Push-out tests and shear capacity influencing factors of PBL shear connector without concrete end-bearing effect

Abstract

Perfobond rib shear connectors (PBLs) are largely applied in steel-concrete composite beams because they provide high shear strength, significant stiffness, and good fatigue durability. In order to clarify the respective roles of the perforating bars and concrete dowels in the shear resistance of PBLs, a total number of 42 tests were carried out on PBL push-out specimens, excluding the concrete end-bearing effect. Experimental variables comprised the concrete compressive strength, hole diameter, number and diameter of the perforating bars, and their positional arrangement within the rib holes. The test results revealed two primary failure patterns: (1) concrete slab splitting failure for specimens with one or without the perforating bar, and (2) splitting failure with transverse cracks of the concrete slab for specimens with two perforating bars. All specimens reinforced with 12 mm and 16 mm perforating bars exhibited yielding or shear failure of the bars, whereas those with 20 mm bars remained unyielded. The corresponding load-slip (P-S) curves revealed three sequential phases: an initial elastic phase, a plastic ascending phase, and a descending phase. A new predictive equation was derived through regression analysis, which has subsequently been incorporated into the Chinese design standard (GB 50917). In addition, an empirical expression for the ascending stage of the P-S curve was obtained through curve-fitting analysis.