Seismic Code Analysis of Buildings without Locating Centers of Rigidity

Static force procedures of most building codes require that the lateral earthquake force at each floor level of an asymmetric-plan building be applied eccentrically from the centers of rigidity. To implement such procedures, it seemed necessary in the past to determine the locations of the centers of rigidity, an often confusing and cumbersome process. This paper presents a new approach for code lateral force analysis of asymmetric-plan buildings without locating the centers of rigidity. This procedure combines the results from three static analyses, which can be implemented directly on most commercially available computer programs for analysis of multistory buidings. The work presented in this paper should dispel the long-held view that locations of the centers of rigidity must be determined to implement the code procedure, thereby removing one of the major difficulties in building analysis.