Mechanism of longitudinal cracking in concrete deck slabs of composite cable-stayed bridges

To reveal the mechanism of longitudinal cracking in concrete deck slabs of composite cable-stayed bridges, static and fatigue experiments were conducted on three prestressed concrete slabs simulating the compressive forces resulting from inclined cables, and the main variables were the magnitudes of compressive stress and the wheel load. First, the evolutions of displacements, strains, crack patterns, and crack widths during static and fatigue loading were investigated. Next, refined finite element models considering rebar ribs and bond behavior were established and validated with experimental results, and the strain distributions in the concrete cover were studied. Then, a parametric study was conducted to investigate the effects of compressive stress and shear-span ratio on the cracking loads. Finally, the mechanism of longitudinal cracking under static and fatigue loading was revealed. Results show that longitudinal cracks are likely to occur under large longitudinal compressive stress and repeated heavy wheel loads. The direction of the crack is strongly dependent on the magnitude of compressive stress. Longitudinal cracks are caused by the combined effects of compressive stress, vertical contact forces between rebars and surrounding concrete, and the transverse bending moment from the localized wheel load.