Papers by Keyword: Three-Point Bending Beam

Abstract: For the study of fracture characteristics of ultra-high performance cementitious composites(ECC),16 different sizes of three-point bending beams were made and ultimate load, ultimate deflection and crack mouth opening displacement ,the curve andcurve of ECC were contructed,with the method of fracture work recommendedby RILEM , the external work was respectively calculated by the curve ofand, which determined the fracture energy of ECC.Results show that two kinds of calculation result are roughly equal;The influence of size effect on fracture character was: fracture energy increased with the increasing of the crack-depth ratio, the fracture energy of concrete specimen is the maximum when the crack-depth ratio is 0.4 ; is proportional to the initial crack-depth of the specimen, but there is no relationship betweenand crack-depth ratio. This paper would have great significance for the study of fracture characteristics of ECC.

Abstract: Based on double-K fracture model, adopt three-point bending beam which has been recommended by RILEM, the fracture properties of three groups reinforced concrete beams were studied. Refer to the relevant literature, fracture parameters of reinforced concrete three-point bending beams are examined. Through the analysis of whole process of crack propagation of reinforced concrete three-point bending beams, the results show that the reinforcement ratios can't preventing the cracking effectively, but can increase the maximum loads, thus improving the relative toughness; the precritical crack propagation length relative values show a linearly increasing trend with the increase of reinforcement ratios; the initial fracture toughness is not affected by the reinforcement ratios, but the unstable toughness has little effects by the reinforcement ratios.

Abstract: This paper presents a damage constitutive model to characterize the softening behavior of asphalt mastic in the fracture process. The three-point bending asphalt mixture beams with different crack locations and aggregate distributions are modeled with the parameterization modeling method. It is found that there is good agreement between the predicted and experimental results. The effects of crack location and coarse aggregate distribution on the crack path are numerically evaluated, and damage distributions near the crack tip are analyzed. Some conclusions are given.

Abstract: Taking into account the initial damage and the accumulation of damage of concrete, Mazars damage model was modified. Based on the modified Mazars damage model, combined with finite element software ANSYS, the fracture failure process of the three-point bending notched beam of concrete was simulated. The initiation load P_ini and maximum load P_max of the three-point bending beam were determined with the damage criterion, and the full relation curve of the load P versus the loading point displacement Δ of the fracture failure process of the three-point bending beam was obtained. The results show that the method of numerical simulation of concrete fracture failure process is feasible, and based on the initiation load of the crack determined by numerical simulation, the initiation toughness of the beam can be easily calculated, and the problem of calculation of the initiation toughness caused by the initiation load can not be accurately determined in the actual experiment is resolved.

Abstract: As cement-based composite, concrete can be properly represented by three phases in microstructure: cement paste, aggregate as well as interfacial transition zone between them. As the matrix compositions of concrete, fracture properties of cement paste and mortar have great influence on fracture performance of concrete, and fracture energy is an important parameter for concrete non-linear fracture mechanics research. Therefore, three-point bending beams of cement paste and mortar with different sizes and strengths were tested. A complete load-deflection (P-δ) curve was directly obtained, and a fit was made for the tail of the P-δ curve using power and exponential function, respectively. And then the fitting results of the two function were compared. It was found that with the increase of specimen size the influence of tail curve on fracture energy is decrease，and considering the influence of tail curve, fracture energy of cement paste and mortar are size-independent. The discussion on the obtained results was made.

Abstract: For micro-fiber reinforced strain-hardening cementitious materials, in addition to the basic characteristics and mechanical properties of fiber and interfacial properties between fiber and matrix, mechanical properties of matrix such as strength and crack resistance are essential parameters for material design, too. Therefore, the fracture properties of cement paste and mortar which are two most basal cementitious materials were studied, using three-point bending beams of which strength and depth are varied. Complete load versus crack mouth opening displacement (P-CMOD) curve directly obtained, and double-K fracture parameters ini Ic K and un Ic K were subsequently determined. The initial cracking load Pini was determined using resistant strain gauges. The results show that an apparent stable crack propagation before unstable failure was observed both in cement paste and in mortar. For cement paste, due to the influence of shrinkage crack, the divergence of the unstable fracture toughness un Ic K is more evident than initial fracture toughness ini Ic K .