Performance Evaluation of Pre-Damaged Fire Effected Deep Beams

Abstract

Deep beam’s behaviour is complex as it is dependent upon several factors, such as supporting area beneath support and load, depth, concrete strength, quantity of flexural and shear reinforcements, and the ratio of shear span to depth, in addition these beams could be vernal able to high temperatures, which has to be strengthened but hasn't been thoroughly researched. This work investigates experimentally load bearing capability of deep beams reinforced with carbon fiber-reinforced polymer (CFRP) sheet to increase the deep beam’s flexural strength following exposure to high temperatures. Total two specimens were cast. The first beam was examined to collapse at room temperature, whereas the second beam underwent testing following exposure to 550° C. Then these two deep beams were retrofitted using CFRP sheets by wrapping them in U shape and then tested to failure. The test results show that there is almost 6% drop in strength of deep beam after being exposed to high temperature, but the failure mood remains same i.e. flexure before strengthening and shear after strengthening. Furthermore, the experimental findings showed that retrofitting method performed exceptionally well in increasing the flexure strength up to 38% and hence improved the post-cracking behaviour of CFRP retrofitted deep beams. Heat exposed retrofitted beam is more ductile than ambient temperature retrofitted beam because of CFRP U-wrap shredding due to weakening of surface concrete thus resulting in increase of peak load deflection up to 13%.