索张拉预应力钢结构火灾行为研究

发布时间：2018-04-02 13:13

本文选题：索张拉　切入点：预应力钢结构　出处：《宁波大学》2013年硕士论文

【摘要】：火灾是对人类生命财产安全威胁最大的灾害之一，如何减小建筑物火灾的危害性一直是人们关注的课题。预应力钢结构的优点是可以节省材料、提高承载能力、充分发挥材料的强度潜力、能获得较大的经济效益，因而其应用也越来越广泛。但预应力钢结构也有显著的缺点，就是不耐火。通过对高强度索的张拉实现对钢结构施加预应力就形成了索张拉预应力钢结构。这种结构具有巨大的内部能量，高强度索在火灾条件下受到高温的作用会发生松弛而导致预应力的损失，可能引起结构的突然破坏，从而对人类生命财产造成严重威胁。因此，对索张拉预应力钢结构火灾下的力学性能研究具有重要的理论意义和工程应用价值。不锈钢材料具有良好的力学性能及优越的抗腐蚀性能，特别是具有较高的高温下强度。本文首先对一组共12个由SUS304不锈钢薄壁圆管制成的索张拉预应力钢桁架进行了火灾下及火灾后的试验研究，考察了不同的受火温度、不同的结构刚度、不同的张拉方式、不同的荷载大小对结构力学性能的影响。然后利用有限元软件Marc对该组钢桁架在实测火灾温度条件下的力学性能进行了模拟计算，并与试验实测结果进行了比较。研究结果表明，，由304不锈钢管制成的预应力空间桁架具有较高的承载力和较强的变形能力，结构破坏的主要形式是整体失稳，结构破坏的原因主要在于火灾高温条件下高强度索发生了松弛，预应力受到了较大的损失。在其他条件相同时单因素对结构性能的影响表现为：火灾下的受火温度对结构挠度有非常重要的影响，一般是温度越高则结构发生的挠度就越大;结构刚度越大，则在火灾下发生的挠度会越小;荷载量越大，则结构在火灾下发生的挠度会越大;在减小火灾下结构的挠度方面，二次张拉要比一次张拉的效果更好;所施加的预应力值越大，则结构在火灾下发生的挠度会越小。Marc软件的模拟结果与火灾下试验结果基本吻合，具有较高的参考价值。
[Abstract]:Fire is one of the most dangerous disasters to the safety of human life and property.The advantage of prestressed steel structure is that it can save the material, improve the bearing capacity, give full play to the strength potential of the material, and obtain greater economic benefits, so its application is becoming more and more extensive.But the prestressed steel structure also has the obvious drawback, namely does not have the fire resistance.This kind of structure has huge internal energy, and the high strength cable under the action of high temperature will relax and lead to the loss of prestressing force, which may cause the sudden destruction of the structure, thus causing a serious threat to human life and property.Therefore, it has important theoretical significance and engineering application value to study the mechanical properties of cable-tensioned prestressed steel structures under fire.Stainless steel has good mechanical properties and excellent corrosion resistance, especially high strength at high temperature.In this paper, a group of 12 cable-tensioned prestressed steel trusses made of SUS304 stainless steel thin-walled circular pipes are studied under fire and after fire. Different fire temperatures, different structural stiffness and different tension modes are investigated.The influence of different loads on the mechanical properties of the structure.Then the finite element software Marc is used to simulate the mechanical properties of the steel truss under the condition of the measured fire temperature, and the results are compared with the experimental results.The results show that the prestressed space truss made of 304 stainless steel pipe has higher bearing capacity and stronger deformation capacity, and the main form of structural failure is overall instability.The main reason of structural failure is that the high strength cable is loosened and the prestress is lost greatly under the condition of fire and high temperature.When other conditions are the same, the effect of single factor on the structure performance is as follows: the temperature of fire has a very important effect on the deflection of the structure, generally, the higher the temperature, the bigger the deflection of the structure and the greater the stiffness of the structure.The smaller the deflection under fire; the greater the load, the greater the deflection of the structure under fire; in reducing the deflection of the structure under fire, the effect of secondary tension is better than that of primary tension; and the greater the value of prestress applied,Then the deflection of the structure under fire will be smaller. Marc software simulation results are in good agreement with the experimental results under fire, which has a higher reference value.
【学位授予单位】：宁波大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU394

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