Load transfer mechanisms and predictive models for steel-concrete joints of hybrid girder bridges: Experimental and theoretical studies

Abstract

This study presents an integrated experimental and theoretical investigation into load transfer mechanisms and resistance prediction method for concrete-filled steel cell (CFSC) joints in steel-concrete hybrid girder bridges. An experimental program involving five large-scale CFSC specimens featuring rear-end bearing plates and perfobond shear connectors was conducted to quantify the synergistic behavior of load-transfer components. Complementary theoretical analyses derived an analytical model to determine individual component contributions to joint resistance. The experimental results indicated that the load transfer mechanism operates through a composite action between rear-end bearing plates and shear connectors, with ultimate failure attributed to localized buckling of stiffeners adjacent to bearing plates. Quantitative resistance partitioning calculated using strain results demonstrates that bearing plates contribute 61 % of total joint resistance during elastic loading stages, decreasing to 58 % in plastic stages, while shear connectors exhibit a corresponding increase from 39 % to 42 %. A predictive model for calculating load transition in CFSCs, based on equivalent spring superposition theory, was developed and shows strong agreement with experimental data from current tests and previous studies. This yields valuable insights for designing and optimizing steel-concrete joints in hybrid girder bridges.