受火后冷却阶段混凝土剪力墙的变形失效研究

陈军

doi:10.3724/j.gyjzG23092702

受火后冷却阶段混凝土剪力墙的变形失效研究

doi: 10.3724/j.gyjzG23092702

陈军

江苏科技大学土木工程与建筑学院, 江苏镇江 212000

详细信息

作者简介:
陈军,工学博士,副教授,主要从事混凝结构抗火研究。电子信箱:chenjun@just.edu.Cn

计量
- 文章访问数: 6
- HTML全文浏览量: 1
- PDF下载量: 0
- 被引次数: 0
出版历程
- 收稿日期: 2023-09-27
- 网络出版日期: 2024-10-18

Research on Deformation and Failure of Concrete Shear Walls During Cooling After Fire

CHEN Jun

College of Civil Engineering and Architecture, Jiangsu University of Science and Technology, Zhenjiang 212000, China

摘要

摘要: 基于数值模拟研究了受火后冷却阶段钢筋混凝土(RC)剪力墙的结构变形和失效。通过有限元热传导分析墙体内部温度梯度,并采用非线性打靶法迭代求解结构模型。模型中同时考虑了混凝土和钢筋的热变形、混凝土的受压应变软化、拉伸硬化、开裂和钢筋屈服以及几何非线性,并显式考虑混凝土的瞬态蠕变。在验证了模型的有效性后,通过数值算例揭示了受火后冷却阶段RC剪力墙的结构变形和失效特征及机理,并对关键影响因素进行了分析。结果表明:RC剪力墙在受火后冷却阶段可能发生屈曲破坏,且其失效时间可早于持续受火的墙体。材料强度的损失、结构中性轴的偏移和混凝土的瞬态蠕变是导致RC剪力墙在受火后冷却阶段发生屈曲破坏的关键因素。墙体高度、墙体厚度和荷载偏心距对受火后冷却阶段RC剪力墙的结构变形和失效具有显著影响。考虑火灾后失效的RC剪力墙的耐火性显著低于持续受火下的耐火性,在火灾持续时间超过15 min时RC剪力墙就可能在火灾后冷却阶段发生滞后失效倒塌。增加配筋率对RC剪力墙火灾后冷却阶段的滞后失效倒塌具有一定的防护作用。
- 受火后 /
- 结构变形 /
- 数值建模 /
- 钢筋混凝土剪力墙 /
- 瞬态徐变
Abstract: The structural deformation and failure of reinforced concrete (RC) walls during cooling after one-sided fire was studied by numerical simulations. Heat conduction analysis was carried out by finite element approximation to obtain the temperature distribution inside the wall,and the nonlinear shooting method was used to iteratively solve the structural model. The model took into account the thermal strain of reinforced concrete at high temperatures, compressive strain softening, tensile hardening, cracking and steel yielding, and geometric nonlinearity. The effects of transient creep of concrete were explicitly considered. After verifying the validity of the model, the structural deformation and failure mechanism of RC walls during the cooling after fire was revealed by a numerical example, followed by parametric studies. The results showed that RC wall may buckle in the post-fire cooling stage and its failure time could be earlier than that of the wall subjected to continuous fire. The loss of the strength of materials, the shifting of the neutral axis and the transient creep of concrete were the key factors leading to the post-fire buckling failure. In addition, the wall height, wall thickness and load eccentricity had a significant effect on the structural deformation and failure of RC walls during cooling after fire. The fire resistance of RC walls considering post-fire failure was significantly lower than that of RC walls subjected to continuous fire. The fire resistance of RC shear walls considering post-fire failure is significantly lower than that subjected to continuous fire, failure of RC shear wall during the cooling after fire could occur when the fire lasts for more than 15 minutes. Increasing the reinforcement ratio has a certain preventive effect on the failure of RC shear wall during the cooling after fire.
- post-fire /
- structural deformation /
- numerical modeling /
- reinforced concrete walls /
- transient creep

HTML全文

参考文献(19)

[1]	肖建庄.高性能混凝土结构抗火设计原理 [M].北京:科学出版社, 2015.
[2]	KODUR V K R, ALOGLA S M. Effect of high-temperature transient creep on response of reinforced concrete columns in fire [J]. Materials and Structures, 2017, 50, 27.
[3]	GERNAY T, PEI J, TONG Q, et al. Numerical analysis of the effects of fire with cooling phase on reinforced concrete members [J]. Engineering Structures, 2023, 293, 116618.
[4]	BUCHANAN A H, RAO V M. Fire resistance of load-bearing reinforced concrete walls [M]. COX G, LANGFORD. Fire Safety Science. London: Routledge,1991: 771-780.
[5]	CROZIER D, SANJAYAN, J. Tests of load-bearing slender reinforced concrete walls in fire[J]. ACI Structural Journal, 2000, 97(2): 243-251.
[6]	魏晓颖,赵军,边会婷,等.火灾下钢筋混凝土剪力墙温度场数值模拟 [J].消防科学与技术,2021, 40(1): 57-63.
[7]	郑永乾,蔡雪峰.火灾下钢筋混凝土墙计算模型及影响因素分析 [J].土木建筑与环境工程,2011, 33(1): 24-30.
[8]	肖建庄,侯一钊,谢青海.高强混凝土剪力墙抗火性能试验研究 [J]. 建筑结构学报, 2015, 36(12): 91-98.
[9]	MUELLER K A, KURAMA Y C. Out-of-plane behavior and stability of five planar reinforced concrete bearing wall specimens under fire [J]. ACI Structural Journal, 2015, 112(6): 701-712.
[10]	CHEN J, HAMED E, GILBERT R I. Structural performance of reinforced concrete walls under fire conditions [J]. Journal of Structural Engineering, 2020, 146(3), 04020006.
[11]	MUELLER K A, KURAMA Y C. Out-of-plane behavior of reinforced concrete bearing walls after one-sided fire [J]. ACI Structural Journal, 2017, 114(1): 149-160.
[12]	CEN. Eurocode 2: Design of concrete structures-part 1-2: general rules-structural fire design: EN 1992-1-2[S]. Brussels, Belgium: European Committee for Standardization, 2004.
[13]	CHEN J, HAMED E, GILBERT R I. Structural performance of concrete sandwich panels under fire [J]. Fire Safety Journal, 2021, 121, 103293.
[14]	SCHNEIDER U. Concrete at high temperatures: a general review [J]. Fire Safety Journal, 1988, 13(1): 55-68.
[15]	FIELDS K, BISCHOFF P H. Tension stiffening and cracking of high-strength reinforced concrete tension members [J]. ACI Structural Journal, 2004, 101(4): 447-456.
[16]	ANDERBERG Y, THELANDERSSON S. Stress and deformation characteristics of concrete at high temperatures. 2. experimental investigation and material behaviour model [J]. Lund Institute of Technology Bulletin, 1976, 54:60-62.
[17]	ASTM. Standard methods of fire tests of building construction and materials: ASTM E119-12[S]. Philadelphia, PA, USA: American Society for Testing and Materials, 2012.
[18]	ISO. Fire resistance tests-Elements of building construction: ISO-834[S]. Geneva, Switzerland: International Organization for Standardization, 1975.
[19]	ACI. Building code requirements for structural concrete and commentary: ACI-318[S]. Farmington Hills, MI, USA: American Concrete Institute, 2011.