Research And Application On The Support System Of Unilateral Formwork Of Basement

With the speeding up of urbanization in our country and urban available landincreasingly nervous, the situation of the foundation pit excavating along the basementwall edges have become common. Under the situation that there’s no templatesupporting working face out of the basement exterior wall’s boundary, only in the formof unilateral supporting system is available. The set-up materials of unilateralsupporting system mainly include two types: shape steel frame and steel tubular scaffoldwith couplers. This paper mainly studies steel tubular scaffold support system withcouplers belongs to the latter.Fasten-style tubular steel scaffolding has introduced into our country more than40years, for the sake of its erection convenient, the advantages of low cost, stronguniversality and applicability, has been widely used. There is no guidance orsuggestions in Chinese JGJ130-2011“Technical code for safety of steel tubularscaffold with couplers in construction”about unilateral template supporting systemwhich under lateral pressure. So this article aims to the steel tubular scaffold supportsystem with couplers as the research object, and hopes to provides reference andguidance significance for similar projects. This thesis mainly includes the followingaspects of content:①Summarizes many accidents templates support collapse in2013, and points outthat unreasonable calculation method, insufficient components management andinsufficient construction management are major causes of formwork supports systemcollapse accidents.②Compared the characteristics between unilateral and double-sided templatesupporting system, and the common forms of unilateral templates system aregraphically described. Put forward a more economic, flexible build-up scheme. Theforms of supporting system composition and structural measures are also described③Elaborated corresponding specification of our country, the United Kingdomand the United States about lateral pressure value calculation formula on the new siteconcrete; Critical force calculation formula of compressive bar of China, Britain andJapan are compared and summarized; Expounds and compares the articulated model,bent frame model and rigid frame model, and on the basis of other scholars’ research, discusses the calculation length expression of semi-rigid frame with lateral displacement. For the convenience of engineering utility, this paper introduces amulti-elastic bearing and multi-section continuous compressive bar calculation model,calculation method and the formula for critical force.④Based on a actual engineering background, using the finite element analysissoftware MIDAS/Gen to execute a three dimension finite element buckling analysis ofunilateral template support system. Determine the weak parts of this engineeringexample of the unilateral formwork supporting frame, and points out that the anchorsare the key point of construction should be strictly controlled as well.⑤Pointed out that the initial defects of components, erection of the initialconditions, and construction measures are the main factors influencing the bearingcapacity of unilateral template support system, and puts forward some correspondingsuggestions to the construction components selection and testing, concrete pouringmethod, and the strengthening of weak positions.