Theoretical analysis of slab-girder constraint effects on the mechanical behavior of debonded link slabs

Slab-girder constraint effects are crucial factors influencing the mechanical behavior of debonded link slabs. However, these effects are rarely considered in existing research, which makes quantifying the mechanical behavior of slabs difficult and impedes their practical application. This study presents a theoretical model that quantifies the loads transferred from the girders to the slabs when vehicle and temperature loads are applied on the girders. The model considers the slab-girder constraint effects at the transverse interface and at the girder end simultaneously. The effectiveness of the model is verified by the reasonable agreement between the calculated maximum tensile stress in the link slabs and the numerical results. Based on the model, the tensile stress in link slabs is subsequently calculated under different constraint conditions and structural parameters to determine reasonable constraint forms for mechanical analyses and to develop feasible measures for the mechanical optimization of link slabs. The results indicate that for the girders subjected to concentrated loads, distributed loads, or negative gradient temperature loads, considering only the constraints of girder-to-slab vertical displacement and rotation is acceptable for quantifying the mechanical behavior of link slabs. However, for the girders under overall cooling loads, the longitudinal slab-girder mutual constraint effect should be considered. Increasing the length and thickness of link slabs, as well as decreasing their elastic modulus, contributes to reducing the tensile stress. Considering the coupling effect, the slab length can be reduced without affecting the mechanical behavior of the slab as long as the elastic modulus-to-slab length ratio remains constant.