Lateral cyclic behavior of bridge columns confined with pre-stressed shape memory alloy wires

Abstract

This study focuses on investigating the effects of the wrapping mode of shape memory alloy (SMA) spirals with a large pre-strain on the lateral cyclic behavior of the bridge columns. The seismic performance of RC columns confined with different NiTiNb SMA spirals spacing and wrapping heights is compared through a series of quasi-static tests. The confined columns are tested under compression and cyclic lateral loadings. The lateral cyclic behavior of confined columns is compared with that of the as-built column. The test results demonstrate that NiTiNb SMA with a large pre-strain significantly improves the ductility and energy dissipation capacity, and has a slight effect on the peak lateral strength of the bridge piers. The SMA spirals reduce the crashing concrete zone and delay the buckling of steel bars in spite of the crack range in the SMA specimens increasing compared with the control column. The reinforcement effect increases as the SMA spirals spacing decreasing, particularly in terms of ductility and energy dissipation. The damage pattern has a slight distinction in the specimens strengthened by different wrapping mode.

Keywords

• bridge columns
• shape memory alloys
• active confinement
• ductility
• quasi-static tests