Performance of FRP Strengthened Concrete Columns Under Simulated Blast Loading

Abstract

In this thesis the effectiveness of CFRP laminates as externally applied column jacketing material was investigated experimentally. The research project forms part of a comprehensive research program with a scope of developing FRP protection systems for reinforced concrete columns subjected to extreme loads. The research program is carried out by a multi-disciplinary team including various institutes of the National Research Council Canada and the University of Ottawa. The experimental program of the current project consists of nine half-scale seismically designed reinforced concrete (RC) columns, tested under combined axial compression and simulated lateral blast loading, applied statically. Seven columns were strengthened by four types of CFRP laminates. The columns were first subjected to service axial loads of 45% of the design axial load capacity, followed by uniformly distributed lateral load up to failure. The columns were analyzed under incrementally increasing static loads, well into the inelastic range of deformations. The FRP was modelled as a linear material up to rupturing in tension. The behaviour of CFRP in compression was modelled with reduced strength and modulus of elasticity. It is found that the use CFRP laminates as column jacketing improves strength and deformability of the columns significantly. The use of CFRP laminate with unidirectional fibers and woven ±45° laminas results in significantly lower lateral deformation than companion unretrofitted columns. The retrofitted columns also develop well distributed strains within the critical plastic region, promoting a better redistribution of stresses. Adding woven ±45° laminas resulted in higher deformability and slightly lower strength than the laminate with only unidirectional fibers. The overall conclusion of the project is that the CFRP jackets, when designed properly, especially with the addition of ± 45 degree fibres result in significantly improved strength and deformability of concrete columns.