The specimen-table interaction effects can significantly affect the accuracy of shaking table acceleration time history. Iterative control is often an important means to improve the reliability of test data. However, masonry, reinforced concrete and other structures are prone to enter the nonlinear mechanical state due to cracking, which is often not suitable for iterative loading. A simulation study is carried out on the iterative control method of the shaking table based on the surrogate specimen model. First, a surrogate specimen model with similar dynamic characteristics to the specimen was constructed, after completing the iterative loading of the shaking table and obtaining the driving command with the surrogate specimen model, a real specimen-shaking table test was carried out. The simulation results show that the shaking table iterative control based on the surrogate specimen model effectively reduces the influence of the specimen-table interaction on the system control performance, and realizes the high precision reproduction of the acceleration time history of the table.

In this paper, the method of partitioned analysis of soil-structure interaction (PASSI) is used to simulate the raft foundation-concrete frame model and pile foundation-concrete frame model in the shaking table test of nuclear island plant on soft soil foundation. The RG160, Chi-Chi and Landers seismic waves with amplitude modulation of 0.05 g, 0.10 g and 0.20 g were chose as input to the two models. Under various working conditions, the soil and structure acceleration amplification coefficient, floor response spectrum, time history of soil pressure at the bottom of raft foundation, pile strain and pile bending moment of shaking table test and numerical simulation test are compared and analyzed. The results show that: the numerical simulation results can reflect the shaking table test results well. After the amplification of soil layer, with the increase of floor, the coefficient of acceleration amplification increases in shaking table test and numerical simulation test, reflecting the same pattern. The response spectrum of soil-structure system obtained by shaking table test and numerical simulation is related to the frequency spectrum characteristics of input ground motion and the vibration characteristics of the system. In the shaking table test, the raft foundation will be overturned, and the time history of soil pressure at the bottom of the raft foundation shows the phenomenon of‘high in the east and low in the west’. However, this phenomenon does not appear in the time history of soil pressure at the bottom of the raft foundation in the numerical simulation. The reason is that the contact nonlinearity between the soil and the foundation is not considered in the numerical simulation. The seismic response of the pile group in the numerical simulation is basically consistent with the macroscopic phenomenon of the test, and there is a quantitative difference, which may be caused by the nonlinearity of the pile in the numerical simulation.

In order to avoid the settlement of seismic isolation bearings caused by uneven foundation settlement and the hidden damage to the superstructure, a vibration signal identification model based on multi-input convolutional neural network (MI-CNN) is proposed to identify the settlement of seismic isolation bearings. First, the horizontal acceleration and displacement signals of seismic isolation bearings are collected, and the samples are expanded using normalised pre-processing and data enhancement methods. Then, the samples are fed into the established network model and trained. Finally, the settlement identification is performed using the trained network model. The results show that compared with the traditional single-input CNN model, the MI-CNN model is easier to train and can maximise the ability of CNN to extract features from the settlement signals, and it has a better accuracy in identifying the settlement location, a smaller error in identifying the settlement degree, and a more stable identification effect for the unbalanced data set. The results of this study can provide new ideas for the settlement identification of seismic isolation bearings.

Earthquake damage to buildings always starts from a damaged component, so the importance analysis of building components helps identify the weakest component in the structure. Traditional researches often focused on structural components, and the importance of non-structural components was not well studied, resulting in the loss of non-structural components being much larger than the loss by structural components. In this paper, based on a large amount of detailed component earthquake loss data from the New Zealand earthquake, three importance analysis methods from random forest, namely the feature importance(FI), the permutation importance(PI) and the SHAP value(shap_values), were used to rank the importance of each component for earthquake losses. Assignment sort summation and normalized summation were used to assemble the results from the three methods representing the combined importance of each component. The normalized summation method can not only identify the relative importance of the components, but also quantify the significance of the differences among different components. The results demonstrate that of the 12 types of components analyzed, non-structural components are more important than structural components in earthquake loss contribution, and wall ornaments are the most important component, followed by slab foundations, but roof framing is the least influential. The results indicate that future earthquake resistance efforts should put more focus on wall ornaments and slab foundations.

To address the limitations of curvature mode indicators in identifying minor structural damage, a method for structural damage identification that combines curvature mode and wavelet transform has been proposed. In this paper, ANSYS was used to establish a finite element model of the wooden beam before and after the damage and carry out modal analysis, and the curvature modes of the wooden beam before and after the damage was subjected to discrete wavelet transform to obtain the wavelet coefficient difference index. the damage location of the wooden beam was judged according to the peak of the wavelet coefficient difference mutation, and the damage degree of the wooden beam was estimated by fitting the relationship between the wavelet coefficient difference and the damage degree. The wooden beam test verified the index. The results show that the wavelet coefficient difference index can accurately identify the damaged location of wooden beams. The damage degree of wooden beams can be quantitatively estimated by fitting the relationship between the wavelet coefficient difference index and the damage degree. The research results provide a theoretical basis for wooden beam damage identification.

In order to better evaluate the T-shaped steel reinforced concrete(SRC) shear walls with the widespread application of steel reinforced concrete members deformation behavior, ABAQUS was used to study the failure morphology and deformation behavior of 324 T-shaped SRC shear wall designed according to specification. Based on to the collected test data, the failure mode of the members is analyzed, and the failure mode division criteria of T-shaped SRC shear wall is proposed. Based on the strain limit value of each material of the member, the component performance is judged, and the influence of axial compression ratio, shear span ratio, flexure shear ratio, steel ratio of the concealed column of the web, longitudinal reinforcement ratio of the concealed column and the characteristic value of the stirrup concealed column on the component deformation performance is considered. Through linear regression analysis of deformation limits and parameters in different performance states, the calculation formula of displacement angle limits in different performance states under different failure types is obtained. The failure probability of each performance state deformation limit is corrected according to ASCE 41, and the value table of each performance state deformation limit with 15%, 20% and 35% failure probability guarantee is obtained. The research shows that the shear span ratio and axial compression ratio have greate impact on component displacement angle limit of each performance state, while the steel ratio of the concealed column web, the longitudinal reinforcement ratio and the characteristic value of the stirrup have relatively small impact on the displacement angle limit of the member, but can improve its ductility. The limit value of displacement angle corrected according to ASCE 41 is reasonable and has certain safety reserves. It provides reference for performance-based seismic design and performance evaluation of T-shaped SRC shear wall.

In order to explore the feasibility of reuse of waste clay bricks, a series of experimental studies were conducted on hysteretic behavior of 6 brick aggregate geopolymer recycled concrete-filled circular steel tubular (BAGRC-FST) columns. Key parameters including steel tube thickness (4 mm and 6 mm), replacement ratio of brick aggregate (0%, 50%, 100%) and axial compression ratio (0.05, 0.25 and 0.50) were considered. The failure mode, skeleton curves and hysteretic curves of the specimens under reciprocating load were obtained, and the change law of seismic performance indicators such as stiffness degradation, hysteresis behavior, peak bearing capacity, ductility, bearing capacity degradation and energy-dissipation capacity of the components were analyzed. The results indicated that the failure mode of the specimen is characterized by bulging and cracking at the bottom of specimens and the breakage of the core concrete in the area where plastic hinges appear, which is similar to that of ordinary CFST columns. The increase of brick aggregate replacement ratio of brick aggregate and axial compression ratio reduces the bearing capacity of specimens, and the increase of steel tube thickness will increase the bearing capacity of specimens. The hysteretic curves of specimens were plump without obvious pinching effect, implying that the BAGRC-FST columns had desired energy-dissipation capacity. Moreover, increasing the axial compression ratio reduces the deformation capacity of specimens and accelerates the degradation of stiffness and bearing capacity. However, increasing the thickness of the steel tube can improve the deformation ability of specimens. The substitution rate of brick aggregate has limited influence on stiffness degradation, ductility, bearing capacity and energy dissipation capacity of the BAGRC-FST columns.

In order to test the micro-vibration control ability of the mass concrete slab in the Beijing High Energy Photo Source, evaluation of the micro-vibration control ability of the mass concrete slab are conducted through two short-period tests and a 24 h long-period monitoring. Test results indicate that: most of the displacement root mean square values distribute between 10 nm and 50 nm in the two short-period tests, and most of the displacement root mean square values distribute below 20 nm in the 24 h long-period monitoring. The mass concrete slab can provide good micro vibration control performance over 10 Hz for the micro vibration in the vertical direction, and over 5 Hz for the micro vibration in the horizontal directions. Through casting the mass concrete slab, the micro vibration level in the vertical direction can be reduced by 24%, the micro vibration level in the horizontal direction can be reduced by 34%. The control ability of the slab to the horizontal micro-vibration is slightly better than that of vertical micro-vibration. Moreover, simplified two-dimensional finite element models are established to discuss the influence of changing the concrete layer’s density, stiffness and thickness on the slab’s micro-vibration control ability. The simulation results indicate that the increasing thickness of reinforced concrete layer or density of the plain concrete layer has no influence on the micro-vibration control ability of slab in the vertical direction, but has adverse effect on that in the horizontal direction.

In order to study the impact of cast-in-place hollow infill walls with flexible connections of PVC joint plates on the seismic performance of reinforced concrete(RC) frame structures, six full-scale specimens were designed and manufactured with hollow concrete walls and PVC joint plates as the main factors, and pseudo static tests were conducted. By comparing and analyzing the seismic performance indicators such as failure characteristics, load displacement curves, skeleton curves, stiffness, displacement ductility, and energy dissipation capacity of cast-in-place hollow infill wall frame structures with pure frame structures, flexible connections with PVC joint plates, and rigid connections without joint plates, it is mainly concluded that the addition of PVC joint plates reduces the improvement effect of hollow concrete infill walls on the lateral stiffness and bearing capacity of the frame structure. The displacement ductility and energy dissipation capacity of the cast-in-place hollow concrete infill wall frame structure have been improved, providing protection for the infill wall. However, the cast-in-place concrete hollow infill wall with flexible connections using PVC joint plates still significantly affects the lateral stiffness and ultimate deformation of the frame structure. When designing the structure, reasonable consideration should be given to its adverse effects on the overall seismic performance of the structure.

In order to improve the seismic performance of prefabricated frame structures, different types of steel energy dissipation hinged dampers have been proposed that the prefabricated beams and columns are connected with steel hinges and the mild steel energy-dissipating elements are installed on the upper, lower or both sides of the hinges. The structural forms and seismic performance of several energy-dissipated hinged dampers were summarized, and a T-shaped energy-dissipated hinged damper with simple structure and good seismic performance was selected to study the seismic performance and mechanical model. ABAQUS software was used to simulate the test of T-shaped damper, on this basis, 24 finite element models were established to analyze the flange weakening degree and T-shaped section size of the T-shaped energy dissipation element, the different influencing factors were quantified to obtain the skeleton curve calculation formula of the energy dissipation hinged damper, finally, the correctness of the formula was verified. The results show that the T-shaped energy dissipation hinged damper has good bearing capacity, ductility and energy dissipation capacity. The proposed skeleton curve has high accuracy, and can provide reference for the design of this kind of damper.