| With the continuous improvement of my country’s grain production,more granaries need to be built to store grain.With the progress of grain trade,more modern large-diameter squat silos have been vigorously developed.However,the large-diameter squat silo has the characteristics of high height and large diameter,there is a certain danger in the construction of the silo roof.At present,most of the construction of the roof of the squat silos in China is to erect a full-scale scaffolding from the bottom as a support,or use a sliding mode to drag a rigid platform to slide the platform to the top of the silo as a support.Therefore,the research is mainly based on the rigid support platform,and the research on the flexible support platform is less.This paper researches on a flexible steel strand cable net support platform,the specific on-site construction method is as follows:after the construction of the silo wall is completed,tension of 24 steel strands on the top of the horizontal and vertical directions to make it a net support platform,both sides are fixed by"U"-shaped pull ring,then lay scaffolding on the top of the steel strand net to carry out subsequent roof construction.Compared with the traditional scaffolding built from the ground as a support,the steel strand net support does not need to set up the scaffolding from the ground,which saves a lot of steel pipe fasteners,saves costs,single warehouse saves 150,000 to 200,000 yuan.and also improves the construction progress,improves safety.Since the steel strand net support platform is a flexible platform,it will have a certain degree of downward deflection after receiving the upper load,so it is necessary to study the downward deflection of the net platform after being loaded,and increase the corresponding height of the upper scaffolding pole according to the amount of downward deflection to ensure the normal construction of the subsequent silo roof.After the site construction is completed,the degree of downward deflection data of the on-site steel strand net is recorded,and then ANSYS finite element simulation analysis is carried out for the same working conditions,and the simulation results are compared with the on-site data,it is found that the finite element simulation result is 18.8cm,the field measurement is about 20cm.The simulation result is slightly smaller than the field measurement.After that,the research on the steel strand net platform was extended,through the ANSYS finite element software,simulation strand nets with different spacing are under load,simulation loads of steel strand nets with different tensions,simulation different diameters of steel strand nets are subjected to different loads,analyze and summarize the down deflection of the steel strand net and the stress change of the silo under different working conditions,the specific research and conclusions are as follows:(1)For the steel strand nets with spacings of 0.6m～1.25m,respectively,simulate upper loads,and it is found that the support requirements can be met when the steel strand spacing is 1.25m.Reducing the spacing of steel strands can reduce the downward deflection of the steel strand net platform,and also can improve the silo stress state.(2)By simulating the upper load of steel strand nets with different pretensions(0～300k N),it is concluded that the pre-tension is 100k N～150k N more reasonable.At the same time,it is also concluded that with the continuous increase of the pre-tension of the steel strand,the stress of the silo and the rate of change of the stress are constantly increasing.(3)The steel strand nets with different strand diameters(24mm～34mm)are simulated by the upper loads,and it is concluded that the steel strand diameter of 30mm is a better steel strand diameter.It can be seen from the change of silo stress caused by the change of the diameter of the steel strand that the stress increment of the silo wall is about 0.060×10~7Pa for every 2mm increase in the diameter of the steel strand.(4)When the load of the steel strand net is only its own weight,the maximum downward deflection generated by the steel strand net platform is 5cm.After the steel strand net platform is subjected to all the loads of the steel bars,concrete,formwork,wooden slats,and scaffolding above,the final deflection is 18.8cm. |
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