Innovative Technique for Seismic Upgrade of RC Square Columns

Abstract

Synopsis: The preliminary results of an experimental investigation on under-designed RC square columns are presented in the paper. The seismic upgrade was achieved by combining steel spikes and GFRP laminates. Two parameters are investigated: the lap splice of the longitudinal steel reinforcement and the level of axial load. A comparison between as-built and strengthened columns is presented in terms of strength and ductility. The shear-top displacement relationships of strengthened columns are analyzed to assess the influence on the global performance of the lap splice. This preliminary analysis confirms that the proposed solution for the seismic strengthening of under-designed columns is very effective when it is necessary to relocalize the potential plastic hinges of columns by increasing their flexural strength. The obtained results will represent the basis for developing design criteria for the strengthening of similar interventions and will represent a reference for the calibration of a model of the strengthened column.