新型混杂纤维UHPC双向板弯曲韧性研究OA北大核心

To investigate the contribution of hybrid fibers to the bending performance of ultra-high performance con-crete(UHPC)slabs,bending tests were conducted on hybrid fiber-reinforced UHPC square slabs.Seven groups of square slab specimens(500 mm×500 mm×50 mm)were designed:one group containing only steel fibers(SF),two groups with SF mixed with macro-polyolefin fibers of two different large aspect ratios,two groups with SF mixed with macro-polyvinyl alcohol fibers of two different large aspect ratios,and two groups with SF mixed with macro-polyethylene(PET)fibers of two different large aspect ratios.The load-deflection curves,initial cracking loads,and peak loads of each group of specimens were measured,and the bending toughness indexes and energy dissipa-tion capacities were calculated and analyzed.The results indicated that the damage to the slabs progressed through three stages:elastic,strengthening,and softening.The deformation curves of the hybrid fiber-reinforced UHPC slabs exhibited notable hardening characteristics.Compared with slabs with only SF,the hybrid fiber-reinforced UHPC slabs demonstrated improved peak loads and bending toughness after cracking.In addition,mixing coarse synthetic fibers with larger aspect ratios enhanced the mechanical properties during the strengthening stage and sof-tening stages of the slabs.Especially,the postcrack toughness and energy dissipation capacity were significantly im-proved.Furthermore,the diameter of the PET fibers should not exceed 0.75 mm.