Strut-and-Tie Method for CFRP Strengthened Deep RC Members

Abstract

In recent years, a great deal of research on the carbon fiber-reinforced polymer (CFRP) composite retrofitted systems has been done. The investigation of CFRP retrofit systems, however, has focused on flexural and shear strengthening for slender concrete members. Very limited work has been done on CFRP strengthened deep concrete structures. For analysis of CFRP strengthened deep reinforced concrete (RC) members, the strut-and-tie method (STM) is also a powerful analysis tool since a bonded CFRP element acts as an additional tension tie. In this paper, a practical analysis and design process for CFRP strengthened deep RC members using the STM is presented. In addition, seven effective factor models accounting for reduction of strength in cracked concrete were also investigated. A total of 17 experimental deep beam test results were compared with the proposed STM approach results. It has been shown that the proposed STM approach with an effective factor model depending on the strut angle provides the best agreement with the test results.