摘要
为研究高温喷水冷却后钢纤维混凝土的力学性能,开展了高温后轴压试验。试验参数包括长径比(33、66)、体积掺量(0.5%、1.0%、1.5%)和温度水平(常温、200℃、400℃、600℃、800℃),获得了应力-应变关系曲线,并提取峰值应力、峰值应变及弹性模量等关键参数。结果表明:掺入钢纤维显著改善了高温喷水冷却后混凝土的延性与裂缝分布特征,有效抑制了混凝土中主裂缝快速贯通,避免了脆性破坏;钢纤维混凝土峰值应力受掺入钢纤维长径比与体积掺量耦合影响,当长径比为33时,钢纤维体积掺量从0.5%增至1.5%时,峰值应力提高12%;而当长径比为66时,钢纤维体积掺量从0.5%增至1.0%时,峰值应力略有上升,但进一步增加至1.5%时,峰值应力反而下降11%;峰值应变的变化与纤维长细比和体积掺量组合相关,对于长径比33的钢纤维,体积掺量从0.5%增加至1.5%时,经历400℃高温后峰值应变增加32%;而对于长径比66的钢纤维,体积掺量从0.5%增至1.0%时,400℃下影响较小,但在经历600℃高温后,峰值应变增加35%;当体积掺量进一步增至1.5%时,经历600℃高温后峰值应变增速趋缓;在普通混凝土、长径比33和长径比66的钢纤维混凝土中,长径比33、体积掺量1%的试块组在各温度下具有最高弹性模量。拟合得到基于温度、钢纤维特征参数及钢纤维对混凝土峰值应力影响系数的高温后本构模型,拟合曲线与试验数据吻合良好,可为火灾后钢纤维混凝土结构的性能评估、修复加固设计及防火优化提供参考。
To investigate the mechanical properties of steel fiber reinforced concrete(SFRC)after high-temperature water spraying cooling,axial compression tests were conducted at elevated temperatures.The test parameters include fiber aspect ratios(33,66),volume fractions(0.5%,1.0%,1.5%),and temperaturelevels(roomtemperature,200℃,400℃,600℃,800℃).From the stress-strain curves,key performance parameters such as peak stress,peak strain,and elastic modulus were extracted along with corresponding fitting formulas.The results show that the incorporation of steel fibers significantly improves the ductility and crack distribution of concrete subjected to hightemperature water spraying,thereby effectively suppressing the rapid propagation of main cracks and preventing brittle failure.The peak stress of SFRC is significantly influenced by the fiber aspect ratio and fiber volume fraction.For a fiber aspect ratio of 33,increasing the fiber volume fraction from 0.5%to 1.5%results in a 12%increase in peak stress.In contrast,for an aspect ratio of 66,increasing the fiber volume fraction from 0.5%to 1.0%only leads to a slight increase in peak stress,but further increasing it to 1.5%reduces the peakstress by 11%.The variation in peak strain is related to the combined effect of fiber aspect ratio,volume fraction and temperature.For fibers with an aspect ratio of 33,increasing the volume fraction from 0.5%to 1.5%results in a 32%increase in peak strain after exposure to 400℃.For fibers with an aspect ratio of 66,the effect is negligible below 400℃,but after exposure to 600℃,the peak strain increases by 35%.This rate ofincrease of peak strain slows down when the fiber volume fraction is further increased to 1.5%o after exposure to 600℃.Among ordinary concrete and SFRC with the aspect ratios of 33 and 66,the concrete with the fiber aspect ratio of 33 and fiber volume fraction of 1%exhibits the highest elastic modulus across all temperature levels.A high-temperature constitutive model for SFRC was developed through fitting experimental data to incorporate the effects of temperature and fiber parameters on concrete peak stress.This model provides a reference for performance evaluation,repair and reinforcement design,and fire resistance optimization of SFRC structures.
作者
周焕廷
阮健
ZHOU Huanting;Ruan Jian(School of Civil Engineering and Architecture,Wuhan University of Technology,Wuhan 430070,China;Sanya Science and Education Innovation Park,Wuhan University of Technology,Sanya 572025,China)
出处
《建筑结构学报》
北大核心
2025年第11期275-283,294,共10页
Journal of Building Structures
基金
国家自然科学基金项目(52378533)。
关键词
钢纤维混凝土
高温
喷水冷却
单轴受压试验
本构模型
steelfiberreinforced concrete
high temperature
water spray cooling
uniaxial compressivetest
constitutive model
