本文選題：PEC柱　切入點(diǎn)：升降溫　出處：《蘇州科技大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：自然火災(zāi)包含升溫和降溫兩個(gè)階段,其中降溫段對結(jié)構(gòu)的耐火性能有很大影響。目前構(gòu)件的耐火極限大多基于標(biāo)準(zhǔn)升溫條件,與實(shí)際結(jié)構(gòu)經(jīng)歷火災(zāi)的過程存在一定差異。試驗(yàn)和分析表明PEC柱在降溫段也可能產(chǎn)生破壞。當(dāng)外界溫度場處于降溫階段時(shí),由于混凝土材料的熱惰性,導(dǎo)致結(jié)構(gòu)內(nèi)部溫度場較外部出現(xiàn)溫度滯后的現(xiàn)象,結(jié)構(gòu)內(nèi)部可能在繼續(xù)升溫,使得結(jié)構(gòu)在火災(zāi)降溫段的承載能力進(jìn)一步降低,最終可能導(dǎo)致結(jié)構(gòu)在降溫段發(fā)生破壞。為全面分析PEC柱在升降溫全過程的耐火性能,本文基于火災(zāi)全過程分析,重點(diǎn)對降溫段可能的破壞進(jìn)行了研究,主要的研究工作如下:(1)應(yīng)用ABAQUS軟件建立了考慮火災(zāi)升降溫全過程的局部填充混凝土(Partially Encased Concrete,簡稱PEC)柱耐火性能分析有限元模型,并采用已有的高溫下及高溫后柱的試驗(yàn)數(shù)據(jù)驗(yàn)證了模型的正確性。(2)考慮降溫段材料屬性較升溫段有所恢復(fù)的特點(diǎn),分別計(jì)算了鋼材和混凝土在升溫段和降溫段的材料屬性。(3)定義場變量,編寫能夠?qū)崿F(xiàn)材料不同溫度階段的材料屬性的自動(dòng)識(shí)別和轉(zhuǎn)換的子程序,實(shí)現(xiàn)升降溫全過程的計(jì)算過程。(4)定義并分析了自然火災(zāi)下的耐火性能指標(biāo)(duration of the heating phase,簡稱DHP),利用驗(yàn)證后的模型分析了PEC柱在全過程火災(zāi)下可能出現(xiàn)的延遲破壞現(xiàn)象。(5)分別考慮荷載比、截面尺寸、長細(xì)比、混凝土強(qiáng)度、截面配筋率等五個(gè)因素對PEC柱DHP值的影響:火災(zāi)荷載比和截面長細(xì)比對PEC柱的耐火性能影響較大;截面尺寸對DHP的影響變現(xiàn)為兩個(gè)過程:當(dāng)荷載比較小時(shí),DHP隨截面尺寸的增大而增大,當(dāng)荷載比較大時(shí),截面尺寸對DHP的影響變小,DHP不隨截面尺寸產(chǎn)生明顯的變化;混凝土強(qiáng)度和截面配筋率對耐火性能的影響不大。并以計(jì)算的數(shù)據(jù)為基礎(chǔ)擬合出包含這些因素的DHP實(shí)用計(jì)算公式。
[Abstract]:The natural fire includes two stages of heating and cooling, in which the cooling section has a great influence on the fire resistance of the structure. At present, the fire resistance limit of the components is mostly based on the standard heating conditions. The test and analysis show that the PEC column may also be damaged in the cooling section. When the external temperature field is in the cooling stage, due to the thermal inertia of the concrete material, As a result of the phenomenon that the temperature field inside the structure lags behind the external temperature field, the internal temperature field of the structure may continue to heat up, which further reduces the bearing capacity of the structure in the fire cooling section. In order to comprehensively analyze the fire resistance of PEC columns in the whole process of rising and cooling, based on the analysis of the whole process of fire, the possible damage of the cooling section is studied in this paper. The main research work is as follows: (1) using ABAQUS software, a finite element model for analyzing the fire resistance of partially filled Encased reinforced concrete columns considering the whole process of fire rising and cooling is established. The validity of the model is verified by the existing experimental data at high temperature and the post column at high temperature. The field variables are defined by calculating the material properties of steel and concrete in the heating and cooling stages, respectively, and a subroutine that can realize the automatic identification and conversion of the material properties at different temperature stages is written. This paper defines and analyzes the duration of the heating phase under natural fire, and analyzes the possible delay damage of PEC column under the whole process of fire by using the verified model. Take into account the load ratio, The influence of five factors, such as section size, aspect ratio, concrete strength and section reinforcement ratio, on the DHP value of PEC column is as follows: the fire load ratio and section length ratio have great influence on the fire resistance of PEC column; The effect of cross section size on DHP is realized in two processes: when the load ratio is small, it increases with the increase of cross section size, and when the load is large, the effect of section size on DHP does not change obviously with section size; The concrete strength and section reinforcement ratio have little effect on the fire resistance. Based on the calculated data, the practical DHP formula containing these factors is fitted.
【學(xué)位授予單位】：蘇州科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU398.9
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本文編號(hào)：1640404