Experimental study on repair and reinforcement methods of concrete beams and cost analysis

It is known that different techniques are applied in order to strengthen reinforced concrete structural elements. In this study, the behavior of beams, which are of great importance in reinforced concrete structures, under bending and shear effects was investigated. Initially, the beams were pre-damaged, followed by repair / strengthening methods with carbon fiber reinforced polymer (CFRP), steel plate and mechanical binders. In the experimental study, a total of 20 ½ scale beam samples were prepared. Samples are produced in the dimensions of 125x250x2500 mm rectangular cross-section, 3Ф12 rebar in the tension zone, 2Ф8 rebar in the compression zone, and the spacing of the confinement bars is Ф5 / 10 cm for the bending behavior, and Ф5 / 35 cm for the beams where the shear behavior is desired. The test specimens were subjected to static vertical loading at four points and the ratio of a / d ( length of shear zone / effective cross sectional height) was set to 3.11. After determining one reference beams for each bending and shear tests, the remaining 9 bending and 9 cutting beams were divided into three groups. Each group allocated for bending beams was loaded up to the damage levels of 1%, 2% and 3% displacement present in TSC-2018. Then the repair / strengthening process was carried out with three different materials and the change in capacity was examined. Shear beams were subjected to preliminary tests up to 50%, 65% and 85% damage after determining the maximum load carrying capacity of the reference sample. After being strengthened by three different repair / strengthening materials, the capacities of the beams were investigated. Following the study, repair / strengthening method with CFRP increases the capacity up to 20% for 1% damage level in bending beams, repair / strengthening method with CFRP increases the capacity up to 28% for 2% damage level, repair / strengthening method with CFRP increases the capacity up to 23% for 3% damage level. According to these results, CFRP was found to be the most effective material for repair / strengthening the beams which damaged under bending effect. Repair / strengthening method with CFRP increases the capacity up to 41% for 50% damage level in shear beams, repair / strengthening method with mechanical binders increases the capacity up to 47% for 65% damage level and repair / strengthening method with mechanical binders increases the capacity up to 50% for 85% damage level. According to these results, mechanical binders was found to be the most effective material for repair / strengthening the beams which damaged under shear effect. The optimum result in terms of the cost for repair / strengthening, has found to be mechanical binders.