CD04-009 REPAIR AND RETROFIT OF RC COLUMNS WITH PRE- STRESSED BANDS FOR IMPROVED SEISMIC BEHAVIOUR H. Moghaddam 1 , M. Samadi 2 1 Sharif University of Technology Tehran, Iran 2 Islamic Azad University of Mashhad, Iran ABSTRACT A new technique of seismic retrofit of RC columns has been applied in this paper. Pre-stressed high strength metal strips are externally applied to RC columns. Eight large-scale RC columns with insufficient transverse reinforcements were tested under constant axial and cyclic lateral load reversals. The level of axial load and the pattern of strengthening were parameters of this study. The ability of the technique for improving the ductility of RC columns and increasing the lateral strength of columns as well as repair of damaged columns was studied. It was observed that the technique is capable to enhance the lateral behavior of RC columns significantly. Very ductile behavior was achieved. The height-wise variations of lateral strain on confining strips are studied. Keywords: RC column, seismic behavior, earthquake, repair, seismic retrofit 1. INTRODUCTION Major failure modes that have been reported for RC columns in previous earthquakes or laboratory tests including shear failre, lap-splice failure, buckling of longitudinal bars inflexural failure, insufficient capacity of plastic hinge rotation can mainly be interpreted due to the inadequte confinement. Several experimental studies have been performed on application of various techniques of seismic retrofit of reinforced concrete columns such as RC jacketing, steel jacketing, glued steel bands, FRP jacketing, FRP collars, post-tensioned cables, etc. [1-5] In this paper, an easy and innovative technique of retrofit of concrete is applied for enhancing the lateral behavior of concrete columns. This technique involves post- tensioning high-strength packaging straps around the column and subsequently locking their ends in metal clips. Various conFigureurations have been applied in laboratory tests of reinforced concrete columns including cantilever, double curvature, double ended, flexible base and hammerhead. [7] In this study the cantilever conFigureuration was selected in which a constant axial load is applied and then lateral reversal cyclic displacements are applied by means of hydraulic jacks. This paper presents the experimental results of a study on the application of this retrofit technique on large-scale models of building columns. The main objective of this research was quantification of the improvement of RC columns behavior by applying this technique. This technique was previously applied for retrofitting the compressive behavior of small scale concrete columns with various
REPAIR AND RETROFIT OF RC COLUMNS WITH PRESTRESSED BANDS FOR IMPROVED SEISMIC BEHAVIOUR
May 07, 2023
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