Abstract
Abstract
This paper analyses the results of several series of tests performed on composite concrete-steel slabs. The objectives of the tests are to: 1) determine the bending moment capacity 2) study the different failure modes 3) compare the theoretically calculated bending moment with the experimentally tested bending moment. The following variables are included in the test series: 1) length of the composite slabs, 2) width of the composite slab 3) thickness of the composite slab 4) steel plate cross sectional dimensions (width and thickness), 5) number of bonded steel plates and 6) loading configurations applied onto the simply supported slab (mid span line load or third span line load to simulate uniformly distributed loads). The reinforcing bars within the composite slab were kept the same for all series of tests.
The composite concrete-steel slabs were formed by bonding steel plates to the soffits of reinforced concrete slabs by means of epoxy glue. In order to obtain full composite action the epoxy glue between the concrete slab and steel plate must be able to transfer the generated shear forces. To achieve the bond between the concrete and steel plate surfaces, the bonded surfaces had to be roughened. The concrete surfaces were roughened by either exposing the main concrete aggregate using brushes, chiselling the concrete paste layer to expose the main aggregate or by scabbeling the cement laitance to expose the main aggregate as per the epoxy supplier’s specifications. The mild steel plates were sand blasted with a dry grid to a white metal finish in order to obtain a 100-140 micron blast profile as per the epoxy supplier’s specification. Pro-StructLV low viscosity epoxy adhesive was used to bind the epoxy to the concrete surface and Pro-Struct 617NS non-sag epoxy was used to bind the steel to the concrete surface.
In tests where full composite action between the steel plates and the concrete slabs was realised, an increase of up to 200% in the bending moment capacity of the slab was realised. The composite concrete-steel slabs failed either by debonding of the steel plate(s), flexural bending or vertical shearing of the composite system