Study On Temperature Reinforcement For Plate And Wall

The action of temperature is one of main actions on the hydraulic concrete structures, so in most of the hydraulic concrete structures the temperature reinforcement must be provided. But all the present methods about temperature reinforcement have some disadvantage, so it is meaningful to make a study on temperature reinforcement.In this paper FEM, which is able to calculate the width of crack, is used to study the temperature reinforcement for two kinds of common hydraulic structures (the plates and the vertical walls restrained by the bedrock in the bottom).In the study of temperature reinforcement for plates, the model of FEM and the factors that influences the distribution and width of temperature cracks are firstly studied. It is indicated that, firstly calculating the width of temperature cracks, we should limit the length of the concrete element to about 100 millimeter and choose the depth of the bedrock at least 20 meter; secondly there is basically no crack in plate acted by yearly air temperature change, but when there is a sudden drop in temperature, some widest crack is possible to appear in a certain time; thirdly in the aspect of temperature drop, the longer the minimum temperature lasts, and the smaller the cooling rate is, the Larger the corresponding maximum crack width is, and the maximum temperature crack width is not necessary to increase with the increase of temperature drop. The widest crack is temporary in a sudden drop of temperature; with the increase of concrete reinforced bar, the maximum crack width reduces, and the amount of cracks increase; with the increase of the bottom plate's geometrical dimension, the maximum temperature crack width increases too; when increasing the thickness of covering layer, the widest crack increases at the surface of the bottom plate. Then, based on the results of a great deal of calculation, the relation curves and tables about the area of steel and the maximum width are givenIn the study of temperature reinforcement for walls, the interface for reinforcement arrangement and factors that influence the distribution of temperature crack in wall are analysed. It is discovered that, firstly it had better choose theinterface for reinforcement 0.3L; secondly, the distribution of the wall's temperature cracks is mainly controlled by the steel which is bellow the interface for reinforcement, and with the increase of steel, the width and depth of the widest crack decreases. The spacing of steel bars has more important effect on the cracks then the diameter of steel. The width and depth of the widest crack increase with the increase of the length of the wall. Then, based on a great deal of calculation, the relation curves and tables about the area of concrete reinforced bar and maximum crack width are given, which are about three walls whose lengths are 15m 20m and 24m respectively, in the action of the temperature drops of 12°CU 15°C and 18°C in 3 days.