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�
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 τuand residual bond strength τrare 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
作者
涂身文
陈宗平
王成
TU Shen-wen;CHEN Zong-ping;WANG Cheng(College of Civil Engineering and Architecture,Guangxi University,Guangxi Nanning 530004,China;Key Laboratory of Disaster Prevention and Structural Safety of Ministry of Education,Guangxi University,Guangxi Nanning 530004,China)
出处
《消防科学与技术》
CAS
北大核心
2022年第5期609-615,共7页
Fire Science and Technology
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
round steel tube
recycled concrete
high temperature spray cooling
ultimate bond strength
residual bond strength
bonding slip constitutive equation
