【作者】 姚伟发；

【导师】 黄侨；

【作者基本信息】 东南大学 ， 桥梁与隧道工程， 2016， 博士

【摘要】 论文结合国内外建筑结构抗火规范和科研情况,调研分析我国桥梁结构火灾特点,借鉴消化吸收国内外已有科研成果和应用技术成果,采用理论及数值分析等多种手段,并制作一定数量的组合梁试件进行火灾试验。在经试验验证了有限元计算模型正确性的基础上,建立多个有限元计算模型,有针对性地研究火灾高温下钢-混凝土组合梁桥结构行为反应的基本原理、影响结构温度场分布的主要因素、组合桥梁结构抗火性能的影响参数及火灾后组合梁的剩余抗弯承载力计算理论等进行研究。主要内容有:分析给出火灾高温下钢-混组合结构在不同约束条件下,结构受力和变形的计算方法,对有限元分析的结果进行判断提供了一种有效的方法;进行了工字形钢-混凝土组合简支梁及箱形钢-混凝土组合简支、连续梁的耐火试验。获得了主要位置测点的温度和变形数据,并通过对试验全过程的观察,进一步了解了组合梁破坏过程和机理。此外,对高温后材料力学性能进行了试验,为高温后组合梁材料的取值提供了试验依据。总结、归纳国内外学者对普通钢材和混凝土材料高温下性能(热工和力学性能)研究成果,根据研究对象的特点,选择了合适的材料模型作为研究的基础。通过大量的、系统的参数分析:升温曲线、混凝土板厚、钢材及混凝土材料属性、混凝土板宽、保护层厚度及钢主梁各组成部分的尺寸等,给出了影响组合梁温度场分布的主要因素。分析了影响工字形及箱形组合梁抗火性能(变形)的因素:外荷载、混凝土板厚度、腹板高度、钢箱梁腹板或底板厚度等,获得了主要影响参数。基于试验研究和有限元分析的结果,对钢-混凝土组合梁在高温后的剩余承载力计算理论进行研究,提出一种考虑温度场分布、计算精度高、方法较为简便的钢-混凝土组合梁高温后抗弯承载力计算方法,并对高温后混凝土的计算强度进行分析,给出更具合理性的参数取值。本文研究认为,火灾高温下钢-混凝土组合连续梁的抗火性能要优于简支梁;组合梁的抗火能力由其变形所决定;影响组合梁温度场分布的主要因素为升温曲线及混凝土板厚。混凝土板厚度对组合梁的抗火性能有着显著的影响,腹板高度的增加能有效地改善了组合梁的抗火性能。论文给出的两种高温后钢-混凝土组合梁的剩余抗弯承载力的塑性计算方法具有良好的计算精度,且计算较为简便。更多还原

【Abstract】 According to the domestic and foreign building structure fire resistance standard and scientific research,investigation and analysis of the characteristics of bridge structure fire,reference at home and abroad existing research and application of technology,a series of studies have been completed by means of theoretical and numerical analysis based on the correctness of the finite element calculation model which is proved to be correct by fire test,including the basic principle of the steel concrete composite beam bridge structure behavior,structure temperature field distribution,fire resistance effect parameters,the calculation theory of residual flexural capacity,and so on.Main contents are:The calculation method of structure stress and deformation under different constraint conditions were obtained,which provide a very useful method for the finite element analysis.Fire tests were completed.The temperature and deformation of the main measuring points were obtained,and the process and mechanism of the failure of composite beams were further understood by observing the whole process of the experiment.In addition,the mechanical properties of the high temperature materials were tested,which provided the experimental basis for the value of the composite beams.The performance(thermal and mechanical properties)of ordinary steel and concrete materials in high temperature have been summarized.According to the characteristics of the research object,the appropriate material models are chosen for the basis of the research.The parameters analysis have been completed,including heating up curve,the thickness of the concrete slab,material properties of steel and concrete,concrete slab width,thickness of protection layer,the steel girder dimensions,the main factors were obtained for temperature field distribution of composite beam.The main influence parameters are obtained by analysis the influence I-shaped and composite box beam fire resistance(deformation)of factors:external load,concrete thickness,web height,plate thickness.Based on the research results of experiment and finite element analysis,the calculation theory of the residual bearing capacity of steel concrete composite beams in high temperature has been studied,Considering temperature field distribution and higher calculation accuracy,a simple calculation method of bearing capacity of steel-concrete composite beams is proposed.The calculation strength of concrete after high temperature is analyzed,and the reasonable parameter values are obtained.The main conclusions of this paper are as following:the fire resistance performance of steel concrete continuous beams is better than that of simply supported beams,and the fire resistance of composite beams is determined by the deformation of composite beams.The main factors that affect the temperature field distribution of the composite beam are temperature rising curve and concrete slab thickness.The external load and concrete slab thickness have significant influence on the fire resistance of composite beams,and the increase of web height can effectively improve the fire resistance of composite beams.The plastic calculation method of the residual bearing capacity of steel concrete composite beams in high temperature is presented,which has a good calculation accuracy and is simple and convenient.更多还原