Concrete has the characteristics of thermal expansion and shrinkage. When the external environment or structure temperature changes, the concrete will deform. If the deformation is controlled, the structure will produce stress. When the stress exceeds the mixed tensile strength, temperature cracks will occur. In some long-span bridges, the thermal stress can reach or even exceed the live load stress.

　　温度裂纹的主要特征是随温度的变化而扩展或闭合。引起温度变化的主要因素是年温差。在一年中，四季的温度不断变化，但变化相对缓慢。桥梁结构的影响主要是由桥梁的纵向位移引起的。一般可采用桥梁伸缩节、支护位移或柔性墩来协调结构措施。

　　The main characteristic of temperature crack is to expand or close with the change of temperature. The main cause of temperature change is annual temperature difference. During the year, the temperature of the four seasons changes continuously, but the change is relatively slow. The influence of bridge structure is mainly caused by the longitudinal displacement of bridge. Generally, bridge expansion joint, support displacement or flexible pier can be used to coordinate structural measures.

　　只有在结构位移有限的情况下，才会出现拱桥、刚构桥等温度裂缝。的年温差一般被认为是1月和7月的平均气温变化。考虑到混凝土的蠕变特性，在计算年温差时应考虑混凝土的弹性模量。阳光。桥面、主梁或桥墩侧暴露后的温度明显高于其他部位，温度梯度呈非线性。

　　Only when the structural displacement is limited, temperature cracks such as arch bridge and rigid frame bridge will appear. The annual temperature difference in China is generally considered as the average temperature change in January and July. Considering the creep characteristics of concrete, the elastic modulus of concrete should be considered when calculating the annual temperature difference. Sunshine. The exposed temperature of bridge deck, main beam or pier side is significantly higher than that of other parts, and the temperature gradient is nonlinear.

　　由于自约束，局部拉应力较大，出现裂纹。阳光和突然冷却是造成结构温度裂缝的更常见原因。温度突然下降。突然的倾盆大雨、冷空气侵入和日落会导致结构的外表面温度突然下降，但由于内部温度变化相对缓慢，温度梯度相对缓慢。在计算日照和突然冷却的内力时，可采用设计准则或实际桥梁数据，不考虑混凝土的弹性模量。

　　Because of the self-restraint, the local tensile stress is large and cracks appear. Sunlight and sudden cooling are the most common causes of structural temperature cracks. The temperature suddenly dropped. The sudden downpour, cold air intrusion and sunset will cause the temperature of the external surface of the structure to drop suddenly, but the temperature gradient is relatively slow due to the relatively slow change of the internal temperature. When calculating the internal forces of sunshine and sudden cooling, the design criteria or actual bridge data can be used without considering the elastic modulus of concrete.