Tensile and Shear Capacity of Post-Installed GFRP Bars in Concrete

Abstract

Post-installed reinforcing bars are frequently used to connect new concrete members to an existing structure. In these applications, uncoated steel reinforcing bars are often used, which are susceptible to corrosion. The use of glass fiber-reinforced polymer (GFRP) reinforcing bars in structural concrete has increased in recent years due to many factors, including their noncorrosive and nonconductive nature, high tensile strength, and nonmagnetic properties. Currently, structural concrete design using GFRP reinforcing bars is covered in ACI 440.1R, which does not include provisions for anchorage to concrete. This research was conducted to begin filling that knowledge gap and determine if the equations for anchorage to concrete with steel reinforcing bars given in ACI 318 are appropriate for use with GFRP reinforcing bars. A series of tests were conducted with tensile and shear loading to characterize behavior of post-installed GFRP reinforcing bars and allow for comparison of their behavior to post-installed steel reinforcing bars. Specifically, two sizes of both steel and GFRP reinforcing bars (No. 5 and 8) were post-installed in concrete slabs using the same chemical adhesive. The confined and unconfined tensile strength of the bars away from concrete edges and in proximity to concrete edges was established. Additionally, shear tests on No. 5 bars were performed. Using the information gathered from these tests, the applicability of ACI 318 design guidelines for post-installed GFRP reinforcing bars is presented.