城市桥梁爆炸失效机理及其安全评估方法研究

发布时间：2018-07-09 10:21

本文选题：城市桥梁 + 爆炸荷载　；参考：《天津大学》2014年硕士论文

【摘要】：城市桥梁作为陆地交通的咽喉，在国民经济和军事交通中均具有至关重要的地位和作用。它的建造不但方便了人们的出行，而且在高度快速、机动的现代生活中具有非常重要的地位。然而，随着日益严重的反恐形势，恐怖袭击或各种偶然爆炸等事故也越来越频繁，因此，炸弹爆炸所引发的城市桥梁爆炸失效问题越来越引起人们的重视。炸药在关键部位爆炸可能会给桥梁结构造成巨大的破坏，导致城市交通拥堵与中断，甚至造成大规模的人员伤亡。研究城市桥梁爆炸失效机理，及时地运用合理的方法确认出桥梁发生爆炸后的损伤状况，准确、科学地对桥梁结构的安全性进行评估具有重要意义。虽然对城市桥梁抗爆方面的研究已受到国内外研究人员和工程设计人员的广泛关注，但城市桥梁在爆炸荷载作用下的安全评估尚未得到足够程度的重视，取得的成果极其有限，很多成果无法直接应用于工程实践。因此，有必要提出一种实用且便捷的城市桥梁抗爆安全评估方法。基于已有成果，本文对城市桥梁爆炸失效机理及其安全评估方法开展了系统的研究，具体内容如下： 1、系统研究了爆炸基本现象、爆炸冲击波的基本理论，总结了爆炸冲击波各参数的经验计算公式。 2、系统阐述了爆炸荷载作用下城市桥梁失效机理与损伤机制的数值模拟方法。 3、根据爆炸荷载引起桥梁整体结构或者局部构件的损伤特点，并结合城市桥梁的现状，提出了一种用于评估爆炸荷载作用下城市桥梁安全性的数值模拟方法。首先提出了一种基于材料屈服强度和爆炸荷载作用后各控制截面上最大累积应力的安全指数的计算公式，然后分析城市桥梁在爆炸荷载作用下的动态响应，得到爆炸事故发生后桥梁控制截面上最大累积应力，从而计算出桥梁的安全指数，最终依据桥梁的安全指数对桥梁整体进行安全评估。 4、以国内某城市中心区主干道一座跨河的大型钢桁架组合拱桥为背景，建立有限元计算模型，运用大型非线性有限元软件ANSYS/LS-DYNA对该桥的动态响应以及安全性进行系统分析与评估，得出在不同计算工况下桥梁的安全性状况，，另外，通过不同工况的计算结果的对比，获得炸药量、炸药所在的车道位置以及纵桥向位置对桥梁安全性的影响规律。
[Abstract]:As the throat of land traffic, urban bridges play an important role in national economy and military traffic. Its construction not only facilitates people to travel, but also plays a very important role in the high speed and mobility of modern life. However, with the increasingly serious anti-terrorist situation, terrorist attacks or various accidental explosions are more and more frequent. Therefore, the explosion failure of urban bridges caused by bomb explosion has attracted more and more attention. Explosive explosion in key areas may cause great damage to the bridge structure, lead to traffic congestion and interruption, and even cause massive casualties. It is of great significance to study the failure mechanism of urban bridge explosion and confirm the damage condition of bridge after explosion by using reasonable method in time. It is of great significance to evaluate the safety of bridge structure scientifically and accurately. Although the research on anti-explosion of urban bridges has been widely concerned by researchers and engineers at home and abroad, the safety assessment of urban bridges under explosion load has not been paid enough attention to, and the results obtained are extremely limited. Many achievements can not be directly applied to engineering practice. Therefore, it is necessary to put forward a practical and convenient method for evaluating the anti-explosion safety of urban bridges. Based on the existing achievements, this paper has carried out a systematic study on the explosion failure mechanism and safety assessment methods of urban bridges. The specific contents are as follows: 1. The basic phenomena of explosion and the basic theory of explosion shock wave are systematically studied. The empirical formulas for calculating the parameters of explosion shock wave are summarized. 2. The numerical simulation method of failure mechanism and damage mechanism of urban bridge under explosion load is systematically expounded. The damage characteristics of the whole structure or local members of a bridge, Combined with the present situation of urban bridges, a numerical simulation method for evaluating the safety of urban bridges under explosive load is proposed. In this paper, a formula for calculating the safety index based on the maximum cumulative stress of each control section after material yield strength and explosive load is proposed, and then the dynamic response of urban bridges under explosion load is analyzed. The maximum accumulated stress on the control section of the bridge after the explosion accident is obtained, and the safety index of the bridge is calculated. Finally, according to the safety index of the bridge, the overall safety of the bridge is evaluated. 4. Taking a large steel truss composite arch bridge across the river in the main road of a central city in China as the background, the finite element calculation model is established. The dynamic response and safety of the bridge are systematically analyzed and evaluated by using the large-scale nonlinear finite element software ANSYS- LS-DYNA, and the safety conditions of the bridge under different calculation conditions are obtained. The influence of explosive quantity, lane position and longitudinal bridge position on bridge safety is obtained.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441

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