Load transfer mechanism and fatigue performance evaluation of suspender-girder composite anchorage joints at serviceability stage

To evaluate the mechanical and fatigue behavior of composite suspender-girder anchorage joints in arch bridges, fatigue tests of two composite joints including pure-shear and shear-compression types were conducted and the load transfer mechanisms were evaluated based on the static loading. The experimental results indicated that both proposed composite anchorage joints presented great combined behavior. The load ratio of PBLs dropped sharply with the increase of embedded depth. Approximately 1/3 of the suspender tensile load was carried by the PBLs in the first row. Due to the redundant PBLs and large embedded depth, few loads were resisted by the bearing plate. Before and after the fatigue loading process, the shear amplitude of PBLs and the vertical stress distribution of concrete were almost consistent, indicating the favorable fatigue performance of joints. Parameterized solid nonlinear finite element models were established and verified by the test results to investigate the effect of total row number of PBLs and presence of bearing plate on the load transfer mechanics. The numerical results showed that the increase of total row number of PBLs enlarged the degree of irregularity of load distribution and reduced the load ratio of bearing plate. Finally, the load ratio formula of PBLs and bearing plate under serviceability stage was derived. The calculated load ratios were in good agreement with the test and numerical results. It was proposed that the total row numbers of PBLs were no >4 or 6 for the joints with or without bearing plate.