THE BUFFETING THEORY IN A FINITE ELEMENT FORMAT

Introduction

In order to focus on the most important aspects of wind induced dynamic response the calculations presented in Chapter 6 (and the ensuing calculations of cross sectional forces presented in Chapter 7) have been performed in a modal format where each displacement component has been given a separate representation. These calculations may also be performed in a finite element format. Such a procedure is presented below. It has the advantage that it will comply with the computational methods usually applied elsewhere in structural mechanics. Thus, from a computer programming point of view, all the well known stiffness and mass properties from other types of structural dynamics problem will be applicable. The only difference is that the wind and motion induced loads need special attention. On the other hand, it should be noted that due to the fairly short correlation lengths and sharply dropping coherence properties of the turbulence components there will be demanding requirements for the choice of largest element length, i.e., the number of degrees of freedom in the finite element system may become cumbersome from a computational point of view. The same applies to the choice of time stepping increment in a time domain solution. In general, convergence should be checked.