Static and Fire Behavior of Prefabricated Composite Beams with Reserved Grout Holes: Experiment and Design Assessment

Abstract

This paper investigates the static and fire resistance behavior of a new type of composite beam, consisting of prefabricated concrete slabs with reserved grout holes connected to steel sections using steel studs. It reports the detailed results of two ambient temperature (reference) tests and eight full-scale standard fire resistance tests, all conducted under four-point bending. The key variables in the tests were degree of shear connection (complete or partial), heating duration (by using unprotected or protected steel sections), and load ratios (0.7 or 0.3). The experimental results confirm that the oversized grout holes facilitated easy construction and had no adverse effects. Due to using solid slabs without steel decking, shear failure of the concrete slab may happen under concentrated load with wide spacing between shear connectors. Nevertheless, this did not affect the bending resistance of the beams. The current design methods for static and fire resistance calculations for conventional composite beams in Eurocode 4 are generally applicable to this new type of composite beam, including calculations of equivalent steel stud and concrete temperatures and plastic design assumption. However, the assumption in EN 1994-1-2 about uniform temperature distribution in the steel section did not accord with the measured steel temperature results.