Connection behaviour of through reinforced concrete beam to concrete-filled steel tube column after exposed to heating

Abstract

The experimental study presented in this paper investigate the post-fire performance of through reinforced concrete (RC) beam to concrete-filled steel tube (CFST) column connection. A total of twelve connection specimens were tested under hogging moment. The connection specimens are grouped into two groups; group A-connections, without fire exposure and group F-connections that are exposed to fire. Two classical connection types were used in this study (type A and B) and one new connection type were proposed herein (type C) by associating additional steel plates to the connection zone. In addition, different beam reinforcement ratios were used. These parameters were considered to evaluate the strength, stiffness, joint classification, ductility, failure modes and strain response of the composite joints. Three failure modes of the connections were found. The connection specimens without fire exposure were found to be a rigid connection. The fire exposure significantly influenced the connection performance, and that influence is varied based on the connection type and beam reinforcement ratio. The proposed connection type is found to have the highest residual capacity among the other connection types. However, a comprehensive analysis of the post-fire behaviour of each connection type is illustrated.