本文選題：簡支梁橋　切入點：彎梁橋　出處：《山東建筑大學》2014年碩士論文　論文類型：學位論文

【摘要】：立交橋廣泛應用于高速公路和城市快速道路中的交通網(wǎng)絡中,受地理環(huán)境和交通路線等方面的影響,立交橋一般由直線段和曲線段共同組成,且在運營過程中受各種外界因素的作用,由偶然事故、恐怖襲擊和戰(zhàn)爭等原因而引起的爆炸作用是不可忽視的,由于立交橋的不規(guī)則特性和復雜性,使得其抗爆性能更加脆弱。爆炸發(fā)生時,可能會使得橋梁發(fā)生局部鋼筋混凝土材料破壞、主梁脫落、甚至是連續(xù)性倒塌破壞。本文分別以立交橋中的簡支梁橋和彎梁橋為研究對象,運用顯式分析接觸算法,建立立交橋空間有限元計算模型,全面分析爆炸荷載作用下立交橋的動力響應和破壞模式。主要的研究內(nèi)容及研究成果有以下幾方面： 以單跨簡支T梁橋為工程研究對象,在靠近主梁左端橋面處放置1000kg炸藥,在爆炸過程中,只引起主梁局部區(qū)域破壞,并未引起橋梁整體倒塌破壞。在爆源點周圍局部區(qū)域內(nèi),距離爆炸點較近的橋梁構(gòu)件的受損程度大于距離炸藥稍遠的橋梁構(gòu)件。遠離爆炸點的橋梁構(gòu)件的損傷非常小,其受損程度與炸藥位置無直接關(guān)系。爆源附近的梁體受到猛烈的爆炸沖擊荷載后向下運動,而主梁端部卻出現(xiàn)明顯上翹。 在簡支T梁橋左端雙墩柱之間放置2000kg炸藥,則橋梁發(fā)生整體倒塌,其倒塌過程先后表現(xiàn)為左端墩柱底截面單元失效破壞、近爆梁端向下墜落、遠爆梁端從蓋梁滑落、近爆梁端碰撞地面、梁體在靠近跨中截面處折斷和遠爆梁端砸斷右側(cè)墩柱等破壞形態(tài)。因此,墩柱是簡支梁橋抗爆設計的關(guān)鍵構(gòu)件,對墩柱采取有效防護措施,可在一定程度上預防橋梁爆炸倒塌。 建立三跨連續(xù)剛構(gòu)彎梁橋的精細化有限元計算模型,分別在彎梁橋面的內(nèi)側(cè)、外側(cè)以及獨柱墩上方施加200kg炸藥的爆炸荷載。研究表明,爆炸作用顯著加劇了彎梁橋主梁的彎扭耦合程度,爆炸造成橋面局部范圍損傷,并不會引起橋梁的倒塌。距離爆源較遠區(qū)域的墩柱的損傷程度與炸藥的位置無關(guān),均表現(xiàn)出單柱墩損傷程度最高、雙柱墩中的外側(cè)墩柱損傷程度高于內(nèi)側(cè)墩柱等特點。 利用流固耦合法和“三階段法”分析彎梁橋獨柱墩柱腳處放置200kg炸藥的爆炸倒塌過程。獨柱墩底部單元在爆炸瞬間失效破壞,獨柱墩頂梁體在重力作用下逐漸下落,主梁右端支座發(fā)揮其約束作用,阻止主梁墜落,導致右端支座附近的梁底單元失效,于是主梁右端下落,繼而梁體懸臂根部折斷,最后梁體向曲線外側(cè)翻轉(zhuǎn)墜落。因此,在彎梁橋的爆炸抗倒塌設計中應加強支座等連接約束構(gòu)件的設計,并對彎梁橋的單柱墩采取加固防護措施。
[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.
【學位授予單位】：山東建筑大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U441;U448.17

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