Rc Members Strengthening by Lateral Post-tensioning of External Metal Strips

ABSTRACT The majority of concrete buildings in the regions of high seismicity in Iran do not meet seismic code requirement, and many of these buildings are vulnerable in severe earthquakes. Concerns for seismic strengthening of concrete grew considerably in the recent years, and has been accelerated since the Bam earthquake 2004. This paper presents the results of experimental and analytical study on the application of strapping technique for retrofitting of concrete columns. Experimental program included axial compressive tests on cylindrical and prismatic small-scale columns which were actively confined by pre-stressed metal strips. Test Results showed significant increase in strength and ductility of columns due to active confinement with metal strips. The effect of various parameters such as pretensioning force in the strip, number of strip layers wrapped around the specimens and spacing of confining strips on strength of concrete is studied. Nonlinear Finite element models of tested specimens were also made and analyzed. The observed stress-strain behaviors of columns with different levels of confinement are compared to those obtained from finite element method.