ABSTRACT
ABSTRACT: In most case it is very difficult to solve the equations governing the motion of nonlinear structural systems in close form. Therefore, methods providing approximate solutions have to be used. Numerical methods are generally adopted. They require high computational efforts and provide solutions including both the transient and the steady part of the response. To reduce computational efforts a/o when only the steady part of the response is of interest, some others mathematical techniques providing approximate solutions can be utilized. These techniques are based on a variational approach or on an approach where the solution is expanded in series. The method to be used is chosen considering the type of nonlinearities, the type of excitations and the complexity of the structural system. The equivalent linearization method (ELM) is one of the above mentioned mathematical techniques. It provides not only an approximate solution but also a linear system equivalent to the actual one. The equivalence of the linear system and the actual one is obtained by minimizing with respect to the unknown equivalent parameters a function defining the difference between them. In this study the accuracy of the ELM in predicting the response of nonlinear structural systems is evaluated. This is done by comparing the obtained solutions with those obtained using the Newmark integration method. A good accuracy of the proposed method in evaluating the peak values of the response is noticed in the case of a single degree of freedom system characterized by a softening behavior and of a nonlinear two degree of freedom system. Both systems are excited by a sinusoidal acceleration applied to the ground.
