Study On Design Method Of Horizontal Tube In High And Large Formwork Support System

Formwork construction is an essential part of concrete structure construction,and formwork support frame is an important design link to ensure the safety of formwork engineering.With the development of the construction industry and national economy,more and more high-rise and large-space buildings appear,leading to a significant increase in the action load and height of formwork supports,and the design and research of formwork supports need to be developed and improved accordingly.The high formwork support system has the characteristics of high erection height,large span and large load,which leads to its relatively poor stability.The horizontal tube in the formwork support system mainly acts as the constraint and lateral support of the upright tube.On the one hand,increasing the horizontal tube will increase the cost while lifting the stability of the frame;on the other hand,too few horizontal tubes will also lead to the increase of the lateral movement of the frame and decrease of the stability.Therefore,design horizontal tube reasonably is an important content concerning economy and safety.The analysis and study of the frame body found that the supporting action of the frame body horizontal rod is directly related to its position.The design of the frame body horizontal rod studied in this paper includes the value of lift height and the top treatment as well as the horizontal rod at bottom frame arrangement under different working conditions of the frame body.At present the setting of horizontal rod of frame is based on experience or normative conclusion,but these design method need further quantitative analysis and demonstration.The value of lift height has a great influence on the stability and economy of the support system of tall formwork.Too small lift height will inevitably increase the construction cost and affect the construction operation while increasing the overall stability;If the value is too large,the overall stability will be affected.The current specification does not give the setting method and number of the horizontal tube for the bottom of the frame body with uneven ground surface,which needs further analysis and research.At the same time,when the level difference under frame body is less than or greater than 1m,the construction method of bottom reinforcing tube and horizontal rod is analyzed and studied.In this paper,the semi-rigid node model of frame fastener is established,and the finite element analysis software ANSYS is used for calculation and analysis.First of all,the frame models with different heights were established for different situations of the upper horizontal bar setting,and the overall stability and lateral displacement of the tall formwork system were studied in depth.The optimal position and number of top horizontal bar strengthening are obtained through analysis.Then the finite element software ANSYS was used to establish the calculation model of the different lift height frame.Through the study,it was found that the step distance should be 1.2 meters,1.5m,1.8m,and the comprehensive analysis of the specific limited conditions concluded that the step distance should not exceed 1.8m.Then,the frame model of different working conditions at the bottom of the frame is established according to the feasible step distance,and the limit situation of the height difference at the bottom of the frame and strengthening measures are analyzed.Then the research results of the horizontal bar setting at the bottom are obtained and the conclusions and suggestions are given.