土木工程-外文翻译---混凝土的施工过程中温度与裂缝控制-建筑结构(编辑修改稿)

土木工程-外文翻译---混凝土的施工过程中温度与裂缝控制-建筑结构(编辑修改稿)内容摘要：

l the concrete is cooled until stability temperature from cement send out heat function basically when expiring, in this period, the temperature stress is mainly because the cooling of the concrete and external temperature change cause, these stresses and remnants stresses that is formed in early days are superposed , mix and congeal the elastic mould amount that goes to and does not change much during this period. (3)Later period: Operation period after the plete cooling of concrete. Temperature stress whether external temperature change cause mainly, these stresses and first two kinds of remnants stresseses are changed and added . Can be divided into two kinds according to the reason why the temperature stress causes: (1)Spontaneous stress: There are not any restraint or totally static structure at the border, if inside temperature is nonlinear distribution, temperature stress appearing 12 because structure restrains from each other. For example, the body of mound of the bridge, the physical dimension is relatively large, surface temperature is low when the concrete is cooled, inside temperature is high, present the stress of drawing on the surface, present the stress of pressing in the middle. (2)Restrain the stress: All of the structure ones or it restrain external one some border,can39。 t out of shape and stress not cause not free. Such as case roof beam roof concrete and guardrail concrete. This two kinds of temperature stresses draw back stresses caused to act on with the doing of concrete together frequently. It is a more plicated job to want to analyse the distribution , size of the temperature stress accurately according to known temperature. In case of great majority , need to rely on the model test or the number value to calculate. To is it make temperature stress have sizable limp to creep concrete, at the stress accounting temperature, must consider the influence that creep , calculate concretly that no longer states thinly here. Control and preventing the measure of the crack of 3 temperature For prevent crack , lighten temperature stress can from control temperature and is it is it set about to restrain terms from two to improve. The measure of controlling temperature is as follows: (1)Is it improve aggregate grade mix , is it do rigid concrete to spend , mix mixture to adopt, is it guide angry pharmaceutical or plastification pharmaceutical ,etc. measure in order to reduce cement consumption of concrete to add。 (2)Add water or the water to cool the broken stone in order to reduce the temperature of building of the concrete while mixing and shutting the concrete。 (3)Reduce the thickness of building while building the concrete on hot day, utilize and build the aspect to dispel the heat。 13 (4)Bury the water pipe underground in the concrete, enter the cold water to lower the temperature openly。 (5)Stipulate rational form removal time, the temperature keeps warm the surface while lowering suddenly, in case that the rapid temperature gradient takes place in the concrete surface。 (6)The concrete with medium and longterm and exposed construction builds a piece of surface or thin wall structure, take the measure of keeping warm in cold season。 The measure of improving condition of restraining is: (1)Divide and sew and divide one rationally。 (2)Prevent the foundation from rising and falling too big。 (3)Rational arrangement construction process, prevent the too big discrepancy in elevation and side from exposing for a long time。 In addition, improve the performance of the concrete and improve and resist the ability of splitting, strengthen maintenance , prevent the surface from being done and contracted , especially guarantee the quality of the concrete is very important to preventing the crack, should pay special attention to avoiding producing and running through the crack , the globality resumed its structure after appearing is very difficult, so should rely mainly on preventing the emergence of the running through crack while constructing. In construction of concrete , for raise turnover rate of template , demand concrete form removal as soon as possible that build newly often. Should consider form removal time properly when concrete temperature is higher than the temperature, so as not to cause the superficial early crack of concrete. Building the early form removal newly, cause very large stress of drawing on the surface, the phenomenon that temperature is assaulted appears. Build initial stage in concrete, 14 because heat of hydration is sent out, the surface causes sizable to draw the stress, surface temperature is also higher than temperature at this moment, remove the template at this moment , surface temperature is lowered suddenly, must cause temperature gradient , thus add and draw the stress on the surface , change and add with the heat of hydration stress, in addition, the concrete dries and co ntracts , the superficial stress of drawing reaches very great number value, have danger of causing the crack, but cover a lightduty heat insulator with on the surface in time after removing the template , for instance foam sponge ,etc., for prevent concrete surface from produce the too big stress of drawing, have remarkable results. Add muscle influence to large volume temperature stress of concrete very light , because large volume concrete include muscle to be rate very much low. Just have influence on the general armored concrete. On terms that temperature is not very high and the stress is less than limit of surrendering, every performance of the steel is steady, and have nothing to do with stress state , time and temperature. Line bloated coefficient of steel and concrete line bloated coefficient difference very light, take place little internal stress very only betwee。