本文選題：扣件式高大模板支架 + 初始缺陷�。� 參考：《重慶大學(xué)》2014年碩士論文

【摘要】：扣件式鋼管是目前我國建筑業(yè)大跨度、高空間模板施工中通用的支架結(jié)構(gòu)，雖然針對(duì)扣件節(jié)點(diǎn)剛度、搭設(shè)參數(shù)對(duì)架體極限承載力的影響進(jìn)行了深入研究，但近年仍發(fā)生了大量的模板坍塌事故，表明當(dāng)前的研究還不能滿足實(shí)際工程的需要。本文選取模板支撐架體初始缺陷對(duì)架體承載能力的影響為研究對(duì)象，對(duì)架體中存在的各種缺陷進(jìn)行詳細(xì)分類，采用有限元模擬計(jì)算手段分析各種初始缺陷對(duì)架體極限承載力的影響程度，并對(duì)現(xiàn)有的三種初始幾何缺陷計(jì)算方法進(jìn)行對(duì)比分析，最后利用ANSYS和MATLAB GUI功能編制初始幾何缺陷的計(jì)算軟件，，為施工現(xiàn)場(chǎng)考慮初始缺陷對(duì)扣件式鋼管支架結(jié)構(gòu)的影響提供技術(shù)手段。 論文的主要研究內(nèi)容和研究結(jié)論包括： ①將扣件式模板支撐體系中存在的初始缺陷按力學(xué)缺陷、材料缺陷、搭設(shè)參數(shù)偏差和初始幾何缺陷進(jìn)行分類。建立了典型模板支撐架體有限元模型，通過ANSYS分析的結(jié)果表明，力學(xué)缺陷中半剛性節(jié)點(diǎn)由鉸接變化為完全剛性連接時(shí)，架體極限承載力值提高了約5.68倍；材料缺陷中鋼管壁厚由3.96mm降低至3.24mm時(shí)，架體極限承載力值降低6.66%左右；初始幾何缺陷值由5mm增加至20mm時(shí)，架體極限承載力值將降低15.32%；因此，架體的極限承載力值對(duì)力學(xué)缺陷、材料缺陷和幾何初始缺陷均較為敏感。 ②因扣件式節(jié)點(diǎn)半剛性力學(xué)性能及其在整體架體中的作用已進(jìn)行了較為深入的理論和試驗(yàn)研究，故采用在有限元模型中直接納入半剛性節(jié)點(diǎn)的方法來考慮實(shí)際模板架體的力學(xué)缺陷，并給出了相應(yīng)的有限元建模方法和參數(shù)取值。 ③通過材料缺陷和幾何參數(shù)偏差對(duì)架體極限承載力值的概率分析表明，在鋼管壁厚、外半徑等材料缺陷以及立桿步距等搭設(shè)參數(shù)偏差中，鋼管壁厚的影響最為顯著，所以采用對(duì)規(guī)范中承載力驗(yàn)算公式加入修正參數(shù)的方式考慮其不利影響，修正參數(shù)的取值按施工現(xiàn)場(chǎng)壁厚的實(shí)測(cè)數(shù)據(jù)確定； ④針對(duì)直接缺陷分析法、一致缺陷（特征）模態(tài)法和假想水平力法這三種初始幾何缺陷計(jì)算方法，對(duì)比其在不同因素（節(jié)點(diǎn)半剛性值、立桿步距等）作用下模板支撐體系極限承載能力的差別及變化規(guī)律，^w以規(guī)范規(guī)定的最大允許偏差為標(biāo)準(zhǔn)，確定了三種計(jì)算方法中的等效初始缺陷參數(shù)的設(shè)置。將三種計(jì)算方法得到的結(jié)果進(jìn)行了對(duì)比分析，表明三種計(jì)算方法考慮初始幾何缺陷后得到的架體極限承載力值比較一致，差別不大，能滿足工程精度要求。 ⑤基于ANSYS的參數(shù)化建模技術(shù)和MATLAB GUI功能編制了考慮扣件式高大模板支架初始缺陷的計(jì)算軟件，為施工現(xiàn)場(chǎng)管理人員準(zhǔn)確計(jì)算其極限承載能力提供了技術(shù)手段。
[Abstract]:Fastened steel pipe is a common support structure in the construction of large span and high space formwork in our country at present. Although the influence of fastener joint stiffness and setting up parameters on the ultimate bearing capacity of frame is deeply studied. However, a large number of formwork collapses still occur in recent years, which indicates that the current research can not meet the needs of practical engineering. In this paper, the influence of the initial defects of the formwork supporting frame on the bearing capacity of the frame is selected as the research object, and the various defects in the frame are classified in detail. The influence of various initial defects on the ultimate bearing capacity of the frame is analyzed by means of finite element simulation, and the three existing calculation methods of initial geometric defects are compared and analyzed. Finally, the calculation software of initial geometric defects is compiled by using ANSYS and MATLAB GUI functions, which provides a technical means for considering the effect of initial defects on fastener steel pipe support structure in construction site. The main contents and conclusions of this paper are as follows: The main contents are as follows: 1. The initial defects in the fastener formwork bracing system are classified according to mechanical defects, material defects, setting parameter deviations and initial geometric defects. The finite element model of the typical formwork bracing frame is established. The results of ANSYS analysis show that the ultimate bearing capacity of the frame is increased by about 5.68 times when the semi-rigid joints are changed from hinged joints to complete rigid connections. When the wall thickness of steel tube decreases from 3.96mm to 3.24mm, the ultimate bearing capacity of frame decreases by about 6.66%, and when the initial geometric defect value increases from 5mm to 20mm, the ultimate bearing capacity of frame decreases 15.32. Therefore, the ultimate bearing capacity of frame is related to mechanical defects. Both material defects and geometric initial defects are sensitive. (2) the mechanical properties of fastener joints and their role in the integral frame have been studied theoretically and experimentally. Therefore, the semi-rigid joints are directly incorporated into the finite element model to consider the mechanical defects of the actual formwork frame, and the corresponding finite element modeling method and parameter selection are given. Through the probability analysis of material defect and geometric parameter deviation to the ultimate bearing capacity value of frame body, it is shown that the influence of steel tube wall thickness is the most significant among the material defects such as steel tube wall thickness, outer radius and the setting up parameter deviation such as step distance of vertical pole. So the unfavorable effect is considered by adding the modified parameters to the calculation formula of bearing capacity in the code, and the value of the revised parameters is determined according to the measured data of the wall thickness in the construction site. (4) for the three initial geometric defect calculation methods, the direct defect analysis method, the uniform defect (characteristic) modal method and the imaginary horizontal force method, the different factors (node semi-rigid value) are compared. According to the maximum allowable deviation stipulated in the code, the setting of equivalent initial defect parameters in the three calculation methods is determined according to the difference and variation law of ultimate load-bearing capacity of formwork bracing system under the action of standing bar walking distance etc. The results obtained by the three calculation methods are compared and analyzed. It is shown that the ultimate bearing capacity of the frame obtained by the three calculation methods after considering the initial geometric defects is consistent and has little difference, and can meet the requirements of engineering precision. 5. Based on the parameterized modeling technology of ANSYS and the function of MATLAB GUI, the calculation software considering the initial defects of fastener type high formwork support is developed, which provides a technical means for the construction site managers to accurately calculate their ultimate bearing capacity.
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TU755.2

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