爆炸作用下立交桥的动力响应与破坏模式

发布时间：2018-03-15 23:13

本文选题：简支梁桥　切入点：弯梁桥　出处：《山东建筑大学》2014年硕士论文　论文类型：学位论文

【摘要】：立交桥广泛应用于高速公路和城市快速道路中的交通网络中,受地理环境和交通路线等方面的影响,立交桥一般由直线段和曲线段共同组成,且在运营过程中受各种外界因素的作用,由偶然事故、恐怖袭击和战争等原因而引起的爆炸作用是不可忽视的,由于立交桥的不规则特性和复杂性,使得其抗爆性能更加脆弱。爆炸发生时,可能会使得桥梁发生局部钢筋混凝土材料破坏、主梁脱落、甚至是连续性倒塌破坏。本文分别以立交桥中的简支梁桥和弯梁桥为研究对象,运用显式分析接触算法,建立立交桥空间有限元计算模型,全面分析爆炸荷载作用下立交桥的动力响应和破坏模式。主要的研究内容及研究成果有以下几方面：以单跨简支T梁桥为工程研究对象,在靠近主梁左端桥面处放置1000kg炸药,在爆炸过程中,只引起主梁局部区域破坏,并未引起桥梁整体倒塌破坏。在爆源点周围局部区域内,距离爆炸点较近的桥梁构件的受损程度大于距离炸药稍远的桥梁构件。远离爆炸点的桥梁构件的损伤非常小,其受损程度与炸药位置无直接关系。爆源附近的梁体受到猛烈的爆炸冲击荷载后向下运动,而主梁端部却出现明显上翘。在简支T梁桥左端双墩柱之间放置2000kg炸药,则桥梁发生整体倒塌,其倒塌过程先后表现为左端墩柱底截面单元失效破坏、近爆梁端向下坠落、远爆梁端从盖梁滑落、近爆梁端碰撞地面、梁体在靠近跨中截面处折断和远爆梁端砸断右侧墩柱等破坏形态。因此,墩柱是简支梁桥抗爆设计的关键构件,对墩柱采取有效防护措施,可在一定程度上预防桥梁爆炸倒塌。建立三跨连续刚构弯梁桥的精细化有限元计算模型,分别在弯梁桥面的内侧、外侧以及独柱墩上方施加200kg炸药的爆炸荷载。研究表明,爆炸作用显著加剧了弯梁桥主梁的弯扭耦合程度,爆炸造成桥面局部范围损伤,并不会引起桥梁的倒塌。距离爆源较远区域的墩柱的损伤程度与炸药的位置无关,均表现出单柱墩损伤程度最高、双柱墩中的外侧墩柱损伤程度高于内侧墩柱等特点。利用流固耦合法和“三阶段法”分析弯梁桥独柱墩柱脚处放置200kg炸药的爆炸倒塌过程。独柱墩底部单元在爆炸瞬间失效破坏,独柱墩顶梁体在重力作用下逐渐下落,主梁右端支座发挥其约束作用,阻止主梁坠落,导致右端支座附近的梁底单元失效,于是主梁右端下落,继而梁体悬臂根部折断,最后梁体向曲线外侧翻转坠落。因此,在弯梁桥的爆炸抗倒塌设计中应加强支座等连接约束构件的设计,并对弯梁桥的单柱墩采取加固防护措施。
[Abstract]:The overpass is widely used in the traffic network of expressway and urban expressway. Affected by geographical environment and traffic route, the overpass is generally composed of straight line and curve section. And in the course of operation by various external factors, the explosion caused by accidental accidents, terrorist attacks and wars can not be ignored, due to the irregular characteristics and complexity of the overpass. It makes the anti-explosion performance more fragile. When the explosion occurs, the bridge may occur local reinforced concrete material damage and the main beam will fall off. In this paper, the simply supported beam bridge and the curved beam bridge in the overpass are taken as the research objects, and the spatial finite element calculation model of the overpass is established by using explicit contact analysis algorithm. The dynamic response and failure mode of overpass under explosive load are analyzed comprehensively. The main research contents and results are as follows:. Taking the single-span simply supported T-beam bridge as the research object, a 1000kg explosive was placed on the bridge deck near the left end of the main beam. During the explosion, it only caused local damage to the main beam, and did not cause the whole bridge to collapse. The damage of bridge members closer to the explosion point is greater than that of bridge members slightly away from the explosive. The damage of bridge members far from the explosion point is very small. The damage degree is not directly related to the location of the explosive. The beam body near the detonation source moves downward after being subjected to a violent blast shock load, but the main beam is obviously upwarped at the end of the beam. If 2000kg explosive is placed between two piers and columns at the left end of a simply supported T-beam bridge, the bridge collapses as a whole. The collapse process of the bridge occurs successively as the failure of the unit at the bottom section of the pier column at the left end, the falling down of the near exploding beam end, and the falling of the far exploding beam end from the cover beam. The beam body is broken near the middle section of the span and the pier column of the right side is broken by the end of the far blasting beam. Therefore, the pier column is the key component in the anti-explosion design of the simply supported beam bridge, and effective protection measures are taken to the pier column. To a certain extent, the bridge can be prevented from collapsing by explosion. The fine finite element model of three span continuous rigid frame curved beam bridge is established. The explosive load of 200 kg explosive is applied on the inside, outside of the curved beam deck and over the single column pier, respectively. The effect of explosion significantly intensifies the coupling degree of bending and torsion of the main beam of curved girder bridge. The explosion causes damage to the local area of the bridge deck and does not cause the bridge collapse. The damage degree of the pier column far from the detonation source is independent of the location of the explosive. All of them showed that the damage degree of single pillar pier was the highest, and the damage degree of lateral pier column in double column pier was higher than that of medial pier column. By using the fluid-solid coupling method and the "three-stage method", the explosion collapse process of 200 kg explosive placed at the foot of the single column pier of a curved beam bridge is analyzed. The unit at the bottom of the single column pier fails at the moment of explosion, and the beam body of the single column pier falls gradually under the action of gravity. The right end support of the main beam acts as a constraint to prevent the main beam from falling, which results in the failure of the beam bottom element near the right end support, so the right end of the main beam falls, and then the cantilever root of the beam is broken, and finally the beam body flips to the outer side of the curve. In the design of explosion resistance to collapse of curved beam bridge, the design of restrained members such as bearing should be strengthened, and the reinforcement and protection measures should be taken to the single column pier of curved beam bridge.
【学位授予单位】：山东建筑大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441;U448.17

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