【摘要】：膜結(jié)構(gòu)因其卓越的建筑表現(xiàn)力日益得到廣泛應(yīng)用,其安全性和耐久性也越來越多地得到人們的重視,它們受到膜材的物理、力學(xué)性能的直接影響。目前對于膜材的研究主要集中在膜材的強度指標(biāo)上,對膜材在實際膜結(jié)構(gòu)中的工作性能研究相對較少。膜結(jié)構(gòu)設(shè)計規(guī)范中采用安全系數(shù)法的目的在于滿足一般工程設(shè)計,安全系數(shù)中各個參數(shù)的影響與取值并不明確。此外,考慮到經(jīng)費及研究周期的局限性,對于膜材以及膜結(jié)構(gòu)的耐久性能的相關(guān)研究工作的開展并不充分。為了補充并完善膜材耐久性問題的研究,本文以建筑膜材PTFE、PVC為研究對象,開展了膜材蠕變理論研究、蠕變試驗、膜結(jié)構(gòu)受力分析及自然暴露試驗研究,建立了膜材的蠕變本構(gòu)模型,給出了環(huán)境影響因子隨時間變化的曲線和擬合公式,分析了考慮膜材蠕變的前提下膜結(jié)構(gòu)受力性能的影響因素及影響程度,得出了蠕變影響因子。最后,結(jié)合材料蠕變和耐候性能的研究,對膜結(jié)構(gòu)進行了考慮材料時變效應(yīng)的受力性能分析,為進一步膜結(jié)構(gòu)設(shè)計計算提供了理論基礎(chǔ)。本文的工作主要包含以下幾方面內(nèi)容:1、建筑膜材的蠕變本構(gòu)模型及蠕變試驗研究�；趶�(fù)合材料理論、蠕變力學(xué)及粘彈性力學(xué),首先對建筑膜材的蠕變特性和機理進行了探討,并介紹了三種類型的蠕變本構(gòu)模型;進而,結(jié)合PTFE建筑膜材蠕變試驗結(jié)果確定了膜材本構(gòu)模型中的相關(guān)參數(shù),通過對比分析,提出并建立了兩種膜材的蠕變本構(gòu)模型——改進的時間硬化模型,作為本文膜材及膜結(jié)構(gòu)蠕變分析計算的基礎(chǔ)。2、PTFE膜材寒地耐候性能研究。本文進行了在哈爾濱地區(qū)為期10年的膜材自然暴露試驗研究,通過對暴露1年、2年、4年和7年的膜材試樣的拉伸強度和撕裂強度進行逐年測試,基于試驗數(shù)據(jù),擬合出PTFE膜材環(huán)境影響因子的變化規(guī)律,以此對膜材力學(xué)性能進行預(yù)測,并為膜結(jié)構(gòu)設(shè)計選材提供了依據(jù)。3、考慮膜材蠕變的典型膜結(jié)構(gòu)受力性能研究�；谀げ牡娜渥冊囼灪捅緲�(gòu)模型,采用有限元分析軟件對兩類典型膜結(jié)構(gòu)——鞍形膜結(jié)構(gòu)和傘形膜結(jié)構(gòu)進行力學(xué)性能分析,探討了各個影響因素對膜結(jié)構(gòu)受力性能的影響;在此基礎(chǔ)上,對數(shù)值模擬結(jié)果進行統(tǒng)計分析,確定了兩種膜材考慮蠕變后其蠕變因子對結(jié)構(gòu)受力性能的影響程度及范圍,并針對其他膜結(jié)構(gòu)進行了蠕變因子范圍適用性的驗證。4、基于兩種膜材蠕變性能和耐候性能的研究,對膜結(jié)構(gòu)設(shè)計計算中膜結(jié)構(gòu)強度安全系數(shù)進行了探討。
[Abstract]:Membrane structures have been widely used because of their excellent architectural performance, and their safety and durability have been paid more and more attention. They are directly affected by the physical and mechanical properties of membrane materials. At present, the research of membrane material is mainly focused on the strength index of membrane material, and the research on the performance of membrane material in actual membrane structure is relatively few. The purpose of adopting the safety factor method in the design code of membrane structure is to satisfy the general engineering design, and the influence and value of each parameter in the safety factor is not clear. In addition, due to the limitation of funding and research cycle, the research work on the durability of membrane materials and structures is not sufficient. In order to supplement and perfect the research on the durability of membrane material, this paper studies the creep theory, creep test, stress analysis of membrane structure and natural exposure test with PTFE,PVC as the research object. The creep constitutive model of membrane material is established, the curve and fitting formula of environmental influence factor changing with time are given, and the influence factors and degree of membrane structure's mechanical properties under the premise of membrane material creep are analyzed, and the creep influence factors are obtained. Finally, combined with the study of creep and weathering properties of the membrane structure, the mechanical properties of the membrane structure considering the time-varying effect of the material are analyzed, which provides a theoretical basis for the further design and calculation of the membrane structure. The work of this paper mainly includes the following aspects: 1. Creep constitutive model of building membrane and creep test. Based on the theory of composite material, creep mechanics and viscoelastic mechanics, the creep characteristics and mechanism of building membrane are discussed, and three kinds of creep constitutive models are introduced. Then, according to the creep test results of PTFE building membrane, the related parameters of the constitutive model of membrane material are determined. Through comparative analysis, two kinds of creep constitutive model of membrane material, an improved time hardening model, is proposed and established. As the basis of creep analysis and calculation of membrane material and membrane structure in this paper. 2 study on weather resistance of PTFE membrane in cold region. In this paper, the natural exposure test of membrane materials was carried out in Harbin area for 10 years. The tensile strength and tear strength of membrane specimens exposed for 1, 2, 4 and 7 years were tested year by year, based on the experimental data. The variation law of environmental influence factors of PTFE membrane materials was fitted to predict the mechanical properties of membrane materials and provide a basis for the design and selection of membrane structures. 3. The mechanical properties of typical membrane structures considering membrane creep were studied. Based on the creep test and constitutive model of membrane material, the mechanical properties of two typical membrane structures, saddle membrane structure and umbrella membrane structure, were analyzed by finite element analysis software, and the effects of various factors on the mechanical properties of membrane structure were discussed. On this basis, the statistical analysis of the numerical simulation results is carried out, and the influence degree and range of creep factor of two kinds of membrane materials on the mechanical properties of the structure after considering creep are determined. The applicability of creep factor range for other membrane structures is verified. 4. Based on the study of creep and weathering properties of two kinds of membrane materials, the strength safety factor of membrane structure is discussed in the design and calculation of membrane structure.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU383

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本文編號：2422020