船舶工程英語(yǔ)(船舶危險(xiǎn)狀態(tài)下的縱向強(qiáng)度計(jì)算)

1、Longitudinal strength of ships with accidental damages船舶危險(xiǎn)狀態(tài)下的縱向強(qiáng)度計(jì)算 Abstract摘要This paper presents an investigation of the longitudinal strength of ships with damages due to grounding or collision accidents. 此文將提到關(guān)于船舶在擱淺和碰撞兩種危險(xiǎn)狀況下的調(diào)查報(bào)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. 給出了破損船體計(jì)算方程式和典型商船事故的直接計(jì)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. 船體

3、梁在中垂和中拱下根據(jù)所給出的方程式計(jì)算極限強(qiáng)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. 為了評(píng)估擱淺的船，計(jì)算時(shí)甲板的剖面模數(shù)要取得大些，而船底剖面模數(shù)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，在估算碰撞條件下船時(shí)甲板的剖面模數(shù)要取得小些，而船底剖面模數(shù)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. 導(dǎo)出的方程適用于67系列商船，21型雙殼油船，18型散貨船，22型單殼油船和6型集裝型船。The mean values, standard deviations and coefficients of variation for the coefficients in these new analytical formulae are obtained. 其主要數(shù)值、標(biāo)準(zhǔn)差、變動(dòng)系數(shù)將從這些新的分析方程中獲得。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. 船長(zhǎng)對(duì)這些數(shù)值的影響是很小的，即使船長(zhǎng)從150m長(zhǎng)到400m。而船的類型不同將有對(duì)船的剩余強(qiáng)度有影響。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. 統(tǒng)一的對(duì)于商船的方程式并不是基于船體主尺度的，這些方程將在下次預(yù)測(cè)剩余強(qiáng)度時(shí)很有作用，

8、并不需要再一步步的近似計(jì)算，在緊急情況下和補(bǔ)救的情況下。Keywords: Residual strength; Hull girder ultimate strength; Section modulus; Damage; Collision;Grounding1. Introduction1.簡(jiǎn)介 Traditionally, ships have been designed to resist all loads expected to arise in their seagoing environment. 一般的，船設(shè)計(jì)用于承受正常情況下的載重。 The objective in s

9、tructural design has been to maintain a ships structural integrity for normal operating conditions. 在船體結(jié)構(gòu)設(shè)計(jì)方面，它的設(shè)計(jì)是維持船體結(jié)構(gòu)完整和使船一般狀況下的運(yùn)行。A combination of the most severe loads is usually selected as the nominal design load. 通常以最多載荷的情況作為標(biāo)準(zhǔn)設(shè)計(jì)載況。 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. 為保存船只和它的貨物不遭受損壞是船只設(shè)計(jì)的必要點(diǎn)，所以已經(jīng)開(kāi)始注重分艙設(shè)計(jì)。National and international standards (Load Line,MARPOL, SOLAS, Classification Societies Rules) have established requirements

11、or watertight bulkheads and subdivision. 我國(guó)和國(guó)際上已經(jīng)制定了明確的標(biāo)準(zhǔn)來(lái)劃分水密艙壁。Structural strength in collision, grounding or internal accidents (such as an explosion) has attracted very little attention. 而對(duì)于碰撞后的結(jié)構(gòu)強(qiáng)度，擱淺或者內(nèi)部受損并不受到關(guān)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. 公眾的關(guān)注在逐漸增強(qiáng)關(guān)于船舶船舶失事、貨船的海上生存能力，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. 這些促使設(shè)計(jì)和程序上在分析方式上的提

13、升在危險(xiǎn)載況下，尤其是船在擱淺和碰撞下的載荷。 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. 船可能在事故后斷裂，由于縱向強(qiáng)度上的不足，然而船體強(qiáng)度的研究是很少的，雖然有一些關(guān)于剩余強(qiáng)度方面的文章，但有待深討。 This paper reports on an investigation of the longitudinal strength of damaged ship hulls for a broad spectrum of collision and grounding accidents. 文章就一個(gè)關(guān)于縱向強(qiáng)度的調(diào)查提出報(bào)告，一個(gè)關(guān)于船體外殼碰撞和擱淺的調(diào)查。Both the hull girder section modulu

15、s and hull girder ultimate strength are calculated. 梁和桁架的剖面模數(shù)將考慮在內(nèi)。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. 我們的目的在于獲得一個(gè)方便可靠的關(guān)系式來(lái)評(píng)價(jià)剩余船體梁的強(qiáng)度，一個(gè)可以用在緊急的狀況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. 理論分析并得出解析公式。典型設(shè)計(jì)的67型商船，21型雙殼油船，18型油船,22型單殼油船和6型集裝箱船。當(dāng)船在失去部分船底板和邊板，將被分析并以此獲得一個(gè)簡(jiǎn)單方程去推測(cè)破損船的的剩余強(qiáng)度。 2. Assumptions and analytical methods2. 假設(shè)和分析方法2.1. Section modulus of hull girders2.1船體剖面模數(shù) 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. 它已被應(yīng)用于實(shí)際中，以簡(jiǎn)支梁理論去分析船體的總縱彎曲，很多實(shí)驗(yàn)也已證明船體的實(shí)際彎曲與簡(jiǎn)支梁理論分析的結(jié)果十分符合。 The hull girder section modulus indicates the bending s

19、trength of the primary hull structures. 船體梁的剖面模數(shù)反應(yīng)了船體結(jié)構(gòu)主要的彎曲強(qiáng)度。The calculation of a midship section modulus is a very important step in basic ship design. 計(jì)算船體中橫剖面模數(shù)是船體設(shè)計(jì)過(guò)程中相當(dāng)重要的一個(gè)步驟。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. 縱向連續(xù)構(gòu)件參與剖面模數(shù)的計(jì)算，而將同時(shí)影響張力和壓力的構(gòu)件當(dāng)作船體梁的部分。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. 船底部和上甲板處的剖面模數(shù)是通過(guò)將剖面對(duì)水平中和軸的慣性矩除以兩者分別到中和軸的距離得到。2.2. Ultimate strength of hull girder2.2 船體的極限強(qiáng)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. 船體的剖面模數(shù)只是初步的屈服強(qiáng)度的象征，而通常的并不代表船體受到的最大的彎曲強(qiáng)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極限的過(guò)程中會(huì)經(jīng)歷彈性彎曲、塑性變形、后屈曲、屈服、斷裂。

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. 極限強(qiáng)度就是求得剛好讓結(jié)構(gòu)發(fā)生失穩(wěn)時(shí)的那個(gè)應(yīng)力值臨界應(yīng)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. 對(duì)于船體梁和船體結(jié)構(gòu)的認(rèn)識(shí)的不斷提高，致使各種方法上的提升。ISSC2000特別理事會(huì)引薦了state-of-the-art技術(shù)用于預(yù)測(cè)船體梁的極限強(qiáng)度。The committee conducted extensive benchmark c

25、alculations and assessed the uncertainties involved in these approaches. 該委員會(huì)進(jìn)行了廣泛的基準(zhǔn)計(jì)算并對(duì)這些方法中的不確定度做了評(píng)測(cè)。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，簡(jiǎn)化分析法是最受

26、設(shè)計(jì)師們喜愛(ài)的， These approaches save modeling time; they generally account for fabrication imperfections and provide reliable results. 這種方法省略了建模的時(shí)間，它通?？紤]先進(jìn)行折減并能提供出可靠的結(jié)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. 在大量的研究中已經(jīng)將簡(jiǎn)化分析法作為他們估算極限強(qiáng)度的方法。2.3. Extent of damages2.3 破損度 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樣的，導(dǎo)致的損失也是不

28、同的，船在事故后需要很多因數(shù)來(lái)描述船體的破損程度。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. 一個(gè)精確的描述可以輕松的的概括幾頁(yè)的內(nèi)容甚至更多，即使不是所有的數(shù)據(jù)在估算后船體強(qiáng)度時(shí)都是必須的。For simplicity, this paper uses definitions that are convenient for calc

29、ulation but retain the main characteristics of accidental damages. 簡(jiǎn)單的說(shuō)，本文用的定義雖然方便了估計(jì)，但仍有例外的時(shí)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. 對(duì)于擱淺，假設(shè)船底板和其縱向附體不計(jì)，同時(shí)主梁沒(méi)有在擱淺的情況下?lián)p壞。This study i

30、nvestigates a broader range of bottom loss, up to 80% of ship breadth, to simulate minor to severe grounding damages. 這些研究調(diào)查了大量的擱淺事件，輕微受損直到80%的型寬從的嚴(yán)重?fù)p壞。 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. 對(duì)于碰撞損壞，假設(shè)邊板和相關(guān)的縱向骨材不計(jì)，損壞從上甲板邊緣開(kāi)始到船體下端，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. 甲板邊板和縱艙壁在假設(shè)中是完整的，大面積的舷側(cè)外板的不計(jì)的從型深

32、的5%到40%處。 The assumptions mentioned above help to simplify the definition of damages. 這種上述提到的假設(shè)方法，用于簡(jiǎn)單的定義損壞，Only one parameter is used to describe the damage. Introduction of additional parameters is avoided. 只用一項(xiàng)系數(shù)來(lái)描述損壞，避免引進(jìn)新的參數(shù)，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. 重點(diǎn)是船體與水的第一層屏障-船殼板，附體對(duì)于破損的船體來(lái)說(shuō)可以不計(jì)，在假設(shè)是可作為污點(diǎn)來(lái)處理，相對(duì)于相對(duì)較厚度的船殼板。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. 對(duì)于船體的破損程度有其它假設(shè),在ABS

35、的規(guī)定中估算船體梁的剩余強(qiáng)度，擱淺損壞發(fā)生在船底船體梁的一定深度下。碰撞損壞包括甲板邊板和舷側(cè)艙壁。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以及其他人在定義碰撞和擱淺，并根據(jù)根據(jù)ABS規(guī)范作了進(jìn)一步的研究，他們分析了ABS規(guī)范下0.8到1.

36、2范圍的損壞。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損壞事件，從微小的到嚴(yán)重的，Wang以及他人也研究了船底梁損壞甚至船底板損壞的情況。2.4. Presentatio

37、n of results2.4 結(jié)果呈現(xiàn) Two means are used to indicate the longitudinal bending strength of a ship hull: hull girder section modulus and ultimate hull girder strength. 有兩種方法用于計(jì)算船體的縱向彎曲強(qiáng)度、主船體剖面模數(shù)和屈曲強(qiáng)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. 甲板和船底的橫剖面模數(shù)、船底屈曲強(qiáng)度在中垂和中拱情況下被估算并無(wú)因次化，且都與完整情況下作比較。 Bottom damage is expressed as a percentage of the ships breadth. Side damage extent is expressed as a percentage of the ships depth.

39、底部損壞被表示成與型寬的比值，舷側(cè)的損壞程度被表示為與型深的比值。The investigation is focused on midship sections of typical commercial ships. 調(diào)查關(guān)注于典型商船船中剖面處。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，但是要作相類似的分析并不難。3. Simple equations for

40、 the residual section modulus3. 簡(jiǎn)單一次方程式計(jì)算剩余剖面模數(shù) Fig. 1 is a sketch of a transverse section, which characterizes the geometry of a ship and ignores many details. 圖1是一幅橫剖面草圖，描繪了船的主要幾何參數(shù)，略去一些多余的細(xì)節(jié)，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. 這可以代表一條雙殼油船的橫剖面、集裝箱船、單殼油船或其它一些典型船，The shaded area is the assumed damage caused by either collision or grounding accident. 陰影部分假設(shè)是由于碰撞和擱淺兒失去的地方。 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.