Document Type : Research Article
PhD Student, Department of Civil Engineering, Kharazmi University, Tehran, Iran
Ferdowsi University of Mashhad
The main purpose of this study investigated the effects of hybrid use of micro glass fiber (GF), micro polypropylene fiber (PF) and macro steel fiber (SF) on the flexural capacity, energy absorption, ultimate load carrying, failure mode and ductility behavior of lightweight aggregate concrete (LWC) beams reinforced with glass fiber reinforced polymers (GFRP) bars. A total of eight beams with a rectangular cross-section and 100 mm wide 200 mm deep 1500 mm long, were cast and tested up to failure under four-point bending. The correction factor (ϕ) calculated of compared with American design codes of ACI 440.1R-06 and ISIS design manual No. 3. The ϕ factor for beams made of hybrid PF, SF into the LWC mixes (PSLWC) and reinforced with 0.9 ρfb; where ρfb is the balanced reinforcement ratio of the GFRP bars is approximately 1.38 times to the ϕ factor for beams made of hybrid GF, PF into the LWC mixes (GPLWC) and hybrid GF, SF added into the LWC mixes (GSLWC) that reinforced with 0.9 ρfb. The results experimental showed the ultimate load carrying capacity increased 5% to 49%, with increasing reinforcement ratio from 0.9 ρfb to 1.4 ρfb. According to experimental observations, failure modes in the beams made of GPLWC, GSLWC and PSLWC also reinforced with 0.9 ρfb failure modes coincides with the failure modes ACI 440.1R-06. The results indicate that the use of GPLWC, GSLWC and PSLWC at beams reinforced with GFRP bars improves the flexural capacity, ultimate load carrying, energy absorption and ductility.