Study On Mechanics' Performance Of The Concrete In Low Temperature

The mechanical property of the concrete has always been a critical problem in the academic fields. However, the strength and deformation are most important property among all the mechanical capabilities of the concrete. With the rapid development of the winter construction, the mechanical performance under low temperature comes to draw people's attentions for it has close relationship with the practical load and safety status of the structure under the low temperature.. During the decades, scholars in China and aboard have carried out comparatively systematic and elaborate study on all the mechanical performance of the concrete and its structure under normal temperature and point out failure Criterion and constitutive models in the different conditions, they have acquired great achievements and applied it in the engineering practice. But people still don't master the mechanical property of the concrete comprehensively for the complex conditions, especially, in the low temperature, the mechanical capability , change of tensile and compression strength, elasticity module, the development law of poison ratio, the differential of all the mechanical indexes. To solve those issues, this article makes a full discussion about the strength and changing law of the concrete in the low temperature after carrying out a strict experiment on the mechanical property of the concrete. It provides a reference to the practical design.The following is the major research work and results:1. Analyzing the relation between the strength and deformation of concrete and all constitutive relations given by the vanguard specialists. Making a detail discussion on the strength guideline of the concrete and damage mode of the concrete of the in the conditions of different loads.2.This article focuses on the influence upon the strength and deformation of the concrete in the low temperature. Making use of the transformed pressure test machine and low-temperature refrigerator, 16 groups, 3 per group, uniaxial tensile experiments are carried out. It educed tensile , compression-strain curves of concrete, tensile strength-caring age curves of concrete and compressive strength-caring age curves of concrete.S.Throuth the thorough analysis, we can get the changing laws of the strength parameter with the variety of temperature and the temperature influence upon the elasticity module. The tensile and compression -strain curves, in the low temperatureconditions, are similar to the ones in the normal temperature. All kinds of physical and mechanical properties don't change the original constitutive relation.4. Generally, we don't have to consider the temperature influence upon the concrete performance. But during the caring age , if the concrete don't experience the low temperature action of frost-resisting critical strength, its strength will decrease. The experiment also shows that after the concrete strength reach the frost-resisting critical strength, its strength and elasticity module will increase slowly with the decrease of the temperature. Only when the concrete strength comes to the peak value, the strain will reduce with the decrease of the temperature. The shape of stress-strain curves will become high and narrow with the decrease of the temperature. The descending part of the curves are much sharper than the ones under the normal temperature. The ductility of the concrete will also get worse and the brittleness will increase.