Shear Capacity of GFRP-Reinforced UHPC Beams without Stirrups
Yail J. Kim and Haftom Gebrehiwot
Appears on pages(s):
fiber-reinforced polymer (FRP); nonmetallic reinforcement; shear; ultra-high-performance concrete (UHPC)
This paper presents the behavior of glass fiber-reinforced polymer (GFRP)-reinforced ultra-high-performance concrete (UHPC) beams without shear stirrups. An experimental program is conducted to examine the implications of variable geometric, loading, and reinforcement configurations, particularly for the effective depth-to-height ratio (0.75 ≤ d/h ≤ 0.90), shear spandepth ratio (1.18 ≤ a/d ≤ 3.23), and GFRP reinforcement ratio (1.35% ≤ ρf ≤ 4.85%) of the beams. Also tested are UHPC cylinders and prisms under axial compression and three-point bending. The strength development of UHPC is remarkable during the first 3 days of casting, after which a gradual and asymptotic growth rate is associated because of saturated pores and the limited attractions of calcium-silicate-hydrate networks. Compared with the factors related to the placement of the GFRP reinforcing bars (d/h and ρf), the a/d is more influential in controlling the capacity and the postpeakdeformation of the beams by altering load-transfer mechanisms. The stress of a shear-compression zone is redistributed under arch action and results in supplementary cracks along the beam span. The horizontal splitting of UHPC at the reinforcing bar level caused by the dowel action of GFRP is dependent upon the reinforcement ratio. Analytical models are formulated, and design guidelines are recommended.