桥梁设计外文翻译---曼哈顿大桥的研究与分析

Proceedings of Bridge Engineering 2 Conference 2007

27 April 2007, University of Bath, Bath, UK

CRITICAL ANALYSIS OF THE MANHATTANBRIDGE

Julian Staden

Departement of Civil and Architectural Engineering, University of Bath

Abstract: This paper provides detailed information about the different aspects of the design of the ManhattanSuspension Bridge. Analytical reasoning is given to why each design feature was designed in the manor it was in order to fulfil th e engineers’ design crite ria. An attempt is also made to illustrate any shortcoming in the design of the structure and any ways in which the engineers could have potentially improved the design of the bridge. Attention will also be paid to the ways in which the bridge would be designed and constructed if it were to be built in the 21st century. The reasons why design principals and construction methods have changed will also be outlined.

Keywords: truss, stiffness, tension, deck, torsion

Figure 1: ManhattanBridge. View from Manhattan side.

1 Overview of The ManhattanBridge

The ManhattanBridge, although unfinished, was opened in 1909 and was the third bridge to span the East River running between Brooklyn and Manhattan. It was built to provide another transport link between the two boroughs.Before construction began there was a great deal of controversy over the proposed designs for thebridge.Eventually a fairly typical looking suspension bridge design was approved that was designed by engineer Leon Moisieff. The bridge was to span 448metres between piers, which was a somewhat shorter distance than the main spans of either the Brooklyn or Williamsburg bridges that neighbore it..Even though the ManhattanBridge made no advancement in the spanned length achievable by a suspension bridge, it did represent a significant stepforward in the progression of bridge building. The bridge was the first to be designed using deflection theory, which quickly replaced all previous methods of bridge design. The design also incorporated steel towers that were only braced in two dimensions rather than three. This was another aspect of bridge design that had not been seen prior to the building of the ManhattanBridge.

The entire structure of the Manhattan suspension bridge was to be designed in steel. The deck structure is comprised of four steel stiffening trusses that were each supported by regularly spaced

suspenders that hang from one of the four main cables. The four cables are supported by the two towers and are held down by anchorages 224metres from each side of the main span.

2 Designing The Structure

The Structure The Manhattan Bridge was the first suspension bridge to be designed using deflection theory in calculating how the horizontal deck and curved cables worked together to carry loads. Until this point, suspension bridges could only be designed using elastic theory which meant assuming small deflections. However, whilst this was an incorrect approximation, as suspended structures were sometimes observed to undergo significant deflections, this was the only mathematical modelling that had been applied up to that time. At the time the ManhattanBridge was designed, this was the first occasion there had been an appropriate opportunity to use Melan’s deflection t heory. This new method of analysis allowed the engineers to design the bridge with a more accurate understanding of how it would actually perform, allowing a greater economy of material usage.

Deflection theory meant that all suspension bridges were proved to be stronger than previously considereddue to the curve in the main cables being more efficient acarrying loads than stiffer forms of bridge. The new theory allowed the ManhattanBridge to be designed to belighter, with smaller stiffening trusses, than it otherwise would have been using elastic theory. These smaller lighter trusses would have been acceptable in normal circumstances .for example,if the bridge was to carry onlyvehicular traffic, but in the case of the ManhattanBridge,it was to also carry subway trains.

Despite the application of the new theory, after the initialise of the bridge, it became clear that there was a significant flaw in its design.

2.1 Inadequacy of Design

Each time a heavy subway train passed over the bridge, it caused local deflection of the stiffening trusses on the side of th e deck of the train’s passage. The deflection on one side induced torsion in the deck. This problem was further accentuated when trains began to pass over each side of the bridge in opposing directions atthe same time. It was reported that at this point, each sideof the deck deflected by up to 1.2 meters, meaning a total relative deflection of over 2 meters. This put significant stresses into the bridge deck and subsequently lead to extensive repairs and stiffening work needing to becarried out in order to allow the bridge to remain serviceable.

In my mind, the most obvious failing in the design of the Manhattan Bridge is the location of the tracks subway .They have been located at each edge, rather than placing them in the central section of the deck, with road lanes separating them. Keeping the tracks close together would have reduced the length of the effective lever arm that the trains’s live loading would have had, reducing the torsion moment induced.

Although I am uncertain as to the design engineer’s reasoning behind locating the subway tracks in these positions, a possible reason becomes apparent when looking at a cross section of the deck.

Figure 2: Cross section showing location of lanes across deck

Figure 3: The four main cables are not evenly separated.

The figures illustrate that the main cables and corresponding stiffening trusses are “paired” on each side to enclose a region of deck resulting in a larger span of deck between them.

As shown in figures 4 and 5 ,these enclosed regions are where the design engineers located the subway tracks and is where the distance between the stiffening trusses is smaller. The engineers would have realised that the heavy live loading from the subway trains would have caused a significantly greater degree of bending across the deck between stiffening trusses in comparison to the bending due to vehicular loading over the same span. Therefore it would have made sense to locate the lighter vehicular live loading over the larger span of deck in the region between the two pairs of trusses. By then locating the subway tracks in the smaller spanning regions of deck, the resulting bending moment from their load is far smaller than if they were located in the central section. This would have meant that the design bending moment across the whole deck could have been of a similar magnitude, allowing the supporting deck structure to be designed more economically than otherwise using a section with a constant moment capacity across the whole deck. I.e. exactly the same the beam section could beused over the decks full width, resulting in simpler construction and less wasted material. These paired cables consequently could have been designed in this way intentionally for the purpose of accommodating the subway tracks. It is possible therefore that the distribution of the load types across the deck in this configuration was a fundamental part of the design of the whole superstructure.

As a great deal of planning was most likely given to the most efficient location of the subway

tracks as discussed above, it is unfortunate that the chosen configuration would go on to cause torsion in the deck..

An alternative solution to changing the location of the subway tracks would have been to use deeper stiffening trusses. These would have helped prevent the deflection of the outer main cables and hence reduced torsion in the deck. However this would have resulted in a significant detrimental effect on the bridges aesthetic qualities.

Overall the bridge was designed adequately in a two dimensional sense, but proper analysis appears not to been carried out in three dimensions, otherwise the torsional deflections could have been prevented.

The whole process would be easily avoided in the design of a modern suspension bridge. Three dimensional finite element analysis software would be used in order to check the structural capacity of the deck in longitudinal and transverse directions.

2.2 Tower Design

The ManhattanBridge was the first suspension bridge to be designed with towers braced only in a plane transverse to the deck..

Figure 4: The towers are braced for stiffness in two dimensions, rather than three Making the towers flexible in the same plane as the main cables allows for any movement at the top of the towers to be taken as bending in the towers. The flexing of the towers prevents large bending moments being transferred straight to the foundations. Therefore smallerfoundations under the piers are needed compared to under more typical tower design for the time the bridge was designed and built. This is possible because the foundations would mostly be there to take the vertical load, rather than a combination of a vertical load and a large bending moment.

The four main steel sections that comprise each tower have however been braced with cross

members in the transverse plane to the deck. Elasticity in this plane would be undesirable and of absolutely no benefit.

The engineers would have been fully aware that without the bracing in this plane, the structure would be much more unstable, and that the columns could potentially buckle under the load of the main cables supporting the deck.

The design of the towers of the ManhattanBridge was the first example of the application of many of the principals adopted in the design of modern suspension bridge towers.

Towards the base of each pier, the steel section increases in size until it meets the masonry footing. These would have been designed in this manner for two reasons. Firstly, the larger area where the steel meets the masonrywould be advantageous in creating a greater area for the steel to bear onto, spreading the load spread evenly over the masonry. Secondly, the larger area of steel meeting the masonry would have made it more possible to form a fixed connection that didn’t allow any rotation.

It appears that the steel piers broaden as they approach the underside of the deck, implying a moment resisting connection. Although this is not the case as the vast majority of this steel is for non-structural purposes, explained previously. However,one practical use it does serve is to act as a cantilever supporting the pedestrian walkway to take it around the towers. Considering there is no fixed connection between the support piers and the deck trusses, it would be presumed that there would be bearings at this point.These would allow the bridge to respond to any movements due to wind, temperature andlive loading, without putting huge stresses into the decks structure. The four main cables are not fixed to the top of the towers. Instead they are free to slide over their supports. This is to prevent any deflection of the main span causing a huge bending moment in the foundation. The connection between the cables and the tower is made directly above each of the four columns, so that the load supported by the cables is directed only into an axial load on each column. This allows for the four columns comprising each tower to be relatively slender.

2.3 Construction

As with any suspension bridge, the ManhattanBridge would have required very large foundations. These foundations would have most likely had to have gone down to bedrock, to ensure that there would be no settlement of the piers. The bridge piers are located within the East River. Each foundation would have been built by floating a caisson to the desired location and then sinking it using very heavy weights. The caissons would have probably been made from timber braced with steel.

After workers had removed all the soil and debris, the caissons would have been filled with concrete to form the foundations. After the foundations would have been completed, the towers would then have been erected. These would be able to stand with no propping due to the fixed connection at their base.

Figure 5: The erected towers

Each tower measured 102.4 meters in height. Construction would have comprised of bolting together relatively small sections of steel, using the masonry pier as a platform to work up from. Bracing would have been bolted onto the main structure as the structure increased in height, ensuring stability.

After the completion of the towers, the main cables would then be spun. Each of the four main cables are comprised of 9472 individual wires, making the total cable thickness come to 0.54 meters in diameter. These main cables each run through a corresponding saddle on the top of the towers. The ends of the cables would havebeen fixed into the anchorages, probably by wrapping the strands around massive steel I bars. These would then have been embedded within the huge masonry anchorages, which would prevent any slip of the main cables. These anchorages would work by gravity, having a massive dead weight.

Figure 6: The towers and main cables are in position but there are no suspending cables or deck at

this stage.

Figure 7: Section through the anchorage showing restraint of the cable.

Figure 8: Large masonry anchorages tie down the main cables. The anchorage shown is on the Manhattan side.

From the main cables, steel cable suspenders would have then been hung at regular intervals across the length of the suspended section of the bridge. This then allowed the deck to begin to be fixed to the suspenders. This was done starting at each tower and working in both directs towards the opposing tower and the anchorages.

Currently, common practice is to begin this process from the centre of the span. However at the time the ManhattanBridge was built, this would have been very impractical, as there would have been no simple means of lifting materials or plants to this location. The building of the deck was however carried out symmetrically in eachdirection. This is an important aspect in suspension bridge construction as it avoids any asymmetrical deflection of the deck, which would add an unnecessary complexity to its construction.

Figure 9: The deck was built from each tower at the same rate towards the middle of the span

3 Susceptibility to Intentional Damage

When the ManhattanBridge was designed, there was probably very little thought given to the idea that somebody might purposely try to destroy it. In some rare cases, potential acts of vandalism would need to be considered when designing a structure. However, a very large structure like the ManhattanBridge would have no areas regarding the bridges structural integrity that would be susceptible to vandals. When designing such structures today, careful consideration

needs to be given to what may happen to the structure if part of it was intentionally destroyed, i.e. as an act of terrorism. Designers would need to consider whether or not the structure could remain standing, even if certain key elements were completely removed. This aspect of design is no common in structures, and the design of a suspension bridge would be no exception.

Without detailed calculation it is very hard to look at the existing bridge structure and judge whether it would collapse completely if certain parts were taken away. In order to try to go about this analysis, the key structural elements that form the core structure of the suspension bridge must be first identified. These are: the main cables, the towers, the suspenders and the anchorages. The deck is not included in this list, as it is not actually supporting anything. This implies that if a section of it were to be removed, the bridge would still stand. The bridge would obviously be rendered useless, but at least there would not be a catastrophic collapse of the structure.

Holding the deck up is the suspenders. These are regularly spaced hanging from the main cables, and fixed to the Warren trusses. At 7.4 metres in depth, these trusses would be able to span a far, far greater distance than that of the spacing between the suspenders supporting them, even with the dead load on the deck acting over the spanned length. The reason for their massive depth is so there is very little deflection due to live loading, meaning the only implication of them spanning further would be a significant amount of deflection. Therefore I can confidently assume that if several hangers next to each other along were removed, the deck, as well as the rest of the structure, would remain intact. Perhaps the most significant point is whether or not the structure could remain standing if one of the main cables was to fail completely through an act of terrorism. This is harder to judge, as the strength of many of the bridges other elements contribute to this. However, a rough guide could be taken from the results of some of the calculations carried about previously. In section 6.1 I calculate that the main cables are designed with a safety factor of 2.6. Assuming this figure to be correct for the purposes of this exercise, we can then say that each of themain cables could support more than twice the area of deck it currently supports before its yield strength id reached. Therefore it could be argued that if one of the cables were to be removed, the adjacent cables would be strong enough to carry the load that the original cable no longer supports. Much of whether or not this would actually happen is very much dependant on the strength of the deck perpendicular to the line of the cables. There would be a good chance that the deck would be unable to span twice the distance, as the bending moment on the deck would significantly increase. Although this may be helped by the fact that there is a great deal of cross bracing beneath the deck across its width. Whether the portion of deck in question could stay up or not, the majority of the deck along with the rest of the structure should still stand.

The most catastrophic collapse could probably only take place if the towers, piers or anchorages of the Manhattan bridge were destroyed. This is because these are the elements that keep the whole of the suspended structure up. The engineers building the bridge would have realised the structural significance of these elements and would have presumably used a factor of safety that reflects this.

Overall, no amount of planning in the design of the bridge could ever make it immune to intentional damage, however if enough thought it given, then a significant loss of life could be avoided if the situation were to ever arise.

References

[1] Sharon Reier 1977 The Bridges of New York.

[2]ThomasRWinpennyManhattanBridge the troubled storey of a New York monumen.

[3] Sharon Reier1977 The Bridges of New York.

http://en.structurae.de/structures/data/photos.cfm?ID=s0000529

http://en.structurae.de/structures/data/index.cfm?ID=s000052

Bibliography

Thomas R Winpenny. ManhattanBridge,the troubled storey of a New York monument. Sharon Reier 1977 The Bridges of New York

https://www.wendangku.net/doc/b9414424.html,

https://www.wendangku.net/doc/b9414424.html,

Weidlinger Associates.，

https://www.wendangku.net/doc/b9414424.html,/Transportation/Bridges-long/manhattan.html

公路桥梁工程2007年第2个会议

2007年4月27日，巴斯，英国巴斯大学

曼哈顿大桥研究与分析

朱利安斯塔登

英国巴斯大学，土木建筑学院

摘要：本文详细的阐述了有关曼哈顿大桥设计的各个方面。分析推理它的每一个典型的设计特点，是为了让我们的设计能够更好的满足设计标准。也试图说明，在这些结构设计中存在的缺陷和一些工程师们所采用的桥梁设计的改进方法。还将注意到可能会在21世纪桥梁建设中用到的设计和建造方法。同时也概述，曼哈顿大桥导致现在悬索桥设计原则和施工方法发生了改变的原因。

关键词：桁架，刚度，张力，桥面，扭转

图1：从曼哈顿大桥的一面看

1曼哈顿大桥概述

曼哈顿大桥，尽管没有完成，但在1909年开通启用了，是第三座跨越布鲁克林和曼哈顿之间河流的桥梁。它是为在布鲁克林和曼哈顿之间提供另外一条运输通道而建设的。施工前开始，发生了许多关于这座桥梁设计方案的争论。最终批准了一个相当典型的由工程师Leon Moisieff.设计悬索桥方案。这座桥两个桥墩之间相距448米，比与它相邻的布鲁克林大桥或威廉斯伯格大桥的主跨要小一些。虽然曼哈顿桥在悬索桥跨越能力上没有取得什么进步，但它在桥梁建设发展的历程中迈出了非常重要的一步。它首次突破性地采用挠度设计理论，并且迅速取代了以前悬索桥所使用的设计方法。钢塔采用的是二维支撑而不是以前的三维支撑。这些桥梁设计方法在曼哈顿桥建成之前是没有的，。

2结构设计

曼哈顿大桥是第一座在水平桥面板与主缆如何共同承受荷载计算中采用挠度理论的悬索桥。直到此时，悬索桥只能利用基于小挠度假设的弹性理论进行设计。不过，这个假设并不是非常准确。采用悬浮结构进行了观察，我们发现有时会出现重大挠度。但这是那个时候可以使用的唯一的数学模型。直到曼哈顿桥的设计出现,才使得Melan的挠度理论第一次有了一个合适的运用机会。这种新的分析方法使得工程师们，可以更加准确的理解实际情况，从而使得材料的使用更加的经济。

挠度理论表明，悬索桥由于曲线主缆能更有效率的承载负荷因而比起其它刚性的桥梁具有更大跨度。比弹性理论，这个新理论能够让曼哈顿桥设计成更轻的加劲桁架形式。这些更小更轻的桁架在正常情况下是可以接受的，例如如果桥是只是承受车辆荷载，但是事实上，曼哈顿大桥还可以设置地铁。尽管应用了新理论，但是在桥梁的建设初期，设计中仍然存在很

明显的缺陷。

2.1设计不足

每次重量很大的的地铁列车在桥上通过时，会造成对列车通过处桥面板边缘桁架加劲梁的偏转，一侧的变形会引起的桥面板的扭转。当列车在同一时间沿先放到方向驶过时，问题会进一步加剧。据报道，在这这中情形下，桥面板偏转可达1.2米，意味着相对挠度会超过2米。这使得强大的压力进入桥面，从而为了桥能正常工作，维修工作会变得更加的困难和更加的频繁。

在我看来，在曼哈顿大桥的设计中最明显的缺陷是地铁的轨道位置。地铁的轨道位置被设计在桥面的两边，而不是将其设计在桥面板的中央部分与道路分隔车道。保持紧密会减少轨迹的长度,火车的直接荷载产生有效杠杆臂，这减少扭力的产生。

虽然我不确定为地铁的设计的工程师的是如何推理进而确定这些轨道的位置。但是，当我们从桥面板的横截面看，原因似乎很明显。

图2：在桥面板中心线处位置的横截面

图3：四个不均匀分开的主缆

这些数字说明，主缆和对应的加劲桁架在每边靠近桥面板区域“配对”，导致在它们之间产生了较大的跨度。

正如图4和图5显示的，设计工程师将地铁轨道设计在这些地区，并使得加劲桁架之间的距离变得较小。工程师们将会意识到，在相同的跨径下，相比车辆荷载而言，直接作用的重载荷的地铁列车可能会在甲板上弯曲加劲桁架之间明显增加的变形。因此，它会作出来寻找

生活的打火机车辆甲板以上的较大的桁架之间的两对跨区域的负荷。届时定位在较小的地铁横跨甲板区域轨道，从他们所产生的弯曲力矩远远小于如果他们是在位于中央部分。这将意味着，在整个设计弯曲甲板时刻可能有一个类似的规模已，使甲板结构的配套设计更经济的状态下使用横跨整个甲板恒转矩能力的部分。即一模一样的梁节可反复使用的甲板的宽度，在简单的建设，减少浪费的材料造成。这些成对电缆因而可能是故意这样设计为容纳地铁轨道的目的。因此，有可能对整个甲板负载类型分布在此配置是一个整个上层建筑设计的基本组成部分。

由于大量的规划是最有可能给予最有效的地铁轨道位置如上所述，但不幸的是，选择的配置将继续在甲板上造成扭转..

另一种解决方案，改变了地铁轨道位置将是利用深加劲桁架。这些将有助于防止外部主缆挠度，从而减少了甲板上扭转。然而，这将导致重大不利影响的桥梁美学特质...

整体桥梁的设计在二维空间设计的很合理，但似乎没有适当的分析三维空间的情况，否则扭转变形本来是可以避免的。

整个过程将容易地避免了在现代悬索桥的设计。三维有限元分析软件将被使用，以测试桥面板在纵向和横向的结构能力。

2.2塔设计

曼哈顿大桥是第一座设计成塔与梁悬浮的悬索桥。

图4：塔身

使塔灵活在同一平面为主要电缆允许任何运动在顶部的塔被视为弯曲在塔上。防止屈曲的大型弯矩塔楼直接到被转移的基础。因此较小的基础桥墩下相比，更需要下典型塔的设计，争取时间，这座桥是设计和建造的。这是有可能的，因为在那里基础最能采取垂直荷载作用下，而不是一个垂直荷载作用下形成的组合和一个大型的弯矩。

四个主要部分构成各种塔钢支撑和十字但已有成员在横平面到甲板上。在这架飞机将弹性

不良而根本没有益处。

工程师将被充分认识到，如果没有这架飞机在支撑，结构会更加不稳定，而且可能列扣下了支持主缆甲板负荷。

在曼哈顿大桥的设计是塔的，在现代悬索桥塔设计采用了多个应用校长的第一个例子。

对各墩基础的增加，钢截面尺寸，直到它满足了砌体落脚的地方。这些是设计以这样的方式，原因有两个。首先，较大的区域，那里的钢符合砌体优先创造一个更大范围内对钢承受到的生产、传播负荷均匀地铺在横梁。其次，在大范围内蒸压加气混凝土砌体的钢会议将使它更能形成一种固定连接，不允许任何的旋转。

看起来在钢桥墩作为他们接近拓宽尾部的甲板上这意味着耐震梁柱连接。虽然这里的情况是不像绝大多数这种钢是为非构造的目的之前解释。然而它确实服务的一项实际使用是充当悬臂支护行人长廊把它周围的高楼。考虑到还没有固定连接甲板桁架桥墩和支持它将会被认为会有轴承在这一点。这将允许这个桥梁回复任何运动由于风、温度和生活没有把巨大的应力加载到甲板结构。

四个主要的电缆不固定至最高的塔。相反他们可以自由地滑过他们的支持。这是为了避免任何引起的大跨度的偏转一个巨大的弯矩的基础。之间的连接电缆和塔是由直接在上面的每一个四柱使负荷是为了支持的电缆仅成一个轴向载荷在每一栏。这允许四柱包括每座塔是相对苗条。

2.3建设

正如其它的悬索桥一样，曼哈顿大桥将需要非常大的基础。这些基金会将很可能不得不有所下降到基岩，以确保不会有解决的码头。桥墩都设在东河。每个基金会将已建成一个沉箱浮到所需位置，然后下沉它使用非常沉重的砝码。沉箱将有可能被制成木材与钢支撑。

工人在拆除后，所有的土壤和碎片，沉箱将被填充混凝土形成的基础。会后，基金会已经完成，便被塔建造。这将是经得起支撑，由于没有在他们的基地固定连接。

每座塔的高度一百零二点四米测量。建筑将有共同组成的支护钢相对较小的部分，并以此作为一个平台，工作从砌筑码头。本来螺栓支撑到主结构作为结构，增加高度，确保稳定。

在塔建成后，主缆然后将打滑。四是主缆每9472个人组成的线，使总厚度来电缆直径0.54米。通过对其中的每个塔的顶部的相应萨德尔鲁恩主缆。两端会被固定于锚地可能是由环绕着大量的钢铁我酒吧的股，电缆的。这些便被嵌入在巨大的砖石锚地，这将防止任何主缆滑。这些碇泊处将工作重心，有一个庞大的自重。

图6：塔和主缆中的位置

图7：通过显示电缆的克制锚固段。

图8：大砌体锚地牵制主缆。锚地显示是在曼哈顿。

从主电缆，钢缆吊杆将然后被挂在对面的桥长定期暂停部分。这就使甲板开始被固定在吊杆。这样做是开始在每个塔和工作都对对方塔和锚碇指示。

目前，一般的做法是开始从跨度中心这一进程。然而在曼哈顿大桥建成时间，这将是非常不切实际的，因为会被解除材料或植物到这个位置没有简单的方法。甲板的大楼进行了对称但在每个方向。这是在吊桥建设的重要方面，因为它避免了任何的甲板，这会增加不必要的复杂性及其构建不对称偏转。

图9：建于甲板上以同样的速度朝中间的跨度从每个塔

3故意伤害

当曼哈顿大桥的设计，有可能很少想过这些的想法，有人可能故意试图摧毁它。在某些罕见情况下，潜在的破坏行为，就需要设计时必须考虑到一个结构。然而，像曼哈顿大桥结构将有非常大的地区就没有桥梁的结构完整性，将可能会受到破坏者。在设计这种结构的今天，需要认真考虑考虑会发生什么事情的结构，如果其中的一部分被有意摧毁，即是恐怖主义行为。设计者需要考虑是否可以继续站立的结构，即使某些关键内容被完全拆除。这种设计在结构方面是不常见的，和一个吊桥的设计会不会例外。

如果没有详细的计算是非常努力寻找在现有桥梁结构和判断是否会全面崩溃，如果某些部分被带走。为了设法去左右这些分析，关键是形成了悬索桥结构要素的核心结构，必须首先确定。它们是：主电缆，塔，吊杆和锚地。甲板不包括在此列表，因为它实际上不是支持什么。这意味着，如果它的部分被删除了，桥仍然立场。这座桥显然是形同虚设，但至少不会是灾难性的结构崩溃。甲板上举行，是吊带。这些经常挂间隔从主电缆，并固定在华伦桁架。在水深7.4米，这将能够桁架跨度远远更大的距离比吊杆支持他们之间的间距，即使在上甲

板跨越长度恒载作用。对于他们巨大的深层原因是很少有这样偏转由于活荷载，意思是他们唯一的意义将是一个跨越进一步大量的偏转。因此，我可以自信地假设，如果几个衣架，彼此相邻，沿被拆除，在甲板上，以及其他的结构，将保持不变。也许最重要的一点是，是否可以继续站立的结构，如果主缆之一是通过失败完全是恐怖主义行为。这是很难判断，作为其他元素的桥梁这么多贡献力量。然而，一个粗略的指南可以采取从对计算结果进行一些有关以前。在第6.1我的计算，主缆与安全系数为2.6的设计。假设这个数字将会为这项工作的目的正确的，我们可以说，在主缆的每一个都能支持超过甲板面积的两倍，它目前支持其屈服强度的ID之前达成。因此，可以说，如果一个电缆分别被删除，相邻电缆将强大到足以承载负荷，原来的电缆不再支持。大部分这是否会真正发生的事情是非常的甲板上垂直于电缆线强度而定。会有一个很好的机会，在甲板将无法跨越的距离的两倍作为甲板上的弯矩将大大增加。虽然这可能是得益于一个事实，即有一个跨在其下方支撑桥面宽度很大。无论是甲板部分可能有问题或不熬夜，随着结构的其余部分仍应站在甲板的多数。

最灾难性的崩溃都可能发生，如果只有塔，码头或锚地的曼哈顿大桥被摧毁。这是因为这些元素是保持悬浮结构整体了。大桥建设的工程师将已经意识到了这些元素的结构意义，将有大概使用了安全因素，反映了这一点。

总的说来，没有规划中的桥梁设计金额可能永远使免疫故意伤害，但是如果认为它给予足够的，那么生命的重大损失是可以避免的，如果是有史以来的情况出现。

参考文献：

[1]莎朗Reier 1977年的桥梁纽约;

[2]托马斯·R Winpenny曼哈顿桥翻腾的层楼的住宅纽约的纪念碑;

[3]莎朗Reier 1977年纽约的桥梁;

http://en.structurae.de/structures/data/photos.cfm?ID=s0000529

参考书目：

托马斯·R Winpenny曼哈顿桥、翻腾的层楼的住宅纽约的纪念碑;莎朗Reier 1977年纽约的桥梁

https://www.wendangku.net/doc/b9414424.html,

https://www.wendangku.net/doc/b9414424.html,

Weidlinger Associates，

https://www.wendangku.net/doc/b9414424.html,/Transportation/Bridges-long/manhattan.html

http://en.structurae.de/structures/data/index.cfm?ID=s000052

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桥梁工程毕业设计外文翻译箱梁

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工业设计外文翻译

Interaction design Moggridge Bill Interaction design，Page 1-15 USA Art Press, 2008 Interaction design (IxD) is the study of devices with which a user can interact, in particular computer users. The practice typically centers on "embedding information technology into the ambient social complexities of the physical world."[1] It can also apply to other types of non-electronic products and services, and even organizations. Interaction design defines the behavior (the "interaction") of an artifact or system in response to its users. Malcolm McCullough has written, "As a consequence of pervasive computing, interaction design is poised to become one of the main liberal arts of the twenty-first century." Certain basic principles of cognitive psychology provide grounding for interaction design. These include mental models, mapping, interface metaphors, and affordances. Many of these are laid out in Donald Norman's influential book The Psychology of Everyday Things. As technologies are often overly complex for their intended target audience, interaction design aims to minimize the learning curve and to increase accuracy and efficiency of a task without diminishing usefulness. The objective is to reduce frustration and increase user productivity and satisfaction. Interaction design attempts to improve the usability and experience of the product, by first researching and understanding certain users' needs and then designing to meet and exceed them. (Figuring out who needs to use it, and how those people would like to use it.) Only by involving users who will use a product or system on a regular basis will designers be able to properly tailor and maximize usability. Involving real users, designers gain the ability to better understand user goals and experiences. (see also: User-centered design) There are also positive side effects which include enhanced system capability awareness and user ownership. It is important that the user be aware of system capabilities from an early stage so that expectations regarding functionality are both realistic and properly understood. Also, users who have been active participants in a product's development are more likely to feel a sense of ownership, thus increasing overall satisfa. Instructional design is a goal-oriented, user-centric approach to creating training and education software or written materials. Interaction design and instructional design both rely on cognitive psychology theories to focus on how users will interact with software. They both take an in-depth approach to analyzing the user's needs and goals. A needs analysis is often performed in both disciplines. Both, approach the design from the user's perspective. Both, involve gathering feedback from users, and making revisions until the product or service has been found to be effective. (Summative / formative evaluations) In many ways, instructional

机械毕业设计英文外文翻译399驱动桥

附录A 英文文献 Drive Axle All vehicles have some type of drive axle/differential assembly incorporated into the driveline. Whether it is front, rear or four wheel drive, differentials are necessary for the smooth application of engine power to the road. Powerflow The drive axle must transmit power through a 90°angle. The flow of power in conventional front engine/rear wheel drive vehicles moves from the engine to the drive axle in approximately a straight line. However, at the drive axle, the power must be turned at right angles (from the line of the driveshaft) and directed to the drive wheels. This is accomplished by a pinion drive gear, which turns a circular ring gear. The ring gear is attached to a differential housing, containing a set of smaller gears that are splined to the inner end of each axle shaft. As the housing is rotated, the internal differential gears turn the axle shafts, which are also attached to the drive wheels. Rear-wheel drive Rear-wheel-drive vehicles are mostly trucks, very large sedans and many sports car and coupe models. The typical rear wheel drive vehicle uses a front mounted engine and transmission assemblies with a driveshaft coupling the transmission to the rear drive axle. Drive in through the layout of the bridge, the bridge drive shaft arranged vertically in the same vertical plane, and not the drive axle shaft, respectively, in their own sub-actuator with a direct connection, but the actuator is located at the front or the back of the adjacent shaft

毕业设计外文翻译附原文

外文翻译 专业机械设计制造及其自动化学生姓名刘链柱 班级机制111 学号1110101102 指导教师葛友华

外文资料名称： Design and performance evaluation of vacuum cleaners using cyclone technology 外文资料出处：Korean J. Chem. Eng., 23(6), (用外文写) 925-930 (2006) 附件： 1.外文资料翻译译文 2.外文原文

应用旋风技术真空吸尘器的设计和性能介绍 吉尔泰金，洪城铱昌，宰瑾李， 刘链柱译 摘要：旋风型分离器技术用于真空吸尘器 - 轴向进流旋风和切向进气道流旋风有效地收集粉尘和降低压力降已被实验研究。优化设计等因素作为集尘效率，压降，并切成尺寸被粒度对应于分级收集的50％的效率进行了研究。颗粒切成大小降低入口面积，体直径，减小涡取景器直径的旋风。切向入口的双流量气旋具有良好的性能考虑的350毫米汞柱的低压降和为1.5μm的质量中位直径在1米3的流量的截止尺寸。一使用切向入口的双流量旋风吸尘器示出了势是一种有效的方法，用于收集在家庭中产生的粉尘。 摘要及关键词：吸尘器; 粉尘; 旋风分离器 引言 我们这个时代的很大一部分都花在了房子，工作场所，或其他建筑，因此，室内空间应该是既舒适情绪和卫生。但室内空气中含有超过室外空气因气密性的二次污染物，毒物，食品气味。这是通过使用产生在建筑中的新材料和设备。真空吸尘器为代表的家电去除有害物质从地板到地毯所用的商用真空吸尘器房子由纸过滤，预过滤器和排气过滤器通过洁净的空气排放到大气中。虽然真空吸尘器是方便在使用中，吸入压力下降说唱空转成比例地清洗的时间，以及纸过滤器也应定期更换，由于压力下降，气味和细菌通过纸过滤器内的残留粉尘。 图1示出了大气气溶胶的粒度分布通常是双峰形，在粗颗粒（>2.0微米）模式为主要的外部来源，如风吹尘，海盐喷雾，火山，从工厂直接排放和车辆废气排放，以及那些在细颗粒模式包括燃烧或光化学反应。表1显示模式，典型的大气航空的直径和质量浓度溶胶被许多研究者测量。精细模式在0.18?0.36 在5.7到25微米尺寸范围微米尺寸范围。质量浓度为2?205微克，可直接在大气气溶胶和 3.85至36.3μg/m3柴油气溶胶。

本科毕业设计桥梁外文翻译

附录一：中文翻译 土木工程师 桥梁工程156 2003年3月发表于BEI 31~37页 2002年1月31日收到 C.詹姆斯 2002年12月9日通过高级土木工程师佩尔 Frischmann ，埃克塞特 关键词：桥梁；河堤；土工布；膜与土工格栅 英国锁城大桥 锁城大桥是横跨住宅发展区的铁路桥梁。由于工程施工受到周围建筑与地形的限制，该工程采取加固桥台、桥墩与桥面的刚构结构，以及预制栏杆等方法提高了大桥的使用安全程度，并降低了大桥建造与维护的费用。因此，城堡大桥科学的设计方案使工程成本降到最低。 一、引言 本文描述的是在受限制地区用最小的费用修建一座铁路桥梁使之成为开放的住宅发展区。锁城地区是位于住宅发展十分紧张的韦斯顿超 图1 锁城大桥位置远景

马雷的东部。监督桥梁建设的客户是城堡建设有限公司，它由二大房建者组成。该区的规划局是北盛捷区议会（NSDC）。该发展地区被分为布里斯托尔和埃克塞特。规划条件规定，直到建成这条横跨的铁路大桥为止，该地区南部区域不可能适应居住。可见锁城大桥的建成对该地区发展的重要性。 发展地区位于萨默塞特的边缘，这个地区地形十分的恶劣，该范围位于韦斯顿以北和A321飞机双程双线分隔线的南面。现在只有一条乡下公路，是南部区域的唯一通道。该地区是交通预期不适合住宅增加的区域。 由于盛捷地区水平高程的限制，新的铁路线在桥台两边必须设有高程差。并且该地区地形限制，允许正常横跨的区域较小，这导致在结构的布局上的一定数量的妥协。为了整个城堡地区的发展，全 图2 锁城大桥地图上位置 桥限速20公里/时，并考虑区域范围内的速度制约。这样在得到客户和NSDC的同意后，桥梁采取了最小半径的方法，这使得桥梁采用了比正常梯度更加陡峭地方法实现高程的跨越。 客户的工程师、工程顾问、一般设计原则和初步认同原则下(AIP)与NSDC发出投标文件。 该合同在2000年7月1授予安迪。投标价值1.31亿美元，合同期定为34周，到2001年4月完成。

汽车车辆类驱动桥的设计外文文献翻译、外文翻译、中英文翻译

附录I Drive axle powertrain at the end of their basic function is to increase the transmission came from the drive shaft or torque, and a reasonable distribution of power to the left and right wheel, in addition to acting on the road and under the frame or body legislation between the vertical, longitudinal and lateral force. General from the main drive axle reducer, differential, gear wheels and drive axle housings and other components. The design of the Drive axle: Drive axle should be designed to meet the basic requirements are as follows: 1. Select the main reduction ratio should be able to ensure the car has the best power and fuel economy. 2. Smaller size, to ensure that the necessary ground clearance. 3. Gear and other pieces of the work of a smooth transmission,and small noise. 4. In a variety of speed and load with a high transmission efficiency. 5. In ensuring adequate strength and stiffness conditions, should strive for the quality of small, especially under the mass-spring should be as small as possible in order to improve vehicle ride comfort. 6. And suspension movement-oriented coordination of steering drive axle, but also with the coordination of steering movement. 7. The structure of simple, good processing, manufacturing, easy disassembly, to facilitate adjustment. Drive axle classification -1-

工业设计产品设计中英文对照外文翻译文献

(文档含英文原文和中文翻译) 中英文翻译原文：

DESIGN and ENVIRONMENT Product design is the principal part and kernel of industrial design. Product design gives uses pleasure. A good design can bring hope and create new lifestyle to human. In spscificity,products are only outcomes of factory such as mechanical and electrical products,costume and so on.In generality,anything,whatever it is tangibile or intangible,that can be provided for a market,can be weighed with value by customers, and can satisfy a need or desire,can be entiled as products. Innovative design has come into human life. It makes product looking brand-new and brings new aesthetic feeling and attraction that are different from traditional products. Enterprose tend to renovate idea of product design because of change of consumer's lifestyle , emphasis on individuation and self-expression,market competition and requirement of individuation of product. Product design includes factors of society ,economy, techology and leterae humaniores. Tasks of product design includes styling, color, face processing and selection of material and optimization of human-machine interface. Design is a kind of thinking of lifestyle.Product and design conception can guide human lifestyle . In reverse , lifestyle also manipulates orientation and development of product from thinking layer.

毕业设计外文翻译

毕业设计（论文） 外文翻译 题目西安市水源工程中的 水电站设计 专业水利水电工程 班级 学生 指导教师 2016年

研究钢弧形闸门的动态稳定性 牛志国 河海大学水利水电工程学院，中国南京，邮编210098 nzg_197901@https://www.wendangku.net/doc/b9414424.html,，niuzhiguo@https://www.wendangku.net/doc/b9414424.html, 李同春 河海大学水利水电工程学院，中国南京，邮编210098 ltchhu@https://www.wendangku.net/doc/b9414424.html, 摘要 由于钢弧形闸门的结构特征和弹力，调查对参数共振的弧形闸门的臂一直是研究领域的热点话题弧形弧形闸门的动力稳定性。在这个论文中，简化空间框架作为分析模型，根据弹性体薄壁结构的扰动方程和梁单元模型和薄壁结构的梁单元模型，动态不稳定区域的弧形闸门可以通过有限元的方法，应用有限元的方法计算动态不稳定性的主要区域的弧形弧形闸门工作。此外，结合物理和数值模型，对识别新方法的参数共振钢弧形闸门提出了调查，本文不仅是重要的改进弧形闸门的参数振动的计算方法，但也为进一步研究弧形弧形闸门结构的动态稳定性打下了坚实的基础。 简介 低举升力，没有门槽，好流型，和操作方便等优点，使钢弧形闸门已经广泛应用于水工建筑物。弧形闸门的结构特点是液压完全作用于弧形闸门，通过门叶和主大梁，所以弧形闸门臂是主要的组件确保弧形闸门安全操作。如果周期性轴向载荷作用于手臂，手臂的不稳定是在一定条件下可能发生。调查指出:在弧形闸门的20次事故中，除了极特殊的破坏情况下，弧形闸门的破坏的原因是弧形闸门臂的不稳定;此外，明显的动态作用下发生破坏。例如:张山闸，位于中国的江苏省，包括36个弧形闸门。当一个弧形闸门打开放水时，门被破坏了，而其他弧形闸门则关闭，受到静态静水压力仍然是一样的，很明显，一个动态的加载是造成的弧形闸门破坏一个主要因素。因此弧形闸门臂的动态不稳定是造成弧形闸门(特别是低水头的弧形闸门)破坏的主要原是毫无疑问。

桥梁专业外文翻译--欧洲桥梁研究

中文1850字 附录 Bridge research in Europe A brief outline is given of the development of the European Union, together with the research platform in Europe. The special case of post-tensioned bridges in the UK is discussed. In order to illustrate the type of European research being undertaken, an example is given from the University of Edinburgh portfolio: relating to the identification of voids in post-tensioned concrete bridges using digital impulse radar. Introduction The challenge in any research arena is to harness the findings of different research groups to identify a coherent mass of data, which enables research and practice to be better focused. A particular challenge exists with respect to Europe where language barriers are inevitably very significant. The European Community was formed in the 1960s based upon a political will within continental Europe to avoid the European civil wars, which developed into World War 2 from 1939 to 1945. The strong political motivation formed the original community of which Britain was not a member. Many of the continental countries saw Britain’s interest as being purely economic. The 1970s saw Britain joining what was then the European Economic Community (EEC) and the 1990s has seen the widening of the community to a European Union, EU, with certain political goals together with the objective of a common European currency. Notwithstanding these financial and political developments, civil engineering and bridge engineering in particular have found great difficulty in forming any kind of common thread. Indeed the educational systems for University training are quite different between Britain and the European continental countries. The formation of the EU funding schemes —e.g. Socrates, Brite Euram and other programs have helped significantly. The Socrates scheme is based upon the exchange of students between Universities in different member states. The Brite Euram scheme has involved technical research grants given to consortia of academics and industrial