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.

　　溫度裂紋的主要特征是隨溫度的變化而擴展或閉合。引起溫度變化的主要因素是年溫差。在一年中，四季的溫度不斷變化，但變化相對緩慢。橋梁結構的影響主要是由橋梁的縱向位移引起的。一般可采用橋梁伸縮節(jié)、支護位移或柔性墩來協調結構措施。

　　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.

　　只有在結構位移有限的情況下，才會出現拱橋、剛構橋等溫度裂縫。的年溫差一般被認為是1月和7月的平均氣溫變化。考慮到混凝土的蠕變特性，在計算年溫差時應考慮混凝土的彈性模量。陽光。橋面、主梁或橋墩側暴露后的溫度明顯高于其他部位，溫度梯度呈非線性。

　　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.

　　由于自約束，局部拉應力較大，出現裂紋。陽光和突然冷卻是造成結構溫度裂縫的更常見原因。溫度突然下降。突然的傾盆大雨、冷空氣侵入和日落會導致結構的外表面溫度突然下降，但由于內部溫度變化相對緩慢，溫度梯度相對緩慢。在計算日照和突然冷卻的內力時，可采用設計準則或實際橋梁數據，不考慮混凝土的彈性模量。

　　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.