Research On Construction Technology Of Formwork Support System For Cone Silo Structure

Restricted by variable section,higher degree of mechanization technique,such as slip-form construction technique is not suitable for conical concrete silo template.Generally,square support frame structure system is adopted,leads to the underutilization of the circular structure characteristics of the conical silo.In addition,many types of steel tube length are required in the square support system,which cause more difficulties in the construction.In this article,according to the structural characteristics of conical silos,annular support frame structure system is proposed.And in the light of the plane characteristics of conical silo,circumferential and radial diagonal bracing is proposed.Then,by means of theoretical analysis and calculation and ANSYS finite element analysis,both the advantage and deficiency of the annular frame were researched and analyzed.After that,the annular system was applied to practical engineering cases.This annular frame system not only enriches and improves the design and construction method of concrete silo formwork support system,but also has certain reference value for other concrete projects with similar cone structure characteristics in the future.The main contents are as follows:1.This paper reviews the main types,construction techniques and concrete pouring methods of concrete silos,and probes into the main construction techniques of conical concrete silos.The recent silo engineering accident cases and the research status at home and abroad are reviewed in this paper.This paper also analyzes the causes of the accident,and expounds the research significance and content of the annular support system of conical concrete silos.2.The research models of square support frame structure system and annular support frame structure system of conical silo formwork are constructed.The advantages of annular support frame over square support frame are studied by theoretical analysis and ANSYS finite element simulation analysis:(1)The vertical rod length type required for erecting the annular support frame of the conical concrete silo is less than 1/2 of that required by the square support frame,the horizontal rod length type required is less than 3/1 of that of the square support frame.So the annular support frame body has fewer length types,thus being more beneficial to construction.(2)In the case of the same number of rods,the same distance between vertical rods,the same step distance between horizontal rods and the same load in both square and annular support frame.By uniformly arranging more vertical rods in the outer ring of the frame body,the annular frame can effectively reduce the maximum stress of any single vertical rod in the outermost ring of the conical section frame body.And it can also reduce the horizontal displacement of the frame body、the settlement value of the vertical rods in the outer ring and the overall structure.Thereby improving both the carrying capacity and the stability of the frame body.3.Taking a cone-shaped concrete silo project as an example,on the basis of fully analyzing the engineering construction difficulties such as the engineering structural form and load situation:(1)The silo is divided into eight construction sections for layered and step-by-step construction,so that the completed part is used as the support of the upper structure frame body.In this way,the height of the frame body erection is reduced,and the construction safety is improved.(2)According to the structural characteristics of the project,the annular support frame structure system and radial bracing arrangement combining radial and circumferential direction are adopted in the construction of the conical silo formwork,and the concrete scheme of formwork frame body in each construction section is given.4.Taking the 500 mm thick inclined wall plate at the representative central cone part of silo engineering as an example,the standard method and ANSYS finite element simulation method are respectively adopted to check the annular support frame body.It is found that the standard method is conservative in calculation,which is about 8% higher than the finite element analysis result,but the deviation is not large.The model simplification of the annular support frame structure system of the conical concrete silo template by the standard method in this project is relatively reasonable.5.By means of field monitoring of the conical silo 500 mm thick inclined,the subsidence and horizontal displacement of the statistics were done through level and total station.Then,based on the analysis of monitoring data of 6 monitoring points,the main influence factors in the process of concrete construction were studied and the rationality of the annular support frame structure system of this case was proved.