A Comparison of Different Methods to Design Cast-in-Place Concrete Diaphragms for Seismic Load

摘要

All three components (horizontal, vertical and foundation) of a building's lateral force resisting system are important; however, past research and effort has concentrated on the vertical systems rather than the horizontal systems. Recently there has been increased emphasis on diaphragm analysis and design. This paper presents a comparison of different diaphragm design methods that have been promulgated over the past several years. The main focus is the design of collectors, which are used to transfer load from the diaphragm into the vertical elements. Some guidelines, such as NEHRP 2010 and NEHRP 2016, use a flexible diaphragm concept, and thus assume that the collector is the full length of the diaphragm. This is not consistent with the fundamental design assumption that concrete diaphragms are rigid and can lead to large and impractical collectors. Other references such as ""Evaluation of Collector Design for Concrete Diaphragms'" by J.S. LeGrue utilize rigid diaphragm or partial length methods for collector design. This paper compares and contrasts the above methods and investigates analytic and experimental studies that have been used to validate these methods.