Experimental test and seismic performance of partial precast concrete segmental bridge column with cast-in-place base

It is well known that the seismic performance of bridge systems is directly related to that of its columns since these provide the lateral resistance of the bridge and dissipate the input energy induced from ground motions. However, segmental bridge columns have small energy dissipation capacity, compared to conventional monolithic columns. In order to improve the energy dissipation capacity of the columns, several approaches have been suggested such as the use of mild steel bars, high-performance steel bars, exterior yielding braces, and elastomeric bearing pads, which are installed at the base of the columns. Recently, a combination of cast-in-place (CIP) and precast has been suggested by other researchers to increase the energy capacity. As an example of CIP application, a new precast segmental column is suggested in this paper and its cyclic behavior is examined. The base of the present circular segmental column is cast-in-place, while the upper parts are given by partial precast hollow circular segments. The column specimen has a height of 7500. mm, a diameter of 1500. mm and reinforcement ratios of 1.23-1.46%. In the cyclic test, the vertical load applied to the top of the column is about 10% of the column's nominal strength. The results of the experimental test show that the column has excellent energy dissipation capacity producing an equivalent viscous damping ratio of about 23% at 4.29 drift ratio (final drift). The ductility ratio is 4.67 and the peak lateral strength is also high, namely about 26% of the total applied vertical load. A simplified analytical model of the column is developed and the results compared to those of the cyclic test. Sectional moment-curvature envelopes are used for the analytical model. Furthermore, nonlinear time history analyses are conducted using Northridge (Newhall) earthquake records. From the seismic analysis, the peak acceleration responses are shown as 0.23-0.25. g. The values are much smaller than the values given by the elastic response spectra of the earthquake records since the column produces the enough energy dissipating and yielding behavior.