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.

By reviewing literature in the field of earthquake engineering, the pulse-component models of earthquake ground motions are collected and organized. The characteristics of various pulse models are compared and discussed. The research significance of these pulse-component models is concluded and organized to form a systematic research framework. According to the existing research results, it is pointed out that the seismic hazard analysis considering the pulse effects in earthquake ground motions is the core in the research framework. Although the pulse models use different mathematical expressions to describe the same pulse characteristics, their performance is similar in structural dynamics. There are similarities between the pulse models with the forward directivity effect and those with the fling-step effect. At last, the details on considering the pulse effects in ground-motion selections for seismic design of structures are discussed.

In order to clarify the differences of wind vibration response of base-isolated buildings calculated by three commonly used biaxial restoring force models of MSS, Casciati and Harvey and Gavin, three models were used to simulate the restoring force of lead-rubber bearing under horizontal uniaxial and biaxial displacement. Comparing the differences of tests or finite element results. The differences in base displacement, top displacement and top acceleration for a numerical example were analyzed using three models. The results show the trends that the restoring forces of three models simulate the lead-rubber bearing in uniaxial cyclic displacement, square and offset square displacement are basically the same. While simulating circular and offset circular displacements, the biaxial restoring force shape of MSS model is different from the finite element results, which cannot simulate the coupling behavior of the bearing accurately, and the error of Casciati model is slightly smaller than that of Harvey and Gavin model. The Casciati model and the Harvey and Gavin model are basically the same in calculating the wind vibration response. For the root-mean-square of the cross-wind response, the differences between the three models are not significant. For the root-mean-square of the along-wind base displacement, top displacement and top acceleration, the MSS model is slightly smaller, while for the peak factors of base displacement in along-wind and cross-wind, the MSS model is slightly larger. For the variation of the peak factor of top acceleration and the ratio of the maximum top acceleration of bidirection to unidirection with wind speed in along-wind and cross-wind, the MSS model differs from others. With the consideration of the simulation of biaxial coupling effect and the difference of wind vibration response, the Casciati model is suggested to consider the influence of biaxial restoring force model on wind vibration response of base-isolated buildings.