Simulation of the Whole Process of Ship-Bridge Collision

The simulation of the whole ship-bridge collision process can be effectively carried out by nonlinear dynamic finite element method. Based on the simple description of the theory, a scenario of a 40000 DWT oil tanker colliding with a bridge across the Yangtze River is designed for simulation. The technology of structure modeling and the determination of related parameters are introduced. The deformation of the bulb bow, the history,of collision force change, the exchange of collision energy and the stress distribution. of the bridge pier-are described in detail, which: are of great value to bridge design and bridge pier damage estimation. mechanical characters in the process of ship-bridge collision are described. More accurate results can be produced by finite element method than that by empirical formulas and simplified analytical methods.

Fast evaluation of ship-bridge collision force based on nonlinear numerical simulation

The max collision force of ship-bridge collision is one of the most important references for bridge design. By means of nonlinear digital simulation method, the collision forces of the collisions between rigid bridge pier and ship bow were calculated out for four different ships, whose tonnages are 5000,10000,50000 and 60000 DWT respectively. Curves of collision force-penetration and absorbed energy-penetration are obtained, and the data of the max loads are then summarized. On the basis of these curves and data, a set of curves describing the relationships between max collision forces and tonnages of the ships are successfully presented, by which the max collision forces of the ships-bridge with different tonnages and in different velocities can be estimated easily and reliably.

Statistical Analysis of Ship Collisions with Bridges in China Waterway

Having carried out investigations on ship collision accidents with bridges in waterway in China, a database of ship collision with bridge (SCB) is developed in this paper. It includes detailed information about more than 200 accidents near ship's waterways in the last four decades, in which ships collided with the bridges. Based on the information a statistical analysis is presented tentatively. The increase in frequency of ship collision with bridges appears, and the accident quantity of the barge system is more than that of single ship. The main reason of all the factors for ship collision with bridge is the human errors, which takes up 70%. The quantity of the accidents happened during flooding period shows over 3～6 times compared with the period from March to June in a year. The probability follows the normal distribution according to statistical analysis. Visibility, span between piers also have an effect on the frequency of the accidents.

Calculation method of ship collision force on bridge using artificial neural network

Ship collision on bridge is a dynamic process featured by high nonlinearity and instantaneity. Calculating ship-bridge collision force typically involves either the use of design-specification-stipulated equivalent static load, or the use of finite element method (FEM) which is more time-consuming and requires supercomputing resources. In this paper, we proposed an alternative approach that combines FEM with artificial neural network (ANN). The radial basis function neural network (RBFNN) employed for calculating the impact force in consideration of ship-bridge collision mechanics. With ship velocity and mass as the input vectors and ship collision force as the output vector, the neural networks for different network parameters are trained by the learning samples obtained from finite element simulation results. The error analyses of the learning and testing samples show that the proposed RBFNN is accurate enough to calculate ship-bridge collision force. The input-output relationship obtained by the RBFNN is essentially consistent with the typical empirical formulae. Finally, a special toolbox is developed for calculation efficiency in application using MATLAB software.

Study on dangerous collision area of ships out of control in Sutong Bridge area

Motion state of ship out of control in bridge area was analyzed.Motion procedure after losing control was divided into two steps.One is drift step within stopping period.The other is drift step without inertia,which is induced by wind and current.Mathematical model for motion of ship out of control,considering wind-induced drift,current-induced drift,stopping ability,etc.,was established.Dangerous collision areas for main pier and auxiliary piers were analyzed according to different calculation conditions.

Simulation Analysis on Navigation Indexes of Wanzhou Yangtze River Highway Bridge after the Anti-Collision Device Construction by Ship Model Test

After the anti-collision facility construction of Wanzhou Yangtze River Highway Bridge, the conditions of navigation in bridge area are complex. In order to study the navigation conditions of the reach and layout optimization measures, ensuring the safety of the ship navigation test has been carried out on the ship model navigation in the bridge area. According to the requirements of the maximum safety limit of the ship model test, the paper puts forward the best route, the control method and the difficulty of navigation through the analysis of the test results, and finally gives the recommendations and suggestions.

Numerical Simulation for Progressive Collapse of Continuous Girder Bridge Subjected to Ship Impact

The three-stage simulation method based on LS-DYNA was introduced in this study to simulate the progressive collapse of a continuous girder bridge after a ship-bridge collision. The pile-soil dynamic interaction and the initial stress and deformation of the whole bridge before the collision were considered. By analyzing the damage, deformation, stress distribution and collapse process of the whole bridge, the results show that the displacement response of the cap beam lags behind the pile cap. The response order of the whole bridge's components depends on their distances from the collision region. The plastic deformation of soil around piles has a positive effect on delaying the further increase in the displacement of piles. The impacted pier's losing stability and its superstructure's excessive deformation are the main reasons leading to the progressive collapse of the continuous girder bridge.

Simulation and Reasonable Design of Bridge Steel Fenders to Reduce Ship Impacts

Steel fenders are increasingly used for ship-impact resistance structures in the design of navigable bridges. As an important approach to investigating this anti-impact structure effectiveness to reduce influences of vessel impact, simulation analyses are still not perfect yet. So this paper is intended to discuss several issues related to ship collision simulations, including steel constitutive relationship, connections between steel box and pile cap, contacts definition and friction consideration, and the determination of impact waterlines and angles. Consequently based on two examples of ship-steel fender-bridge structure systems, some conclusions about effectiveness and design of fenders to reduce ship impact are drawn.

基于性能的通航桥梁抗船撞评估方法及应用研究

为合理有效地开展通航桥梁抗船撞性能评估,提出基于性能的桥梁抗船撞标准化评估方法。基于现行《公路桥梁抗撞设计规范》(JTG/T 3360-02-2020),从抗撞性能等级确定、设防代表船型确定、船撞力计算、船撞效应计算以及抗撞性能验算等方面,采用结构性能目标作为评估准则,建立桥梁抗撞性能评估各环节流程的标准化评估方法。以江苏扬中三桥为应用实例,运用该方法进行该桥20号墩抗撞性能评估,结果表明:20号墩桩基顺桥向抗弯性能不满足JX1级要求,其余验算结果满足要求,桥墩抗撞性能综合评估结果为不满足要求。参照评估结果该桥加装了浮动式防撞设施。桥梁抗撞性能评估标准化,可准确高效实现桥梁抗撞性能等级确定、船撞效应计算、抗撞性能验算等预期的评估功能要求。

桥墩倾斜方向对自浮式防撞装置防护效果影响研究

随着航道上大跨度桥梁的建设愈加广泛,其桥墩在水面附近往往具有一定的倾斜角度。为研究桥墩倾斜方向对自浮式防撞装置防护效果的影响,文章基于装备自浮式防撞装置的2种倾斜方向的桥墩与6000DWT级散货船为研究对象进行非线性有限元仿真碰撞计算,分析桥墩倾斜方向对不同航速船舶撞击下桥墩撞击力、系统能量转换、船艏结构破坏的影响。结果表明:外倾式桥墩受到撞击力更小,其防撞装置通过变形吸收能量更多、防护效果更好。研究成果可为大跨度桥墩设计与防撞装置的开发提供重要的参考价值。

山区河流典型桥梁船撞概率分析模型比较

船撞桥概率是多学科交叉融合、多因素影响的复杂研究,目前山区河流中梁桥和拱桥在计算船撞桥概率选取规范模型时不太相同。现有船撞桥概率模型及适用条件有所不同,采用美国AASHTO规范模型、LARSEN模型以及三概率参数积分模型,开展船舶对山区河流典型桥梁撞击概率及规律分析。通过分析连续钢构梁桥、上承式拱桥两种桥型的桥在最高、最低通航水位下涉水桥墩的年撞击概率,分析水位变化对年撞击概率的影响规律,得到山区河流梁桥和拱桥的模型适用性。结果表明,三种规范模型下的年撞击概率皆随着通航量的增加而不断增加,AASHTO模型与三概率参数模型,对于梁桥的概率计算结果变化趋势大致相似;对于拱桥,三概率参数积分模型对拱桥撞击横向、纵向位置的变化较为敏感,更适用于山区水位变化较大的拱桥。成果可为不同桥型在船撞概率模型选取提供参考。

A nonlinear dynamic macro-element for demand assessment of bridge substructures subjected to ship collision

For the dynamic demand assessment of bridge structures under ship impact loading,it may be prudent to adopt analytical models which permit rapid analysis with reasonable accuracy.Herein,a nonlinear dynamic macro-element is proposed and implemented to quantify the demand of bridge substructures subjected to ship collisions.In the proposed nonlinear macro-element,a combination of an elastic-plastic spring and a dashpot in parallel is employed to describe the mechanical behavior of ship-bows with strain rate effects.Based on the analytical model using the proposed macro-element,a typical substructure under 5000 deadweight tonnage(DWT) ship collision is discussed.Our analyses indicate that the responses of the structure using the nonlinear macro-element agree with the results from the high resolution model,but the efficiency and feasibility of the proposed method increase significantly in practical applications.Furthermore,comparisons between some current design codes(AASHTO,JTGD60-2004,and TB10002.1-2005) and the developed dynamic analysis method suggest that these design codes may be improved,at least to consider the effect of dynamic amplification on structural demand.

张靖皋长江大桥南航道桥南塔防撞方案研究

张靖皋长江大桥南航道桥为主跨2300 m的双塔双吊跨钢箱梁悬索桥,桥下船舶通航密度大、船舶平均吨位大、船舶碰撞概率高、南塔所受船撞力计算值大。经综合分析,传统被动防撞方案均不能很好满足南塔防撞要求,故提出采用锁口钢管桩围堰外挂软体护舷的新型防撞方案。该防撞方案通过在承台外围设锁口钢管桩围堰形成裙墙,在围堰外侧外挂软体护舷,并在围堰与承台之间空隙处填充耗能材料实现防撞及消能,裙墙同时兼作临时施工围水设施以及起到永久冲刷防护和船撞消能作用。为验证新型防撞装置的防撞效果并选择合适的耗能材料,进行船桥碰撞有限元分析。最终采用填充沙粒的新型防撞装置方案,该方案可削减36.68%南塔承台撞击力,防撞效果好。新型防撞方案施工简单,后期仅需对钢管桩作防腐处理,撞后便于修复,工程造价低。

考虑桩-水-土耦合的船桥碰撞损伤特性

船桥碰撞问题是一种复杂的非线性动力学问题,现存规范经验公式只能对其最大碰撞力进行预测,无法全面预测船-桥结构的损伤特性,而有限单元法可有效地对这一不足进行补充。通过LS-DYNA软件研究考虑桩土作用和流固耦合效应的船桥碰撞损伤特性,通过数值仿真与试验结果、AASHTO规范公式的对比分别验证钢筋混凝土材料模型的准确性以及桩-水-土耦合方法的有效性;分析典型碰撞场景下船舶和桥墩桩基结构的碰撞损伤特性;讨论船速和船撞角度等因素对船桥碰撞损伤的影响。结果表明:典型船桥碰撞场景下船舶和桥墩结构的损伤均较为严重;船撞速度、角度越大,碰撞力峰值也越大;桩土作用和流固耦合效应均不可忽略。该结果可为船舶和桥墩结构设计提供一定参考。

分离式楔形桥船防撞结构的有限元仿真分析

桥船防撞结构是保护桥梁和船舶免受碰撞事故影响的重要装置。本文采用有限元方法,对为满足航道通航升级而设计的楔形桥梁防撞结构进行了船舶撞击仿真模拟,分析了不同撞击位置、不同撞击角度下防撞墩的应力分布情况。

船桥碰撞非线性数值仿真研究

为了研究湘江流域典型桥梁船桥碰撞时的撞击力和能量转换过程,为后续大桥的防船撞设计提供参考,以株洲建宁大桥为研究背景,按照实际尺寸建立货船和桥墩模型,并使用ABAQUS有限元软件对其进行非线性动力仿真分析,研究了船桥碰撞过程中,船的撞击速度、吨位和撞击角度对撞击力的影响,以及船的变形情况和船桥碰撞中的能量转化关系。研究结果表明:船撞力峰值和船速存在正相关关系;船舶的吨位越大,撞击力峰值越大并且撞击的时间越长;船的撞击角度与碰撞时间之间没有呈现出明显的规律;船的撞击速度、吨位和撞击角度3种影响因素对船桥碰撞的撞击力和船体变形均有影响,但主要因素还是船速和船的吨位;在碰撞过程中,船的撞击动能基本转化为塑性变形能,船体变形主要集中在船艏碰撞区域,远离碰撞区域的船身部位没有明显的变形。

船桥撞击力的神经网络预测与经验公式研究

为了减少船舶与桥梁撞击对人身和财产安全造成的危害,研究船舶与桥梁撞击力的最大值及其与其他影响因素之间的关系具有十分重要的意义。该文首先利用ANSYS/LS-DYNA软件建立了船舶撞桥的有限元模型,计算了不同撞击速度和撞击角度下船桥撞击力的最大值,并将计算结果与各国规范进行比较;然后,利用反向传播(back propagation,BP)神经网络技术,结合仿真计算数据,在最大撞击力值、撞击速度和撞击角度这3个训练参数下,创建了船桥最大撞击力的预测模型;最后,通过分析撞击速度和角度的散点图,拟合了1个最大撞击力与撞击速度和角度关系的经验公式,并将经验公式、有限元仿真计算结果和神经网络预测结果进行比较,验证了经验公式的准确性。该研究为快速评估船桥撞击是否会导致灾难性后果提供了1种有效的方法。

浮式钢防撞箱受力性能数值分析

浮式钢防撞箱在船桥碰撞中具有良好的塑性吸能防撞性能。为探究影响防撞箱防撞性能的因素,该文基于有限元软件Ansys/LS-DYNA,建立了船-防撞箱-桥墩系统碰撞模型,对碰撞机理及过程进行数值模拟,探讨防撞箱与桥墩连接方式、尖舱尖角、防撞箱刚度等对桥墩所受撞击力的影响,提出撞击力曲线的三阶段划分方法。分析表明:浮式防撞箱内壁直接固结、与桥墩外壁耦合连接会降低撞击力,最大撞击力随着防撞箱与桥墩间距的增大而变大;防撞箱尖舱尖角宜取为80°~100°;防撞箱碰撞区钢板厚度存在一个最优值;最大撞击力随着非碰撞区钢板厚度的增大而变大,超过8 mm增大幅度降低。

基于LS-DYNA的船-桥墩碰撞分析

基于ANSYS/LS-DYNA及Hypermesh建立了船舶-桥墩碰撞有限元模型,着重针对一典型工况对桥墩遭受撞击作用后的动力响应进行分析并确定其失效模式。然后通过模拟一系列的船舶撞击桥墩的工况为船撞力简化计算公式的拟合提供大量的数据样本并对得到的数据进行统计分析拟合出船撞力的简化计算公式,并与国内外相关规范的规定进行对比分析,相关结果表明,我国规范中规定的船舶撞击力相对偏小。

基于有限元法的桥梁抗船撞性能计算分析

跨越内河通航水域的桥梁不断增多,船舶大型化发展已成为大发展趋势,船舶碰撞桥梁的风险日趋加大,迫切需要按照航道区段标准统一的要求,提出实施范围航道区段设防代表船型、船队,并在此基础上开展桥梁安全风险隐患自查评估。针对桥梁的船撞性能进行研究,包括:墩/柱抗弯强度验算、墩/柱抗剪强度验算、墩/柱弯曲变形性能验算等,在此基础上给出增设固定式钢覆复合材料防撞设施、加装主动预警装置等有效建议,提高桥墩的抗撞性能,对日后防范桥梁安全风险隐患有重要意义。