Inexpensive strengthening technique for partially loaded reinforced concrete beams: Experimental study

Abstract

This paper constitutes a special importance for developing countries where an affordable trowel-based strengthening system is needed. This paper also provides an affordable strengthening solution when it is not possible to entirely remove the effect of live load on the strengthened element. A series of 13 ferrocement strengthened beams of 2,400 mm in length and a rectangular cross section of 120x200 mm were tested. The beams were cast and preloaded to different load fractions (45 and 60%) of its ultimate capacity; then the load was partially released (by 15% of the ultimate load) and maintained, while the beams were then strengthened and reloaded until failure. The load released simulates the removed live load while strengthening an actual beam. The research reported in this paper features designing and manufacturing a special loading frame to apply, release, and reapply the loads on the tested beams. The frame allows implementing the strengthening process while maintaining the strengthened beams partially loaded. The use of flat and U-shaped ferrocement layers of three different volume fractions (VFs) of mesh reinforcement have been assessed. The overall response of the specimens was investigated in terms of the load carrying capacity, crack patterns, and propagation and modes of failure, and the deformational characteristics that include deflection, ductility, and energy absorption characteristics. The results indicated that the ferrocement strengthening system is effective in enhancing both strength and ductility of the RC beams. 2015 American Society of Civil Engineers.