Performance-based design for improving impact resistance of RC bridge piers with CFRP grid-reinforced ECC

This study explores the performance-based design of a composite material named carbon fiber reinforced polymer (CFRP) grid-reinforced engineering cementitious composite (ECC) to improve the impact resistance of reinforced concrete (RC) bridge piers. The finite element (FE) model of a benchmark bridge with its pier strengthened with CFRP grid-reinforced ECC is built in LS-DYNA, whereas a medium truck model is employed to impose the impact loading. The accuracy of the FE model is verified against (1) experimental results of a scaled column colliding with a moving truck and (2) the pier damage observed after a real-world bridge-truck collision accident. Subsequently, numerous FE analyses are conducted to (1) identify the accumulation of shear damage under the sequence of engine-cargo impacts, (2) pinpoint flexural damage at different column heights, and (3) derive closed-form expressions to quantify the shear/flexural demand parameters under different truck loads, and the associated intact and residual capacity models provided by the composite pier. These demand/capacity parameters are further utilized to compute shear and flexural-based damage indexes to quantify distinct damage modes and damage states by developing a series of limit state models. To this end, a complete performance-based collision design workflow is devised to strengthen the existing RC bridge piers using the CFRP grid-reinforced ECC composite material. Two case studies are further carried out to verify the effectiveness of the proposed design framework, which provides a sound reference for both researchers and practitioners to employ the CFRP-ECC composite material as a viable retrofit measure to enhance the impact resilience of RC bridge piers.