Multiaxial Intensity And Failure Criteria Of Concrete

This paper studies and discusses the multiaxial strength and failure criteria, including light-weight aggregate concrete and ordinary concrete. Concrete is materials widely used in engineering construction. For fully brought into play strength, improved design level and reduced the cost of project, a study of its mechanical properties has the extremely significance.The actual concrete structure is in obvious multi-axial stress state.At present, existing the criterion of concrete in complex stress intensity has the following characteristics. Firstly, the ultimate strength surface is smooth, continuous and convex. Secondly, if the concrete is isotropic before destructed, ultimate strength envelops in partial plane is symmetry with triple intensity, and in the strain state or smaller compressive state (equivalent to smallerξor static water stress value) it approximate for the triangle, withξincreasing more and more close to compares round. Thirdly, Stretching meridian and compressed meridian are the ringent and convex curve, both with the hydrostatic stress axis, which is only one point of intersection that is a point of equal tension in three axis.So far, the failure criterion is obvious disadvantages. The damage enveloping surface is ringent. With the hydrostatic pressure increases, the compressive strength has been rising, and intersection of stretching meridian and compressed meridian was discontinuous. These are not actual conditions. This paper suggests that in the three axis pressure under the hydrostatic pressure, concrete should also be able to succumb to its surface should be a closed, continuous, the surface of convex. Based on the suggestion for three axis hydrostatic pressure, concrete should also be able to destroy and its surface should be closed, continuously and convex.Compared with ordinary concrete, the research and application of lightweight aggregate concrete were relatively late. Because of its merit such as low density, high intensity, heat insulation and heat preservation, fireproof, the anti-seismic performance, lightweight aggregate concrete obtained fast development and widely applied in engineering field. Different from ordinary concrete failure surface only intersected tension side of surface hydrostatic stress, in the high stress area stretching meridian of lightweight aggregate concrete intersected compressed meridian, and ultimate strength surface was a closed space surface.Since concrete material is a kind of geotechnical engineering materials, both qualitative differences should not. The destruction of concrete has general properties of rock destruction and yield. So I can suggest for concrete failure criteria referencing geotechnical materials failure criteria. This paper will put forward egg-shaped failure surface of lightweight aggregate concrete, using for reference the yield and the failure criterion in allusion to geotechnical materials. And contrasted experiment data of lightweight aggregate concrete, the precision of the failure model is verified.