Analysis and design problems for PR composite frames subjected to seismic loads

摘要

The design and analysis of partially restrained frames for seismic loads present some interesting and challenging issues to practicing engineers. The most important are how to determine the moment- rotation characteristics for the connections, the effect of floor slabs, and the influence of the partially--restrained connections on the dynamic characteristics of the frames. The use of databases for the determination of the appropriate moment--rotation curves is discussed and found lacking. A more rational, mechanistic approach to the problem is described and its merits discussed. The influence of floor slabs is shown to be important and simplified techniques to handle this effect are proposed. The behavior of FR frames under seismic loads is shown to be equivalent to that of PR frames once the dynamic characteristics are properly modeled. The design of PR frames will require both the development of new preliminary design approaches and advanced analysis tools because the conventional equivalent lateral load analysis cannot account for the dynamic effects properly.