摘要
预应力钢结构是一种具有广泛应用前景的结构形式,但在火灾作用下,其整体性能将发生变化并引起整体结构破坏。在前期工作的基础上,从结构响应机理出发建立了平面预应力钢桁架结构火灾高温下的结构响应计算模型。该模型可任意设置多道折线钢索单元并多次张拉施加预应力。从方便应用的角度出发,对高温下钢材的EC3本构模型进行了简化,使其各阶段有了统一表达式。利用该计算模型分别对两种不同布索方案的预应力管桁架进行了火灾行为分析,讨论了不同参数变化对火灾作用下整体结构承载力的影响规律。结果表明,钢索的设置方案、预应力度、外荷载、材料等级等因素对于火灾下预应力钢结构的整体性能和承载力均产生一定影响,不同的布索方案将对应不同的临界温度,外荷载较大时临界温度较小,而预拉力的影响又与布索方案有关。此结论对于深入开展预应力钢结构火灾行为分析及其抗火设计具有重要的指导意义。
Pre-stressed steel structures is a kind of special structures which has been widely used in engineering practice.However,big changes of behaviour of the whole structures will take place if subjected to fire,which will result in structural failure.Hence,a computational model of the planar pre-stressed steel truss subjected to fire load is established based on the previous work about the structures at ambient temperature,with main consideration to the response mechanism of the structures in fire.The model provides the convenience that the cables with higher tensile strength used in the structures can be set arbitrarily and stretched more times.For the convenience of application,the EC3 constitutive model of the steel materials in fire is simplified,and the suggested formula for each stage are unified.The fire behaviour of the pre-stressed tubular steel trusses in which the cables are set in two different ways is analyzed with the model presented here and the effect of different factors on the bearing capacity of the structures in fire are discussed based on numerical results.It is shown that the plan of cable-setting,value of pre-tension,external loads and material grade have great effects on the behaviour and bearing capacity of the pre-stressed steel trusses in fire.Particularly,different plan of cable-setting results in different critical temperature.The bigger external loads correspond to the smaller critical temperature,and the effect of pre-tension on the temperature is dependent on the plan of cable-setting.The above conclusion can be used as a basis of in-depth analysis of fire behaviour of pre-stressed steel structures and fire-resistant design of the structures.
出处
《建筑结构学报》
EI
CAS
CSCD
北大核心
2010年第S2期210-214,共5页
Journal of Building Structures
基金
浙江省科技计划项目(2008C23013)
宁波市自然科学基金项目(2009A610138)
关键词
预应力钢桁架
索张拉
数值模型
火灾行为
pre-stressed steel truss
cable-pre-tension
fire behaviour
numerical model
