Study On Lateral Pressure Of Freshly Poured Concrete Formwork Of Inclined Tower

Since the application of reinforced concrete in the construction field at the end of the 18 th century,the formwork side pressure of concrete has been a research hotspot in the engineering field.There are many factors affecting the lateral pressure of the formwork,and the influence mechanism is particularly complicated.The standards and specifications of different countries are similar empirical formulas,and the influencing factors considered are quite different,the applicable conditions are not the same,and the test data on which the specifications are based is older.Therefore,the applicability of the current formula for calculating side pressure of the template needs to be verified.At the same time,the research on the lateral pressure of the formwork is mainly focused on the vertical structure,and the side pressure of the inclined structure is equivalent to the side pressure of the vertical structure at the same height.This paper studies the influence of the inclination angle on the lateral pressure of the formwork through the theoretical analysis,numerical simulation,model experiment and real bridge experiment.The main research contents are as follows:(1)Analyze the various factors affecting the lateral pressure on the formwork in the formula for calculating the pressure on the lateral pressure in the national standards.The relationship between the lateral pressure of the vertical structure template and the lateral pressure of the inclined structure template is theoretically derived,and the two-dimensional finite element model with different inclination angles is established using the finite element software Fluent.The comparison of theoretical values with the results of finite element analysis verifies the feasibility of the current conclusions and provides theoretical support for the experiments.(2)In order to further study the influence of the inclination angle on the side pressure of the formwork,three test pieces of reinforced concrete inclined tower columns with inclination angles of 45°,60° and 75° were made.A real bridge experiment(inclination angle of 59°)of the Linzhou Yingbin Bridge to test the lateral pressure.The high-precision vibrating wire pressure box is used to test the concrete pouring process and the regularity of the side pressure and temperature of the formwork over time.(3)Analyze and study the experimental values from the distribution of the lateral pressure of the formwork,along with changes in height,the relationship between temperature and side pressure.And compare and analyze the calculated value of the current standard with the measured value to supplement the standard calculation formula.After that,the side pressure formula is modified.And based on the test results of the model test,a prediction model of lateral pressure is established.Studies have shown that: during the pouring of concrete,the lateral pressure of the formwork increases first and then decreases.After the pouring is completed,the lateral pressure of the formwork will continue to increase after a period of time due to the hydration heat reaction,and this peak is much larger than before.Later,due to the decrease in temperature and the effects of shrinkage and creep,the lateral pressure is reduced again.And the maximum lateral pressure did not appear at the bottom.The lateral pressure of the formwork of the inclined structure is much greater than that of the vertical structure.It cannot simply be equated with the lateral pressure of the formwork of the inclined structure.And as the tilt angle of the formwork increases,it increases first and then decreases.