EXPERIMENTAL INVESTIGATION OF THE PERFORMANCE OF DEMOUNTABLE COMPOSITE BEAM SHEAR CONNECTORS AT AMBIENT & ELEVATED TEMPERATURES
Razvan M. Sencu1,٭ and Yong C. Wang1
1School of Mechanical, Aerospace and Civil Engineering, The University of Manchester,
Manchester, United Kingdom
This paper presents the results of an experimental programme to investigate the performance of a new composite shear connector that can be used to build deconstructable composite floors. A total of 15 push-out tests were conducted to quantify the effects of different design parameters, including different nominal temperature levels (20oC, 100oC, 300oC, 450 oC, 600oC), with the steel decking perpendicular to the steel section, two different shear stud lengths and two different grades of concrete (C40/50 and C20/25). The tests were mainly carried out under steady-state condition where the specimen temperatures were increased to the desired target and the load was then applied until failure of the specimen. A few transient tests were also carried out in which a load equal to the load carrying capacity of the steady-state test at 600oC was applied followed by increasing the specimen temperature until failure. The main failure mode at temperatures not exceeding 400oC was initiated by diagonal fracture of concrete in the trough of the steel sheeting, leading to concrete sliding along the steel sheeting and shear stud fracture at the point of complete failure of the specimen. At elevated temperatures above 400oC, the failure mode changed to shear stud fracture. The Eurocode 4 calculation equations were shown to produce shear connector resistances to be in reasonable agreement with the steady state test results at both ambient and elevated temperatures, even though the Eurocode equations were developed for welded shear studs. However, these equations gave calculated shear connector resistances higher than the transient state test results. All of the tests indicate that the demountable shear studs have sufficient deformation capacity (>6mm) to enable plastic distribution of forces in the shear studs in composite beams, as suggested in Eurocode EN 1994-1-1, however, shear connector slips at high temperatures (just over 6mm) were considerably lower than those at ambient and low temperatures (>20mm).
Demountable Shear Connectors; Elevated Temperatures; Composite Floor Systems; Slip-Damage Mechanism.