Experimental Study On Shear Behavior Of High Ductile Concrete Deep Beams

The High Ductile Concrete(referred to as HDC)is a kind of new structure material with high toughness,high crack resistance and high damage resistance,which has the characteristics of strain hardening and multi crack development under the action of tensile and shear loading.Due to the bridging effect by the fibers crossing the cracks at the shear plane,the HDC material can not only raise the shear strength,and can significantly improve the shear deformation capacity compared to the concrete material.Therefore,the deep beams made by HDC material relying on bridging effect by the fibers can not only improve the shear bearing capacity,and can improve the brittle shear failure characteristics of deep beams.This paper studied HDC double shear performance experiment research and HDC deep beam shear performance experimental study,the main research contents are as follows:(1)Through the double shear tests of 7 sets of specimens with size of 100 mm × 100 mm × 300 mm,the characteristics of shear failure mode and load-shear deformation curves are analyzed,peak strength and deformation at peak load of HDC specimens influenced by fiber volume fraction of fiber and compressive strength are studyed,and an evaluation method of shear toughness is proposed.(2)Based on Rotated Angle Softened Truss Model,the distribution of the random direction of the PVA fibers is equivalent to the distribution of reinforcements of the horizontal direction,the shear force transfer mechanism of HDC double shear specimens under shear load is analyzed and the shear strength calculation method of HDC double shear specimens based on Rotated Angle Softened Truss Model is established finally.(3)Through the shear tests of 8 sets of deep beams with the section size of 200mm×300mm,span to height ratio of 2,the characteristics of shear failure modes of RC deep beams and HDC deep beams are analyzed,the shear strength of HDC deep beams influenced by stirrup ratio and ratio of longitudinal reinforcement and the characteristics of load deformation curves are studyed.(4)Based on Softened Strut And Tie Model,the distribution of the random direction of the PVA fibers is equivalent to the distribution of reinforcements of the horizontal direction and vertical direction,the shear bearing capacity of HDC deep beams is analyzed and the shear strength calculation method of HDC deep beams based on Softened Strut And Tie Model is established finally.