Title: Axial Capacity Model for Shear-Damaged Columns

Author(s): Kenneth J. Elwood and Jack P. Moehle

Publication: Structural Journal

Volume: 102

Issue: 4

Appears on pages(s): 578-587

Keywords: axial load; column; seismic; shear

DOI: 10.14359/14562

Date: 7/1/2005

Abstract:
This paper introduces a model to estimate the axial capacity of a column that has previously experienced shear failure. The model is applicable to existing reinforced concrete building columns vulnerable to shear failure during earthquakes. The axial load on a shear-damaged column is assumed to be supported by a combination of compression of the longitudinal reinforcement and force transfer through shear-friction on an idealized shear-failure plane. The effective coefficient of friction from the classical shear-friction equation is related to the drift ratio at axial failure using the results from 12 full-scale pseudostatic column tests. The model, which represents the general observation from experimental tests that the drift ratio at axial failure of a shear-damaged column is inversely proportional to the magnitude of the axial load and directly proportional to the amount of transverse reinforcement, provides relations among axial load, transverse reinforcement, and the interstory drift at axial load collapse.