Full Session with Abstracts
Anchorage of externally bonded FRP sheets is gaining a lot of attention recently to improve the performance of strengthened concrete members. In this study, the use of GFRP U-wraps and flexural GFRP sheets is examined with and without the use of GFRP anchors. Eccentrically loaded high strength concrete beams introduce a disturbed shear region that is evaluated experimentally and analytically. Four identical beams are tested with different strengthening schemes. The first one is a control beam without any strengthening. The second one is strengthened in flexure with a GFRP sheet and in shear with a GFRP U-wrap without adding any GFRP anchors in shear. The third has identical strengthening system to the second beam except for anchoring the U-wraps with GFRP splay anchors in shear within the disturbed region. The fourth beam is similar to the third beam expect for using two additional steel bars as NSM reinforcement in addition to the flexural GFRP, GFRPU-wraps and GFRP anchors. The behavior of the four beams are compared to each other experimentally and a Strut and Tie Model (STM) is proposed as a tool to predict the response of GFRP strengthened disturbed regions. Two different truss profiles are used to model the tested beams. It is observed that the more detailed truss model yield more accurate predictions due to the fact that it has more gradual variation of the truss forces in the struts and ties of the disturbed region. An innovative approach is devised to develop the tension forces in the two main ties represented by the main steel bars and the GFRP flexural sheets.