Repair of Cracked Steel Girders Connected to Concrete Slabs Using Carbon-Fiber-Reinforced Polymer Sheets

Abstract

This paper presents the results of an experimental study on the repair of artificially damaged steel–concrete composite beams repaired using adhesively bonded carbon-fiber-reinforced polymer (CFRP) sheets. Eleven, 2 m long, beams composed of W150×22 steel sections with 465×75mm concrete slabs were tested in four-point bending. Severe damage was first introduced in ten beams by saw cutting the tension flange completely at mid span, to simulate a fatigue crack or a localized severe corrosion. Standard modulus (SM) and high modulus (HM) CFRP sheets were then used to repair nine damaged beams. The length and number of CFRP layers applied to the cracked flange on the underside, or on both sides, were varied. Results showed that the damage had reduced flexural strength and stiffness by 60 and 54%, respectively. Nevertheless, CFRP-repaired beams achieved various levels of recovery, and in some cases, exceeded the original capacities. The strength of beams repaired with sheets, ranging in length from 8 to 97% of the span, varied from 46–116% of the original undamaged strength, whereas the stiffness range was 86–126% of original stiffness. SM-CFRP failed by debonding whereas HM-CFRP was ruptured. Bonding the sheets to both sides of the flange was not very advantageous over bonding to the underside only.