Experimental and Analytical Seismic Studies of MRF's and MRF-CBF Dual Systems with Concrete Filled Tube Members

Lehigh University, Bethlehem PA

Investigators

Abstract

Composite construction for buildings provides an effective system for resisting non-seismic (e.g., gravity and wind) loads. Concrete filled steel tube (CFT) columns are one form of composite construction. CFT-related research studies to date under the U.S.-Japan Cooperative Research Program on Earthquake Engineering have investigated the performance of individual members and connections under seismic loading conditions. However, there currently is a lack of knowledge of the seismic performance of complete structural frames with CFT members and related connections. This project will focus on the seismic performance of CFT structural frame systems. The project will: (1) investigate the seismic performance of CFT column-wide flange beam MRF; (2) investigate the seismic performance of MRF-CBF dual frame systems with CFT columns and CFT braces; (3) evaluate analytical modeling and analysis procedures for CFT column-wide flange beam MRFs and MRF-CBF dual frame systems with CFT columns and CFT braces; and (4) review and improve design criteria and methodologies for structural frame systems with CFT members. The objectives of the project will be achieved through integrated analytical and experimental investigations. The analytical investigation will focus on nonlinear time history analysis of MRFs and MRF-CBF dual systems. Using the improved design criteria, three CFT test frames will be designed. Each test frame will be a 5/6 scale model of the lower three stories of a two-bay six-story frame designed for the theme structure of the U.S. Japan Cooperative Program. The three frames include: (1) and MRF with square CFT columns and wide flange beams; (2) an MRF-CBF dual system with square CFT columns and CFT unbonded braces; and (3) a MRF-CBF dual system with square CFT columns and CFT bonded braces. The experimental investigation will execute a series of pseudo-static tests on each test frame using a simulated seismic loading that consists of imposed lateral displacement histories at the first, second, and third floor levels. The project will acquire new knowledge of the seismic performance of structural systems with CFT members that cannot be obtained from studies of isolated members and connections, and will generate technical information needed by design professionals for the seismic resistant design of composite structural systems. This project is supported under initiative NSF94-154 "US-Japan-Cooperative Research in Composite and Hybrid Structures."