【作者】 徐东丰；

【导师】 巫祖烈；

【作者基本信息】 重庆交通大学 ， 结构工程， 2006， 硕士

【摘要】 本文首先介绍桥墩防撞装置的分类与型式、船舶撞击刚性桥墩的撞击力公式以及船舶碰撞桥墩的研究方法等,指出了目前防撞装置存在的不足,即装置结构尺寸偏大,且只保护桥而不保护车或船的问题。从实际工程应用出发,为了解决这一问题,提出了一种新型的泡沫铝桥墩防护装置。根据泡沫铝的压缩力学性能与能量吸收性能研究,发现泡沫铝的压缩应力-应变曲线存在很长的平台屈服区,且在压缩荷载作用下,泡沫铝在较低的应力水平既能产生很大的塑性变形,因此它是一种优良的缓冲吸能材料。为了解本文使用的泡沫铝的力学性能,进行了泡沫铝准静态压缩试验,并获得了一系列可靠的泡沫铝物理力学性能参数。其后,利用已有的研究成果,建立了简化的汽车与带有泡沫铝防护装置的桥墩相碰撞的数学模型和求解碰撞系统动态响应的外部动力学理论。根据冲击试验的原理,设计了模拟车-桥(船-桥)碰撞的试验系统,并对带有泡沫铝防护装置的桥墩进行摆锤冲击试验。通过大量的冲击试验,以应力与加速度为评价指标,对比分析了泡沫铝的不同厚度、不同结构型式、有无防撞装置等对桥墩作用的影响规律。试验结果表明:对于泡沫铝的普通结构,同一厚度,不同荷载作用下,桥墩的应力与加速度量值前后相差很大,且随着荷载增加两者均增大;不同厚度,同种荷载作用下,两者前后差异很小。对于桥墩防撞装置有、无的情形,同种荷载作用下,有防撞装置的桥墩相比裸墩,其应力与加速度显著减小,降幅均达到50%以上。而对于不同类型的泡沫铝结构,在保护桥墩方面,由于加工因素的影响,相比于普通结构型式,异型结构的优越性不是很明显。在试验基础上,利用大型有限元软件ANSYS/LS-DYNA对车-桥(船-桥)碰撞进行了模拟计算,计算与试验结果吻合较好。通过计算得出了泡沫铝吸能曲线、铁球的撞击动能曲线、铁球速度曲线与撞击力曲线等。有限元计算表明:同种荷载作用下,泡沫铝厚度不同,撞击力基本相同;泡沫铝同一厚度,不同荷载作用下,但随着荷载的增加,撞击力曲线先是略微降低,后又增加的趋势。相比于裸墩,泡沫铝防护装置能降低2倍以上的撞击力。试验和计算表明:相对于承受相同荷载的裸墩,泡沫铝桥墩防护装置均能显著降低荷载对桥墩的作用,并且可以同时保护车-桥(船-桥)。因此,泡沫铝桥墩防护装置是一种优良的桥墩防护系统。更多还原

【Abstract】 This paper introduces the classification and types of pier’s protection devices, ship-pier impact force formula, and ship-pier collision researching method etc. And points out the disadvantages of the current protection devices of piers, which is that the structural dimensions is too huge to protect the ship, they can only protect bridges. Considering practical engineering application, a new type of foam aluminum protection device of piers is advanced to solve the question.According to research of static mechanical properties and energy absorption properties of foam aluminum, it is found that compressive stress-strain curve is long plastic yield platform, which leads to large plastic deformation of foam aluminum with lower stress levels under compressive load. Therefore, it is concluded that foam aluminum is an excellent buffering and energy-absorbing material. To explore the mechanical properties of foam aluminum used in this paper, quasi-static compression test of foam aluminum is conducted, and a series of reliable experimental data is obtained.Then,based on the existed achievements, mathematic model of automobile colliding with pier with foam aluminum protection device is simplified to build exterior dynamics theory of colliding systems.Based on the principles of impact experiments, this paper designs impact system to simulate collision of automobile with bridge (ship- bridge), and carries out collision experiments of pendulum with pier of foam aluminum protection device. Through a number of tests, judging from acceleration and stress, different thickness of foam aluminum, different structural types and piers with devices or not are contrastively analyzed to get their disciplinary effect on piers. The experiment results show that, for common structure of foam aluminum , under the same thickness and different loads, its stress and acceleration in addition differences evidently, and both increasing with load increasing; under the same load but different thickness, both vary little;comparing pier with device with pier, the stress and acceleration of pier with device is remarkable lower than that of its contrast;for different structure of foam aluminum, the structure with bore is superior than pier due to processing effect on protecting pier.Based on the test, collision of automobile with bridge (ship-bridge) is analyzed resorting of the large-scale finite element LS-DYNA, and calculation results fit the experiment results well. By means of the analyses, internal energy-time curve of foam aluminum, kinetic energy–time curve and velocity-time curve of iron ball, and impact force-time curve are obtained. Analysis results of the finite element indicate that, for different thickness of foam aluminum, impact force is basically equal under the same load, impact force-time curve fall at the beginning, then rise when the load increase. comparing with impact force of pier, that of the pier with aluminum protection device can reduce 2 times.The experiments and calculations show that aluminum protection device can decrease the effect of the load on pier evidently, at the same time it can protect automobile- bridge (ship- bridge), therefore, foam aluminum device of piers is an eminent protection system of piers.更多还原