桥梁设计外文翻译

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附录 2 外文资料翻译

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11.7.4 De?ection

11.7.4.1 Dead Load and Creep De?ection

Global vertical de?ections of segmental box-girder bridges due to the effects of dead load and post-tensioning as well as the long-term effect of creep are normally predicted during the design process by the use of a computer analysis program. The de?ections are dependent, to a large extent, on the method of construction of the structure, the age of the segments when post-tensioned, and the age of the structure when other loads are applied. It can be expected, therefore, that the actual de?ections of the structure would be different from that predicted during design due to changed assumptions.

The de?ections are usually recalculated by the contractor’s engineer, based on the actual construction sequence.

11.7.4.2 Camber Requirements

The permanent de?ection of the structure after all creep de?ections have occurred, normally 10 to 15 years after construction, may be objectionable from the perspective of riding comf ort for the users or for the con?dence of the general public. Even if there is no structural problem with a span with noticeable sag, it will not inspire public con?dence. For these reasons, a camber will normally be cast into the structure so that the p ermanent de?ection of the bridge is nearly zero. It may be preferable to ignore the camber, if it is otherwise necessary to cast a sag in the structure during onstruction.

11.7.4.3 Global De?ection Due to Live Load

Most design codes have a lim it on the allowable global de?ection of a bridge span due to the effects of live load. The purpose of this limit is to avoid the noticeable vibration for the user and minimize the effects of moving load iMPact. When structures are used by pedestrians as well as motorists,the limits are further tightened.

11.7.4.4 Local De?ection Due to Live Load

Similar to the limits of global de?ection of bridge spans, there are also limitations on the de?ection of the local elements of the box-girder cross section. For example, the AASHTO Speci?cations limit the de?ection of cantilever arms due to service live load plus iMPact to 1??of the cantilever length,except where there is pedestrian use [1].

11.7.5 Post-Tensioning Layout

11.7.5.1 Exter nal Post-Tensioning

While most concrete bridges cast on falsework or precast beam bridges have utilized post-tensioning in ducts which are fully encased in the concrete section, other innovations have been made in precast segmental construction.Especially prevalent in structures constructed using the span-by-span method, post-tensioning has been placed inside the hollow cell of the box girder but not encased in concrete along its length. This is know as external post-tensioning. External post-tensioning is easily inspected at any time during the life of the structure, eliminates the problems associated with internal tendons, and eliminates the need for using expensive epoxy adhesive between precast

segments. The problems associated with internal tendons are (1) misalignment of the tendons at segment joints, which causes spalling; (2) lack of sheathing at segment joints; and (3) tendon pull-through on spans with tight curvature (see Figure 11.39). External prestressing has been used on many projects in Europe, the United States, and Asia and has performed well.

11.7.5

The provision for the addition of post-tensioning in the future in order to correct unacceptable creep de?ections or to strengthen the structure for additional dead load, i.e., future wearing surface, is now required by many codes. Of the positive and negative moment post-tensioning, 10% is reasonable. Provisions should be made for access, anchorage attachment, and deviation of these additional tendons. External, unbonded tendons are used so that ungrouted ducts in the concrete are not left open. 11.8 Seismic Considerations

11.8.1 Design Aspects and Design Codes

Due to typical vibration characteristics of bridges, it is generally accepted that under seismic loads,some portion of the structure will be allowed to yield, to dissipate energy, and to increase the period of vibration of the system. This yielding is usually achieved by either allowing the columns to yield plastically (monolithic deck/superstructure connection), or by providing a yielding or a soft bearing system [6].

The same principles also apply to segmental structures, i.e., the segmental superstructure

needs to resist the demands imposed by the substructure. Very few implementations of segmental struc-tures are found in seismically active California, where most of the research on earthquake-resistant bridges is conducted in the United States. The Pine Valley Creek Bridge, Parrots Ferry Bridge, and Norwalk/El Segundo Line Overcrossing, all of them being in California, are examples of segmental structures; however, these bridges are all segmentally cast in place, with mild reinforcement crossing the segment joints.

Some guidance for the seismic design of segmental structures is provided in the latest edition of the AASHTO Guide Speci?cations for Design and Construction of Segmental Concrete Bridges [2], which now contains a chapter dedicated to seismic design. The guide allows precast-segmental construction without reinforcement across the joint, but speci?es the following additional require-

ments for these structures:

?For Seismic Zones C and D [1], either cast-in-place or epoxied joints are required.

?At least 50% of the prestress force should be provided by internal tendons.

?The internal tendons alone should be able to carry 130% of the dead load.

For other seismic design and detailing issues, the reader is referred to the design literature provided

by the California Department of Transportation, Caltrans, for cast-in-place structures [5-8].

11.8.2 Deck/Superstructure Connection

Regardless of the design approach adopted (ductility through plastic hinging of the column or through bearings), the deck/superstructure connection is a critical element in the seismic resistant system. A brief description of the different possibilities follows.

11.8.2.1 Monolithic Deck/Superstructure Connection

For the longitudinal direction, plastic hinging will form at the top and bottom of the columns. Since most of the testing has been conducted on cast-in-place joints, this continues to be the preferred option for these cases. For short columns and for solid columns, the detailing in this area can be readily adapted from standard Caltrans practice for cast-in-place structures, as shown on Figure 11.40. The joint area is then essentially detailed so it is no different from that of a fully cast-in-place bridge. In particular, a Caltrans requirement for positive moment reinforcement over the pier can be detailed with prestressing strand, as shown below. For large spans and tall columns, hollow column sections would be more appropriate. In these cases, care should be taken to con?ne the main column bars with closely spaced ties, and joint shear reinforcement should be provided according to Reference [3 or 7]. The use of fully precast pier segments in segmental superstructures would probably require special approval of the regulating government agency, since such a solution has not yet been tested for bridges and is not codi?ed. Nevertheless, based upon ?rst principles, and with the help of strut–tiemodels, it is possible to design systems that would work in practice [6]. The segmental superstructure should be designed to resist at least 130%

of the column nominal moment using the strength reduction factors prescribed in Ref. [2]. Of further interest may be a combination of precast and cast-in-place joint as shown in Figure 11.41, which was adapted from Ref.

[8]. Here, the precast segment serves as a form for the cast-in-place portion that ?lls up the remainder of the solid pier cap. Other ideas can also be derived from the building industry where some model testing has been performed. Of particular interest for bridges could be a system that works by leaving dowels in the columns and supplying the precast segment with matching formed holes, which are grouted after the segment is slipped over the reinforcement [9]

11.8.2.2Deck/Superstructure Connection via Bearings

Typically, for spans up to 45 m erected with the span-by-span method, the superstructure will be supported on bearings. For action in the longitudinal direction, elastomeric or isolation bearings are preferred to a ?xed-end/expansion-end arrangement, since these better distribute the load between the bearings. Furthermore, these bearings will increase the period of the structure, which results in an overall lower induced force level (bene?cial for higher-frequency structures), and isolation bearings will provide some structural damping as well.In the transverse direction, the bearings may be able to transfer load between super- and sub-structure by shear deformation; however, for the cases where this is not possible, shear keys can be provided as is shown in Figure 11.42. It should be noted that in regions of high seismicity,for structures with tall piers or soft substructures, the bearing demands may become excessive and a monolithic deck–superstructure connection may become necessary.For the structure-on-bearings approach, the force level for the superstructure can be readily，determined, since once the bearing demands are obtained from the analysis, they can be applied to the superstructure and substructure. The superstructure should resist the resulting forces at ultimate (using the applicable code force-reduction factors), whereas the substructure can be allowed to yield plastically if necessary.

11.8.2.3 Expansion Hinges

From the seismic point of view, it is desirable to reduce the number of expansion hinges (EH)to a minimum. If EHs are needed, the most bene?cial location from the seismic point of view is at midspan. This can be explained by observing Figure 11.43, where the superstructure bending midspan and for an EH at quarterspan. For the latter, it can be seen that the moment at the face The location of expansion hinges within a span, and its characteristics, depends also on the stiffness of the substructure and the type of connection of the superstructure to the piers. presents general guidelines intended to assist in the selection of location of expansion hinges.

11.8.2.4 Precast Segmental Piers

Precast segmental piers are usually hollow cross section to save weight. From research in

other areas it can be extrapolated that the precast segments of the pier would be joined by means of unbonded prestressing tendons anchored in the footing. The advantage of unbonded over bonded tendons is that for the former, the prestress force would not increase signi ?cantly under high column displace-ment demands, and would therefore not cause inelastic yielding of the strand, which would other-wise lead to a loss of prestress.

The detail of the connection to the superstructure and foundation would require some insight into the dynamic characteristics of such a connection, which entails joint opening and closing providing that dry joints are used between segments. This effect is similar to footing rocking, which is well known to be bene ?cial to the response of a structure in an earthquake. This is due to the period shift and the damping of the soil. The latter effect is clearly not available to the precast columns, but the period shift is. Details need to be developed for the bearing areas at the end of the columns, as well as the provision for clearance of the tendons to move relative to the pier during the event.If the upper column segment is designed to be connected monolithically to the superstructure, yielding of the reinforcement should be expected. In this case, the expected plastic hinge length should be detailed ductile, using closely spaced ties [3,5].

11.9 Casting and Erection

11.9.1 Casting

There are obvious major differences in casting and erection when working with cast-in-place

cantilever in travelers or in handling precast segments. There are also common features, which must be kept in mind in the design stages to keep the projects simple and thereby economic and ef ?cient,such as

? Keeping the length of segments equal and segments straight, even in curved bridges; ? Maintaining constant cross section dimensions as much as possible;

? Minimizing the number of diaphragms and stiffeners, and avoiding dowels through form- work.

11.9.1.1 Cast-in-Place Cantilevers

The conventional form traveler supports the weight of the fresh concrete of the new segment by means of longitudinal beams or frames extending out in cantilever from the last segment. These beams are tied down to the previous segment. A counterweight is used when launching the traveler forward. The main beams are subjected to some de ?ections, which may produce cracks in the joint between the old and new segments. Jacking of the form during casting is sometimes needed to avoid these cracks. The weight of a traveler is about 60% of the weight of the segment.The rate of construction is typically one segment per traveler per week. Precast concrete anchor blocks are used to speed up post-tensioning operations. In cold climates, Conventional Travelers Construction Camber Control

curing can be accelerated by various heating processes.The most critical practical problem of cast-in-place construction is de?ection control. There are ?ve categories of de?ections during and after construction:

?De?ection of traveler frame under the weight of the concrete segment;

?De?ection of the concrete cantilever arm during construction under the weight of segment plus post-tensioning;

?De?ection of cantilever arms after construction and before continuity;

?Short- and long-term de?ections of the continuous structure;

?Short- and long-term pier shortenings and foundation settlements.The sum of the various de?ection values for the successive sections of the deck allows the construc-

tion of a camber diagram to be added to the theoretical pro?le of the bridge. A construction camber for setting the elevation of the traveler at each joint must also be developed.

11.9.1.2 Precast Segments

Opposite to the precast girder concept where the bridge is cut longitudinally in the precast segmental methods, the bridge is cut transversally, each slice being a segment. Segments are cast in a casting yard one at a time. Furthermore, the new segment is cast against the previously cast segment so that the faces in contact match perfectly. This is the match-cast principle. When the segments are reassembled at the bridge site, they will take the same relative position with regard to the adjacent segments that they had when they were cast. Accuracy of segment geometry is an absolute priority, and adequate surveying methods must be used to ensure follow-up of the geometry.Match casting of the segments is a prerequisite for the application of glued joints, achieved by covering the end face of one or both of the meeting segments with epoxy at the erection. The epoxy serves as a lubricant during the assembly of the segments, and it ensures a watertight joint in the?nished structure. Full watertightness is needed for corrosion protection of internal tendons (ten-dons inside the concrete). The tensile strength of the epoxy material is higher than that of the concrete, but, even so, the strength of the epoxy is not considered in the structural behavior of the joint. The required shear capacity is generally provided by shear keys, single or multiple, in com-bination with longitudinal post-tensioning.With the introduction of external post-tensioning, where the tendons are installed in PE ducts,outside the concrete but inside the box girder, the joints are relieved of the traditional requirement of watertightness and are left dry. The introduction of external tendons in connection with dry joints greatly enhanced the ef?ciency of precasting.

11.9.1.3 Casting Methods

There are two methods for casting segments. The ?rst one is the long-line method, where all the segments are cast in their correct position on a casting bed that reproduces the span. The second method, used most of the time, is the short-line method, where all segments are cast in the same place in a stationary form, and against the previously cast segment. After casting and initial curing, the previously cast segment is

removed for storage, and the freshly cast segment is moved into place.

11.9.1.4 Geometry Control

A pure translation of each segment between cast and match-cast position results in a straight bridge(Figure 11.45). To obtain a bridge with a vertical curve, the match-cast segment must ?rst be translated and given a rotation in the vertical plane (Figure 11.46). Practically, the bulkhead is left ?xed and the mold bottom under the conjugate unit adjusted. To obtain a horizontal curvature, the conjugate unit is given a rotation in the horizontal plane (see Figure 11.47). To obtain a variable superelevation, the conjugate unit is rotated around a horizontal axis located in the middle of the top slab (Figure 11.48).All these adjustments of the conjugate unit can be combined to obtain the desired geometry of the bridge.

11.9.2 Erection

The type of erection equipment depends upon the erection scheme contemplated during the design process; the local conditions, either over water or land; the speed of erection and overall construction schedule. It falls into three categories, independent lifting equipment such as cranes,deck-mounted lifting equipment such as beam and winch or swivel crane, and launching girder equipment.The principle of the method is to erect or cast the pier segment ?rst, then to place typical segments one by one from each side of the pier, or in pairs simultaneously from both sides. Each newly placed precast segment is ?xed to the previous one with temporary PT bars, until the cantilever tendons are installed and stressed. The closure joint between cantilever tips is poured in place and continuity tendons installed and stressed.In order to carry out this erection scheme, segments must be lifted and installed at the proper location. The simplest way is to use a crane, either on land or barge mounted. Many bridges have Bridge with superelevation.been erected with cranes as they do not require an investment in special lifting equipment. This method is slow. Typically, two to four segments per day are placed. It is used on relatively short bridges. An alternative is to have a winch on the last segment erected. The winch is mounted on a beam ?xed to the segment. It picks up segments from below, directly from truck or barge. After placing the segment, the beam and winch system is moved forward to pick up the next segment and so on. Usually, a beam-and-winch system is placed on each cantilever tip. This method is also slow; however, it does not require a heavy crane on the site, which is always very expensive, especially if the segments are heavy.When bridges are long and the erection schedule short, the best method is the use of launching girders, which then take full advantage of the precast segmental concept for speed of erection.There are two essential types of self-launching gantries developed for this erection method. The ?rst type is a gantry with a length slightly longer than the typical span (see Figure 11.49). During erection of the cantilever, the center leg rests on the pier while the rear leg rests on the cantilever tip of the previously erected span, which must resist the corresponding reaction. Prior to launching,the back spans must be made continuous. Then, the center leg is moved to the forward cantilever tip, which must resist the weight of the gantry plus the weight of the pier segment.

This stage controls the design of the gantry, which must be made as light as possible, and of the cantilever.The second type of gantry has a length that is twice that of the typical span (see Figure 11.50).The reaction from the legs during the erection and launching of the next span is always applied on the piers, so there is no concentrated erection load on the cantilever tip. Each erection cycle consists of the erection of all typical segments of the cantilever and then the placement of the pier segment for the next cantilever, without changing the position of the truss.The gantries can be categorized by their cross section: single truss, with portal-type legs, and two launching trusses with a gantry across. The twin box girders of the bridge in Hawaii were built with two parallel, but independent trusses (see Figure 11.51), with a typical span of 100.0 m, segment

weights of 70 tons; the two bridge structures are 27.5 m apart with different elevations and longi-tudinal slopes. This system is a re?nement of the ?rst type of gantry applied to twin decks with variable geometry.Normally, the balanced cantilever method is used for spans from 60 to 110 m, with a launching girder. One full, typical cycle of erection is placing segments, installing and stressing post-tensioning tendons, and launching the truss to its next position. It takes about 7 to 10 days, but may vary greatly according to the speci?cs of a project and the sophistication of the launching girder. With proper equipment and planning, erection of 16 segments per day has been achieved.

译文

11.7.4 挠度

11.7.4.1 恒载和徐变

部分箱梁的整体变形是由恒载和后加张力造成的，也包括在设计过程中用电脑分析软件正常算出的徐变的长期影响。在很大程度上，挠度取决于结构的构造，后张是各部分的龄期和使用荷载作用时结构的龄期。因此，可以认为，由于假定的改变，结构的实际挠度会和设计的不同。在实际结构的基础上，工程师通常会重新计算挠度。

11.7.4.2 起拱需要

通常10年到15年，所有徐变挠度全部产生后的结构永久变形会令使用者行驶不舒适或者令公众失去信心。即使结构没有明显的缺陷，也不会提升公众的信心。因此，结构通常会做成拱形，从而是变形接近零。如果在建造过程中必须有一个缺陷，那么忽视起拱就更合适了。

11.7.4.3 活载引起的整体变形

由于活载的影响，大多数设计规范对桥跨的整体变形都有限制。这种限制的目的是避免对使用者的明显震动和尽量减小活载的影响。对于行人和驾驶员使用的结构，这种限制更严格。

11.7.4.4 活载引起的局部变形

类似于对桥跨整体变形的限制，局部的箱梁横截面也有变形限制。比如，AASHTO 规范规定除了行人使用情况外，悬臂梁挠度取决于活载挠度加上桥跨的3001

。

11.7.5 后张布置

11.7.5.1 外部后张

当大多数混凝土桥使用支架建造或者现浇梁桥使用充满混凝土截面的预应力钢束是，其他新方法已经用于现浇部分结构。特变盛行于逐跨施工法的结构中，后张拉置于箱梁箱室中而不是沿混凝土结构的长度布置。这就是外部后张。外部后张很容易在结构的任何时期检查，消除内部钢筋的问题和避免在各现浇块间使用昂贵的环氧胶黏剂。内部钢筋的问题是在结合处未对准引起开裂的钢筋；在结合部分缺乏覆盖物；以一定曲率穿过桥跨的钢筋(见图11.39)。外部预应力已经用于欧洲，美国和亚洲的项目，并且用的很好。

图11.36 内部钢筋的问题

为了纠正不合理的徐变变形和在恒载增加时加固结构而增加的预应力的供应，换言之令人讨厌的外边，现在为很多规章所需求。对后张拉的正面和负面的弯矩，10%是合理的。规定应该适用于入口，锚固处和增加钢筋的偏差。外部未粘接钢筋被使用着，从而保证混凝土中的管道不是开着的。

11.8 关于地震的考虑

11.8.1 设计方面和设计规范

由于典型的振动特性的桥梁,人们普遍认为在地震荷载作用下,一些部分的结构将被允许屈服以消散能量,并提高振动系统的周期。通常情况下,这种屈服通常是柱子产生可塑性屈服(巨大的板或者上部结构连接)或者软支撑系统屈服达到的[6]。

同样的原理也适用于节段性结构,即分段上层建筑的需要承担子结构产生的需求。很少在地震活跃的加利福利亚发现节段性结构，那儿有美国大多数的抗震研究。节段性结构的例子华彬溪桥,鹦鹉渡轮等都在加利福利亚，然而，这些桥都被适当的部分加强。

一些节段性结构抗震设计的知道提供在最新版本的AASHTO的设计与施工节段性混凝土桥梁规范[2]中,该规范有一章致力于抗震设计。该规范允许装配式预制结构不需要在结合处加强，但对这些结构指定的下列附加的要求：对于地震带C和D，必须使用就地浇筑或者环氧粘接剂。

内部钢筋至少要有50%的预应力。

内部钢筋应该能够承担130%的恒载。

对于其他抗震设计和细化问题,读者应参考加州交通部提供的现浇结构的设计资料[5-8]。

11.8.2 板和上部结构连接

无论什么设计方法(通过铰接或通过轴承)，板/上部结构连接在抗震中是一个关键要素。下面的是不同可能的一个简短描述。

11.8.2.1 整体板和上部结构连接

在纵向，柱的顶部和底部将形成塑性铰。由于大多数的测试都是在就地浇筑的连接处进行的，在这些情况下这都是首选。对短柱和实心柱,在这一地区的详细标准可以很容易从加利福利亚运输部对于现浇结构的实验中实现，如图11.40所示。然后联合区从本质详细情况是和现浇桥相同的。特别是一个加利福利亚运输部对一个墩的加固可以用预应力钢绞线详细表述,如下所示。大跨度和高大的圆柱、空心柱部分会更合适。在这种情况下,应该小心地主柱界限,并根据文献[3或7]提供结合处的剪力。

图11.40 板/墩的现浇接头

图11.41 预应力现浇墩

11.8.2.2 板/上部结构通过轴承连接

通常情况下对于跨越到45米逐跨施工法，上层建筑将会通过轴承支撑。在纵向上,橡胶或隔震支座优先安排杆的一端/或者膨胀的一端,因为这些更好的分配轴承间的荷载。此外,这些轴承将增加结构的龄期,从而在整体上减小感应力(对高频结构有益),隔离轴承也会提供一些结构阻尼。

在横方向，轴承也许能通过剪切变形转移上部结构间的荷载；然而，在某些不肯能的情况下，能如图11.42所示的提供剪力键。应该指出的是,地震高发区,对于有高墩和软弱下部结构的建筑，轴承更加为人所需，整体板和上部结构连接是必需的。

对于结构上加轴承的方法，上部结构的力可以很容易控制，因为轴承的要求从分析中满足，他们就能用于上部结构和下部结构。上部结构必须抵抗最后的合力(使用适当的减力因素),而在下部结构中可以产生屈服。

图11.42 板/顿轴承连接

11.8.2.3 膨胀铰链

从地震的观点来看,我们希望将膨胀铰链(EH)的数量降到最低。如果EH是必需的,从地震的观点看，最有利的位置是中跨。这可以通过观察图11.43来解释，上部结构弯曲时,造成柱的塑料链接(Mp),已经绘制了中跨有塑性铰链和四分之一跨有塑性铰链的情况。对于后者,我们可以看到柱面在四分之三Mp范围变化，

但是中跨有铰链时，只能在二分之一范围变化。

膨胀铰链在一个跨度的位置及其特性,也依赖于基础的刚度和上部结构到墩的连接类型。表11.1提出了选择膨胀铰链位置的一般准则。

图11.43 地震中中跨和四分之一跨有铰链的纵向上部结构

表11.1 部分桥梁中膨胀铰链的位置

11.8.2.4 预制节段墩

预制节段性桥墩通常挖孔减轻重量。从其他方面的研究推断墩的预制节段可以通过未粘接的锚固的预应力钢筋连接。粘接钢筋上未粘接的优势在于以前，预应力不会再高柱位移要求中显著增长，因此不会引起导致预应力损失的非弹性屈服。

上部结构和基础连接的细节需要洞察这个连接的动态特点，这就需要接头的开端和结尾有干燥的接头用于各部分。这个影响类似于从所周知的有利于回应地震中结构的基础摇摆。后者影响显然不适用于现浇柱,但适用于弯矩转换。

如果上部柱段是设计用来连接到上部结构，加固屈服是有望的。在这种情况下，期望的塑性铰链长度应该用空间关系[3,5]详细延展。

11.9 浇筑和安装

11.9.1 浇筑

在运输现浇构件和处理现浇节段时，浇筑和安装有明显的不同。但也有共同特点，就是必须记住设计阶段应保证方案简单，经济和效率。比如：·保持各段的长度相等和直，曲线桥也如此

·始终尽量保证横截面尺寸

·尽量减少横隔板和加劲肋的数量，并且模板中出现销钉

11.9.1.1 现浇悬臂梁

传统起重机

传统形式的起重机通过纵梁或者最后一段外伸框架的形式支撑新鲜混凝土。这些梁连接以前的片段。有个平衡力推动起重机向前。主梁受到可能在新老部分连接处产生裂缝的变形。灌注期间需要顶起模板来避免这些裂缝。起重机的重量大概是一个节段重量的60%。建造的比例通常是一个一个起重机一个节段。预应

力混凝土固定块用于加速后张法施工。在寒冷天气，可以通过各种加热装置来加速固化。

结构曲面控制

最关键的实际问题是现浇施工挠度控制。施工前后有五类挠度：

·混凝土节段重量下起重机支架的挠度

·建造时施加后张节段的重量下悬臂梁的挠度

·悬臂梁建造后到连接前得挠度

·连续构建的短期和长期挠度

·长期和短期墩缩短和基础沉降

板的连续截面的各种挠度的总和允许给桥假想外形加一个拱形图。在每个连接处设置起重机标高也必须得到发张。

11.9.1.2 预制块

桥纵向分块来预制大梁的观念相反的，桥被横向分割，每一块是一个节段。各节段一块一块的在浇筑场地浇筑。而且新阶段是引着前面节段浇筑的，以便两面能更好的连接。这就是配合浇筑原则。当各部分在桥址重新组装是，他们会依照和浇筑时相同的位置关系。节段的集合精确性是绝对的重点，并且充分的测量方法必须用来保证接下来的几何关系。

是实施粘接，达到用环氧树脂覆盖相接节段一面或者两面的前提。环氧树脂在组装节段时充当润滑剂，并且它保证结构完成时连接处的水密性。完全水密性是内部钢筋腐蚀防护必须的。环氧树脂材料的抗拉强度比钢筋的大，但即使如此，环氧树脂的抗拉强度在连接处结构行为也不考虑。所需的抗剪能力基本由剪力键提供。

通过外部后张的采用，钢筋安装在聚乙烯管内部，混凝土外面和箱梁内部，连接处达到传统的保证水密性的要求。混凝土内干燥连接的外部钢筋的采用打打提高了现浇的效果。

11.9.1.3 浇筑方法

有两种浇筑节段的方法。第一种是长线法，即在复制跨度的床位上按正确的位置浇筑所有的节段。第二种方法是短线法，大多数时间用这种方法，即所有的

节段在一个静止的地方挨着前一个节段浇筑。浇筑和初步加工后，前面的节段移到仓库，而新的节段移到那个位置。(见图11.44)

11.9.1.4 几何控制

筑和配合浇筑位置简单平移造就一座直桥(见图11.45)。要让桥获得垂直的弧度，配合浇筑在垂直方向平移并有一个转动角a(见图11.46)。实际上在隔离壁是保持直的。要获得水平弯曲，连接单元在水平面有一个转角b(见图11.47)。要获得不同的超高，连接单元要绕顶板中建的水平轴线转动(见图11.48)。

所有的这些连接单元的调整总结为获得桥的几何方面的期望。

图11.44 典型短线预制操作

图11.47 平曲线桥

图11.48 带超高的桥

11.9.2 安装

安装设备的类型取决于设计节段的安装方案构思，当地水陆情况，安安装速

度和总体建造安排。分成三部分，独立的其中设备，比如吊车；旋转导缆器，比如卷扬机；梁拽进装置。

11.9.2.1 悬臂平衡法

这种方法的原则是先竖起或浇筑桥墩节段，然后从墩的一边一个一个放置典型节段，或者从两边同时进行。每个新的预制节段都通过临时的齿眼和前面的一个连接，知道悬臂钢筋安装和受力。悬臂端连接处的闭合施工到位并且连续钢筋安装和受力。

为了实施建造计划，各节段必须在适当的位置举起和安装。最简单的方法是用起重机，不管是在陆地上还是驳船上。很多桥当还没有特别的起重设备时都是用起重机建立的。这种方法很慢。通常一天放置两到四段。这种方法用于相对较短的桥。另一种好的方法是在最后个竖立节段使用卷扬机。卷扬机安装在适合节段的梁上。卷扬机从下面的货车或者驳船上直接拾起节段。放置好节段后，梁和卷扬机系统向前移动来拾起下一个节段。通常梁卷扬机系统放置在每个悬臂端。这种方法同样很慢，但是，这不需要就地使用又贵又重的卷扬机，特别是在节段很重的时候。

当桥很长但建造时间安排很短时，最好的方法是用顶推法，该法能充分利用预制节段从而加快建造速度。

这种建造方法有两种基本的自顶推构台。第一种类型是一种比典型跨度稍微长一点的构台(见图11.49)。悬臂施工过程中，中心支腿依赖于桥墩而后部支腿依赖于前面竖起跨的悬臂端，该支腿必须承受相对运动。在拽进前，前跨必须保证连续。然后，中心支腿想悬臂端移动，该支腿必须承受构架和桥墩节段重量的和。这个阶段控制着构台的设计，必须保证尽量轻。

第二种类型构台有典型跨两倍的长度(见图11.50)。支腿在建造和下一跨推进期间的反应通常作用在桥墩上，所以在悬臂端没有集中的建造荷载。每个建造周期由所有类型悬臂节段和下一个悬臂段的安装，同时不改变构架的位置。

构台类型可以根据横截面划分：带有入口型支腿的简单构架，带有跨越构架的双推进构台。在夏威夷桥的双线箱梁是通过两条平行线建造的，但又有独立的构架(见图11.51)，典型跨度是100.0米，节段重量70吨；两座桥结构以不同的高度和纵坡相距27.5米。这个体系是第一种构台的改良。

通常，平衡悬臂法用于60到110米的顶推法中。一个完整的，典型的建造周期是放置节段，安装和张拉预应力钢筋，推进构架到下一个位置。这大概用7到10天，但根据项目的细节和推进梁的改进有不同的变化。有合适的设备和计划，可达到一天建造16个节段。

图11.49

工业设计专业英语英文翻译

工业设计原著选读 优秀的产品设计 第一个拨号电话1897年由卡罗耳Gantz 第一个拨号电话在1897年被自动电器公司引入，成立于1891年布朗强，一名勘萨斯州承担者。在1889年，相信铃声“中央交换”将转移来电给竞争对手，强发明了被拨号系统控制的自动交换机系统。这个系统在1892年第一次在拉波特完成史端乔系统中被安装。1897年，强的模型电话，然而模型扶轮拨条的位置没有类似于轮齿约170度,以及边缘拨阀瓣。电话，当然是被亚历山大格雷厄姆贝尔（1847—1922）在1876年发明的。第一个商业交换始建于1878（12个使用者），在1879年，多交换机系统由工程师勒罗伊B 菲尔曼发明,使电话取得商业成功,用户在1890年达到250000。 直到1894年，贝尔原批专利过期，贝尔电话公司在市场上有一个虚拟的垄断。他们已经成功侵权投诉反对至少600竞争者。该公司曾在1896年，刚刚在中央交易所推出了电源的“普通电池”制度。在那之前，一个人有手摇电话以提供足够的电力呼叫。一个连接可能仍然只能在给予该人的名义下提出要求达到一个电话接线员。这是强改变的原因。 强很快成为贝尔的强大竞争者。他在1901年引进了一个桌面拨号模型，这个模型在设计方面比贝尔的模型更加清晰。在1902年，他引进了一个带有磁盘拨号的墙面电话，这次与实际指孔，仍然只有170度左右在磁盘周围。到1905年，一个“长距离”手指孔已经被增加了。最后一个强的知名模型是在1907年。强的专利大概过期于1914年，之后他或他的公司再也没有听到过。直到1919年贝尔引进了拨号系统。当他们这样做，在拨号盘的周围手指孔被充分扩展了。 强发明的拨号系统直到1922年进入像纽约一样的大城市才成为主流。但是一旦作为规规范被确立，直到70年代它仍然是主要的电话技术。后按键式拨号在1963年被推出之后，强发明的最初的手指拨号系统作为“旋转的拨号系统”而知名。这是强怎样“让你的手指拨号”的。 埃姆斯椅LCW和DCW 1947 这些带有复合曲线座位，靠背和橡胶防震装置的成型胶合板椅是由查尔斯埃姆斯设计，在赫曼米勒家具公司生产的。 这个原始的概念是被查尔斯埃姆斯（1907—1978）和埃罗沙里宁（1910—1961）在1940年合作构想出来的。在1937年，埃姆斯成为克兰布鲁克学院实验设计部门的领头人，和沙里宁一起工作调查材料和家具。在这些努力下，埃姆斯发明了分成薄片和成型胶合板夹板，被称作埃姆斯夹板，在1941年收到了来自美国海军5000人的订单。查尔斯和他的妻子雷在他们威尼斯，钙的工作室及工厂和埃文斯产品公司的生产厂家一起生产了这批订单。 在1941年现代艺术博物馆，艾略特诺伊斯组织了一场比赛用以发现对现代生活富有想象力的设计师。奖项颁发给了埃姆斯和沙里宁他们的椅子和存储碎片，由包括埃德加考夫曼，大都会艺术博物馆的阿尔弗雷德，艾略特诺伊斯，马尔塞布鲁尔，弗兰克帕里什和建筑师爱德华达雷尔斯通的陪审团裁决。 这些椅子在1946年的现代艺术展览博物馆被展出，查尔斯埃姆斯设计的新的家具。当时，椅子只有三条腿，稳定性问题气馁了大规模生产。 早期的LCW（低木椅）和DWC（就餐木椅）设计有四条木腿在1946年第一次被埃文斯产品公司（埃姆斯的战时雇主）生产出来，被赫曼米勒家具公司分配。这些工具1946年被乔治纳尔逊为赫曼米勒购买，在1949年接手制造权。后来金属脚的愿景在1951年制作，包括LCW（低金属椅）和DWC（就餐金属椅）模型。配套的餐饮和咖啡桌也产生。这条线一直

桥梁工程毕业设计外文翻译箱梁

桥梁工程毕业设计外文翻译箱梁

西南交通大学本科毕业设计（论文） 外文资料翻译 年级: 学号: 姓名: 专业: 指导老师:

6 月

外文资料原文： 13 Box girders 13.1 General The box girder is the most ?exible bridge deck form. It can cover a range of spans from25 m up to the largest non-suspended concrete decks built, of the order of 300 m. Single box girders may also carry decks up to 30 m wide. For the longer span beams, beyond about 50 m, they are practically the only feasible deck section. For the shorter spans they are in competition with most of the other deck types discussed in this book. The advantages of the box form are principally its high structural ef?ciency (5.4), which minimises the prestress force required to resist a given bending moment, and its great torsional strength with the capacity this gives to re-centre eccentric live loads, minimising the prestress required to carry them.

毕业设计外文翻译资料

外文出处： 《Exploiting Software How to Break Code》By Greg Hoglund, Gary McGraw Publisher : Addison Wesley Pub Date : February 17, 2004 ISBN : 0-201-78695-8 译文标题： JDBC接口技术 译文： JDBC是一种可用于执行SQL语句的JavaAPI（ApplicationProgrammingInterface应用程序设计接口）。它由一些Java语言编写的类和界面组成。JDBC为数据库应用开发人员、数据库前台工具开发人员提供了一种标准的应用程序设计接口，使开发人员可以用纯Java语言编写完整的数据库应用程序。 一、ODBC到JDBC的发展历程 说到JDBC，很容易让人联想到另一个十分熟悉的字眼“ODBC”。它们之间有没有联系呢？如果有，那么它们之间又是怎样的关系呢？ ODBC是OpenDatabaseConnectivity的英文简写。它是一种用来在相关或不相关的数据库管理系统（DBMS）中存取数据的，用C语言实现的，标准应用程序数据接口。通过ODBCAPI，应用程序可以存取保存在多种不同数据库管理系统（DBMS）中的数据，而不论每个DBMS使用了何种数据存储格式和编程接口。 1．ODBC的结构模型 ODBC的结构包括四个主要部分：应用程序接口、驱动器管理器、数据库驱动器和数据源。应用程序接口：屏蔽不同的ODBC数据库驱动器之间函数调用的差别，为用户提供统一的SQL编程接口。 驱动器管理器：为应用程序装载数据库驱动器。 数据库驱动器：实现ODBC的函数调用，提供对特定数据源的SQL请求。如果需要，数据库驱动器将修改应用程序的请求，使得请求符合相关的DBMS所支持的文法。 数据源：由用户想要存取的数据以及与它相关的操作系统、DBMS和用于访问DBMS的网络平台组成。 虽然ODBC驱动器管理器的主要目的是加载数据库驱动器，以便ODBC函数调用，但是数据库驱动器本身也执行ODBC函数调用，并与数据库相互配合。因此当应用系统发出调用与数据源进行连接时，数据库驱动器能管理通信协议。当建立起与数据源的连接时，数据库驱动器便能处理应用系统向DBMS发出的请求，对分析或发自数据源的设计进行必要的翻译，并将结果返回给应用系统。 2．JDBC的诞生 自从Java语言于1995年5月正式公布以来，Java风靡全球。出现大量的用java语言编写的程序，其中也包括数据库应用程序。由于没有一个Java语言的API，编程人员不得不在Java程序中加入C语言的ODBC函数调用。这就使很多Java的优秀特性无法充分发挥，比如平台无关性、面向对象特性等。随着越来越多的编程人员对Java语言的日益喜爱，越来越多的公司在Java程序开发上投入的精力日益增加，对java语言接口的访问数据库的API 的要求越来越强烈。也由于ODBC的有其不足之处，比如它并不容易使用，没有面向对象的特性等等，SUN公司决定开发一Java语言为接口的数据库应用程序开发接口。在JDK1．x 版本中，JDBC只是一个可选部件，到了JDK1．1公布时，SQL类包（也就是JDBCAPI）

驱动桥外文翻译

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工业设计外文翻译

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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

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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.

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驱动桥设计_毕业设计论文

驱动桥设计 摘要 现代工程车辆技术追求高效节能、高舒适性和高安全性等目标。前一项目标与环境保护密切相关,是当代全球性热门话题,后两项目标是车辆朝着高性能化方向发展必须研究和解决的重要课题。转向系统的高性能化是指其能够根据车辆的运行状况和驾驶员的要求实行多目标控制,以获得良好的转向轻便性、较好的路感和较快的响应性。 汽车转向系统是影响汽车操纵稳定性、行驶安全性和驾驶舒适性的关键部分。在追求高效节能\高舒适性和高安全性的今天,电控液压助力转向系统作为一种新的汽车动力转向系统,以其节能、环保、更佳的操纵特性和转向路感,成为动力转向技术研究的焦点。 本文通过查阅相关的文献，介绍了EHPS系统的结构组成和工作原理，在参考现有车型的结构数据的基础上，设计计算转向系的主要参数，确定转向器的结构参数和动力转向部分结构参数，在分析其助力特性的基础上，设计合理的助力特性曲线，并通过MATLAB作出助力特性图，同时提出一种基于车速和转向盘转动角速度的控制策略，根据EHPS系统的特点，通过AMESim和Simulink建立整个系统的模型。通过联合仿真可以得出EHPS系统比HPS系统能提供更好的助力特性和转向路感。 关键词：EHPS；助力特性；结构设计；AMESim与Simulink建模 ABSTRACT

High effective energy saving,high comfort performance and high security are thegoals of contemporary.The first goal closely concerns with environment protecting,is also the popular topic around the world.The last two goals are the important subjects must be researched and solved in making automobile high performance.To make the steering system high performance is that the system can carry out mufti-goals control according to the vehicle states and drive requirements to acquire the steering handiness,better road feeling,better anti-interfering performance and faster response. The motor turing system is the essential part which affects the automobile operation stability,the travel security and the driving comfortablet.Nowadays we pursue highly effective energy conservation,the high comforrtableness and high secure.The electrically hydraulic power steering (EHPS) taking as one kind of new automobile power steering system,it takes the power steering engineering research the focal point by its energy conservation,the environmental protection,the better handling characteristic and changes the road feeling. According to consult relevant literature, this paper introduces the structure and the principle of EHPS, bases the further study of EHPS on the structural parameter date of a certain type of the light lorry, calculates the main parameters of steering system and power steering and devises the hydraulic circuit of EHPS. On the basis of the analysis of EHPS, this paper designs a reasonable EHPS power curve, including plotting the curve with the technique of MATLAB. Taking into account the steady steering and emergency steering, it advances the control strategy plan based on speed, steering wheel angle velocity, the steering wheel torque. Based on the structural characteristics of EHPS, this paper proposed AMESIM and SIMULINK joint simulation of the entire EHPS system. Accord to the result we can know that EHPS can offer more secure handle, more saving energy and way feeling. Key words:EHPS;Characteristics of power; Structure design; AMESim and Simulink Modeling

工业设计外文翻译---不需要设计师的设计

Design Without Designers 网站截图： https://www.wendangku.net/doc/7318791908.html,/baidu?word=%B9%A4%D2%B5%C9%E8%BC%C6%D3%A2%CE%C4%CE%C4%CF%D 7&tn=sogouie_1_dg 原文： Design Without Designers I will always remember my first introduction to the power of good product design. I was newly arrived at Apple, still learning the ways of business, when I was visited by a member of Apple's Industrial Design team. He showed me a foam mockup of a proposed product. "Wow," I said, "I want one! What is it?" That experience brought home the power of design: I was excited and enthusiastic even before I knew what it was. This type of visceral "wow" response requires creative designers. It is subjective, personal. Uh oh, this is not what engineers like to hear. If you can't put a number to it, it's not important. As a result, there is a trend to eliminate designers. Who needs them when we can simply test our way to success? The excitement of powerful, captivating design is defined as irrelevant. Worse, the nature of design is in danger. Don't believe me? Consider Google. In a well-publicized move, a senior designer at Google recently quit, stating that Google had no interest in or understanding of design. Google, it seems, relies primarily upon test results, not human skill or judgment. Want to know whether a design is effective? Try it out. Google can quickly submit samples to millions of people in well-controlled trials, pitting one design against another, selecting the winner based upon number of clicks, or sales, or whatever objective measure they wish. Which color of blue is best? Test. Item placement? Test. Web page layout? Test. This procedure is hardly unique to Google. https://www.wendangku.net/doc/7318791908.html, has long followed this practice. Years ago I was proudly informed that they no longer have debates about which design is best: they simply test them and use the data to decide. And this, of course, is the approach used by the human-centered iterative design approach: prototype, test, revise. Is this the future of design? Certainly there are many who believe so. This is a hot topic on the talk and seminar circuit. After all, the proponents ask reasonably, who could object to making decisions based upon data? Two Types of Innovation: Incremental Improvements and New Concepts In design—and almost all innovation, for that matter—there are at least two distinct forms. One is