Experimental study of a new kind of double‐layer shaking table

Abstract

Existing large‐scale electrohydraulic shaking tables (EHSTs) have limited frequency bandwidth because of the capacity of electrohydraulic systems. Here we propose a double‐layer shaking table (DLST) which is capable of generating excitations over a wide band of frequencies. The lower table is a conventional EHST with a long‐stroke actuator which can generate low‐frequency excitations. The upper table is fixed atop the lower table, and equipped with a short‐stroke actuator which can generate high‐frequency excitations. The FFT/IFFT signal separation process, three‐variable control algorithm, and feedforward compensation technique are employed to control the shaking table. The two tables are controlled simultaneously to ensure the upper table reproduces ground motions over a wide frequency bandwidth. A series of experiments were performed on a unidirectional DLST. The results suggest that the DLST can successfully reproduce excitations over a wide band of frequencies, and demonstrate that the proposed control methods are effective. The control procedure in which the upper table tracks the full‐frequency signal to compensate for the tracking errors of the lower table is recommended.

Shaking table substructure test of tuned liquid damper for controlling earthquake response of structure

“…The three variable controller mainly consists of three variable feedback and feedforward controllers. 36,39 The three variable feedback controller is to collect the displacement and acceleration feedback signals of the shaking table in realtime to synthesize the velocity signals and transmit the three-state feedback signals to the servo-hydraulic controller to calculate the next step driving command. The advantage of velocity and acceleration feedback is to improve the resonance frequency and damping ratio while keeping the stability of the system.…”

Time history iteration algorithm for offline real‐time hybrid testing

“…Notably, RTHT can be conducted with servo-hydraulic actuators, 7 shaking tables, 8 or a combination of the two. 9 To conduct RTHT, three problems must be properly addressed: (1) the computation of the numerical substructures should be efficient and stable; (2) the loading of the experimental substructure should be accurate and have low latency; (3) the communication between the substructures should be synchronized and have a small time delay.…”

“…Experimental studies play an important role in civil engineering research. Structural testing techniques fall into three main categories: quasi‐static tests, 1 shaking table tests, 2 and hybrid tests 3 . Quasi‐static testing mainly adopts the static cyclic test method, which can obtain the hysteretic properties of the structure and provide design guidelines.…”

Study on mechanism analysis, specimen influence, and compensation control of large compound shaking table

“…Some typical structures usually not only have large weights but also have high base frequencies, such as dams (Shi et al, 2014), nuclear power plants (Chang et al, 2020), and masonry buildings (Foraboschi and Vanin, 2013). In addition, for complex structures such as large-span grid structures (Tian et al, 2017), the effects of high-order modes and low-order modes need to be considered at the same time, and the dynamic response of structures subjected to ground motions with different spectra need to be considered, which puts forward higher requirements for the frequency bandwidth of the excitation signal (Pan et al, 2021). Thus, there is an urgent demand for a large-scale seismic simulation shaking table that can reproduce target signals with a wide frequency range and large load capacity.…”

“…Finally, the feasibility of the proposed frequency splitting schemes and OIC method was verified by a series of numeric simulations and experiments. Pan et al (2021) compared the effects of two signal-separation methods and found that the FFT-IFFT method was better. Then, the FFT-IFFT method was used to separate the control signal, and the three-variable control (TVC) algorithm with feedforward compensation was used to control the double-layer shaking table.…”