Effective beam width for flat plate frames having edge beams

The effective beam width method has been widely used to predict lateral drifts and slab moments in flat plate frames subjected to lateral loads. However, the effective beam width method may not account for the contribution of the lateral stiffness provided by edge beams of the frames. This study examines the contribution of edge beams to the lateral stiffness of flat plate frames using the results of prior analytical and experimental research. It was observed that the lateral stiffness of flat plate frames with edge beams is larger than that of corresponding frames without edge beams. To account for the effect of the edge beam contribution on the effective beam width method, this study proposes a factor that modifies the effective beam width in the effective beam width method. To verify the accuracy of the effective beam width method with the proposed modification factor, this study estimated the lateral stiffness of the two-storey frames using the effective beam width method with the proposed modification factor, and compared that estimate with the lateral stiffness determined using experimental test results.