Seismic response control of large-span machinery building on top of ship lift towers using ER/MR moment controllers

A feasibility study using a vertical ship lift to provide a fast passage for ships crossing a large dam is currently being carried out in China. One of the problems encountered in the feasibility study is how to reduce the excessive seismic response of a large span machinery building on top of the huge ship lift towers due to a whipping effect. This paper explores the possibility of using electrorheological (ER) or magnetorheological (MR) moment controllers to prevent the whipping effect on the machinery building while not increasing the seismic response of the ship lift towers. The basic equations of the ER/MR moment controller for the machinery building are derived. A set of governing equations for seismic response control of the machinery building-ship lift tower system with ER/MR moment controllers is then established. A special performance index for seismic response control of the structure is introduced, and a semi-active control strategy for controlling the bending moment response in the building column is presented. Finally, taking a real huge ship lift structure to be built in China as an example, the effectiveness of the proposed moment controllers and a control algorithm is examined and a series of parametric studies are carried out to determine the beneficial control parameters for the ship lift structure concerned. The results show that if the parameters of the smart moment controllers and the control performance index are properly selected, the moment controllers can effectively control the seismic whipping effect on the building.