Experimental assessment of the residual capacity of axially loaded blast-damaged square RC columns

Abstract

The aftermath of the Oklahoma City Bombing and the events of September 11, 2001 in the United States led to intense research into the response of infrastructure to explosion effects and the attendant risk of progressive collapse of building structures. The research has not addressed the residual capacity of blast-damaged columns. The challenge to structural engineers is determining the residual capacity of blast-damaged columns and deciding which should be demolished and which can be repaired cost-effectively. This paper presents the results of an experimental program designed to investigate the residual capacity of blast-damaged columns in the laboratory.The blast-damaged columns, from an earlier field test program, were first subjected to the design axial service load of 1000 kN. Columns capable of resisting the service load were subjected to additional lateral loading to determine their residual flexural capacity. The test results show that columns with reduced tie spacing exhibited higher post-blast residual capacity from the explosion at the same scaled distance. Also, a high axial load ratio was observed to adversely affect the flexural load capacity of the reinforced concrete columns in a numerical parametric analysis done using the finite element program LS-DYNA.