Experimental and numerical analysis of CFRP strengthened RC columns subjected to close-in blast loading

This paper presents an experimental and analytical study examining the blast load performance of steel reinforced (RC) concrete columns retrofitted with externally bonded carbon fiber reinforced polymer (CFRP) sheets. As part of the experimental program, twelve columns reinforced with different thicknesses and strengthening methods of CFRP sheets were tested under close-in explosions. The performances of the columns are compared to a control set of specimens without CFRP reinforcement. The results demonstrate that the use of CFRP significantly improves the blast performance of RC columns by reducing the maximum and residual displacements, enhancing the damage tolerance and eliminating secondary blast fragments. The results also indicate that increasing the thickness of the CFRP sheet can improve the ductility of a column. However, CFRP reinforcement on both the compressive and tensile faces can affect the failure mode of the columns. As part of the analytical study, the response of the test columns is predicted using an improved nonlinear single-degree-of-freedom (SDOF) analysis method and finite element modeling. Parametric studies were also performed to investigate the effects of the CFRP sheet thickness, bond strength, anchorage system, axial load and strengthening method on the blast performance of RC columns retrofitted with CFRP sheets.