Strut-and-tie models of repaired precast concrete bridge substructures with CFRP shell

Strut-and-tie models (STM) have been developed for original and repaired precast reinforced concrete (RC) bridge assemblies tested under quasi-static cyclic loads. The original assemblies, built using accelerated bridge construction techniques, are half-scale column-to-footing and column-to-pier cap specimens connected using grouted splice sleeves. The repaired assemblies are strengthened over the plastic hinge region using a unidirectional carbon fiber reinforced polymer (CFRP) shell, post-installed headed steel bars, and non-shrink concrete. The repair technique was successful and the load and displacement capacities of the damaged assemblies were restored. Generic modeling parameters are established for the STM procedure, enabling the models to be adapted to new repair applications. Special attention is focused on the struts within the CFRP shell. All assemblies are modeled using sectional analysis in conjunction with the predicted STM load to estimate a bilinear force–displacement response. The STM and bilinear force–displacement response envelopes obtained from the models show satisfactory agreement with the experiments of the original and repaired bridge assemblies in terms of initial stiffness, lateral load and displacement capacity.