Accumulated Damage-based Experimental Study on Seismic Performance of HRBF500 Rebar Reinforced RC Bridge Columns

Abstract

The evolution of the damage and seismic behaviour of the reinforcement concrete (RC) bridge columns reinforced with HRBF500 rebar was investigated in this paper. Nine bridge column specimens with various strengths of longitudinal reinforcement, reinforcement ratios, axial compression ratios and stirrup ratios were tested under horizontal cyclic loading. The influences of the designed parameters of the mechanical properties such as failure mode, loading-displacement curve, skeleton curve, strength and stiffness degradation and energy dissipation were analysed in the view of damage. There are four conclusions brought by the tested results. The damage process of specimens could be divided into turn-crack development stage, damage accumulation stage and failure stage. The damage will accumulate gradually and the strength and stiffness will also be degenerated, resulting in lower ductility and energy dissipation capacity of the specimens, as the displacement amplitude increases. The failure modes are similar, with plastic hinges occurrence varying from 30 to 260 mm above the concrete bases, accompanied by the steel buckling, fractured and the concrete local crushing. The good ductility and energy dissipation capacity of the HRBF500 reinforced concrete bridge columns are illustrated by the relatively plumper shuttle-shaped hysteresis curves obtained. The damage development was faster and energy was comparably larger of the specimens under the variation of displacement amplitude cycle loading, comparing with the constant displacement amplitude cycle loading. The bearing capacity of the specimens will be certain influenced by the increased reinforcement ratios and the larger energy dissipation capacity, with more longitudinal bars. The axial compression ratio also has an important influence on the damage development of the specimens. There are not considerable increments of bearing capacity, with the increment of reinforcement ratio, however, the ductility and energy dissipation ability will be improved obviously. The laws of damage development analysed by the experimental results were shown in this paper. The seismic damage assessment and seismic damage model of this kind of structural members were established by the experimental results above.