PUNCHING SHEAR BEHAVIOUR OF HIGH STRENGTH CONCRETE SLAB-COLUMN CONNECTIONS REINFORCED WITH GFRP BARS

摘要

The catastrophic nature of punching shear failure exhibited by flat plate system requires a great attention and robust predictions of the behaviour of slab column connections. This paper presents an experimental study carried out to investigate the punching shear behaviour of fibre-reinforced polymer (FRP) reinforced concrete (RC) interior slab-column connections made of high strength concrete (HSC). Three full-scale HSC specimens were constructed and tested up to failure. The three connections were reinforced with GFRP sand-coated bars with reinforcement ratios of 1.0, 1.5 and 2.0% without any shear reinforcement. The typical dimensions of the test specimens were 2800 × 2800 × 200 mm with a 300 mm square column extending 1000 mm above and below the slab, representing the region of negative bending moment around an interior supporting column of a parking structure. All specimens were simply-supported along all four edges with the corners free to lift. The connections were subjected to vertical load and unbalanced moment that were monotonically applied through the column tips. The behaviour of the specimens in terms of the deformation and strength characteristics is discussed. Increasing the reinforcement ratio increased the punching shear capacity and decreased the reinforcement strains and deflections at the same load level. The test results were also compared to the predictions of the relevant North American codes where applicable.