Numerical modeling of MDOF structures with sliding supports using rigid-plastic link

In this paper, the responses of multi-degree-of-freedom (MDOF) structures o n sliding supports subjected to harmonic or random base motions are investi gated Modeling of the friction force under the foundation raft is accomplis hed by using a fictitious rigid link which has a rigid-perfectly plastic ma terial. This will result in identical equations of motion for the sliding s tructure, both in the sliding and non-sliding (stick) phases which greatly simplifies the implementation of the method into a numerical algorithm. In this model the phase transition times are determined with high accuracy. Th is has two advantages: first, it prevents the so-called high-frequency osci llation of the relative velocity at the end of the sliding phase, and secon d, the time steps can be selected so that each falls exactly within one pha se of motion. In this case, the stiffness matrix of the structure remains c onstant throughout each phase and thus any method for solving the non-linea r differential equations of motion (e.g. Newmark method) can be used withou t iteration. The proposed method, besides its simplicity, is numerically ve ry efficient and considerably reduces the required analysis time compared w ith most of the other methods. Copyright (C) 2001 John Wiley & Sons, Ltd.