【正文】 erature changes have influence on stress state of structure which cannot be ignored. Since temperature crack caused in the construction is mainly met , the causes of cracks and Processing measures in the construction is explored in this paper. causes of the cracks Cracks in concrete are a variety of reasons, mainly temperature and humidity changes, brittle and uneven concrete, as well as the structure is irrational, failure of raw materials (such as alkaliaggregate reaction), template deformation, and so on the basis of differential settlement. The concrete to harden off a large number of cement during the hydration heat, the internal temperature rising on the surface caused by tensile stress. Late in the cooling process, due to coagulation on the basis of or be bound by the old, will emerge in the concrete tensile stress. Lower temperatures in the concrete surface will be a lot of tensile stress. When the tensile stress beyond the capacity of concrete crack, the cracks will appear. A number of concrete changes in the internal humidity or changes very little slow, but possible changes in surface humidity or more dramatic changes. Such as conservation, failed to keep dry when wet, surface shrinkage deformation of concrete subject to internal constraints, but also often leads to cracks. Shortterm loading at the time of ultimate tensile deformation only ( ~ ) 104, the limit of longterm loading spaces when the only stretch deformation ( ~ ) 104. Unevenly as a result of raw materials, watercement ratio of instability, and transportation and pouring in the process of segregation phenomena, in the same piece of concrete in the tensile strength is uneven, there are many low tensile capacity, easy to fracture in a weak position. In reinforced concrete, the tensile stress is mainly borne 第 107 頁 by the steel, concrete is subject to pressive stress. In plain concrete or reinforced coagulation on the edge of the site if the structure of the tensile stress appears to be relying on its own concrete mitment. 2. thermal stress analysis According to the formation of thermal stress can be divided into the following three stages: (1) early: Since the beginning of pouring concrete to cement the end of exothermic basic general about 30 days. Two characteristics of this stage, first, to release a large number of cement hydration heat, and the other is the elastic modulus of coagulation dramatic changes. Modulus of elasticity as a result of changes within this period in the formation of residual stress in the concrete. (2) mediumterm: from the basic role of cement heat until the end of the stable temperature of the concrete cooling time, during this period, the temperature stress was mainly due to cooling and the outside concrete caused by temperature changes, stress and early formation of these residual stress superposition phase, during which the coagulation of the elastic modulus changed little. (3) late: concrete pletely cooling period after the operation. Thermal stress is mainly caused by external temperature changes, the stress and the first twophase superposition of residual stress. Under the thermal stress caused by the reasons can be divided into two categories: (1) selfstress: there is no constraint on the border or pletely static structure, if the internal temperature distribution is nonlinear, due to structural constraints arising from their cotemperature stress. For example, the conversion layer of its relatively larger size, concrete cooling surface temperature low, the internal temperatures are high, the surface tensile stress, pressive stress appears in the middle. (2) bound by stress: the structure of all or part of the boundary bound by the outside world can not