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毕业论文的外文翻译

〖来源:www.246ent.com〗
〖时间:2016年10月26日〗〖

篇一:毕业论文的外文翻译

附录3:
The status and Development Trend of the supporting
1 Supporting Role
The new Boston Convention and Exhibition Center features signature V-columns that support a one-acre ballroom and provide lateral stability to large, column-free exhibit areas.August 2005 • Modern Steel Construction HNTB/Rafael Viñoly Architects/Photographer:
Brad Feinknopf August 2005 Modern Steel Construction At 1.7 million sq. ft, the $850 million Boston Convention and Exhibition Center (BCEC) is the largest public building ever constructed in New England. To provide a largely column-free exhibition floor, the structural engineering team of LeMessurier Consultants and Walter P. Moore collaborated closely with the architects to develop efficient structural steel solutions, including the signature V-columns used throughout the building. The creative use of structural teel proved crucial to the esthetic, functional, and budgetary success of this South Boston waterfront venue.Challenging Spaces
The 516,000 sq. ft exhibit hall presentedthe most obvious structural challenges. Planners required that it be virtually column free to support a wide variety of events, with a 45’ ceiling and rigging capacity of 1,500 lb on a 10’ by 10’ grid. Floor loading of the exhibit hall was 400 The loading is on a floor slab that occurred at grade level; however, becauseof poor soil conditions, the slab was supportedby deep foundations instead of being simply a slab-on-grade. Meeting rooms with 15’ ceilings and 60’ clear spans between columns were originally programmed to support 250 psf live loads. However, framing studies demonstrated that a 100 psf loading,combined with strategic concentrated load criteria, could satisfy the user requirements and save significant cost. The 41,000 sq. ft column-free ballroom is raised 75’ above grade at the north end of the building to provide harbor views. The ballroom was designed with a 45’ceiling and a 150 psf capacity floor that can also accommodate rhythmic floor excitations without objectionable vibrations. Lobby spaces below ictated 60’ clear spans for the floor framing. Conceptual design of the floor system followed the rhythmic excitation criteria in AISC Design Guide 11: Floor Vibrations Due to Human Activity.
While it was not practical from a design point of view to satisfy these criteria rigorously in the final design , collaborative work with vibration consultants led to the addition of mass to the ballroom floor by adding a topping slab in one region and a by hanging a kitchen from the floor in another region. Validation testing conducted on the completed floor system showed that the measured frequency, damping, and accelerations conformed to perceptibil- 80’-tall pipe columns support the 300’-wide high roof, while its lateral stability is provided through bracing down to the low roof at only four locations between expansion joints. Low roof V-columns provide both gravity support and lateral stability to the entire exhibit hall roof while maximizing useable exhibit hall floor space.
Ity thresholds that were even lower than those required for design. The scale of the building presented other challenges. At 1,595’ long and 811’ wide, expansion joints for thermal and seismic movements were carefully located and sized. Most of the steel structure is exposed to view , requiring careful design and coordination with the architects. Certain connection details were specified to have shop fabricated mockups for review by the engineers and architects. Once approved in the shop, these became the prototypes for subsequent production connections. Even typical interior wall partitions demanded extra thought: The high floor – to -floor distances required by the large, open spaces necessitated supplementary steel framing so standard wall components could be used.
Exterior walls incorporated horizontal ladder frames composed of HSS spanning 30’ from column to column, creating a mid-height support for the curtain wall systems. Also, exhibition support services for power, air, water, and Internet connections required that hundreds of floor boxes be carefully integrated within the floor framing system.
The 60-acre site provided another major structural challenge. Like much of Boston, it lies outside the original shoreline on man-placed fill susceptible to amolified seismic forces. This dictated deep foundations for the superstructure and at-grade floor construction. With the water table hovering just 8’ below the surface, below - grade space was eliminated from consideration. The structural slab-on-grade, including the exhibit hall slab and meeting room columns with up to 800 kip loads, were supported on 4,300 driven precast (120 ton capacity) concrete piles. More heavily loaded columns (1,200-4,000 kips) at the exhibit hall and ballroom were supported on drilled caissons. Over 54 miles of precast piles and three miles of caisson shafts were installed to support the structure. Choosing structural steel for the majority of the elevated framing reduced foundation costs and provided needed ductility.
The structural engineers specified a 7.5” floor slab—3” composite steel deck with 4.5” normal weight concrete—to provide adequate composite beam capacity and to accommodate more highly concentrated floor loads. The floor assembly also provided the significant diaphragm strength needed in a building of this scale, while providing sufficient thickness to integrate floor boxes. The signature roof over the 1,200’ by 480’ exhibit hall gives the building much of its architectural character. The highest part of the roof is 300’-wide and gently Aaron White curves as it rises from the south end of the building, resulting in a double-curved
roof that cantilevers at the northern end and overhangs the main entrance.
2 V-Columns
Low roofs flank the high roof, covering meeting rooms and creating 90’-wide “snow pockets.” The structural engineers placed four V-columns at 90 centers to efficiently support the heavy roof snow loads simultaneously provide adequate lateral resistance while taking up minimum exhibit floor space.
The V-columns consist of two diagonal 16” round HSS pipes. Each Is supported on a conical pedestal consisting of a W14 steel core encased in cast-in-place concrete. The Vs start 7.5’ above the exhibit floor to clear pedestrian and forklift traffic.
The main roof trusses, comprised of web-horizontal W14 segmented chords and W14 web members, were shop fabricated in two 60’ cantilevered sections and two 90’ interior sections to efficiently span the overall 300’ width. Maximum truss depths of 14’ allowed economical shop assembly and over-the-road shipment.
V-columns were also used to create distinctive cantilevered balconies and visual cues at the four main building entrances from the encircling ring road. The one-acre ballroom and its clear-span roof are also elegantly supported by pairs of V-columns.
3 Originality and Innovation
The architects and structural engineers used structural steel throughout the building to creatively solve a multitude of challenges. For example:
A steel bracing system provided lateralload resistance for the high roof while it simultaneously supported crucial pedestrian passageways between the east and west meeting rooms. The soffits of these passageways also cleverly support operable partitions that subdivide the exhibition space.
A lightweight steel-framed wall with glass infill hung from the roof skillfully blocks noise between adjacent spaces while preserving the aesthetic and hiding the expansion joint in the roof.
To economically access one mile of rigging points above the massive exhibit hall, designers collaborated with the fabricator and erector to devise a prefabricated catwalk system comprised of bent plate walking surfaces and Vierendeel truss handrails in 30’ sections.
4 Collaborative Effort
Basic floor framing and columns were designed using software developed by LeMessurier Consultants. More complex roof framing and lateral load systems were analyzed and designed using SAP2000. A common origin for all computer models allowed linking of work produced in different offices of the two structural engineers. During the shop drawings process, data files were shipped via Internet to the fabricator for loading into SDS/2 detailing software. Engineers worked closely with a fabricator expeditor to speed processing of RFIs, shop drawings, and other submittals. BCEC opened June 2004 in time to An efficient erection scheme simplified the construction of the exhibit hall’s low roof V-columns and trusses. LeMessurier Consultants host events peripheral to the Democratic National Convention.
Its architecture—and especially its elegant structural systems—received immediate acclaim, including an AISC Innovative Design and Excellence in Architecture with Steel (I.D.E.A.S.) Award in 2005. Peter J. Cheever is Vice President of LeMessurier Consultants. Aaron C. White is Senior Associate in Walter P. Moore’s Tampa office. Read more about the Boston Convention & Exhibition Center in the I.D.E.A.S. Awards coverage featured in the June 2005 issue of MSC at www.modernsteel.com

支撑的现状及发展趋势
1 支撑的创新
占地面积170万平方英尺,耗资8亿五千万美元的波士顿会展中心,是迄今为止新英格兰建造的最大的公共建筑。为了提供一个大的无柱展览场地,由LeMessurier Consultants和Walter P. Moore组成的结构工程队同建筑师们紧密合作,力求提出有效的结构型钢方案,包括在展厅中广泛应用的V形柱。结构型钢创造性地应用于这个南波士顿滨水场馆,被证实在建筑美学、功能和造价上都取得了巨大的成功。
有挑战的空间
这个516000平方英尺大的展览大厅对结构提出了一个最明显的挑战。建设方要求展厅要能够满足在里面举办各种活动的要求,即要求展厅内几乎不能有柱子;并且要满足在10′×10′的网格上具备能承受1500磅荷载的能力,用以承受45′厚的屋盖和传动索具。展厅楼面的荷载是每平方英尺400磅。荷载作用在与室外地坪位于同一水平面的楼地面上;尽管如此,由于地基状况不好,楼地面并不是简单地被地基支撑,而是通过深基础支撑。
会议室的楼板为15′厚,净跨度为60′,按最初计划计算要承受每平方英尺250磅的荷载;但是后来结构研究证明:只需每平方英尺100磅的均布荷载和一个主要的集中荷载标准组合,就能满足会议室使用者的要求并且能节省一笔相当可观的费用。
无柱舞厅有41000平方英尺大,为了提供一个观海平台,舞厅在展厅的北面尽头部位高出地坪75英寸。舞厅设计采用45′厚的楼板和能承受每平方英尺150磅荷载的楼地面,这种楼地面也满足整体楼地面的韵律感并且没有过大的振动。下面的休息场地规定需60′的净跨才能满足楼板骨架。
楼地面体系的概念设计需遵从韵律感,在美国钢结构协会设计手册(11)有:楼面振动由人的活动引起。本展厅在最终设计阶段,从设计的观点上严格满足这些标准是不切合实际的,最终通过和振动专家合作决定采用增加楼板的质量:在舞厅楼板的一个区域添加一个顶板,同时在楼板的另一块区域上悬挂一个厨房。对整个楼板体系的试验测试显示:测得的频率、阻尼以及加速度均在可接受的范围内,甚至比设计的控制要求还要低。
建筑物如此大的规模也面临着诸多挑战。在长1595′宽811′的范围内,温度伸缩缝和抗震缝的位置和大小被精确确定。大部分钢结构需暴露在外能被直接看到,需要细心设计并同建筑师协调。某些节点细节先被指定在工厂做成了模型,再由工程师和建筑师共同讨论。一旦这些模型被认可,它们会成为以后工厂批量生产的成品节点原型。甚至典型的内隔墙都需要专门的构思:大跨、开放性的建筑空间要求楼层之间一定高的距离,这也使辅助的钢框架体系成为必要,所以标准的墙组件能够被应用。外墙和水平的阶梯型框架组成了在柱与柱之间跨度为30′的HSS,并产生了隔墙体系的一个中高支撑。除此之外,展览所需的供电、通风、供水以及因特网接入等服务,要求有上百个楼地面管路同楼板骨架体系形成一个完整的整体。
60英亩大的建筑场地又对结构提出了另一个较大的挑战。就像波士顿大多数地方,它位于海岸线以外人工填土的地基上,没有足够个抗震能力.这样上部结构以及与地坪齐平的楼地面结构就需要深基础的支撑。由于地下水位在地表以下8′的位置,地下对结构的影响被免于考虑。地坪以上的结构,包括展厅的楼板和会议室里承受800千磅荷载的柱子,被4300根混凝土预制桩(120吨承载力)支撑。展览大厅和舞厅里还有更多承受较大荷载的柱子(1200-4000千磅),被采用钻恐沉箱基础支撑。整个结构被总计超过54英里的预制桩和超过3英里的沉箱基础共同支撑。为大部分上部结构选择合适的结构用钢,能有效地减少基础费用并使结构具有所需的延性。
为了使组合梁能提供足够的承载力和使楼板具有足够的承担集中荷载的能力,结构工程师指定楼板厚度7.5″,4.5″厚的标准重度混凝土同3″厚钢板结合的组合梁。组合的楼板也能提供这种规模建筑物所需要的横隔板强度,同时提供足够的楼板厚度以便铺设各种管路并与其形成整体。
在1200′×480′大的展览大厅上,是有鲜明特点的屋盖,它给此展厅增添了许多建筑特征。屋盖的最高部分是一个300′宽、曲率很大的曲线,它的弧线从此建筑物的最南端开始上升,形成了一个双曲线型屋盖,并在此建筑物的最北端形成悬臂悬于展厅的主入口上空。
2 V形柱
低屋盖部分在侧面育高屋盖相接,覆盖了会议室并且形成了90′宽的“雪袋子”。结构工程师们设计放置了四个间隔为90′的V形柱,以更有效地承担巨大的雪荷载,同时达到占用展厅最小的面积而提供足够的抗侧移刚度的目的。
V形柱由两根倾斜的直径有16″的HSS钢管组成。每根钢管都支撑在一个圆锥形的底座上,底座由一个W14钢核心体外包现浇混凝土组成。V形柱在展厅地面上7.5′高的地方接于底座,以提供人员和叉车等车辆通行。
屋盖主要的桁架采用工厂定制加工的方式,由W14钢弦杆和W14钢腹杆组成,采用两个60′宽的悬臂外伸截面和两个90′宽的内部截面,有效地横跨了全部的300′的宽度。最大的桁架有14′高,选用比较经济的工厂组装方式和 现场发货方式。在展厅的环形道路沿线有四个主入口,造型别致的悬臂夹层和有特色的竖杆得益于V形柱的采用。一英亩大的舞厅以及它的净跨屋顶非常优美地支撑在一对V形柱上。
新创意和新方法
建筑师和结构工程师们创造性地在整个建筑中应用了钢结构,解决了一系列的挑战。比如:高屋盖承受着横向荷载,同时支撑着东、西会议室之间起关键作用的过道,而钢结构支撑体系给它提供了足够的抵抗力。这些过道的拱腹同样灵巧地支撑着隔墙,这些隔墙又细分了展厅的空间。
一种悬挂于屋盖的轻质钢框架玻璃填充墙,巧妙地起到了对相邻房间隔音的效果,同时又掩盖了屋盖的伸缩缝保留了建筑的美学效果。
为了比较经济地实现在厚重的展厅上面布置一英里长的索具点,设计方同构件加工方和施工方合作发明一种预制通道系统,这个系统由带有可以在其表面行走的曲形钢板和截面为30′的空腹桁架扶手组成。
3 协作的成果
基本的楼板骨架体系和柱用LeMessurier Consultants开发的软件设计。更多复杂的屋盖结构和横向的荷载体系是用SAP2000分析和设计的。所有的计算机分析模型的一般原型在不同事务所都经过了两名结构工程师的复核。在绘制施工图阶段,数据文件通过Internet传输至构件制造方以便于输入SDS/2详细设计软件。为了加快RFIs、施工图绘制以及其他工作的进程,工程师和一个督促制造方的人员进行了紧密合作。
按照议会的要求,旨在召开工程相关会议的BCEC于2004年6月成立了。它的建筑风格——尤其是它的优美的结构体系——立刻赢得了称赞,并在2005年获得美国钢结构协会颁发的“钢结构建筑创新设计优胜奖”。
转体之后,水平的转体结构被混凝土封固。在浇灌混凝土之前,上下部转盘被焊接在一起。聚四氟乙烯板被移除,滑道和撑脚被焊接在一起。桥墩上和拱脚的预埋的加固钢筋也被焊接在一起。
 

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