Abstract

When a seismic force acts on bridges, the pier can be damaged by the horizontal inertia force of the superstructure. To prevent this failure, criteria for seismic reinforcement details have been developed in many design codes. However, in moderate seismicity regions, many existing bridges were constructed without considering seismic detail because the detailed seismic design code was only applied recently. These existing structures should be retrofitted by evaluating their seismic performance. Even if the seismic design criteria are not applied, it cannot be concluded that the structure does not have adequate seismic performance. In particular, the performance of a lap-spliced reinforcement bar at a construction joint applied by past practices cannot be easily evaluated analytically. Therefore, experimental tests on the bridge piers considering a non-seismic detail of existing structures need to be performed to evaluate the seismic performance. For this reason, six small scale specimens according to existing bridge piers were constructed and seismic performances were evaluated experimentally. The three types of reinforcement detail were adjusted, including a lap-splice for construction joints. Quasi-static loading tests were performed for three types of scale model with two-column piers in both the longitudinal and transverse directions. From the test results, the effect on the failure mechanism of the lap-splice and transverse reinforcement ratio were investigated. The difference in failure characteristics according to the loading direction was investigated by the location of plastic hinges. Finally, the seismic capacity related to the displacement ductility factor and the absorbed energy by hysteresis behavior for each test were obtained and discussed.

Highlights

  • Detailed seismic design standards have been introduced recently in countries in low to moderate seismicity regions

  • In the case of a single-column pier, a plastic hinge is generated at the bottom of the pier where the bending moment is at its maximum

  • When the detailed seismic design criteria are not applied, the longitudinal reinforcing bars at the plastic hinge region were often connected by a lap-splice due to the convenience of construction

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Summary

Introduction

Detailed seismic design standards have been introduced recently in countries in low to moderate seismicity regions. When the detailed seismic design criteria are not applied, the longitudinal reinforcing bars at the plastic hinge region were often connected by a lap-splice due to the convenience of construction. In order to increase the ductility of reinforced concrete piers that behave in flexure, it is necessary to prevent compressive failure of the concrete in the cross section by bending For this purpose, core concrete is confined by a transverse reinforcement bar. In order to know the seismic capacity in each direction, an experiment on the horizontal load in each direction is required Referring to these existing studies, it is shown that the seismic capacity of the columns with lap-splices is very low and varies according to the details of the transverse reinforcing bar. For multi-column piers, seismic performance evaluation is required for these details of the reinforcing bars for each loading direction.

Loading Protocol
Findings
Hysteresis Curve of Longitudinal Loading Specimen
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