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As a kind of special terrain, the landslide disaster generated by liquefiable layer slopes under earthquake has become a major engineering challenge due to its large scale and long slip distance. In order to study the seismic response and damage mode of liquefiable layer slope, this paper follows the research line of “geological generalization, physical modeling, and result analysis”, and takes the liquefiable layer slope in the upper reaches of the Yellow River Class secondary terrace as the object of study, generalizes the physical model of the slope, and carries out shaking table test. Based on the PGA amplification coefficient, Fourier analysis and HHT time–frequency characterization of the model slope, it was found that the PGA amplification coefficient increases gradually along the slope height, reaches the maximum value at the top of the liquefiable layer and then decreases gradually, which indicates that the liquefiable sand layer has an obvious energy dissipation effect, and on the horizontal direction of model slope is a tendency to the surface effect; the seismic waves at the discontinuous interface change drastically, and the Hilbert time–frequency spectrum transforms from multiple peaks to a single peak; with the increase of the intensity, the intrinsic frequency of the overall model decreases, and the high-frequency component within the liquefiable sand layer decreases from 5–15Hz to 0–5Hz, indicating that the liquefiable layer has a filtering effect; the damage process of the liquefiable layer slope is the tensile crack at the top of the slope — seismic subsidence at the top of the slope — the shear yielding at the angle of the slope — shear surface penetration at the slope face — overall slope instability and flow-slip damage. The research results will provide a reference for the study of the disaster mechanism of the liquefiable layer slope.

The conventional control methods typically assume that the controlled structure behaves as a deterministic system, overlooking variations in structural dynamic properties and uncertainties in earthquake motions. To overcome this constraint, this study introduces an innovative approach: an online learning deep neural network fuzzy control method (DFNN). In the proposed method, Offline training was conducted using training samples generated through the Linear–quadratic regulator (LQR) to determine the initial parameters of DFNN. An ON–OFF system was introduced for real-time control signal adjustment. The input and corrected control signals were utilized as training samples to train and modify the parameters of the DFNN system, enabling online learning capabilities. Numerical and experimental investigations were performed to evaluate the effectiveness of passive control (OFF), fuzzy logic control, deep neural network fuzzy control, and online learning deep neural network fuzzy control using a numerical three-story steel frame structure and an experimental two-story steel frame structure with one magneto-rheological (MR) damper. The simulation and shaking table test results demonstrate that DFNN can adaptively adjust the parameters of the neural network, leading to significantly higher control efficiency compared to fuzzy logic control and deep neural network fuzzy control, particularly when the structural properties and earthquake motions differ from the training samples.

To maximize vibration reduction efficiency and reduce the risk of detuning, this study proposes a multiobjective optimization design method for shape parameters affecting the nonlinear characteristics of nonlinear gas-spring damper (NGSD) based on the NSGA-II algorithm. A numerical model of a MDOF structure with attached NGSD is developed and optimized under white noise excitation, and the effectiveness of the optimized NGSD in mitigating structural seismic responses is validated through shaking table tests. By comparing with the optimal TMD, the control effectiveness and parameter sensitivity of the optimized NGSD under various near- and far-field seismic excitations are investigated. Results show that the optimization design is carried out with the performance objective of minimizing the RMS of structural displacement and acceleration response, and a set of relatively optimal piston radius and initial volume parameters are obtained, resulting in the control effectiveness of NGSD on the RMS response of MDOF structure’s displacement and acceleration as high as 77% and 39%, respectively. The maximum reduction effectiveness of optimized NGSD on the peak structural acceleration and displacement response under seismic excitation is 18% and 19% respectively, and the RMS reduction ratios are even as high as 56% and 61%, indicating the efficacy of using NSGA-II for parameter optimization. Moreover, the optimized NGSD demonstrates comparable control effectiveness to the optimal TMD with a shorter stroke and stable performance across different seismic excitations, indicating low sensitivity of optimal parameters to excitation frequency.

The effect of soil-structure interaction (SSI) cannot be neglected in semi-active vibration control of structures located on soft soil. To investigate the mitigating effect of magnetorheological (MR) damper on the semi-active control of structures considering the SSI, shaking table tests were conducted to evaluate the performance of the MR damper-based semi-active control system for structures on soft soil. In addition to a novel fuzzy control method based on online learning deep neural network (OL-DFNN), various control strategies, including passive OFF, passive ON, ON–OFF and deep neural network fuzzy control (DFNN) were systematically evaluated. The test results showed that the OL-DFNN control method exhibited superior adaptability to varying ground motion and structural dynamic characteristics compared to the other control methods. In particular, the OL-DFNN controller effectively mitigated the peak displacement and root mean square displacement, outperforming the passive OFF, passive ON, ON–OFF and DFNN control strategies. The test results highlight the effectiveness of the OL-DFNN control method in addressing the challenges posed by dynamic and time-varying characteristics in structural vibration control systems considering SSI.

The control performance of a passive dynamic vibration absorber (DVA) is known to be sensitive to its frequency deviation. This study upgrades the conventional device and proposes an adaptive-passive variable frequency gas-spring DVA (APVF-GSDVA) for controlling the structural seismic response, while an adaptive control algorithm is developed that requires only a single input signal. The DVA’s vibration frequency is precisely modulated by adjusting the gas pressure in the gas-spring, aligning it with the inherent frequency of the multi-degree-of-freedom (MDOF) structure. The working principle and control algorithm of the APVF system is introduced and derived in detail, the corresponding gas-spring DVA and implementation are designed, and the configuration of the entire control system is realized. An adaptive variable frequency test scheme is designed and the frequency retuning function of the prototype APVF-GSDVA device installed on an MDOF structure is experimentally validated. The seismic response control effectiveness of the retuned DVA is demonstrated by comparing the detuned DVA, highlighting the necessity of implementing adaptive frequency adjustment of the gas-spring DVA. Experimental findings demonstrate that APVF-GSDVA accurately identifies the inherent frequency of the MDOF structure in ambient excitation, it then adjusts the pressure of the gas-spring according to the frequency-pressure relationship, optimally retuning the DVA. A retuned GSDVA can effectively suppress the structural seismic responses, compared to a detuned DVA, its control effectiveness on peak and RMS responses can be improved by a maximum of nearly 13.5% and 53.3% at a frequency deviation of 10%. Furthermore, results from two “detuning-retuning” test paths with distinct seismic excitations indicate that the retuned DVA exhibits superior control effectiveness, underscoring the significance of the adaptive frequency adjustment function in passive DVAs.

Vertical seismic performance is an important issue for the seismic design of large-scale engineering structures. The structure, which is relatively flexible and unrestricted vertically, may resonate and its response is obviously magnified under vertical earthquake excitations. The main objective of this study is to investigate the earthquake-resistance performance of a quayside container crane under vertical seismic excitations. To this end, a geometric-scaled model of 1:50 was firstly constructed according to the similitude law. Then using this model, a hammering modal test and a series of shaking table tests were successively conducted to obtain the dynamic characteristics and vertical seismic responses. Furthermore, the experimental results were compared with the computed results of prototype obtained from numerical analysis and agreed fairly well. From dynamic response results, it is found that the large-scale structure has relatively high vertical earthquake-resistance capacity and could satisfy the seismic design requirement. The findings reported in this paper are expected to provide some valuable information for studying other similar structures in the future.

This paper presents the shaking table tests and an analytical study of structures with a suspended mass under coupled horizontal and tilting ground motions (CHT) caused by an earthquake. Shaking table tests of a 1:10 scaled model for a converter valve hall with a suspended mass in a high-voltage direct current electric power transmission station are carried out. The equations of motion for the structure, including the influence of the rotary inertia of the suspended mass, are derived. The responses of the model to different ground motions during an earthquake are investigated. It is found that the tilting ground motion plays a significant role in predicting the seismic response of the structure, and it needs to be considered in association with the horizontal ground motion. The response of the structure with a suspended mass to CHT ground motion is much larger than that to horizontal ground motion. The possibility of replacing the steel cables with springs as the suspending components is also investigated, and the spring is shown not to influence the acceleration and displacement responses greatly, but it significantly reduces the tension in the suspending components. Therefore, when a suspended mass is used as a mass-pendulum mitigation system, it is more advantageous to use springs or members having a low axial rigidity as the suspending components. In addition, the effects of the length of the cables and springs on the seismic response of the model with a suspended mass are also explored. It is found that the shorter the cables (or springs), the better the mitigation effects of the suspended mass on the main structure.

Roller doors are popularly used in cities due to their compact design, low cost, and ease of use. However, roller doors are made of thin metal sheets and have low inherent damping, which causes roller doors in their closed configuration to experience strong vibration when subjected to external excitations, such as wind and passing vehicles. These vibrations also result in severe noise radiation. It is therefore necessary and important to minimize the vibrations and the noise emanating from the roller doors. This research develops a novel application method to suppress the vibration of existing roller doors and to mitigate the induced noise, and the main principle is using the high damping property of viscoelastic materials through retrofit to increase the damping of the roller door. The key component of the retrofit is a viscoelastic stripe of three layers: a self-adhesive layer, a viscoelastic layer and a constraining metallic layer. The proposed method can be easily applied to the existing roller doors and has nearly no negative impact on its daily usage. To validate the feasibility of this method, shaking table tests were conducted and investigated on a roller door model with and without viscoelastic retrofit, and the experimental results demonstrate that the proposed retrofit method can effectively mitigate the vibration and therefore reduce the induced noise for an existing roller door.

The seismic isolation efficiency of different friction-based devices needs verification by shaking table test, but faces problems in scaling before the test due to their frictional nonlinearity. To solve the scaling problems, a simplified civil structure, isolated by a self-centering spring-friction device, was numerically scaled in different ways considering the effect of friction action. The seismic responses of the scaled models were scaled back to those of the prototype and compared with the seismic responses of the prototype. The scaling problems and solutions were validated by a shaking table test on simply supported bridges using friction pendulum bearings (FPBs). The results show that both the unscaled gravity on a shaking table and the unscaled non-uniform friction distribution cause an inaccurate friction force in the structural motion equations of scaled models, and thus causing the scaling errors. One new and valid solution, i.e. changing the friction coefficient and scaling the non-uniform friction distribution to keep an accurate friction force for the scaled models, is put forward to avoid the scaling errors thoroughly. Another new solution shows that an increasing peak ground acceleration (PGA) can increase the other forces, while weakening the ratio of inaccurate friction force in the structural motion equations of the scaled models, which therefore reducing the scaling errors of acceleration and relative displacement responses, but not the scaling errors of residual displacement responses. In addition, the time-varying friction, the interface separation and collision of bearings, and other complex factors are found to cause scaling errors and need further investigation.

The suspended mass pendulum (SMP) conventionally used is a type of frequency sensitive vibration control device. It is vulnerable to detuning due to large amplitude oscillations, which can lead to a significant loss in vibration control performance. Although active or semi-active control systems can solve the problem of frequency detuning, the reliability and stability of the sensors and actuators in the control system are difficult to guarantee for large-scale civil structures. To overcome this issue, this study proposes a passive adaptive suspended mass pendulum (PASMP) that uses a curved support. First, the mathematical equations describing the curved support are derived to show that it can keep the frequency of the pendulum constant at large swing angles. Then the kinematic equations of a single-degree-of-freedom (SDOF) structure installed with the PASMP are established. A parametric analysis is conducted to verify how the parameters of the control system, including the excitation period, pendulum length and mass ratio, affect the dynamic responses of the main structure. Furthermore, to verify the effectiveness of the PASMP and the validity of the theoretical analysis, a two-story frame structure is chosen as the model structure in shaking table tests. Also, the proposed PASMP is applied to a transmission tower to numerically verify its effectiveness of vibration suppression under different seismic excitations. The numerical and experimental results demonstrate that the PASMP can more effectively suppress the vibration of structures than the conventionally used SMP.

Theoretical analyses show that the velocity pulse characteristics of ground motions adversely affect structural responses of mega-sub isolation systems. This study presents an extensive shaking table test conducted to investigate the seismic responses of a mega-sub isolation system under near-fault ground motions with velocity pulses. Two steel frames were used as test specimens, representing aseismic and seismic isolation models. Two representative groups of actual ground motion records with velocity pulse characteristics were selected as inputs, along with their corresponding synthetic counterparts with the same acceleration spectrum, but without velocity pulses. Test results showed that near-fault ground motions with velocity pulses had an adverse effect on the seismic responses of the mega-sub structure system, especially on the displacement of the isolation layer in the isolation structure. Compared with the mega-sub isolation system, more nonlinear behaviors were observed in the aseismic system. Finite element analysis of the mega-sub aseismic and isolation systems was conducted by using SAP2000. Satisfactory agreement was observed between the simulation and test results, and the differences between them were discussed in detail. The obtained conclusions can provide a scientific basis and valuable reference for the seismic design and safety evaluations of mega-sub isolation systems under near-fault ground motions with velocity pulses.

The seismic response of buried pipeline is significantly affected by the soil around the pipeline. In this study, a numerical analysis model of the pipeline and the soil around the pipeline is built, and the finite element numerical analysis of its seismic response law is conducted to address the problem of pipeline soil seismic coupling response. A shaking table test of the seismic response of buried pipeline under two-way seismic excitation is performed based on the developed two-way layered shear continuum model soil box. The peak strain response at the middle section of the pipeline grows fastest, the peak strain of the pipeline under non-uniform seismic excitation constantly exceeds that under uniform excitation, and the axial strain of the pipeline exhibits more sensitivity to earthquake than the bending strain, as indicated by the results of numerical analysis and shaking table test. The peak value of soil acceleration response under non-uniform excitation exceeds under uniform excitation. The displacement of soil increases with the height. The pipeline soil interaction becomes more intense under non-uniform excitation, and the relative movement between pipeline and soil becomes more significant. The seismic excitation more significantly affects the axial displacement of soil. The peak value of soil acceleration response varies from larger along the pipeline to larger along the axis with the increase of the loading grade. A slight difference exists between the peak value of axial and transverse acceleration response of the pipeline. The peak value of pipeline acceleration response declines in the axial direction than the peak value of soil acceleration response, whereas it rises in the transverse direction than the peak value of soil acceleration response, especially under non-uniform excitation. As revealed by the above results, the effect of bidirectional non-uniform seismic excitation on the lateral pipeline soil interaction is enhanced, and soil is more seriously damaged.

Split-foundation (SF) building structures, as a kind of hill-side buildings, are widely used in mountainous regions due to the scarcity of plain areas. In order to experimentally investigate the seismic responses of the SF structure, shaking table test was carried out on two 1/8-scale models: a split-foundation RC frame structure supported by foundations at two different levels and a conventional RC frame structure supported by foundations at one single level. The failure patterns, dynamic characteristics, acceleration responses, displacement responses, and torsion responses of the two models were assessed and compared under seismic ground motions. The test results indicate that the two models were severely damaged after the last intensity level excitation and showed an intermediate failure mechanism. The damage to the SF model was uneven and special with relatively severe damage of the upper grounded columns. The difference in natural frequencies between the two models resulted from the effect of the lower story on lateral stiffness, and the effect was relatively dramatic in the transverse direction. The difference in structural stiffness led to larger acceleration amplification factors of the SF model and smaller acceleration amplification factors in the longitudinal direction. Although the restriction at upper ground level created a certain effect on displacement responses of the SF model especially in the first story, the curve shapes of displacement responses of the two models were similar from the first floor to fourth floor. In addition, the torsion responses of the SF model, especially in the first story (upper ground story), were obviously much larger than those of the conventional model. The torsional effect cannot be ignored in the SF structure which is a torsionally sensitive structure.

In order to study isolation measures for plate-shell integrated concrete liquid storage structure (PSICLSS), shaking table tests were carried out to investigate the seismic responses of PSICLSS. The isolation performance of rubber isolation and sliding isolation bearings for PSICLSS was studied and shape memory alloy (SMA) was used to reduce the residual displacement of sliding isolation PSICLSS. The results show that the sliding isolation bearing can effectively reduce the seismic response of PSICLSS; however, there is a large residual displacement in the isolation layer. On the other hand, SMA-sliding isolation can provide a reliable recentering capability for isolating PSICLSS and does not cause amplification of structural response.

Compared to ground supported tank, column supported tank has the advantages of saving land space, having strong adaptability and making gas transmission cost small. It can be mass-produced in the center of a city, which has been widely used in practices. However, its seismic responses are much different from those of cylindrical tank. Limited research works and standard codes involve uplift effect and retrofitting measure of column supported tanks. Therefore, a shaking table test is conducted with a model tank designed by quasi-dimensional analysis method. To solve the problem of the anchored tank that may suffer damage under severe earthquake, a designed resilient tank is presented with mild steel dampers. The seismic responses of those two tanks are compared with each other, including the structural displacement parallel to excitation direction, the strain of tank walls and columns, the uplift displacement and the structural force. The results show that due to the uplift effect and the energy dissipation of dampers, the resilient tank has larger horizontal displacement, but less base shear and overturning moment than the anchored tank. Its strains of columns and walls in excitation direction decrease obviously, while those in perpendicular direction increase but with small variation, resulting in more balanced force allocation of the resilient tank. When encountering plastic failure, the dampers can be replaced in a very short time, making the normal use of the tank quickly even extreme condition. The resilient tank can save repairing time and cost. It can help resume the gas supply function of a city quickly after severe earthquake.

Considering the importance of wind turbine tower, its vibration under multi-hazard action consisting of vortex-induced load and seismic load needs to be controlled, especially as the height of the wind turbine tower increases, it increases the risk of its higher-order vibration. To address this issue, theoretical equations for vortex-induced load based on the governing equation of particle damping system are put forward, the vibration control of a 1/20 scale wind turbine model is studied, and the experimental and numerical analyses are conducted. Many studies have shown that wind turbine tower equipped with tuned mass damper (TMD) can result in an RMS response reduction ratio ranging from 20% to 40%. Compared to TMD, particle tuned mass damper (PTMD) has better vibration control effect under single seismic load, and still achieves good vibration control ability with a maximum RMS (root–mean–square) reduction ratio of 35.55% under multi-hazard action. Furthermore, MPTMD (multiple particle tuned mass damper) is proposed for controlling higher-order vibration mode, achieving a maximum RMS reduction ratio of 65.93%. Combining the spectrum diagram result, the ability to control higher-order mode vibration of MPTMD is confirmed.

A new method to simulate soil-structure interaction effects in shaking table tests has recently been presented by the authors. In this method, analog circuits or digital signal processors are used to produce soil-foundation interaction motions in real time. Their expressions of soil-structure interaction motions are based on published rigorous formulations of impulse response functions or flexibility functions of foundations resting on or embedded in homogeneous or layered soils of semi-infinite extent. In this paper the method is further extended to take the "far field" soil non-linearity into account. An example of non-linear soil-structure interaction simulation using the present method is also described.

In this paper, the dynamic interaction of human body and structure is studied The shaking table experiment with a person standing on a rigid table supported by springs is firstly carried out to determine the dynamic characteristics of the coupled system. It is shown that the body mainly contributes only one degree of freedom to the human-structure coupled system. Then, the two-degree-of-freedom (TDOF) coupled model of the human-structure system is developed through the energy variation by considering the standing human body as an elastic bar of two segments with distributed mass, stiffness and damping. Based on the experiment data, the dynamic parameters of the TDOF coupled system are determined by using the least square method (LSM). The mechanical parameters such as the damping ratio and the distributions of mass and stiffness of the human body model of two segments are identified by adopting the inversing technique Finally, the determined body model is applied to analyze the free vibration of beams and plates occupied by standing persons. The governing differential equations of the human-beam system and the human-plate system are, respectively, derived out. The dynamic characteristics of the human-structure interaction are obtained by the use of the complex mode theory. The results are compared with the experimental ones and those from the finite element simulations. Good agreement is observed for all cases.

This paper focuses on the influence of frozen soil on seismic response of a building supported by pile foundation. Firstly, the saturated sand soil is frozen artificially, and then shaking table tests are conducted. Specifically, seismic responses of buildings with different natural frequencies and with different freezing depths of the saturated soil are investigated, respectively. In this study, it is confirmed that for buildings with high rigidity, the effect of interaction becomes smaller when the soil is frozen. Moreover, it is observed that the resonant frequency of frozen ground is closer to the natural frequency of superstructure, and thus the response of the superstructure becomes larger. It is also observed that the bending moment along the pile is remarkably reduced by improving the rigidity of the soil.

Shaking table tests were conducted on typical models of subway structures subjected to several seismic shaking time histories to study seismic response of subway structures in soft ground as well as to provide data for validation of seismic design methods for underground structure. Three types of tests were presented herein, namely green field test, subway station test, and test for joint structure between subway station and tunnel. The similitude and modeling aspects of the 1g shaking table test are discussed. The seismic response of Shanghai clay in different depths was examined under different input waves to understand the acceleration amplification feature in both green field and in the presence of underground structure. Damage situation was checked on internal sections of both subway station and tunnels by halving the model structure. Structure deformation was investigated in terms of element strain under different earthquake loadings. The findings from this study provides useful pointers for future shaking table tests on underground structures/facilities, and the seismic response characteristic of underground structure derived from the shaking table test could be helpful for validating seismic design method for subway station.