Experimental and Numerical Study of Seismic Response in CFRP-Strengthened and Damaged Rectangular Hollow Bridge Piers

This study aims to investigate the seismic performance and response of moderately damaged, rectangular hollow bridge pier specimens strengthened with carbon fiber-reinforced polymer (CFRP). For this purpose, two 1:8 scaled-down specimens were designed and fabricated and pseudodynamic tests were conducted. These tests focused on parameters such as the intensity of ground motion and the presence of strengthening. A nonlinear model of CFRP-strengthened, moderately damaged, rectangular hollow pier specimens was also developed using OpenSees finite-element software (version 2.4.5). The model facilitated a parameter analysis that included the axial pressure ratio, layers of circumferential CFRP, longitudinal CFRP, and shear-to-span ratio. The sensitivity of each parameter was evaluated using the grey correlation method. The results revealed that the hollow pier specimens experienced elastic, elastoplastic, and plastic damage stages in response to increasing seismic intensity. The CFRP jackets effectively limited the buckling deformation of the longitudinal reinforcement, enhancing the response load of the specimen by approximately 8.3% and reducing the cumulative hysteretic energy consumption by about 39%. The proposed nonlinear finite-element model successfully predicted the hysteresis performance of the CFRP-strengthened specimens, and the calculation method accurately predicted the peak lateral load of the specimens. The axial pressure ratio and layering of the longitudinal CFRP demonstrated the most significant sensitivity to the peak lateral load and ductility factor of the CFRP-strengthening specimens, respectively.