摘要
针对混凝土薄壁箱梁的耐火性能,综合考虑火灾高温下影响钢筋混凝土结构性能的多种参数,密度、导热系数、比热容以及混凝土的初始湿度,给出含有潜热函数的高温冲击模式,利用数值模拟程序分析了火灾高温下混凝土薄壁箱梁的温度分布,研究了荷载比、保护层厚度对ISO834标准火灾升温过程中混凝土薄壁箱梁变形的时变效应规律。研究表明:保护层厚度、荷载比和火灾时间对混凝土薄壁箱梁挠度影响较大;增加混凝土保护层厚度,可有效提高火灾下混凝土薄壁箱梁抵抗竖向变形的能力,并且保护层厚度与挠度之间保持非线性关系;挠度随荷载比的提高呈非线性增长趋势;火灾时间越长,挠度递增幅度越大。
Aimed at fire resistance for concrete thin walled box girder, based on the influence parameters including density, concrete heat conduction and specific heat as well as initial moisture about reinforcement concrete structure subjected to fire, the analysis was pe-formed to study the transient temperature field distribution for reinforced concrete thin walled box girder and time-dependent law of deflection exposed to the ISO834 standard fire, then the determination of mechanical response due to thermal and mechanical load was simulated. The simulation results indicate that： the protective layer thickness, load ration and fire time have a great effect on the deflection of reinforced concrete thin walled box girder, the fire resistance of reinforced concrete thin walled box girder increases nonlinearly with the increase of protective layer thickness; the time-dependent curve for deflection is to non-linearly increase with the raise of load ration, its swell level is to decrease with the increment of the protective thickness ; deflection is wide elevated with fire time. Therefore, the increment of concrete protective thickness is effective to fire resistance for the concrete thin walled box girder.
出处
《西南科技大学学报》
CAS
2008年第2期23-27,共5页
Journal of Southwest University of Science and Technology
基金
国家交通部西部交通建设科技项目(200531881215
200731881232)
关键词
桥梁工程
混凝土薄壁箱梁
高温冲击
时变效应
Bridge engineering
Concrete thin walled box girder
High temperature attack
Time-dependent effect
