Experimental study on properties of aseismic braces used in pipe line systems

Recent earthquakes have demonstrated that the damage of bracing and suspension components is the major reason to the failure of piping systems. This paper presents the results of nine sets of quasi-static tests on three types of aseismic braces by use of the load protocol provided by FM1950. The three types of braces include the steel wire brace, the beam clamp brace, and the threaded rod brace. The ultimate capacity corresponding to the limit displacement of FM1950 protocol was determined by the fragility analysis and further transformed to the response acceleration of pipe line systems. The threaded rod brace is the one having the highest bearing force among the three types of braces, and also the one most widely used. Therefore, another six sets of quasi-static test on two types of threaded rod braces respectively with 12mm and 16mm diameter hangers were further conducted following the FEMA461 protocol to investigate the size effect of the threaded rod brace. It is found that the size of hangers has little influence on the aseismic performance of threaded rod braces, while those with smaller hangers have larger deformability.