高温后钢筋混凝土梁性能退化规律研究
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摘要
随着经济高速发展和城市化步伐的加快,意外引起的火灾导致建筑物破坏和人员伤亡时有发生。建筑物发生火灾后,结构的力学性能如何变化一直是研究人员普遍关注的热点问题。近年来,国内外发表了许多有关高温下的混凝土与钢筋混凝土结构的研究成果,主要集中于建筑物在大火侵袭下,结构内部温度和结构挠度、内力等随时间的变化,并获得了很多有价值的研究结论。但由于火灾对建筑物的影响因素十分复杂,这些问题至今还没有得到很好的解决。
本文主要做了以下的研究工作：
一、通过高温后混凝土试块的抗压试验研究,得出了高温后混凝土抗压强度与受火温度、受火时间、冷却方式等影响因素的关系,并依此给出了火灾强度损失标准。
二、通过高温后混凝土试块的碳化性能试验研究,得出了高温后混凝土碳化性能与受火温度、受火时间、冷却方式等影响因素的关系,为火灾后混凝土结构进行耐久性能的评估提供了指导依据。
三、通过高温后RC梁的抗弯性能试验,研究了各高温影响因素对梁抗弯承载力的影响,归纳了温度裂缝和荷载裂缝的发展规律及相互关系,并验证了平截面假定的适用性。
四、运用ANSYS有限元分析软件分析了不同高温工况下的温度场分布,采用等效截面缩减法计算了高温后RC梁的剩余承载力,与试验结果吻合良好。
With fast economic development and rapid city growth, fire accidents may take place which results in building destruction and personal casualties. It is a topic of general interest that how the mechanic performance of the structure has changed after the building fire. Many investigations on the high temperature behavior of concrete have been reported and a lot of valuable research findings is received, which focused on the continual changes of structural temperature, deflection and interior force after exposure to fire. However, the effects of fire on building are rather complicated and still unsolved so far.
In this paper, the following research works are done:
(1) The relationship between compressive strength of concrete and the influence factors such as different temperature, different time and refrigeration mode is obtained based on the experiment of concrete block, and classification standards of fire is proposed.
(2) The carbonation depth of concrete after high temperature is studied based on the experiment of concrete block, and the relationship between carbonation depth and the influence factors such as different temperature, different time and refrigeration mode is obtained, and the guidance to the assessment of the durability of concrete structures after fire is provided.
(3) The residual load-carrying capacity of RC beams after high temperature is studied based on the experiment. The effects of influence factors to residual load-carrying capacity is researched, and the relationship and development law of temperature crack and load crack is summarized. In addition, applicability of the plane section assumption is verified.
(4) The temperature field of different temperature condition is obtained based on ANSYS, a finite element analysis software. And the residual load-carrying capacity of RC beams after high temperature is calculated by equivalent cross-section reduced method, which is well coincided with the experimental results.
本文主要做了以下的研究工作：
一、通过高温后混凝土试块的抗压试验研究,得出了高温后混凝土抗压强度与受火温度、受火时间、冷却方式等影响因素的关系,并依此给出了火灾强度损失标准。
二、通过高温后混凝土试块的碳化性能试验研究,得出了高温后混凝土碳化性能与受火温度、受火时间、冷却方式等影响因素的关系,为火灾后混凝土结构进行耐久性能的评估提供了指导依据。
三、通过高温后RC梁的抗弯性能试验,研究了各高温影响因素对梁抗弯承载力的影响,归纳了温度裂缝和荷载裂缝的发展规律及相互关系,并验证了平截面假定的适用性。
四、运用ANSYS有限元分析软件分析了不同高温工况下的温度场分布,采用等效截面缩减法计算了高温后RC梁的剩余承载力,与试验结果吻合良好。
With fast economic development and rapid city growth, fire accidents may take place which results in building destruction and personal casualties. It is a topic of general interest that how the mechanic performance of the structure has changed after the building fire. Many investigations on the high temperature behavior of concrete have been reported and a lot of valuable research findings is received, which focused on the continual changes of structural temperature, deflection and interior force after exposure to fire. However, the effects of fire on building are rather complicated and still unsolved so far.
In this paper, the following research works are done:
(1) The relationship between compressive strength of concrete and the influence factors such as different temperature, different time and refrigeration mode is obtained based on the experiment of concrete block, and classification standards of fire is proposed.
(2) The carbonation depth of concrete after high temperature is studied based on the experiment of concrete block, and the relationship between carbonation depth and the influence factors such as different temperature, different time and refrigeration mode is obtained, and the guidance to the assessment of the durability of concrete structures after fire is provided.
(3) The residual load-carrying capacity of RC beams after high temperature is studied based on the experiment. The effects of influence factors to residual load-carrying capacity is researched, and the relationship and development law of temperature crack and load crack is summarized. In addition, applicability of the plane section assumption is verified.
(4) The temperature field of different temperature condition is obtained based on ANSYS, a finite element analysis software. And the residual load-carrying capacity of RC beams after high temperature is calculated by equivalent cross-section reduced method, which is well coincided with the experimental results.
引文
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[2]Mohamedbhai, G.T.G. Effect of exposure time and rates of heating and cooling on residual strength of heated concrete[J]. Magazine of Concrete Research,1986, 38(9):151～158.
[3]Sullivan, P.J.E, Khoury, G.A. and Grainger, B.N. Apparatus for measuring the transient thermal strain behavior of unsealed concrete under constant load for temperatures up to 700℃[J]. Magazine of concrete Research,1983,35(125): 229～236.
[4]Khoury, G.A., Grainger, B.N. and Sullivan, P.J.E. Strain of concrete during first heating to 600℃ under load[J]. Magazine of concrete Research,1985,37(133): 195～215.
[5]Cabriel A. Khoury Brain N. Grainger and Patrick J.E.Sullivan. Strain of concrete during first cooling from 600℃ under load[J]. Magazine of concrete Research, 1986,38, No.134:3～12.
[6]G.A.Koury,C.E.Majorana,F.Pesavento and B.A.Schrefler. Modelling of heated concrete[J].Magazine of Concrete Research,2002,54(2):77～101.
[7]J.Papayianni, T.Valiasis. Residual mechanical properties of heated concrete incorporation different pozzolanic materials[J]. Materials and structures,1991, 24:115～121.
[8]W.M.Lin, T.D.Lin, L.J.Powers-Couche, Microstructures of fire-damaged concrete [J]. ACI material.1996,93(3):199～205.
[9]B.Georgali, P.E.Tsakiridis.Microstructure of fire-damaged concrete[J]. A case study. Cement & concrete Composites.2005,27:255～259.
[10]Chih-Huang Chiang, Cho-Liang Tsai. Time-temperature analysis of bond strength of a rebar after fire exposure[J]. Cement and concrete research,2003, 33:1651～1654.
[11]Chi-sun poon, Salman Azhar, Mike Anson, Yuk-Lung Wong. Strength and durability recovery of fire-damaged concrete after post-fire-curing[J]. Cement and Concrete Research,2001,31:1307～1318.
[12]Jian zhuang Xiao, Gert Konig.Study on concrete at high temperature in China-an overview [J]. Fire Safety Journal.2004, (39):89～103.
[13]过镇海,时旭东.钢筋混凝土的高温性能及其计算[M].北京：清华大学出版社,2003.
[14]李卫,过镇海.高温下混凝土的强度和变形性能的试验研究[J].建筑结构学报,1993,14(1)：8～16.
[15]时旭东,过镇海.高温下钢筋混凝土受力性能的试验研究[J].土木工程学报,2000,33(6)：6～16.
[16]覃丽坤,宋玉普,王玉杰,张众,于长江.高温对混凝土力学性能影响的试验研究[J].混凝土,2004,(5)：9～11.
[17]王孔藩,许清风,刘挺林.高温下及高温冷却后混凝土力学性能的试验研究[J].施工技术,2005,34(8)：1～3.
[18]贾艳东,田傲霜,张斌,许传矗,李季.不同时间高温后混凝土性能的试验研究[J].辽宁工程技术大学学报,2006,25(6)：864～866.
[19]张素梅.高温冷却后混凝土材料的力学性能研究[J].商品混凝土,2009,10：40～41.
[20]侯高峰,韦军.高温后不同强度等级混凝土力学性能的试验研究[J].研究探索,2010,28(3)：68～70.
[21]吕天启.高温后混凝土静置性能的试验研究及已有建筑物的防火安全评估[D].大连理工大学工学博士学位论文,2002,7.
[22]余江滔.火灾后混凝土构件损伤评估的试验及理论研究[D].同济大学工学博士学位论文,2007,2.
[23]陈磊,李彬,滕桃居,陈太林.混凝土高温力学性能分析[J].混凝土,2003(7)：26～28.
[24]阎慧群.高温(火灾)作用后混凝土材料力学性能研究[D].四川大学,2004.
[25]阎继红.高温作用下混凝土材料性能试验研究及框架结构性能分析[D].天津大学,2000.
[26]吕天启,赵国藩,林志伸.高温后静置混凝土力学性能试验研究[J].建筑结构学报,2004,25(1)：63～70.
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[28]安然,王清远,阎慧群,等.高温后混凝土力学性能研究[J].四川建筑,2005,26(6)：69～72.
[29]阎慧群.高温(火灾)作用后混凝土材料力学性能研究[D].四川大学,2004.
[30]陈丽红.不同温度作用后混凝土强度变化规律的研究[J].四川建筑科学研究,2007,33(5)：118～121.
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