Study on Shear Behavior of MCL-shaped Composite Dowels in UHPC

Abstract

MCL-shaped composite dowels are innovative shear connectors with excellent mechanical properties and have wide application prospects in composite structure bridges. To explore the shear behavior of MCL-shaped composite dowels in UHPC, longitudinal and transverse push-out tests were designed and conducted according to their mechanical characteristics in the innovative corrugated composite bridge decks. Finite element models of two types of push-out tests were established considering nonlinear factors such as the materials and interface contact, and they were verified against the test results. The load transfer process and failure mechanism of two types of push-out tests are expounded by conducting stress analysis of the structure based on the finite element models. Based on the mechanical characteristics and failure mode, a formula was developed to calculate the longitudinal ultimate shear capacity of MCL-shaped composite dowels with the failure mode of steel dowel failure. Based on a comparison with the existing formula, a formula was determined to calculate the transverse ultimate shear capacity of MCL-shaped composite dowels with the failure mode of UHPC crushing. The results indicate that the longitudinal and transverse shear behaviors of the MCL-shaped composite dowels are significantly different. The longitudinal shear behavior of the MCL-shaped composite dowels showed good ductility, while the transverse shear behavior showed high shear stiffness and ultimate shear capacity. The main mechanical indexes calculated by the finite element models are in good agreement with the test results, and the applicability of the finite element models was verified. The longitudinal failure mode of the MCL-shaped composite dowels shows that the steel dowels produce large plastic deformation causing its root section to enter the yield state, while the transverse failure mode shows that the UHPC under the steel dowels is crushed. The mean and standard deviation of the ratios between the calculated values and test values of the longitudinal and transverse ultimate shear bearing capacities are (1.18 and 1.06) and (0.13 and 0.01), respectively, which indicate that the calculated values agree well with the test values.