發(fā)布時(shí)間：2018-02-13 04:03

  本文關(guān)鍵詞： 鋼纖維混凝土 防火涂料 高溫 力學(xué)性能 有限元模擬 SEM　出處：《湖南大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著社會(huì)經(jīng)濟(jì)的高速發(fā)展和城市化步伐的加快,都市變得高樓林立,人口開始過度集中,意外導(dǎo)致的火災(zāi)引起建筑物破壞和人員傷亡的現(xiàn)象時(shí)有發(fā)生。人們?yōu)榱朔乐够馂?zāi)隱患,通常會(huì)在公共建筑、隧道建筑等表面涂刷一層混凝土防火涂料。而設(shè)置有防火涂層和無防火涂層混凝土構(gòu)件高溫后的力學(xué)性能就會(huì)有很大不同。本文研究表面涂有一定厚度防火涂料的鋼纖維混凝土高溫力學(xué)性能。本文首先研究了目標(biāo)溫度、防火涂料厚度以及鋼纖維摻量對(duì)鋼纖維混凝土高溫后力學(xué)性能的影響。然后利用有限元模擬了涂有防火涂料的混凝土在升溫、恒溫以及降溫過程中的溫度應(yīng)力以及溫度場(chǎng)的分布。最后運(yùn)用電子掃描顯微鏡(SEM)觀察了高溫后鋼纖維混凝土的微觀結(jié)構(gòu),分析了混凝土內(nèi)部結(jié)構(gòu)的高溫?fù)p傷以及鋼纖維與混凝土基體的界面區(qū)隨溫度的變化規(guī)律。主要研究結(jié)果如下：(1)防火涂料在高溫下會(huì)很好的隔離鋼纖維混凝土,降低混凝土表面的溫度,從而延緩和減輕混凝土結(jié)構(gòu)的火災(zāi)損傷。在鋼纖維混凝土表面涂上防火涂料,歷經(jīng)一定的高溫條件后,其力學(xué)性能(抗壓強(qiáng)度、劈裂抗拉強(qiáng)度、抗折強(qiáng)度)下降的風(fēng)險(xiǎn)大大降低,殘余力學(xué)強(qiáng)度值增加。(2)在一定的高溫作用下,隨著防火涂層厚度的增加,鋼纖維混凝土的抗壓強(qiáng)度、劈裂抗拉強(qiáng)度、抗折強(qiáng)度均呈增加的趨勢(shì),其中800℃高溫條件下,防火涂層的影響效果最為顯著,隨著防火涂料層厚度的增加,這種增強(qiáng)的效果開始削弱,鋼纖維混凝土力學(xué)性能的增長(zhǎng)開始變得緩慢。(3)當(dāng)鋼纖維混凝土表面帶有一定厚度的防火涂料時(shí),隨著鋼纖維摻量的增加,高溫后混凝土力學(xué)性能降低的幅度均有所減小。目標(biāo)高溫條件一致時(shí),鋼纖維摻量越大,混凝土力學(xué)強(qiáng)度越大。(4) 在恒溫階段,隨著恒溫時(shí)間的增加,試件表面與試件中心溫度的差值逐漸降低。并且恒溫也減小了混凝土內(nèi)外的應(yīng)力差。在自然冷卻降溫階段,混凝土的峰值應(yīng)力先增大后降低,混凝土在降溫階段也有一定程度的高溫?fù)p傷。隨著防火涂料厚度的增加和鋼纖維摻量的增加,試件表面和試件中心的溫差均呈現(xiàn)降低的趨勢(shì)。(5) 隨著溫度的升高,混凝土內(nèi)部結(jié)構(gòu)逐漸開始劣化,水化產(chǎn)物逐步分解,在800℃下,與普通混凝土相比,表面設(shè)置防火涂料的鋼纖維混凝土基體的高溫?fù)p傷程度降低,水泥石劣化程度較小。隨著溫度的升高,鋼纖維與混凝土基體的界面區(qū)的水泥石逐漸變成粉末狀,混凝土與鋼纖維之間的粘結(jié)力降低。然而目標(biāo)溫度相同時(shí),當(dāng)混凝土表面涂有防火涂料,界面區(qū)水泥石的損傷程度大大降低,水泥石與鋼纖維的粘結(jié)力較表面無防火涂料的鋼纖維混凝土好。
[Abstract]:With the rapid development of social economy and the acceleration of urbanization, the city has become overcrowded, the population is beginning to be overconcentrated, and the accidental fire has caused the destruction of buildings and casualties from time to time. Usually in public buildings, A layer of concrete fire resistant coating is painted on the surface of tunnel buildings. The mechanical properties of concrete members with and without fire resistance coating will be very different after high temperature. This paper studies the surface coating with a certain thickness of fire resistant coating. The mechanical properties of steel fiber reinforced concrete (SFRC) at high temperature are studied in this paper. The effect of thickness of fire resistant coating and the amount of steel fiber on the mechanical properties of steel fiber concrete after high temperature. Then the finite element method is used to simulate the temperature rise of concrete coated with fire resistant coating. The distribution of temperature stress and temperature field in the process of constant temperature and cooling. Finally, the microstructure of steel fiber reinforced concrete (SFRC) after high temperature was observed by means of electron scanning microscope (SEM). The high temperature damage of concrete internal structure and the variation of interface zone between steel fiber and concrete matrix with temperature are analyzed. The main results are as follows: 1) Fiberproof coatings can isolate steel fiber reinforced concrete well at high temperature. Reduce the temperature of concrete surface, thus delay and reduce the fire damage of concrete structure. Apply fire resistant coating on the surface of steel fiber concrete, after a certain high temperature condition, its mechanical properties (compressive strength, splitting tensile strength, splitting tensile strength), The risk of decreasing the flexural strength is greatly reduced, and the residual mechanical strength is increased. At a certain high temperature, the compressive strength and splitting tensile strength of the steel fiber reinforced concrete increase with the increase of the thickness of the fire resistant coating. The flexural strength of the coating is increasing, especially at 800 鈩，

本文編號(hào)：1507278