Research On Construction Technology Of Formwork Support System For Super High Laminated Large Cantilever Structure

In recent years,the form of building structures are complex and diverse,the complex structure forms such as large span and large cantilever are also becoming more and more common.However,due to the imperfect restrictions on cantilevered formwork supports and other special formwork supports in the existing codes,lacking of uniform design standards and the experience in the stress state and construction points of the superhigh laminated cantilevered formwork support system.Therefore,the construction analysis and research of superhigh laminated cantilevered formwork support system has become the focus of the industry.This paper takes the super-high laminated cantilever structure of a health industrial park in Yantai as the background,through combining theoretical calculation,field measurement and finite element analysis,we studied the internal force distribution law of the formwork support system,the influence of the cantilever platform on the support system and the optimization analysis of the cantilever platform in the pouring and maintenance process of the roof layer cantilever structure.The research contents and results are as follows:(1)By summarizing the construction difficulties of superhigh laminated large cantilever structure,we proposed three construction scenarios.It is compared and analyzed from the aspects of safety,economy and environmental protection.Finally,the formwork support scheme of the cantilevered platform of the Bailey frame is determined as the best choice.(2)Using the standard method to check the single-layer cantilever structure formwork support frame,we obtained he theoretical calculation of the axial force of the bracket vertical rod,and used finite element software MIDAS/GEN to analyze the safety of the Berret cantilever platform.It shows that the safety of the arrangement of the ultra-high cantilevered formwork support system adopted in this paper meets the specification requirements.(3)The field measurement of the super high laminated cantilever support system was carried out,we can acquire the axial force,settlement of the support frame and vertical deformation of the cantilevered berley frame during the casting and maintenance of the roof layer cantilevered structure.Compared with the finite element simulation results,it verified the applicability of the finite element model and the feasibility of the analysis results.The main reason for the deviation between the simulation results and the measured data is that the finite element model fails to consider the influence of temperature,rainwater and temporary construction load during the construction process.(4)Using Midas/Gen to model and analyze the laminated cantilever support system under the most unfavorable working conditions,and analyzed the load distribution law of the cantilevered support frame of 12 floors and roof floors.By changing the position and number of the support points of the cantilever platform,we carried out the optimized analysis to it,Compared with the original design,the maximum axial force of the support frame is reduced by26.48%,and the load distribution is more uniform.