Dynamic Response of a Steel Concentrically Braced Frame

Large-scale shake table tests were conducted to examine the dynamic response of steel concentrically braced frames. The specimen was a single-bay, single-story frame with a pair of square-tube braces placed in a chevron arrangement. The gusset plates connecting the brace to the framing elements were provided with an elliptical clearance to permit free out-of-plane rotation. The specimen was subjected repeatedly to unidirectional ground motion with increasing magnitude until the braces fractured. The test results demonstrated excellent performance of the gusset plate connections. The specimen response was reproduced by a numerical model using fiber elements. This model was able to predict the occurrence of brace fracture and post-fracture behavior of the frame. Observations from the shake table tests and aspects of the numerical analysis are reported in this paper.