Fire tests on composite steel-concrete beams prestressed with external tendons

This paper presents an experimental study on fire resistance of composite steel-concrete beams prestressed with external tendons. A total of four beams were tested under combined fire load and positive moment. Parameters investigated include load level, prestress level and type of cable strands configuration. Results show that the tested beams without fire protection had fire resistance of 20 min to 30 min. The fire resistance of composite steel-concrete beams prestressed with external tendons was highly influenced by the stress in the cable strands. The tested beams with bent-up cable strands had more fire resistance than the tested beams with straight cable strands. Prestress level had little influence on failure temperature of the tested beams, but the slack of cable strands induced failure of the test beams at high temperature. Furthermore, a finite element (FE) model was developed and successfully used to predict the fire behavior of the prestressed composite steel-concrete beams.