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The re-centring ability and durability of important bridges have been the main objectives in recent provisions of seismic design codes. To achieve better recoverability and durability for piers, th...

Lack of corrosion resistance and post-earthquake resilience will inevitably result in a considerable loss of function for concrete bridge piers with conventional steel reinforcement. As an alternative to steel reinforcement, shape memory alloy (SMA)-based reinforcing bars are emerging for improving the seismic performance of concrete bridge piers. This paper presents an assessment of concrete bridge piers with different reinforcement alternatives, namely steel reinforcement, steel-SMA hybrid reinforcement and SMA reinforcement. The bridge piers with different reinforcements are designed having a same lateral resistance, or in other words, the flexural capacities of plastic hinges are designed equal. Based on this, numerical studies are conducted to investigate the relative performance of different bridge piers under seismic loadings. Seismic responses in terms of the maximum drift, residual drift as well as dissipated energy are obtained and compared. The results show that all the three cases with different reinforcements exhibit similar maximum drifts for different earthquake magnitudes. The SMA-reinforced bridge pier has the smallest post-earthquake residual displacement and dissipated energy, whereas the steel-reinforced pier shows the opposite responses. The steel-SMA hybrid reinforcement can achieve a reasonable balance between the residual deformation and energy dissipation.

This paper presents the tensile strength of glass fibre-reinforced polymer (GFRP) reinforcing bars embedded in concrete that is exposed to tap water, saline solutions and ambient humidity under accelerated conditions. These conditions were used to simulate the effect of river water, seawater or atmospheric moisture on the GFRP bars. In addition, the electrical impedance method was employed to evaluate the water content at different depths of a concrete cover under a variety of ambient humidity conditions. The effects of seawater, water-to-cement ratio (W/C) of the concrete cover, environmental humidity and cover depth were studied. The results revealed that the GFRP bars embedded in concrete exhibited a substantial strength loss when exposed to tap water or high ambient humidity. The degradation of concrete-wrapped GFRP bars immersed in saline solution could be different. This discrepancy is due to the variation of the degradation mechanism after exposure to chloride ions and is related to the cover depth. The depth of the concrete cover also had an evident influence on the durability results of GFRP bars subjected to various humid environments. Furthermore, reducing the W/C of the concrete cover had negative effects on the GFRP reinforcing bars.