Dynamic response analysis of cracked concrete beams subjected to moving load considering the effect of reinforcement

Due to the restraint effect of steel reinforcing bars, the local flexibility of cracked cross-sections of the concrete beam is different from that without reinforcement. Considering the influence of reinforcement, the dynamic equation of cracked concrete beams under moving load was established. Based on the force balance and deformation compatibility between the reinforcement and concrete, the local flexibility of cracked cross-sections was modified. The massless spring was used to simulate the crack, and natural vibration characteristics of the cracked beam were obtained taking into account the effect of the reinforcement. Dynamic responses of the reinforced concrete beam were acquired by solving the governing equation with the Newmark method. Taking the simply-supported beam subjected to moving vehicle load as an example, responses of the cracked reinforced concrete beam under different load speeds, crack depths, crack locations, and reinforcement ratios were analyzed. The results show that the restraint effect of the steel reinforcing bars at the crack location can significantly affect dynamic responses of the beam. The displacement response of the cracked beam will generally decrease after considering the stiffness provided by the reinforcement. Moreover, the effect of the reinforcement shows an increasing trend as the severity of the cracking damage grows. The resonance phenomenon of the cracked beam under moving load is more detrimental compared to that of the undamaged beam. Resonance speeds of the cracked beam increase and resonance responses decrease to a certain extent after considering the effect of the reinforcement. Owing to the difference in the resonance speeds of the cracked and intact reinforced concrete beam, the displacement response of the intact beam is larger than that of the cracked beam under certain load speeds. © 2024 Chinese Vibration Engineering Society. All rights reserved.