Keywords: stud connector, finite element method, push-out tests, combined forces, shear behavior, load-slip curve.

Stud Connectors are widely used in steel-concrete composite structures, especially in composite bridges. The mechanical behaviour of stud connectors is studied by push-out experiments or beam experiments, which are costly when considering different effects of parameters. Thus the finite element method is necessary to investigate the mechanical behaviour of stud connectors for a wider range of parameters.

This paper presents a nonlinear finite element model for a push-out specimen using ABAQUS to study the mechanical behaviour of stud connectors. The model was based on a simplified quarter structure of the push-out specimen. Symmetric constraints were applied on the symmetric surfaces. Material nonlinearity was considered in the finite element models. A concrete damage-plastic model was used in the finite element models; in which three different phases were considered for the concrete equivalent uniaxial stress-strain curve for compression: the elastic phase, the plastic ascending (hardening) phase and the plastic descending (softening) phase. For the stud structural and reinforcement steel materials, tri-linear curves were used. Ductile and shear criteria were applied in the stud material model to simulate the damage initiation of the studs, and the energy type damage evolution with exponential softening laws to describe the progressive damage. The surface-to-surface formulation was created between steel-concrete contact surfaces and stud-concrete contact surfaces. Rebar elements were embedded inside the concrete blocks. The dynamic explicit analysis method was taken to calculate the finite element models which is inexpensive compared with implicit analysis, and very efficient when solving discontinuous and contact problems.

The calculated load-slip curves were compared with the experimental load-slip curve, which proves that the nonlinear finite-element model after verification can provide a good estimate of the load-slip curve of the stud connecter under pure shear and combined forces. An extensive parametric study of eleven specimens was performed by considering different stud diameters, concrete strengths and applied tensile forces. The shear resistance of stud connectors increases with the increase of stud diameter and concrete strength, and the stud diameter has a greater influence on the shear resistance than the concrete strength. Under combined forces, the shear resistance of the stud connector decreases as the applied tensile force increases.

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