Behaviour of cold-formed lipped C-channel with ferrocement jacket composite column under axial compression

Abstract

One of the major challenges for strengthening or upgrading steel structures is to increase column capacity to withstand large expected loads. The main objective of the present study was to investigate the behaviour of build-up lipped Cold Formed steel (CFS) C-channel column assembled with ferrocement jacket. Generally the data and information are limited on the behaviour and performance of CFS column in composite construction.. One of the limiting features of CFS is the thinness of its section that makes it susceptible to torsional, distortional, lateral-torsional, lateral-distortional and local buckling. Hence, a reasonable solution was to propose a composite construction of structural CFS section and ferrocement jacket, which would minimize the buckling of the web and reduce the distortion of CFS sections. This study comprised of three major components, i.e. experimental, theoretical and finite element analysis through ANSYS (version 11). Experimental work involved small-scale and full-scale laboratory testing. The first phase comprised of push-out test specimens while the second phase focussed on full-scale testing of eighteen CFS-ferrocement composite column specimens. All eighteen full-scale axially loaded column specimens with variable parameters were tested till failure. The experimental test results show good agreement with the predicted value calculated from AISI S100 (2007). It was found that the capacity of shear connector with 12 mm diameter bolts was the best in transferring shear force into steel section-ferrocement jacket interface. The strength capacity of CFS-ferrocement composite columns were improved by 245% than that of bare steel columns. Also it was found that axial load capacity of CFS-ferrocement jacket composite columns (CFFCC) increased with the increased thickness of CFS. The results of the finite element model agreed well with the experimental results based on the graphs plotted for load versus axial shortening of the proposed composite column system relationships.