between constitutive parameters and restoring force, and the calculation is simple. The parameter sensitivity analysis of concrete employing the Kent-Scott-Park constitutive model and the composite damper using the trilinear constitutive model is conducted respectively, and the results are compared with those obtained by the local parameter sensitivity analysis method. The results show that the higher sensitivity parameters selected by the two methods for the constitutive parameters of concrete are consistent, while the local parameter sensitivity analysis method is not suitable for the composite damper. The proposed method can determine the parameter sensitivity of the constitutive parameters of the composite damper. A six-story steel frame structure equipped with a composite damper was subjected to a hybrid simulation with model updating numerical simulation using different model update methods. The effects of parameter identification were compared and it was found that the constitutive parameters selected by the proposed method were easier to identify, and the hybrid simulation with model updating numerical simulation had higher accuracy and efficiency, which verified the correctness and effectiveness of the method.

To investigate the seismic performance of partially encased composite columns-reinforced concrete shear walls (referred to as PEC column-RC shear walls), two different connection types were designed and subjected to low-cycle reversed loading tests. The study focused on their failure processes, hysteretic behavior, energy dissipation capacity, stiffness degradation, and strength degradation. Additionally, finite element models were developed to simulate their behavior, which were validated against the experimental results. The models were also used to analyze the seismic performance of PEC column-RC shear walls under different concrete strength grades and axial compression ratios. The results indicate that PEC column-RC shear walls ultimately experience shear failure, yet they exhibit high ductility and energy dissipation capacity, demonstrating excellent seismic performance. In practical engineering applications, the weak-axis connection method for PEC columns can effectively meet seismic performance requirements. As the concrete strength increases, the load-bearing capacity of PEC column-RC shear walls improves, although the ductility decreases. With an increase in the axial compression ratio, the rate of increase in load-bearing capacity diminishes. It is recommended to keep the axial compression ratio below 0.4 in practical engineering designs.

Vertical ground motion is a serious threat to bridges and other structures in high intensity areas, and the relationship with horizontal ground motion is complicated. However, the current Code for seismic design of railway engineering(GB 50111—2006) (2009 edition) does not make special provisions for the vertical design response spectra. Some other specifications only stipulate that the vertical response spectra should be taken as a fixed ratio of the horizontal spectra, which may make the estimation of vertical ground motion unreliable. In view of the urgent need to revise the current seismic design code for railway engineering in China, 4 350 ground motion records at home and abroad were selected, and a quantitative study on the ratio of vertical to horizontal acceleration spectra according to the site category and magnitude classification was carried out. The results show that the ratio of vertical to horizontal response spectra generally exceeds the fixed value of 0.65 given by the current codes such as Code for seismic design of buildings (GB 50011—2010), and is significantly affected by the site category and seismic intensity. Therefore, it was proposed to introduce vertical site coefficient to characterize the vertical ground motion effect, and the method of calculating the vertical site coefficient, which is applicable to code for seismic design of railway engineering, was determined through the trial calculation and comparison with the relevant provisions of Specifications for seismic design of highway bridges (JTG/T 2231-01—2020). The peak ratios of vertical and horizontal acceleration response spectra under different site categories and seismic defense intensities were calculated, and the proposed values of vertical site coefficients were given. The research findings presented in this paper can serve as a reference for determining the value of vertical acceleration design spectra in seismic design codes for railway engineering.

In view of the special performance requirements of the rocking wall, the rocking wall structure is often trapped in the dilemma of construction technology, rocking range and cost control in engineering application. Based on the concepts of economic benefits, convenient construction, and easy replacement after earthquake, an energy-consuming connection device between the frame and the rocking wall was developed. Additionally, a hinge support with controllable swing of the rocking wall was also designed for the test models. Thus, a new type of reinforced concrete (RC) frame-rocking wall damping structure is proposed by loveraging the structural advantages of the rocking wall structures and the principle of passive control technology. Then, 1/10 scale shaking table tests of six-story RC frame structure and RC frame-rocking damping wall were conducted to verify the effectiveness of the structure. The dynamic characteristics, acceleration response, and displacement response of the test models under different earthquakes were studied by shaking table tests. The failure mode and seismic performance of the test models were also described. The results show that the rocking wall damping system can effectively consume seismic input energy and attenuate structural dynamic response, reducing the maximum peak acceleration and the maximum peak displacement of the structure by 36% and 20.15%, respectively. Moreover, the rocking wall damping structure can also effectively suppress the vibration of the main structure by using the principle of passive damping, improving the lateral deformation mode of the frame structure. Additionally the damage process of the structure is delayed, enhanced the overall seismic capacity of the structure.