Predictive control of seismic responses of a novel seismic isolation – non-seismic isolation composite structure system based on Levenberg-Marquardt algorithm

Abstract

In order to reduce the seismic responses of adjacent structures, this paper proposes a novel seismic isolation – non-seismic isolation composite structure system, which is made up of a seismic isolation structure and a non-seismic isolation structure adjoined via controllers, and whose seismic responses are controlled with good effect by the principle of interacting control between the seismic isolation and non-seismic isolation structures. With a novel five-layer seismic isolation – non-seismic isolation composite structure system as an example, this paper builds a calculation model for the structure, derives the kinematic equations for the interacting control within this structural system, and adopts linear quadratic regulator (LQR) optimal control to analyze the control effect of this system and study the effect of time lag on the interacting control within this system. To address the issue of time lag in the interacting control between structures, an improved BP algorithm (Levenberg-Marquardt) is further adopted to set up a four-layer feedforward network to forecast the seismic responses of this novel composite structure system; the network structure is trained using the data acquired from LQR control under the action of the first 500 sampling points of the seismic motion taft, and the structure undergoes predictive control using the untrained seismic motion data of El Centro. The research results show that the interacting control of such a novel seismic isolation – non-seismic isolation composite structure system can achieve a good result, with the displacement response of the topmost layers of both structures decreasing by above 50 %; time lag may have an adverse effect on the control of the composite structure system, so that the structure’s seismic response increases by 20 % ∼ 40 %. The issue of time lag in interacting control can be addressed by adopting neutral network for predictive control, so that the structure’s seismic responses are 11 % ∼ 25 % lower than when it is not predicted. Levenberg-Marquardt algorithm demonstrates a strong learning ability and a curve approximation ability. The time history curves of the structure’s seismic responses under predictive control of this algorithm are highly overlapped with the time history curves under LQR optimal control with zero time lag.