Abstract:
The finite element (FE) software ABAQUS was used to establish a three-dimensional fine FE model for the shear behavior of the keyed joints in the precast segmental ultra-high-performance concrete (UHPC) bridge girders. Material nonlinearity, geometric nonlinearity, and plastic damage of UHPC material were carefully considered in the model. The predicted load-slip curves and failure modes of the joints from the FE model are in a good agreement with the experimental results. The verified FE model was then used to analyze the shear behavior of the keyed joints. The results showed that: the shear capacity of the joints and its corresponding slip increase with the increase of the applied confining pressure or UHPC strength, but the influence of UHPC compressive strength on the shear capacity of the keyed joint is greater than that of UHPC tensile strength; in addition, there is no fixed correlation discipline between UHPC tensile strength and compressive strength, and thus for the calculation of the shear capacity of UHPC joints, the effects of UHPC tensile strength and compressive strength should be considered separately; due to the inhomogeneity of the shear stress distribution, the calculation of the shear capacity of the keyed joint should also consider the strength reduction effect of the multi-keys. In addition, the results of parametric analysis on the layout of keyed joints showed that: when the width and total height of the keys have the same dimension, the shear capacity of the joint increases with the decrease of the relative height of keys; however, when the relative height of keys is less than 1/2, the shear capacity of the joint remains basically unchanged; when the total area and number of keys are the same, the cooperative work ability between multiple keys becomes stronger with the increase of the key spacing; the depth of the keys has little effect on the shear capacity of the joint. Compared with the currently widely used formula for calculating the shear capacity of ordinary concrete joints, the FE predicted shear capacity of UHPC keyed joint is significantly smaller than the predicted result from the calculation formula, and the deviation increases with the increase of confining pressure. Therefore, it is necessary to propose a new calculation formula for the shear capacity of UHPC keyed joints.