Title: Shear-Flexure-Torsion Interaction Features of Reinforced Concrete Bridge Columns-An Experimental Study

Author(s): S.S. Prakash and A. Belarbi

Publication: Symposium Paper

Volume: 265

Issue:

Appears on pages(s): 427-454

Keywords: circular columns; combined loading; damage index; performance-based design; square columns; torsion.

DOI: 10.14359/51663307

Date: 10/1/2009

Abstract:
Reinforced concrete (RC) bridge columns are subjected to combined flexural, axial, shear, and torsional loading during earthquake excitations. This combination of loading can result in complex flexural and shear failure. The work presented herein included an experimental study conducted to understand the behavior of RC circular columns under combined loading. The main variables considered are the ratio of torsion to bending moment, and the level of detailing for high and moderate seismicity (low or high spiral reinforcement ratio). This paper presents the results of tests on eight reinforced concrete columns subjected to cyclic bending shear, cyclic pure torsion, and various levels of combined cyclic bending and torsional moments. It discusses the effects of combined loading on the hysteretic lateral load-deformation response, torsional moment-twist response, reinforcement strain variations, and plastic hinge characteristics. It also includes diagrams of interaction between bending and torsional moment. In addition, the results of this study highlight the significance of proper detailing of transverse reinforcement and its effect on torsional resistance under combined loading. Test results demonstrate that combined loading decreases both flexural and torsional capacity. Further, they show a significant improvement in the performance of columns with an increase in the spiral reinforcement ratio.