【摘要】：混凝土預制構(gòu)件生產(chǎn)周期內(nèi)經(jīng)常會出現(xiàn)裂縫問題,這是一個比較普遍的現(xiàn)象,也是長期困擾工程技術(shù)人員的技術(shù)難題。本文以一實際工程為背景,從溫度變形、收縮變形、約束以及混凝土早期受拉徐變四個方面,探究混凝土拱肋立式預制施工期溫度及收縮裂縫形成原因,并由預制形式的相似性,延伸到混凝土T梁和混凝土小箱梁施工期裂縫問題的研究。在此基礎(chǔ)上,結(jié)合混凝土結(jié)構(gòu)特點提出預制構(gòu)件施工期裂縫控制措施,以滿足工程應用需要。本文主要研究內(nèi)容如下：(1)混凝土構(gòu)件立式預制施工期溫度應力研究闡述混凝土溫度變形裂縫產(chǎn)生的一般機理,給出溫度問題基本方程,根據(jù)平底模立式預制構(gòu)件溫度應力計算公式推導出弧形底模立式預制構(gòu)件溫度應力計算公式,并探討與溫度應力計算相關(guān)參數(shù)的選取。(2)混凝土構(gòu)件立式預制施工期收縮及徐變效應研究闡述混凝土收縮裂縫產(chǎn)生的一般機理,總結(jié)收縮主要形式以及收縮常用的計算模式,并總結(jié)了早期受拉徐變方面相關(guān)研究,給出混凝土早期受拉徐變一般計算方法。(3)背景工程分析結(jié)合現(xiàn)場施工調(diào)查情況以及拱肋裂縫特點,從溫度、收縮、外約束以及施工過程四個方面對立式預制混凝土拱肋裂縫問題進行分析,根據(jù)初步分析的結(jié)果,對拱肋裂縫問題進行驗算。根據(jù)立式預制混凝土拱肋溫度應力計算公式,求得溫度及收縮應力理論值；根據(jù)拱肋早期自約束應力計算公式以及外約束應力計算公式,求得拱肋早期溫度應力。(4)混凝土拱肋立式預制施工期溫度及收縮應力有限元模擬總結(jié)混凝土結(jié)構(gòu)溫度及收縮應力有限元模擬的一般方法,結(jié)合背景工程,通過有限元軟件模擬混凝土拱肋的早期溫度場、混凝土拱肋的早期溫度應力以及混凝土拱肋的溫度及收縮應力,并將模擬結(jié)果與理論計算值進行對比分析。(5)混凝土構(gòu)件立式預制施工期裂縫控制研究從混凝土構(gòu)件預制形式、底模約束以及溫度作用三個方面進行了立式預制構(gòu)件施工期裂縫影響研究,分析了各個因素的影響程度,并提出了相應的施工建議。
[Abstract]:Cracks often occur in the production cycle of concrete prefabricated components, which is a relatively common phenomenon and a technical problem that has plagued engineers and technicians for a long time. Taking a practical project as the background, this paper probes into the reasons for the temperature and shrinkage cracks of concrete arch rib during the construction period from four aspects: temperature deformation, shrinkage deformation, restraint and early tensile creep of concrete. From the similarity of prefabricated form, it extends to the crack problem of concrete T-beam and concrete box girder during the construction period. On this basis, combined with the characteristics of concrete structure, the crack control measures of prefabricated members during construction period are put forward to meet the needs of engineering application. The main contents of this paper are as follows: (1) the temperature stress of concrete members during vertical precast construction is studied. The general mechanism of temperature deformation cracks in concrete is expounded, and the basic equation of temperature problem is given. According to the calculation formula of temperature stress of vertical prefabricated member with flat bottom die, the formula of calculating temperature stress of vertical prefabricated member with arc bottom die is derived. The selection of parameters related to the calculation of temperature stress is discussed. (2) the shrinkage and creep effect of concrete members during vertical prefabrication is studied and the general mechanism of concrete shrinkage cracks is discussed. This paper summarizes the main forms of shrinkage and the commonly used calculation models of shrinkage, and summarizes the related studies on early tension-creep. The general calculation method of early tensile creep of concrete is given. (3) the background engineering analysis combined with the on-site construction investigation and the characteristics of arch rib cracks, from the temperature, shrinkage, Four aspects of external restraint and construction process of precast concrete arch ribbed cracks are analyzed. According to the results of preliminary analysis, the arch rib cracks are checked and calculated. According to the formula of temperature stress of vertical precast concrete arch rib, the theoretical values of temperature and shrinkage stress are obtained. According to the calculation formula of early self-restraint stress and external constraint stress of arch rib, The temperature and shrinkage stress of concrete arch rib during the prefabrication period are obtained. (4) the finite element simulation of temperature and shrinkage stress of concrete arch rib during the prefabricated construction period is summarized. The general method of finite element simulation of temperature and shrinkage stress of concrete structure is summarized and combined with the background engineering. The early temperature field of concrete arch rib, the early temperature stress of concrete arch rib and the temperature and shrinkage stress of concrete arch rib are simulated by finite element software. The results of simulation and theoretical calculation are compared and analyzed. (5) the crack control of concrete members during vertical precast construction is studied from the precast form of concrete members. In this paper, the influence of vertical prefabricated members on crack during construction is studied from three aspects: bottom formwork constraint and temperature action. The influence degree of each factor is analyzed, and corresponding construction suggestions are put forward.
【學位授予單位】：東南大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U445.57

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本文編號：2374843