Mechanical response and performance evaluation of waterproof adhesive layer for steel-concrete composite beam bridge deck in seasonally frozen regions

In seasonal frozen regions, the waterproof adhesive layer (WAL) of steel-concrete composite beam (SCCB) bridges tends to deteriorate early under the combined effects of wheel loads (WL) and freeze-thaw cycles (FT). To address these issues, this study evaluated the stress distribution of WAL under the combined effects of temperature and dynamic loads. It quantitatively analyzed how the amount of waterproof adhesive material (WAM), temperature, WL, and FT affect the shear performance, pull-off strength, waterproofing, and fatigue of WAM. Results show that under service conditions, longitudinal shear stress in WAL can reach 0.38 MPa, and vertical tensile stress can reach 0.03 MPa. The combined effects of WL and FT can significantly accelerate adhesion deterioration, reducing shear strength by up to 85.5% and peel strength by up to 76.5% in later stages. These findings provide a theoretical basis for selecting and designing WAM materials for SCCB bridge decks in seasonal frozen regions.