BOLTED SHEAR CONNECTORS IN ULTRA HIGH PERFORMANCE CONCRETE COMPOSITE SLABS WITH STEEL DECK: A NUMERICAL INVESTIGATION

Abstract

This study presents a comprehensive three-dimensional nonlinear finite element (FE) model developed in ABAQUS to investigate the behavior of bolted shear connectors embedded in Ultra high performance concrete (UHPC) composite slabs with steel decking. Material nonlinearity was modelled using ductile and shear damage criteria for steel material and the Concrete Damaged Plasticity (CDP) model for UHPC. Model accuracy was validated against experimental push-out tests from the literature, showing a good agreement in load-slip response and peak load. Following validation, an extensive parametric study was conducted to assess the influence of UHPC compressive strength, connector diameter, and reinforcement configuration. Increasing the UHPC compressive strength from 120 MPa to 180 MPa increased the shear capacity from 96.8 kN to 133.4 kN, corresponding to an enhancement of 1.38 times. Among all parameters, the connector diameter exhibited the most pronounced influence, with an increase of 1.52 times. The results is mainly due to enhanced confinement and bearing resistance around the connector. In contrast, modifications to the reinforcement cage such as using double reinforcement layers or reducing bar spacing, resulted in only marginal (1-3%) improvements. The findings provide valuable insights into shear transfer mechanisms in steel-UHPC composite systems and offer a validated numerical framework for optimizing connector design.