發(fā)布時(shí)間：2018-05-11 16:17

  本文選題：混凝土軸壓柱 + 升溫曲線��； 參考：《華中科技大學(xué)》2013年碩士論文

【摘要】：建筑火災(zāi)發(fā)生頻繁，從而帶來(lái)嚴(yán)重?fù)p失。由于混凝土結(jié)構(gòu)是廣泛使用的結(jié)構(gòu)形式，深入了解混凝土結(jié)構(gòu)構(gòu)件抗火性能對(duì)于防災(zāi)減災(zāi)具有重要意義。目前結(jié)構(gòu)抗火性能研究中大多數(shù)假定周?chē)鷾囟拳h(huán)境為標(biāo)準(zhǔn)升溫曲線形式，計(jì)算誤差偏大，也不夠合理。本文采用FDS消防軟件來(lái)模擬發(fā)生火災(zāi)時(shí)構(gòu)件表面的實(shí)際升溫曲線，以此作為結(jié)構(gòu)構(gòu)件溫度場(chǎng)有限元分析的邊界條件來(lái)計(jì)算構(gòu)件內(nèi)部的溫度場(chǎng)。在此基礎(chǔ)上，將火災(zāi)的高溫作用等效為荷載，研究考慮火災(zāi)高溫作用的統(tǒng)一結(jié)構(gòu)設(shè)計(jì)方法。 本文首先運(yùn)用FDS，模擬單室火災(zāi)發(fā)展過(guò)程，，得到環(huán)境升溫曲線；以實(shí)際升溫曲線為第三類(lèi)邊界條件并利用有限元分析軟件ANSYS計(jì)算構(gòu)件截面溫度場(chǎng)的分布，為等效火災(zāi)荷載的簡(jiǎn)化計(jì)算提供基礎(chǔ)；通過(guò)理論和數(shù)值分析，改進(jìn)了等效火災(zāi)荷載的簡(jiǎn)化計(jì)算方法，進(jìn)一步修正已有的計(jì)算公式，四面受火柱的算例分析表明運(yùn)用簡(jiǎn)化公式計(jì)算的結(jié)果精度符合工程要求。 本論文得到的主要結(jié)論如下：火災(zāi)發(fā)展過(guò)程中，室內(nèi)各點(diǎn)的溫度隨時(shí)間不斷升高，測(cè)點(diǎn)位置、開(kāi)口狀態(tài)、火源位置以及大小均會(huì)對(duì)實(shí)際的溫升曲線有影響。對(duì)結(jié)構(gòu)抗火性能設(shè)計(jì)中一律采用標(biāo)準(zhǔn)升溫曲線作為環(huán)境溫度不夠準(zhǔn)確。運(yùn)用ANSYS進(jìn)行結(jié)構(gòu)熱分析表明：混凝土是熱惰性材料，隨著時(shí)間的推移，截面內(nèi)同一等溫線不斷向內(nèi)部推進(jìn)。對(duì)截面削弱過(guò)多的500℃界限，本文采用兩臺(tái)階簡(jiǎn)化模型，以減少截面削弱過(guò)多結(jié)果過(guò)于保守的情形。計(jì)算結(jié)果表明，對(duì)于四面受火柱此種簡(jiǎn)化方法可以有效提高約10%的精度。
[Abstract]:Building fires occur frequently, resulting in serious losses. As concrete structures are widely used, it is very important to understand the fire resistance of concrete structural members for disaster prevention and mitigation. At present, most of the researches on the fire resistance of structures assume that the surrounding temperature environment is a standard heating curve, and the calculation error is too large and unreasonable. In this paper, FDS fire protection software is used to simulate the actual heating curve of the component surface in case of fire, which is used as the boundary condition for the finite element analysis of the temperature field of the structural member to calculate the temperature field inside the member. On this basis, the high temperature action of the fire is equivalent to the load, and the unified structure design method considering the fire high temperature is studied. In this paper, we first use FDS to simulate the development process of single chamber fire, and get the environmental heating curve, taking the actual heating curve as the third kind of boundary condition and using the finite element analysis software ANSYS to calculate the temperature field distribution of the section of the component. It provides the foundation for simplified calculation of equivalent fire load, improves the simplified calculation method of equivalent fire load through theoretical and numerical analysis, and further modifies the existing calculation formula. The analysis of fire column on four sides shows that the accuracy of the simplified formula is in line with the engineering requirements. The main conclusions obtained in this paper are as follows: during the development of fire, the temperature of each point in the room increases with time, and the location of the measuring point, the opening state, the location of the fire source and the size of the fire will affect the actual temperature rise curve. It is not accurate to use the standard temperature curve as the ambient temperature in the design of structure fire resistance. The structural thermal analysis with ANSYS shows that concrete is a thermal inert material, and the same isotherm in the section pushes forward to the inside with time. In this paper, a simplified two-step model is used to reduce the over-conservative results of section weakening by using a two-step simplified model for the 500 鈩

本文編號(hào)：1874671