Seismic Shear Strengthening of Reinforced Concrete Short Columns Using Ferrocement with Expanded Metal

Abstract

Typical reinforced concrete short column is brittle in shear rather than flexure under lateral cyclic loading due to its shear deficiency.  This paper presents the improvement of seismic behaviour of the reinforced concrete short columns which were strengthened by using ferrocement with expanded metal.  Full scale experiments were conducted for two strengthened concrete columns with different volume fractions of expanded metal and the control specimen under lateral cyclic loading.  It was found that the seismic behaviour in terms of the shear strength, stiffness, displacement ductility, and energy dissipation were significantly improved.  The expanded metal mesh with the high specific surface provided the better performance for controlling the crack propagation.  The brittle shear failure mode of the stirrup was reduced and the ductile flexure mode of the longitudinal reinforcement was dominant.  The reduced shear force of the stirrup was compensated by the shear force of the expanded metal reinforcement which experienced relatively large strain.  The technique of steel angle installation at the corners of column can successfully prevent the effect of sharpened corner wrapping of the mesh.  A model to predict the shear strength of the strengthened column is presented in term of the global efficiency factor for expanded mental.