Seismic(vibration) isolation technology is an effective measure to improve the seismic performance and comfort of over-tracking buildings, and the design methods optimization of such structures has practical significance and urgency. This study proposes an evaluation model based on the ratio of benefit to life cycle cost that suitable for over-tracking seismic (vibration) isolation structures. The effects of key structural parameters such as period ratio, mass ratio, stiffness and damping of the isolation layer on the benefits of the over-tracking seismic (vibration) isolation structures were studied. Based on genetic algorithms, an optimal design method for over-tracking seismic (vibration) isolation structures is proposed. The research results show that the seismic losses of the structure after adding isolation layers are mainly concentrated in the substructure, and the greater the mass ratio of the upper and lower structures, the smaller the seismic losses. The period ratio of the upper and lower structures has a greater impact on the overall seismic losses of the structure. The larger the period ratio, the smaller the seismic losses. The stiffness of the isolation layer is positively correlated with the isolation efficiency. After using the optimization algorithm to optimize the prototype structure, both seismic losses and vertical acceleration vibration levels were reduced, verifying the feasibility of this method and providing reference for engineering design.

In the accelerated process of urbanization, the deterioration of aging buildings, and the rapid climate change in current times, the resilience and sustainability of buildings have become increasingly important. Post-earthquake rehabilitation of buildings often requires significant economic and downtime cost, while also causing severe environmental impacts such as carbon emission. However, it is still lack of reasonable and rapid assessment method for evaluating seismic environmental impact. Therefore, this study proposes an improved building life cycle seismic environmental impact assessment method, using the input-output database and the “ repair cost-ratio”assumption to convert existing seismic economic loss data into environmental impacts, considering the key factors that reduce the feasibility of building rehabilitation due to residual deformation. It quantifies the life cycle seismic environmental impact of buildings under seismic risk through seismic hazard analysis, structural analysis, damage analysis, and loss analysis. Based on this method, the life-cycle seismic environmental impact assessment of steel frame buildings strengthened by self-centering braces (SCB) and buckling-restrained braces (BRB) was carried out. The results show that if the reduction in rehabilitation feasibility caused by residual deformation is not considered, the seismic environmental impact will be seriously underestimated. After considering the residual deformation, compared with BRB, the frame strengthened by SCB shows a significant advantage in reducing the impact of the seismic environment with the minimal residual deformation.

In order to quantitatively assess the effect of different infill wall construction methods on the seismic performance of reinforced concrete(RC) frames, domestic and foreign pseudo static test data of masonry infilled RC frames were collected, and a total of 68 specimens with detailed data in 19 literatures were selected as samples to analyze and compare the effects of three types of construction methods, namely, flexible connection of infill walls, integrity enhancement of infill walls, and installation of damping devices, on the strength, initial stiffness, ductility factor and equivalent viscous damping factors of the specimens. The results show that compared with the traditional construction methods, the strength and stiffness of specimens with flexible connection infill walls decrease, and the deformation capacity increases. The method of enhancing integrity can improve the strength, stiffness and deformation capacity, and it is a better method to reinforce the infill walls of existing buildings. The strength and stiffness of the structure with damping energy dissipation devices are reduced, but the deformation and energy dissipation capacity of the structure are improved, which can be used as a resilience improvement for new buildings if the construction cost is acceptable.

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.

Study the influence of different seismic response control methods on the seismic performance of inter-story isolated multi-tower structure with a large chassis, identify the advantages of different methods in improving the seismic performance, and then provide reference for the seismic response control of such structures. Three control schemes were designed based on a real engineering practice of such building, including adding viscous fluid dampers in the isolation system, adding viscous fluid dampers in the large chassis, and increasing the stiffness of the large chassis. The elastic-plastic finite element models of three control schemes and the prototype structure were established by using the Perform-3D. The seismic responses of these four structures were analyzed and compared, and the control effects of three control schemes on the seismic responses were identified. The following conclusions are drawn that introducing viscous dampers to isolation system is an optimal scheme for controlling the displacement of isolation system and floor acceleration of large chassis, but it significantly increased the seismic responses of tower. The control effects of increasing the stiffness of large chassis on the inter-story drift ratio of large chassis, as well as on the inter-story drift ratio and floor acceleration of tower are the best. All three schemes have negligible control effects on the inter-story drift ratio of tower.

Shape memory alloys (SMA) have the characteristic of superelasticity and shape memory property, and are increasingly applied to civil engineering. A novel SMA-based device is proposed, which has the seismic mitigation and displacement limiting capacities. The device connects with the superstructure and substructure of the bridge through axis pins. The novel device not only can restrain the bridge in a safe range, but also can dissipate the seismic energy, and protect the bridge from earthquake damage. This study comments with pseudo-static tests on a single SMA cable specimen and the novel device. The constitutive models of the SMA cable and the novice device are proposed based the test results. A finite element model of a cable-stayed bridge with a main span of 360 meters was established in OpenSeesPy software for investigation. Seven far-field and seven near-field earthquake records were selected to study the seismic responses of the cable-stayed bridge with the novel device equipping 0, 5, 10, 15, 20, 30, 40, 50 SMA cables. The study results indicate that the maximum longitudinal displacement of the girder decreased significantly with the number of SMA cables increased. However, this reduction was accompanied by a slight increase in the average maximum curvature at the base of the main tower. For example, the seismic mitigation device with 10 SMA cables reduced the average maximum displacement of the girder by 51.8% and 36.8% under seven far-field and seven near-field earthquakes, respectively. However, the corresponding average maximum curvature at the tower base increased by 5.1% and 16.0%, respectively. Consequently, the proposed SMA-based seismic mitigation device can effectively reduce the displacement of the girder at the cost of a small curvature increment at the tower base.

The 1970 Tonghai M_s7.7 earthquake is the strongest and the most intensity earthquake in Yunnan Province in the last 100 years. The Tonghai Basin experienced an abnormally high intensity ranging from IX to X degrees, resulting in severe damage. Based on data such as the thickness of the Neogene strata and shallow velocity structure of the basin, this study establishes a three-dimensional model that includes the 1970 Tonghai seismogenic fault and the Tonghai Basin. Multiple source models with asperities at different depths on the fault plane and the three-dimensional spectral element method are used to simulate the seismic ground motion of the Tonghai earthquake. By comparing the simulated distribution of peak ground velocity (PGV) with intensity and analyzing the strong motion distribution, as well as the generation of intensity anomaly zones, the reasons behind them are examined. The study indicates that the hammer-like distribution of the near-fault strong ground motion in Tonghai earthquake may be caused by the rupture directivity effect, and the mountain on the northeast side of the fault surface has a significant amplifying effect on the ground motion. The prominent amplification area in the Tonghai Basin is mainly located in the depressed area corresponding to the intensity anomaly zone of IX degree in the southwest of the basin. The PGV simulated by different source models in this area is significantly higher than that in other areas of the basin. The intensity anomaly zone simulated by the source model with asperities at depths of 10~16 km is significantly larger than that of the observed intensities, while the source models with asperities at depths of 2~8 km are relatively closer. The main cause of the intensity anomaly zone is the superposition of body waves and surface waves within the basin. The different depths of the asperities result in significant differences in the dominant frequency and amplification factor within the basin, with the shallowest asperities model causing amplification at the deepest part of the basin approximately twice of that of the deeper asperities model.

To capture the characteristics of faults accurately, considering a typical coal mine as an example, the geological model of fault zone and fault plane is established by the numerical calculation method, and the influence of thickness of fault fracture zone and fault plane on mining of coal mine working face under normal fault condition is studied. The study shows that the smaller the stiffness of the fault plane is, the more time steps need to be calculated for the model balance. Under given conditions for the thickness of the fault zone, the influence of the fault plane gradually increases as the working face advances closer to the fault plane under the conditions of different contact surface stiffness, the stress peak in front of the working face tends to rise with the increase of interface parameters, and the stress peak is the highest when there is no interface, and the vertical displacement of the working face roof increases gradually with the decrease of the interface stiffness. The stress in front of the working face increases with the increase of the thickness of the fault zone under the same interface parameters. The vertical displacement of the roof increases with the thickness of the fault zone. With the increase of the vertical distance from coal seam under different interface parameters, the displacement difference between the two sides of the fault of the high strata is larger than that of the low strata, and the two separate plates is also larger in the high strata. Under the condition of different fault zone thicknesses, the displacement difference between the two sides of the fault increases with the advance of working face. The slip amount of the point with higher strata is larger than that of the point with lower strata in a certain range of vertical distance. The slip amount on the two sides of the fault increases with the increase of the thickness of fault. This study has certain guiding function for coal mining under the influence of faults.

The deep overburden in coastal soft soil areas will magnify ground motion significantly, which will have adverse effects on engineering construction. Based on the frequency domain analysis method of seismic response in one-dimensional horizontal soil layer, inputting different seismic waves, the equivalent linearized dynamic calculation model is used to analyze the shallow site seismic motion characteristics of different site conditions under 7-degree seismic fortification. The calculation results show that the maximum acceleration, the maximum shear stress, the maximum shear strain and relative displacement of the shallow soil layer within 70 m can be significantly affected by the difference of shallow soil layer thickness or seismic wave spectrum. The variation of relative displacement with depth does not conform to the characteristics of cosine function recommended by the code. The cosine curve apparently underestimates the rate of change in displacement (shear strain) at the shallower position and overestimates the rate of change in displacement (shear strain) at the deeper position. In this paper, a fitting relation is proposed to estimate the relative displacement of shallow soil layers within 70 m in coastal soft soil areas under 7-degree seismic fortification. This fitting relation has certain limitations, but can provide reference for seismic response analysis of underground engineering in coastal areas.

In offshore engineering, large-diameter steel pipe piles are often installed with hydraulic hammers. Accurate analysis of pile drivability is of great significance in practice. In order to study the relationship between cone tip resistance of cone penetration test(CPT) and unit of hammering energy, the resistance to energy ratio was defined as the ratio of unit of equivalent cone tip resistance to unit of hammering energy resistance by converting cone tip resistance into unit equivalent cone tip resistance. Based on 9 sites, 72 steel pipe piles driving records and CPT test results, the relationship of resistive energy ratio with depth in different soil layers (silt, sand and clay) was discussed, and a method based on CPT cone tip resistance was proposed. The results show that the variation of unit equivalent cone tip resistance with depth is consistent with that of unit of hammering energy with depth, but the change of resistance to energy ratio with depth in different soil layers are different. The relationship between the resistance energy ratio and depth in different soil layers was obtained, and it was possible to obtain the unit of hammering energy required for pile driving directly from the cone tip resistance of CPT. The method proposed in this paper is verified with an example in practice, and the results show that it is feasible. Because only the CPT cone tip resistance is needed to calculate the unit of hammering energy with the proposed method, it could be used to quickly evaluate the drivability of piles.

Viscous-spring artificial boundary is one of the effective means to solve the problem of dynamic soil-structure interaction, but it usually requires a lot of nonlinear dynamic time-history calculation in the process of analysis, and the efficiency is low. This paper aims to establish an efficient calculation method for solving the governing equations of dynamic soil-structure interaction problem with viscoelastic artificial boundary. Therefore, the efficiently inelasticity-separated solve idea is introduced to construct the nonlinear dynamic soil-structure interaction analysis model based on the inelasticity-separated finite element method and viscous-spring artificial boundary. The derived dynamic governing equation is basically same as the governing equation of the fixed boundary that only need to directly add the spring-damper stiffness of the viscous-spring artificial boundary into the initial stiffness matrix and damping matrix of the near-field soil-structure model. In addition, an improved Woodbury approximation method is proposed by combining Woodbury formula with the combined approximation approach, which can reduce the time and space complexity in solving governing equation, and realize the efficient solution of the dynamic governing equation of dynamic soil-structure interaction problem by using viscous-spring artificial boundary. The proposed method retains the advantages of viscous-spring artificial boundary and inelasticity-separated finite element method, and the correctness and efficiency are verified by a numerical example.

High polymer cementitious Gobi soil is made by mixing high polymer with Gobi soil in a certain ratio, which can effectively improve the mechanical properties of Gobi soil. In order to study the dynamic residual deformation characteristics of high polymer cementitious Gobi soils, the effects of high polymer mass ratio, surrounding pressure, consolidation ratio and dynamic stress ratio on the residual shear strain and residual body strain of high polymer cementitious Gobi soils were investigated in this paper using medium-sized dynamic triaxial tests. The results show that the high polymer cementitious materials can effectively reduce the dynamic residual deformation of Gobi soil, and the residual shear strain of polymer cementitious Gobi soil after 30 cycles of loading is 15.0%~18.8% of that of natural Gobi soil, and the residual body strain is 12.1%~22.2% of that of natural Gobi soil. The reduction of residual shear strain was 85.0% and 95.2%, and the reduction of residual body strain was 87.9% and 95.5% for 3% and 12% of high polymer mass ratio. The larger the high polymer mass ratio, the larger the reduction. Projection pursuit regression (PPR) was used to analyze the influence weights of each influence factor on the residual deformation, and the influence weights of the dynamic residual shear strain and residual body strain of the polymer cementitious Gobi soil were obtained as high polymer mass ratio to peritectic dynamic stress ratio to consolidation ratio. An exponential function was used to fit the relationship between residual deformation and vibration times of polymer cementitious Gobi soil, and a modified residual deformation model of high polymer cementitious Gobi soil was established, which can respond to the effect of high polymer mass ratio.