Experimental Analysis On Shear Performance Of Ultra High Toughness Cementitious Composites Members

The ultra high toughness cementitious composites (Often abbreviated UHTCC) is a new kind of composites reinforced by Polyvinyl alcohol fibers less than2%volume ratio. It greatly improves the toughness of the cement matrix material. The characteristics of this material is different from the previous fiber-reinforced materials by increasing the volume fraction of fiber. It’s a new type of composites which is based on the design of micro structure material. The characteristic of the composites has ultra high ductility, it’s stable tensile strain can reach3%under tensile load and can produce multiple fine cracks. The composite has strain-hardening characteristic on load.In efforts to study the mechanical properties of ultra high toughness cementitious composites, some specimens were tested to examine performances. The experimental research is based on "a kind of material, two kinds of elements, three emphases". The material is ultra high toughness cementitious composites; reinforced ultra high toughness cementitious composite beams and the coupling beams of ultra high toughness cementitious composite are tested. Combined with the application of new materials, the main work of this paper includes the following three aspects:1The basic mechanical properties of ultrahigh toughness cementitious composites are investigated by uniaxial tensile and compression test. Based on tests, the optimal compounding method which can reduce the mixing time, make fiber dispersed uniformly and get better flow ability can be acquired. Complete stress-strain curves of uniaxial compressive test and tensile test of the ultra high toughness cementitious composite materials are obtained. The material constitutive equation on the ultra high toughness cementitious composite provides reference for further theoretical analysis and numerical simulation.2Based on the test results of9ultrahigh toughness cementitious composite materials beams and a reinforced concrete beam, At the same time the shear bearing capacity of the modified compression field theory is analyzed. According to the effects of stirrup ratio, reinforcement ratio and the shear span ratio, shear strength of beams are investigated and compared quantitatively. Secondly the shear deformation characteristics and ductility on the beams of ultrahigh toughness cementitious composite are analyzed. Finally the failure mode, the load-displacement curve, the diagonal crack widths and ductility are analyzed in different influence factor.3On the basis of experimental ultra high toughness cementitious composites coupling beams and concrete coupling beams, the failure mode, load-displacement response, strains of reinforced bar and shear distortion of coupling beams subjected to cyclic load or static load are investigated in detail. Test results reveal that the ultra high toughness cementitious composites coupling beams have excellent performance. The ultra-high toughness of cement-based composite materials with beam skeleton curve, ductility, stiffness degradation and energy dissipation are analyzed. Finally the recommended formula of ultrahigh toughness cementations composite coupling beams are proposed by the statistical analysis of test results. After a comprehensive analysis on the effects of the ultra high toughness cementitious composites on failure mode, ductility, energy dissipation, capacity and shear resistance capacity of coupling beams. Some suggestions for shear design of ultra high toughness cementitious composites coupling beams are proposed. At the same time, the specimens are calculated by the theory and the results were compared and analyzed. Finally the finite element analysis is applied on the some specimens. The bearing capacity and reinforcement strain are analyzed.Research shows that ultra high toughness cementitious composite material has superior toughness performance and the ultra high toughness cementitious composite members have excellent ductility and energy dissipation. The ultra high toughness cementitious composite material can be applied in practical engineering.