火灾下钢筋混凝土简支板力学响应机理

丁发兴; 王文君; 蒋彬辉; 余志武

doi:10.6052/j.issn.1000-4750.2021.08.0664

火灾下钢筋混凝土简支板力学响应机理

doi: 10.6052/j.issn.1000-4750.2021.08.0664

丁发兴^{1, 2,},
王文君^1,,
蒋彬辉^1, ,,
余志武^1,

1.
中南大学土木工程学院，湖南，长沙 410075
2.
湖南省装配式建筑工程技术研究中心，湖南，长沙 410075

基金项目: 国家自然科学基金面上项目(51978664)；湖南省自然科学杰出青年基金项目(2019JJ20029)；中南大学中央高校基本科研业务费专项资金项目(2021zzts0218 )

详细信息

作者简介:
丁发兴(1979−)，男，浙江温州人，教授，博士，从事钢-混凝土组合结构抗火与抗震研究(E-mail: dinfaxin@csu.edu.cn)

王文君(1994−)，女，湖南岳阳人，博士生，从事钢-混凝土组合结构抗火研究(E-mail: wenjunwang@csu.edu.cn)

余志武(1955−)，男，湖南岳阳人，教授，博士，从事钢-混凝土组合结构抗火与抗震研究(E-mail: zhwyu@csu.edu.cn)

通讯作者:
蒋彬辉(1987−)，男，湖南娄底人，副教授，博士，从事钢结构抗火与结构抗连续性倒塌研究(E-mail: binhuijiang@csu.edu.cn)

中图分类号: TU352.5
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出版历程
- 收稿日期: 2021-08-26
- 录用日期: 2021-12-14
- 修回日期: 2021-12-08
- 网络出版日期: 2021-12-14
- 刊出日期: 2023-02-01

MECHANICAL RESPONSE OF SIMPLY SUPPORTED REINFORCED CONCRETE SLABS UNDER FIRE

DING Fa-xing^{1, 2
,},
WANG Wen-jun^1
,,
JIANG Bin-hui^{1
, ,},
YU Zhi-wu^1
,

1.
School of Civil Engineering, Central South University, Changsha, Hu’nan 410075, China
2.
Engineering Technology Research Center for Prefabricated Construction Industrialization of Hu’nan Province, Changsha, Hu’nan 410075, China

摘要

摘要: 拉力膜理论针对的是板大变形下开裂状态的研究，对于火灾下板发生大变形尚未开裂的机理缺乏合理的解释。为此该文采用合理的材料热工性能和热-力耦合本构关系，应用ABAQUS有限元软件对火灾下钢筋混凝土简支单向板和双向板的温度场和热力耦合场进行了三维实体有限元分析，在实验验证的基础上深入探讨火灾下混凝土和钢筋的应力变化规律以及钢筋混凝土简支板的力学响应机理。分析结果表明：简支板发生了激烈的应力重分布现象，其变形过程经历弹性、弹塑性、塑性以及受拉开裂四个阶段，在弹塑性和塑性阶段板底混凝土双向受压的倒拱效应使得双向板抗火性能优秀；当火灾下钢筋混凝土简支板实验没有达到力学响应的受拉开裂阶段时，板底直接受火区域不会出现开裂现象；与单向板相比，双向板进入塑性与受拉开裂阶段的时间大幅度延长，且塑性与受拉开裂阶段变形速率减缓，因此其抗火性能更优。
- 钢筋混凝土简支板 /
- 力学响应 /
- 有限元 /
- 应力重分布 /
- 倒拱效应
Abstract: The tensile membrane theory for the cracking state of reinforced concrete (RC) slabs does not explain the mechanism that enables the slabs to bear the load under a large deformation before the cracking at slab bottom. Therefore, three-dimensional solid finite element (FE) models of simply supported one-way RC slabs and two-way RC slabs in both heat transfer analysis and thermo-mechanical coupling analysis were established using the ABAQUS software, based on reasonable thermal parameters and thermo-mechanical coupling constitutive of materials. Using the verified model, the stress variation law of concrete and steel bars and the mechanical response of simply supported RC slabs under fire were further investigated. The results show that: simply supported RC slabs undergo intense stress redistribution, and their responses show four stages, namely elastic, elastic-plastic, plastic and, tensile cracking stages. In elastic-plastic and plastic stages, the bidirectional compression of bottom concrete, namely inverted arch effect, makes the fire resistance of two-way RC slab excellent; there is no cracking in the fire area of the slabs until the tensile cracking stage; Compared with one-way RC slabs, the time for two-way RC slabs to enter the plastic and tensile cracking stage is postponed, and the deformation rate in the plastic and tensile cracking stage is also slowed down. Therefore, the two-way RC slabs have better fire resistance.
- simply supported reinforced concrete slab /
- mechanical response /
- finite element /
- stress redistribution /
- inverted arch effect

HTML全文

图 1 钢筋混凝土简支板有限元模型

Figure 1. FE model for simply supported RC slabs

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图 2 单向板实测温度与计算温度对比图

Figure 2. Comparison of temperature-time curves between test results and analysis results of one-way slab

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图 3 双向板实测温度与计算温度对比图

Figure 3. Comparison of temperature-time curves between test results and analysis results of two-way slabs

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图 4 单向板跨中实测挠度与计算挠度对比图

Figure 4. Comparisons of deflection-temperature curves of slabs between test results and analysis results of one-way slabs

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图 5 双向板跨中实测挠度与计算挠度对比图

Figure 5. Comparisons of deflection-time curves between test results and analysis results of two-way slabs

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图 6 单向板B4和双向板A2应力分布图

Figure 6. Diagram of stress distribution of one-way slab B4 and two-way slab A2

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图 7 单向板B4和双向板A2典型截面混凝土应力分布

Figure 7. Concrete stress variation of one-way slab B4 and two-way slab A2 in typical sections

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图 8 实验板裂缝图

Figure 8. Diagram of crack of slabs in the experiment

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图 9 简支板高温力学响应图

Figure 9. Mechanical response of simply-supported slabs under high temperature

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10 不同时刻单向板跨中截面混凝土应力分布

10. Stress distribution of concrete of one-way slab in mid-span section at different moment

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11 不同时刻双向板跨中截面混凝土应力分布

11. Stress distribution of concrete of two-way slab in mid-span section at different moment

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表 1 实验试件各参数

Table 1. Properties of specimens.

学者	试件编号	长度L×宽度B× 板厚h/mm	钢筋屈服强度 f_y /MPa	混凝立方体抗压强度f_cu/MPa	保护层厚度 c/mm	钢筋直径 d/mm	钢筋间距 s/mm	板自重g+外荷载q/ (kN/m²)	受火面积/ mm²	支撑方式
陈礼刚^[2]	B2	4300×3300×120	338	38.33	20	10	150	5.0	3050×1500	对边简支
	B3	4300×3300×120	338	38.33	15	10	100	5.0	3050×1500	对边简支
	B4	4300×3300×120	338	38.33	20	10	100	5.0	3050×1500	对边简支
LIM等^[3]	A1	4300×3300×100	468	36.70	25	12	200	5.5	4000×3000	四边简支
杨志年^[4]	A2	6660×5000×120	422	32.30	15	8	200/180	5	5400×3800	四边简支
WANG等^[5]	A3	3300×3300×100	414	28.00	15	8	200	4.5	2400×2400	四边简支
WANG等^[6]	A4	3900×3300×100	485	34.00	15	8	200	4.5	3000×2400	四边简支

下载: 导出CSV

表 2 不同判别标准下简支板耐火极限

Table 2. Fire resistance of simply supported slabs under different criteria.

板类别	耐火极限 /min
板类别	T₅₉₃	T₁₄₀	L/20	δ_v
单向板	105	89	51	−
双向板	103	89	53	−

下载: 导出CSV

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