【摘要】：綠色高性能纖維增強(qiáng)水泥基復(fù)合材料(GHPFRCC)是一種使用大摻量粉煤灰取代水泥的新型建筑材料,較普通混凝土有出色的延性和較高的能量吸收能力。火災(zāi)現(xiàn)在已經(jīng)成為影響結(jié)構(gòu)安全的重要因素,高溫作用會導(dǎo)致混凝土的力學(xué)性能降低,影響混凝土結(jié)構(gòu)的安全性。本文研究了高溫后GHPFRCC三軸抗壓性能以及GHPFRCC加固火損框架柱的抗震性能。主要內(nèi)容包括以下幾方面:(1)進(jìn)行了高溫后GHPFRCC三軸抗壓試驗(yàn)。通過三軸抗壓試驗(yàn)測得GHPFRCC試塊經(jīng)歷不同高溫后的抗壓強(qiáng)度和應(yīng)變,分析加載速率、圍壓和溫度等因素對三軸抗壓強(qiáng)度、彈性模量和應(yīng)變的影響。試驗(yàn)表明:16組不同配合比和最佳配合比試塊的抗壓強(qiáng)度隨經(jīng)歷溫度的增加而降低,隨圍壓的增加而提高;極限荷載對應(yīng)應(yīng)變均達(dá)到2%以上;25℃、200℃時抗壓強(qiáng)度受圍壓影響較小,此時強(qiáng)度主要是由材料強(qiáng)度和纖維提供,400℃、600℃、800℃試塊的抗壓強(qiáng)度由圍壓提供。加載速率對GHPFRCC抗壓強(qiáng)度影響不是很大。(2)進(jìn)行了框架柱的火損試驗(yàn)。進(jìn)行2根GHPFRCC框架柱和2根C30混凝土框架柱耐火試驗(yàn),分析框架柱截面溫度場分布及火損情況。試驗(yàn)結(jié)果表明,GHPFRCC框架柱表面溫度最高為242℃,柱角溫度可達(dá)358℃,C30框架柱表面溫度最高為388℃,柱角溫度可達(dá)456℃,GHPFRCC框架柱截面溫度總體低于C30框架,表明GHPFRCC抗火性能良好。主要是因?yàn)镚HPFRCC中的纖維在高溫時熔化形成細(xì)密的貫通孔隙,構(gòu)件內(nèi)部水蒸氣可以通過孔隙逸出,保持了框架柱截面有效面積,遲緩了熱量的傳遞和對流,抑制了柱內(nèi)溫度的上升,使柱體處于較低溫度。(3)進(jìn)行了GHPFRCC加固火損框架柱的擬靜力試驗(yàn)。對4根火損柱中的1根GHPFRCC框架柱和1根C30框架柱進(jìn)行通長加固。將2根加固后的框架柱、2根未加固的火損柱、2根未受火的框架柱(共6根)進(jìn)行擬靜力試驗(yàn),對比分析GHPFRCC加固火損框架柱、火損框架柱和未受火的框架柱的抗震性能和耗能能力。試驗(yàn)中未加固的火損C30框架柱和未受火的C30框架柱破壞較嚴(yán)重,柱身出現(xiàn)多條較寬的主裂縫,柱側(cè)面出現(xiàn)較多的斜向裂縫,柱底柱角混凝土被壓碎破壞;未受火的GHPFRCC框架柱和GHPFRCC加固的火損框架柱破壞較輕,柱身裂縫均為細(xì)密裂縫,均勻分布在柱底部,側(cè)面裂縫也大多為水平方向,柱底沒有被壓壞脫落,構(gòu)件破壞是由于柱身和底座形成鉸而引起。結(jié)果表明,GHPFRCC加固的火損框架柱較未加固的火損框架柱的抗震性能及耗能能力均有較大提高;GHPFRCC加固火損框架柱的剛度損失速度要低于未加固的火損框架柱;GHPFRCC框架柱的極限荷載承載力要整體好于相應(yīng)的C30框架柱。
[Abstract]:Green high performance fiber reinforced cement matrix composite (GHPFRCC) is a new type of building material which uses large amount of fly ash instead of cement. It has better ductility and higher energy absorption ability than ordinary concrete. Fire has become an important factor affecting the safety of concrete structures. High temperature will lead to the reduction of mechanical properties of concrete and affect the safety of concrete structures. In this paper, the triaxial compressive behavior of GHPFRCC after high temperature and the seismic behavior of frame columns strengthened with GHPFRCC are studied. The main contents are as follows: (1) the triaxial compression test of GHPFRCC after high temperature is carried out. The compressive strength and strain of GHPFRCC specimen were measured by triaxial compression test. The effects of loading rate, confining pressure and temperature on triaxial compressive strength, elastic modulus and strain were analyzed. The test results show that the compressive strength of different mix ratio and optimum mix ratio of w / 16 groups decreases with the increase of temperature and increases with the increase of confining pressure, and the compressive strength is less affected by confining pressure when the corresponding strain of ultimate load is more than 2% at 25 鈩，

本文編號：2169753