船舶工程英语(船舶危险状态下的纵向强度计算)

1、Longitudinal strength of ships with accidental damages船舶危险状态下的纵向强度计算 Abstract摘要This paper presents an investigation of the longitudinal strength of ships with damages due to grounding or collision accidents. 此文将提到关于船舶在搁浅和碰撞两种危险状况下的调查报告。Analytical equations are derived for the residual hull girder st

2、rength and verified with direct calculations of sample commercial ships for a broad spectrum of accidents. 给出了破损船体计算方程式和典型商船事故的直接计算方法。Hull girder ultimate strengths of these sample vessels under sagging and hogging conditions are also calculated, based on which correlation equations are proposed. 船体

3、梁在中垂和中拱下根据所给出的方程式计算极限强度。To evaluate a grounded ship, using the section modulus to the deck would be optimistic, while using the section modulus to the bottom would be conservative. 为了评估搁浅的船，计算时甲板的剖面模数要取得大些，而船底剖面模数要取得小些。 On the contrary, to evaluate a collided ship, using the section modulus to the d

4、eck would be conservative, while using the section modulus to the bottom would be optimistic. 相反的，在估算碰撞条件下船时甲板的剖面模数要取得小些，而船底剖面模数要取得大些。The derived analytical formulae are then applied to a fleet of 67 commercial ships, including 21 double hull tankers, 18 bulk carriers, 22 single hull tankers and six

5、 container carriers. 导出的方程适用于67系列商船，21型双壳油船，18型散货船，22型单壳油船和6型集装型船。The mean values, standard deviations and coefficients of variation for the coefficients in these new analytical formulae are obtained. 其主要数值、标准差、变动系数将从这些新的分析方程中获得。The ship length exhibits little influence on these coefficients because

6、 they are close to the mean values although ship length spans from 150 to 400 m. The ship type shows some influence on the residual strength. 船长对这些数值的影响是很小的，即使船长从150m长到400m。而船的类型不同将有对船的剩余强度有影响。Uniform equations are proposed for commercial ships which do not depend on a ships principal dimensions. Th

7、ese formulae provide very handy tools for predicting the residual strength in seconds, without performing step-by-step detailed calculations, an obvious advantage in cases of emergency or salvage operation. r 2002 Elsevier Science Ltd. All rights reserved. 统一的对于商船的方程式并不是基于船体主尺度的，这些方程将在下次预测剩余强度时很有作用，

8、并不需要再一步步的近似计算，在紧急情况下和补救的情况下。Keywords: Residual strength; Hull girder ultimate strength; Section modulus; Damage; Collision;Grounding1. Introduction1.简介 Traditionally, ships have been designed to resist all loads expected to arise in their seagoing environment. 一般的，船设计用于承受正常情况下的载重。 The objective in s

9、tructural design has been to maintain a ships structural integrity for normal operating conditions. 在船体结构设计方面，它的设计是维持船体结构完整和使船一般状况下的运行。A combination of the most severe loads is usually selected as the nominal design load. 通常以最多载荷的情况作为标准设计载况。 Protection of a ship and the cargo it carries from damages

10、 incurred by accidents, though an essential issue in the design of watercraft, has been focused on subdividing a ship into compartments. 为保存船只和它的货物不遭受损坏是船只设计的必要点，所以已经开始注重分舱设计。National and international standards (Load Line,MARPOL, SOLAS, Classification Societies Rules) have established requirements

11、or watertight bulkheads and subdivision. 我国和国际上已经制定了明确的标准来划分水密舱壁。Structural strength in collision, grounding or internal accidents (such as an explosion) has attracted very little attention. 而对于碰撞后的结构强度，搁浅或者内部受损并不受到关注。 Public sensation increases each time there is a major loss of ships, cargo and li

12、fe atsea, or when there is oil pollution from damaged ships. 公众的关注在逐渐增强关于船舶船舶失事、货船的海上生存能力，或者由于船失事而引起的海上石油污染。This motivates the development of design procedures and related analysis methods for accidental loads, in particular, the loads due to ship collision or grounding accidents. 这些促使设计和程序上在分析方式上的提

13、升在危险载况下，尤其是船在搁浅和碰撞下的载荷。 A ship may collapse after an accident because of inadequate longitudinal strength.However, the consequences of an accident on a ships strength are seldom investigated.Although there are some papers published on the residual strength of damaged ship hulls 1,2, this field still

14、 remains unexplored. 船可能在事故后断裂，由于纵向强度上的不足，然而船体强度的研究是很少的，虽然有一些关于剩余强度方面的文章，但有待深讨。 This paper reports on an investigation of the longitudinal strength of damaged ship hulls for a broad spectrum of collision and grounding accidents. 文章就一个关于纵向强度的调查提出报告，一个关于船体外壳碰撞和搁浅的调查。Both the hull girder section modulu

15、s and hull girder ultimate strength are calculated. 梁和桁架的剖面模数将考虑在内。We aim to obtain simple relations to assess residual hull girder strength, which may be used ashandy and reliable tools to help make timely decisions in the event of an emergency. 我们的目的在于获得一个方便可靠的关系式来评价剩余船体梁的强度，一个可以用在紧急的状况下方便可靠的方法去判定

16、的方法。Theoretical analyses are presented and analytical formulae are derived. Typical designs of 67 commercial ships, including 21 double hull tankers, 18 bulk carriers, 22 single hull tankers and six container carriers, which have lost portions of bottom shell plating and side shell plating, are anal

17、yzed to obtain such simple equations for predicting residual strength of damaged ships. 理论分析并得出解析公式。典型设计的67型商船，21型双壳油船，18型油船,22型单壳油船和6型集装箱船。当船在失去部分船底板和边板，将被分析并以此获得一个简单方程去推测破损船的的剩余强度。 2. Assumptions and analytical methods2. 假设和分析方法2.1. Section modulus of hull girders2.1船体剖面模数 It has been a proven pra

18、ctice to use simple beam theory to analyze the global bending of hull girders. Many experiments have confirmed that the bending behavior of ships agrees quite well with the beam theory. 它已被应用于实际中，以简支梁理论去分析船体的总纵弯曲，很多实验也已证明船体的实际弯曲与简支梁理论分析的结果十分符合。 The hull girder section modulus indicates the bending s

19、trength of the primary hull structures. 船体梁的剖面模数反应了船体结构主要的弯曲强度。The calculation of a midship section modulus is a very important step in basic ship design. 计算船体中横剖面模数是船体设计过程中相当重要的一个步骤。Structural members that are continuous in the longitudinal direction are included in the calculation of the section m

20、odulus. Only members that are effective in both tension and compression are assumed to act as part of the hull girder. 纵向连续构件参与剖面模数的计算，而将同时影响张力和压力的构件当作船体梁的部分。The section modulus to the deck or to the bottom is obtained by dividing the moment of inertia by the distance from the neutral axis to the mo

21、lded deck line at the side or to the base line, respectively. 船底部和上甲板处的剖面模数是通过将剖面对水平中和轴的惯性矩除以两者分别到中和轴的距离得到。2.2. Ultimate strength of hull girder2.2 船体的极限强度 The hull girder section modulus is an indicator of initial buckling or initial yielding, which is usually not the state at which the ship achiev

22、es its true maximum bending capacity. 船体的剖面模数只是初步的屈服强度的象征，而通常的并不代表船体受到的最大的弯曲强度。Plates and longitudinals may experience elastic buckling, plastic buckling, post buckling, yielding, and/or fracture in the process of approaching hull girder ultimate strength. 板材和骨材在拉伸逐步接近屈服极限的过程中会经历弹性弯曲、塑性变形、后屈曲、屈服、断裂。

23、 The so-called ultimate strength of hull girder corresponds to the maximum bending capacity beyond which the ship will break its back due to extensive yielding and buckling. 极限强度就是求得刚好让结构发生失稳时的那个应力值临界应力。 The continuous improvement of knowledge regarding the behavior of hull girders and structural me

24、mbers has led to the development of various methods.ISSC 2000 Special Task Committee VI.2 4 reviews the state-of-the-art technology for predicting hull girder ultimate strength. 对于船体梁和船体结构的认识的不断提高，致使各种方法上的提升。ISSC2000特别理事会引荐了state-of-the-art技术用于预测船体梁的极限强度。The committee conducted extensive benchmark c

25、alculations and assessed the uncertainties involved in these approaches. 该委员会进行了广泛的基准计算并对这些方法中的不确定度做了评测。Among all groups of approaches (closed-form formulae, simplified analytical methods and nonlinear FEM simulations), the simplified analytical methods are favored by most analysts. 在所有的方法中，简化分析法是最受

26、设计师们喜爱的， These approaches save modeling time; they generally account for fabrication imperfections and provide reliable results. 这种方法省略了建模的时间，它通常考虑先进行折减并能提供出可靠的结果，Extensive related studies have placed simplified methods as the first choice when one tries to calculate ultimate hull girder strength. A

27、 program of this kind, ALPS/ISUM3, is used in this investigation. 在大量的研究中已经将简化分析法作为他们估算极限强度的方法。2.3. Extent of damages2.3 破损度 Every accident is different. The resulting damage also varies. Accidents require many parameters to describe the damage a ship sustains after an accident. 每次的事故都是不一样的，导致的损失也是不

28、同的，船在事故后需要很多因数来描述船体的破损程度。A comprehensive description can easily fill a couple of pages or more, even though not all of the data is necessary for calculating hull girder strength. 一个精确的描述可以轻松的的概括几页的内容甚至更多，即使不是所有的数据在估算后船体强度时都是必须的。For simplicity, this paper uses definitions that are convenient for calc

29、ulation but retain the main characteristics of accidental damages. 简单的说，本文用的定义虽然方便了估计，但仍有例外的时候。 For a grounding, it is assumed that the bottom shell and the attached bottom longitudinals are lost. No girders are assumed to be damaged after a grounding. 对于搁浅，假设船底板和其纵向附体不计，同时主梁没有在搁浅的情况下损坏。This study i

30、nvestigates a broader range of bottom loss, up to 80% of ship breadth, to simulate minor to severe grounding damages. 这些研究调查了大量的搁浅事件，轻微受损直到80%的型宽从的严重损坏。 For a collision, it is assumed that the side shell and the attached longitudinals are lost. The damage starts from the deck at the side and extends

31、 downward. 对于碰撞损坏，假设边板和相关的纵向骨材不计，损坏从上甲板边缘开始到船体下端，The deck stringer plate and longitudinal bulkhead that attach to the damaged side are assumed to be intact after an accident. A broad range of side shell loss, ranging from 5% to about 40% of ship depth, is considered. 甲板边板和纵舱壁在假设中是完整的，大面积的舷侧外板的不计的从型深

32、的5%到40%处。 The assumptions mentioned above help to simplify the definition of damages. 这种上述提到的假设方法，用于简单的定义损坏，Only one parameter is used to describe the damage. Introduction of additional parameters is avoided. 只用一项系数来描述损坏，避免引进新的参数，The focus is on shell plating, the first barrier from water flooding.

33、Structures attached to the damaged shell are not considered with the assumption that they may be approximated by smearing as equivalent thickness of shell. 重点是船体与水的第一层屏障-船壳板，附体对于破损的船体来说可以不计，在假设是可作为污点来处理，相对于相对较厚度的船壳板。There exist other assumptions with regard to damage extents. In the ABS Guide for as

34、sessing hull-girder residual strength 5, a grounding damage includes bottom girders attached to the damaged bottom shell to a certain depth; collision damage includes deck stringer plate and slope bulkhead plating attached to the damaged side shell plating for a specified extent. 对于船体的破损程度有其它假设,在ABS

35、的规定中估算船体梁的剩余强度，搁浅损坏发生在船底船体梁的一定深度下。碰撞损坏包括甲板边板和舷侧舱壁。Paik et al. 1 defined collision and grounding damages according to this ABS Guide. For sensitivity studies, they analyzed 0.8 to 1.2 times the specified damage extents described in the ABS Guide. Paik以及其他人在定义碰撞和搁浅，并根据根据ABS规范作了进一步的研究，他们分析了ABS规范下0.8到1.

36、2范围的损坏。Wang et al. 2 analyzed a broad range of bottom damage, spanning from minor to substantial damage. Wang et al. also investigated cases where there is damage in bottom girders in additional to damage to the bottom shell. Wang以及他人分析了大量的船底损坏事件，从微小的到严重的，Wang以及他人也研究了船底梁损坏甚至船底板损坏的情况。2.4. Presentatio

37、n of results2.4 结果呈现 Two means are used to indicate the longitudinal bending strength of a ship hull: hull girder section modulus and ultimate hull girder strength. 有两种方法用于计算船体的纵向弯曲强度、主船体剖面模数和屈曲强度。Section modulii to thedeck and bottom, and ultimate bending strengths of hull girder under sagging and

38、hogging are calculated and presented in dimensionless format; all are compared with their values at intact condition. 甲板和船底的横剖面模数、船底屈曲强度在中垂和中拱情况下被估算并无因次化，且都与完整情况下作比较。 Bottom damage is expressed as a percentage of the ships breadth. Side damage extent is expressed as a percentage of the ships depth.

39、底部损坏被表示成与型宽的比值，舷侧的损坏程度被表示为与型深的比值。The investigation is focused on midship sections of typical commercial ships. 调查关注于典型商船船中剖面处。Sections beyond midship are not analyzed in this paper but the same analysis may be performed on those sections readily. 船中以外的剖面在此文中不作分析，但是要作相类似的分析并不难。3. Simple equations for

40、 the residual section modulus3. 简单一次方程式计算剩余剖面模数 Fig. 1 is a sketch of a transverse section, which characterizes the geometry of a ship and ignores many details. 图1是一幅横剖面草图，描绘了船的主要几何参数，略去一些多余的细节，This transverse section may be a double hull tanker, a bulk carrier, a container carrier, a single hull ta

41、nker or any other type of ship. 这可以代表一条双壳油船的横剖面、集装箱船、单壳油船或其它一些典型船，The shaded area is the assumed damage caused by either collision or grounding accident. 阴影部分假设是由于碰撞和搁浅儿失去的地方。 For an intact hull, the cross-sectional area, height of neutral axis above the base line, distance of the deck at the side to the neutral axis, moment of inertia and section modulus are A; z0; z1; I and eSMT0; respectively.