Seismic Behavior of Newly Constructed Three-Bay Steel X-Braced RC Space Frame

Abstract

Bracing is one of the most effective systems which is widely used to improve the seismic performance of reinforced concrete (RC) plane frames. However, studies on the use of bracing in newly constructed RC space frame (RCSF) are rare. This paper presents the experimental results of two 1/4-scale, two-story, and three-bay RCSFs under cyclic loading. A RCSF without brace was designed and constructed as a control system, which was termed as "RCSF". Another one was constructed and strengthened with steel X-braces, which was termed as "SBRCSF". The seismic performance of RCSF was compared with those of SBRCSF. The test results show that compared with the RCSF, the seismic performance of the SBRCSF was improved significantly in terms of hysteresis loop, strength, stiffness degradation, and energy dissipation capacity. In addition, unlike the inter-story failure mechanism of the RCSF, the SBRCSF specimen exhibited an overall failure mechanism, which is significant for the seismic design of RCSFs. Moreover, the tested SBRCSF could bear loads in a manner similar to that of untested RCSF after the failure of the steel braces, thereby revealing the redundancy of SBRCSF and showing the advantageous of the use of steel braces for space frame.