主管:中华人民共和国应急管理部
主办:应急管理部天津消防研究所
ISSN 1009-0029  CN 12-1311/TU

消防科学与技术 ›› 2022, Vol. 41 ›› Issue (5): 609-614.

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高温后喷水冷却圆钢管再生混凝土界面黏结性能试验研究

涂身文1,陈宗平1,2,王 成1   

  1. (1. 广西大学 土木建筑工程学院,广西 南宁530004;2. 广西大学 工程防灾与结构安全教育部重点试验室,广西 南宁530004)
  • 出版日期:2022-05-15 发布日期:2022-05-15
  • 作者简介:涂身文(1990-),男,广西大学土木建筑工程学院硕士,主要从事钢与混凝土组合结构研究,广西壮族自治区南宁市西乡塘区大学东路100号,530004。

Experimental study on interface bonding properties of recycled concrete with water-cooled circular steel tube after high temperature

TU Shen-wen1, CHEN Zong-ping1,2, WANG Cheng1   

  1. (1. College of Civil Engineering and Architecture, Guangxi University, Guangxi Nanning 530004, China; 2. Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education, Guangxi University, Guangxi Nanning 530004, China)
  • Online:2022-05-15 Published:2022-05-15

摘要: 为了研究高温喷水冷却后圆钢管再生混凝土的界面黏结性能变化规律,以历经最高恒温温度、再生粗骨料取代率、界面锚固长度为3个变化参数,进行了27个高温喷水冷却后圆钢管再生混凝土试件和2个自然冷却试件(对照组)的静力推出试验,以位移控制的加载方式为主,使自由端的钢管单独受力(核心混凝土不受力),圆钢管内的混凝土从下向上推出。通过试验观察了圆钢管再生混凝土试件破坏的全过程和形态,获取了加载端和自由端的荷载-滑移曲线,分析了各个变化参数对黏结性能的影响规律。试验结果表明:经过高温喷水冷却后,圆钢管再生混凝土试件加载端和自由端的荷载-滑移曲线形态相似,且和自然冷却试件的曲线相似,同时也和前期做的钢管普通混凝土的曲线具有相似性;加载端和自由端的荷载-滑移曲线大致分为上升段、缓慢下降段和平缓段;并且自由端的初始滑移晚于加载端。定义了极限黏结强度τu和残余黏结强度τr。圆钢管再生混凝土试件表面上应变沿试件高度方向大致呈指数分布。经历消防喷水冷却后,随历经最高温度的升高,黏结强度先增大后减小,在400 ℃时,黏结强度达到最大值,当大于400 ℃时,黏结强度降低。历经高温后试件的平均残余黏结强度分别是常温下试件的1.25倍、1.75倍、1.38倍和1.50倍。再生粗骨料取代率的变化对黏结强度的影响不明显,常温下γ=50%时,黏结强度达到最大值;温度为200 ℃且γ=75%时,黏结强度也为最大。这和自然冷却下钢管再生混凝土的结论类似。锚固长度的增大也使圆钢管再生混凝土试件平均极限黏结强度和残余黏结强度均有不同程度增大。提出了高温喷水冷却后圆钢管再生混凝土极限黏结强度和残余黏结强度的计算公式,用此公式所得计算结果均比较理想。今后对界面黏结性能的研究,可以从增加钢管内壁的粗糙度、钢管内部加入加劲肋和钢管内增设不同长度的螺栓角度进行探讨,进而进一步丰富界面黏结性能的理论研究,以期为消防喷水后建筑结构构件的其他力学性能提供理论基础,同时为现实生活中火灾后钢-混凝土组合结构的灾后评估和加固提供参考。

关键词: 圆钢管, 再生混凝土, 高温喷水冷却, 极限黏结强度, 残余黏结强度, 黏结滑移本构方程

Abstract: Abstract: In order to study the change law of the interfacial bonding properties of recycled concrete for round steel tubes after high temperature water spray cooling, 27 circular steel tubes after high temperature water spray cooling were carried out with the maximum constant temperature, the replacement rate of recycled coarse aggregate, and the interface anchoring length as three parameters. The static push-out test of the steel tube recycled concrete specimen and 2 natural cooling specimens (control group) is mainly based on the displacement-controlled loading method, so that the steel pipe at the free end is stressed alone (the core concrete is not stressed), and the steel pipe in the round steel pipe is stressed. Concrete is pushed out from the bottom up. The whole process and shape of the failure of the recycled concrete specimen of the circular steel tube were observed through experiments, the load-slip curves of the loaded end and the free end were obtained, and the influence of various parameters on the bonding performance was analyzed. The test results show that after high-temperature water spray cooling, the load-slip curves of the loading end and the free end of the circular steel tube recycled concrete specimen are similar in shape, and similar to the curve of the natural cooling specimen, and are also similar to that of the ordinary concrete of the steel tube made in the previous stage. The curves are similar; the load-slip curves of the loaded and free ends are roughly divided into ascending, slowly descending, and gentle segments; and the initial slip of the free end is later than that of the loaded end. The ultimate bond strength τu and residual bond strength τr are defined. The strain on the surface of the circular steel tube recycled concrete specimen is approximately exponentially distributed along the height direction of the specimen. After being cooled by fire-fighting water, the bond strength first increases and then decreases with the increase of the maximum temperature. The average residual bond strength of the specimens after high temperature is 1.25 times, 1.75 times, 1.38 times and 1.50 times that of the specimens at room temperature, respectively. The change of the replacement rate of recycled coarse aggregate has no obvious effect on the bond strength. When γ=50% at room temperature, the bond strength reaches the maximum value; when the temperature is 200 ℃ and γ=75%, the bond strength also reaches the maximum. This is similar to the conclusion of the steel tube recycled concrete under natural cooling. The increase of anchorage length also increases the average ultimate bond strength and residual bond strength of recycled concrete specimens with circular steel tubes to varying degrees. The calculation formulas for the ultimate bond strength and residual bond strength of recycled concrete of circular steel tubes after high temperature water spray cooling are proposed, and the calculation results obtained by this formula are satisfactory. In the future, the research on the interface bonding performance can be discussed from the perspective of increasing the roughness of the inner wall of the steel pipe, adding stiffeners inside the steel pipe and adding bolts of different lengths in the steel pipe, and further enriching the theoretical research on the interface bonding performance, in order to provide fire water spraying. The other mechanical properties of post-building structural components provide a theoretical basis, and at the same time provide a certain reference for post-disaster assessment and reinforcement of steel-concrete composite structures subjected to fire in real life.

Key words: Key words: round steel tube, recycled concrete, high temperature spray cooling, ultimate bond strength, residual bond strength, bonding slip constitutive equation