高延性混凝土无腹筋梁受剪性能试验研究

提出采用高延性混凝土改善梁的抗剪性能和变形能力，设计了8个高延性混凝土梁和3个作为对比试件的混凝土梁，并通过静力试验研究不同剪跨比和配筋率高延性混凝土无腹筋梁的破坏形态和破坏机理。高延性混凝土无腹筋梁的剪切破坏形态有挤压破坏、剪压破坏、弯剪破坏和剪拉破坏。试验结果表明:高延性混凝土梁的剪切破坏均表现出一定的延性，与普通混凝土梁的脆性剪切破坏具有明显不同；高延性混凝土梁的剪切裂缝开展缓慢，说明高延性混凝土良好的拉伸应变硬化和多裂缝开展特性能够有效控制剪切裂缝的发展，防止混凝土压碎剥落，显著提高梁的抗剪性能和耐损伤能力；相比普通混凝土无腹筋梁，高延性混凝土无腹筋梁的受剪承载力和变形能力均有明显提高，表明采用高延性混凝土可以显著改善无腹筋梁的脆性剪切破坏模式；剪跨比和纵筋配筋率对高延性混凝土梁的剪切破坏形态和承载力影响较大，其受剪承载力随剪跨比的增大而降低，随配筋率的增大而有所提高。

EXPERIMENTAL STUDY ON THE SHEAR BEHAVIOR OF HIGH DUCTILE FIBER REINFORCED CONCRETE BEAMS WITHOUT STIRRUPS

In order to improve the shear behavior and deformability of the beams without stirrups, 8 high ductile fiber reinforced concrete (HDC) beams were designed, and 3 reinforced concrete (RC) beams were designed for comparison. The failure mechanism and mode of beams on different shear span ratios and longitudinal reinforcement ratios were studied by static loading tests. The shear failure modes of HDC beams without stirrups are extrusion failure, shear-compression failure, bending-shear failure, and shear-tension failure. The research shows that: all of HDC beams have shown ductility to some extent, which were clearly different from the shear failure mode of RC beams without stirrups; the tensile strain hardening and multiple cracking of HDC can effectively control the development of shear cracks of HDC beams during the failure process, prevent from the crushing and spalling of concrete, and significantly improve the shear capacity and damage resistance ability of HDC beams; comparing with RC beams, the shear capacity and deformability of HDC beams has been enhanced notably, which suggests that the brittle shear failure mode of beams without stirrups can be obviously improved; both the shear span ratio and longitudinal reinforcement ratio have great influences on the failure form and bearing capacity of HDC beams without stirrups. And the shear bearing capacity will be reduced when the shear span ratio is increased, and will be increased with the increase of longitudinal reinforcement ratio.