Concrete Construction matter
T. Pauly, M. J. N. Priestley
Abstract
Viewed in terms of accepted practices, concrete construction operations leave much to be desired with respect to the quality, serviceability, and safety of completed structures. The shortcomings of these operations became abundantly clear when a magnitude 7.6 earthquake struck northern Paki-stan on October 8, 2005, destroying thousands of buildings, damaging bridges, and killing an esti-mated 79,000 people. The unusually low quality of construction operations prevalent was a major cause of the immense devastation.
Keywords: Concrete Placing Curing Construction Technology
Placing Concrete
If concrete is placed in the surface, the sur-face should be filled with water sufficiently to prevent it from absorbing the concrete of its water. If fresh concrete is to be placed on or nearby to concrete that has solidified, the surface of the placed concrete should be cleaned absolutely, preferably with a high-pressure air or water jet or steel-wire brushes. The surface should be wet, but there should be no much water. A little quantity of cement grout should be brushed over the whole area, and then followed immediately with the application of a 1/2-in Layer of mortar. The fresh concrete should be placed on or against the mortar.
In order to decrease the disintegration re-sulting from carriage after it is placed. The con-crete should be placed as nearly as probably in its
final point. It should be placed in layers to permit uniform compaction. The time interval between the placing of layers should be limited to assure perfect bond between the fresh and previously placed concrete.
In placing concrete in deeper patters, a ves-sel should be used to limit the free fall to not over 3 or 4 ft, in order to prevent concrete disintegra-tion. The vessel is a pipe made of lightweight metal, having adjustable lengths and attached to the bottom of a hopper into which the concrete is deposited. As the patters are filled, sections of the pipe may be removed.
Immediately after the concrete is placed, it should be compacted by hand pudding or a me-chanical vibrator to eliminate voids. The vibrator should be left in one position only long enough to reduce the concrete around it to a plastic mass; then the vibrator should be moved, or disintegra-
tion of the aggregate will occur. In general, the vibrator should not be permitted to penetrate concrete in the prior lift.
The mainly advantage of vibrating is that it permits the use of a drier concrete, which has a higher strength because of the reduced water content. Among the advantages of vibrating con-crete are the following:
1.The decreased water permits a reduction in the cement and fine aggregate because less cement paste is needed.
2.The lower water content decreases shrinkage and voids.
3.The drier concrete decreases the cost of finishing the surface.
4.Mechanical vibration may replace three to eight hand puddles.
5.The lower water content increases the strength of the concrete.
6.The drier mixture permits theremoval of some patters more quickly, which may reduce the cost of patters.
Curing Concrete
If concrete is to gain its maximum strength and other desirable properties, it should be cured with adequate moisture and at a favorable tem-perature. Failure to provide these conditions may result in an inferior concrete.
The initial moisture in concrete is adequate to hydrate all the cement, provided it is not should replace the moisture that does evaporate. This may be accomplished by many methods, such as leaving the patters in place, keeping the surface wet, or covering the surface with a liquid curing compound, which comes being to a water-tight membrane that prevents the escape of the initial water. Curing compounds may be applied by brushes or pressure sprayers. A gallon will cover 200 to 300 sq ft.
Concrete should be placed at a temperature not less than 40 or more than 80°F.A lower tem-perature will decrease the rate of setting, while a
higher temperature will decrease the ultimate strength.
Placing Concrete in Cold Weather
When the concrete is placed during cold weather, it is usually necessary to preheat the water, the aggregate, or both in order that the ini-tial temperature will assure an initial set and gain in strength .Preheating the water is the most ef-fective method of providing the necessary tem-perature. For this purpose a water reservoir should be equipped with pipe coils through which steam can be passed, or steam may bedischarged directly into the water, several outlets being used to given better distribution of the heat.
When the temperatures of the mixtures are known, some specific charts may be used to cal-culate the temperature of concrete. A straight line pass all three scales, passing through every two known temperatures, will assure the determina-tion of the third temperature. If the surface of sand is
dry, the fact lines of the scales giving the temperature of concrete should be used. However, if the sand contains about 3 percent moisture, the dotted lines should be used.
Specifications usually demand that freshly placed concrete shall be kept at a temperature of not less than 70°F for 3 days or 50°F for 5 days after it is placed. Some proper method must be provided to keep the demanded temperature when the cold weather is estimated.
Reinforcing steels for concrete
Compared with concrete, steel is a high strength material. The useful strength of ordinary reinforcing steels in tension as well as compres-sion, i.e., the yield strength, is about 15 times the compressive strength of common structural con-crete, and well over 100 times its tensile strength. On the other hand, steel is a high-cost material compared with concrete. It follow that the two materials are the best used in combination if theconcrete is made to resist the compressive stresses and the compressive force, longitudinal steel reinforcing bars are located close to the ten-sion face to resist the tension force., and usually additional steel bars are so disposed that they re-sist the inclined tension stresses that are caused by the shear force in the beams. However, rein-forcement is also used for resisting compressive forces primarily where it is desired to reduce the cross-sectional dimensions of compression members, as in the lower-floor columns of multi-story buildings. Even if no such necessity exits , a minimum amount of reinforce- ment is placed in all compression members to safeguard them against the effects of small accidental bending moments that might crack and even fail an unre-inforced member.
For most effective reinforcing action, it is essential that steel and concrete deform together, i. e., that there be a sufficiently strong bond be-tween the two materials to ensure that no relative movements of the steel bars and the surrounding concrete occur. This bond is provided by the rela-tively large chemical adhesion which develops at the steel-concrete interface, by the natural roughness of the mill scale of hot-rolled rein-forcing bars , and by the closely spaced rib-shap-ed surface deformations with which reinforcing bars are furnished in order to provide a high de-gree of interlocking of the two materials.
Steel is used in two different ways in con-crete structures: as reinforcing steel and as prestressing steel .reinforcing steel is placed in the forms prior to casting of the concrete. Stresses in the steel, as in the hardened concrete, are caused only by the loads on the structure, except for possible parasitic stresses from shrinkage or similar causes. In contrast, in priestesses concrete structures large tension forces are applied to the reinforcement prior to letting it act jointly with the concrete in resistingexternal.
The most common type of reinforcing steel is in the form of round bars, sometimes called rebars, available in a large range of diameters,from 10 to 35 mm for ordinary applications and in two heavy bar sizes off 44 and 57 mm these bars are furnished with surface deformations for the purpose of increasing resistance to slip be-tween steel and concrete minimum requirements for these deformations have been developed in experimental research. Different bar producers use different patterns, all of which satisfy these requirements.
Welding of rebars in making splices, or for convenience in fabricating reinforcing cages for placement in the forms, may result in metal-lurgical changes that reduce both strength and ductility, and special restrictions must be placed both strength and ductility, and special restric-tions must be placed both on the type of steel used and the welding procedures the provisions of ASTM A706 relate
specifically to welding.
In reinforced concrete a long-time trend is evident toward the use of higher strength materi-als, both steel and concrete.
Reinforcing bars with 40ksi yield stress , almost standard 20 years ago , have largely been replaced by bars with 60ksi yield stress , both because they are more economical and because their use tends to reduce congestion of steel in the forms .
The ACI Code permits reinforcing steels up to Fy=80ksi. Such high strength steels usually yield gradually but have no yield plateau in this situation the ACI Code requires that at the speci-fied minimum yield strength the total strain shall not exceed 0.0035 this is necessary to make cur-rent design methods, which were developed for sharp-yielding steels with a yield plateau, appli-cable to such higher strength steels. there is no ASTM specification for deformed bars may be used , according to the ACI Code , providing they meet the requirements stated under special circumstances steel in this higher strength range has its place, e.g., in lower-story columns of high-rise buildings.
In order to minimize corrosion of rein-forcement and consequent spelling of concrete under sever exposure conditions such as in bridge decks subjected to deicing chemicals , galvanized or epoxy-coated rebars may be specified.
Repair of Concrete Structures
Reinforced concrete is generally a very du-rable structural material and very little repair work is usually needed. However, its durability can be affected by a variety of causes, including those of design and construction faults, use of inferior materials and exposure to aggressive en-vironment. The need for a repair is primarily dic-tated by the severity of the deterioration as de-termined from the diagnosis. Good workmanship is essential if any thing more than just a cosmetic treatment to the creation is required.
1. performance requirements of repair system
Having established the causes of the defect by carefully diagnosing the distress, the next step should be to consider the requirements of the re-pair method that will offer an effective solution to the problem (see fig.).
①Durability
It is important to select repair materials that provide adequate durability. Materials used for the repair job should be at least as durable as the substrate concrete to which it is applied.
②Protection of steel
The mechanism of protection provided to the reinforcing depends on the type of repair ma-terials used. For example, cementations materials can protect the steel from further corrosion by their inhibitive effect of increasing the alkalinity of the concrete, whereas epoxy resin mortars can give protection against the ingress of oxygen,moisture and other harmful agents.
③Bond with substrate
The bond with the substrate must produce an integral repair to prevent entry of moisture and atmospheric gases at the interface. With most re-pair materials, the bond is greatly enhanced with the use of a suitable bonding aid such as an un-filled epoxy resin systems and slurry of Portland cement, plus any latex additives for a Portland cement-based repair system. Precautions should also be taken
to remove all loose and friable ma-terials from the surfaces to be bonded.
④Dimensional Stability
Shrinkage of materials during curing should be kept to a minimum. Subsequent dimensional change should be very close in the substrate in order to prevent failure
⑤Initial Resistance to Environmentally In-duced Damage
Some initial exposure conditions may lead to premature damage lo repairs. For example, partially cured Portland cement repairs can dete-riorate from hot weather preventing full hydration of the cement. To prevent this from happening extra protection during curing time may be nec-essary.
⑥Ease of Application
Materials should be easily mixed and ap-plied so that they can be worked readily into small crevices and voids. Ideally, the material should not stick to tools, and should not shear while being trowel led nor slump after placement.
⑦Appearance
The degree to which the repair material should match the existing concrete will depend on the use of the structure and the client' s re-quirements. A surface coating may be required when appearance is important or when cover to reinforcement is small.
2. Selection of Repair Methods
A suitable repair counteracts all the defi-ciencies which are relevant to the use of the structure.
The selection of tile correct method and material for a particular, application requires careful consideration, whether to meet special requirements for placing strength, durability or other short-or long-term properties. These con-siderations include:1. Nature of the Distress
If alive crack is filled with a rigid material, then either the repair material will eventually fail or some new cracking will occur adjacent to the original crack. Repairs to live cracks must either use flexible materials to accommodate move-ments or else steps must be taken prior to the re-pair to eliminate the movement.
2. Position of the Crack
Techniques which rely on gravity to intro-duce the material into the crack are more suc-cessfully carried out on horizontal surfaces but are rarely effective on vertical ones.
3. Environment
If moisture, water or contaminants are found in the crack, then it is necessary to rectify the leaks Repair to slop leaks may be further com-plicated by the need to make the repairs while the structure is in service and the environment is damp.
4. Workmanship
The skill the operatives available to carry put the repairs is another relevant factors. Some-times this can mean the difference between a permanent repair and premature failure of the re-pair material.
5. Cost
The cost of repair materials is usually small compared with the costs of providing access, preparation and actual labor.
6. Appearance
The repair surface may be unsightly, par-ticularly when it appears on a prominent part of the building. In this case, the repair system will include some form of treatment over the entire surface.
Reference
[1]Philip Jodidio, Contemporary European Architecture, Taschen, Koln, pp.148-153
[2]Ann Breen & Dick Rigby, Waterfronts, McGraw-Hill, Inc. New York, 1994, pp.297-300
[3]Ann Breen & Dick Rigby, The New Waterfront, Thames and Hudson, London, 1996, pp.118-120
[4]Ann Breen & Dick Rigby, The New Waterfront, Thames and Hudson, London, 1996, pp.52-55
[5]Robert Holden, International Landscape Design, Laurence King Publishing, London, 1996, pp.10-27
[6] A new concept in refrigerant control for heat pumps ,J.R.Harnish,IIR Conference Pa-per,Cleveland,Ohio.May,1996
[7]Carrier Corporation-Catalog 523 848,
1997
[8]Waste Heat Management Handbook, Na-tional Bureau of Standardc Handbook 121, Pub-lica-tion PB 264959, February,1997
Ten design principles for air to air heat pumps,Allen Trask,ASHRAE Journal,July,1997
重庆科技学院学生毕业设计（论文）外文译文
学院建建筑工程学院
专业班级工管103
学生姓名李
学号201044241
附件1：外文资料翻译译文
混凝土施工事项
T.Pauly, M.J.N.Priestley
摘要：根据一般承认的惯例看,巴基斯坦的混凝土结构建筑物在结构上的质量，效用和安全需要上都留下了很多值得关注的问题。当2005 年10月8日发生在巴基斯坦北部的一个7.6级地震的时候，这些施工技术上的缺点袒露无遗了,破坏了数以千计建筑物、桥梁, 而且造成估计79,000人的死亡。在巴基斯坦这种十分低质量的混凝土施工技术是造成这次极广破坏的主要原因。
关键字：混凝土浇筑养护建筑工艺
混凝土浇筑
若混凝土在地面上浇筑，地面应该具有足够的含水量以避免它吸收混凝土中的水分。如果新混凝土将被浇筑在已经凝固的混凝土上或其旁边，已浇混凝土表面应该彻底清除干净，最好使用高压空气、高压水流或钢丝刷。其表应潮湿，但不应有集水，应当在整个范围内刷上少量的水泥浆，然后立即铺上一层厚度为1/2in的砂浆。新混凝土应铺筑在砂浆上或其旁边。
为减少混凝土在浇筑后由于运输导致的离析，混凝土的制备应该尽可能靠近最后浇筑的地方。它应该分层浇筑以使每层可被均压实。每层浇筑间隔的时间应该限制在能够保证新浇筑的混凝土与前面浇筑的有良好的结合。
当向较深的模板中浇筑混凝土时，就应该使用一根导管来限制混凝土的自由降落高度不超过3或4ft，以防止混凝土离析。这种导管是由轻金属制成的管子，具有可调节的长度而且被连接到储存的混凝土的罐的底部。当模板被浇筑满后，就可以抽出管节。
混凝土一浇筑完成，应立即用手提振捣器或机器振捣器进行捣密后就应该移走，否则就会发生骨料离析。一般来说，振捣器不应该集中在先前提起的混凝土上。
振捣主要优点是它允许使用较干的混凝土，由于减少了混凝土的含水量，这种混凝土有较高的强度。振捣混凝土的优点如下：
1、水分的减少允许水泥和细集料的用量，因为这时需要较少的水泥浆。
2、较低的含水量可减少收缩和空隙。
3、较干的混凝土减少混凝土表面处理的费用。
4、机械振捣可代替3—8个手持振捣棒。
5、较低的含水量可提高混凝土的强度。
6、较干的混合料允许较早地拆除一些模板，这样可降低模板的造价。
混凝土的养护
若混凝土想要获得最高强度或其它必要特性，则应该对其用足够的水分和适当的温度进行养护。如果没能提供这些条件，则会导致劣质的混凝土。
混凝土中最初的水分足够所有水泥的水化反应，只要在使用前没有被蒸发。这可以用多种方法来实现，例如把模板留在混凝土中，保持表面潮湿，或在混凝土表面覆盖一层液体养生化合物，它可以形成一种不透水的隔膜来阻止混凝土中的水分遗失。养生化合物可以用刷子或压力喷嘴加到混凝土表面。一加仑可以覆盖200—300ft2。
混凝土应该在40°F以上或80°F以下进行浇筑。低温会降低凝结速度，而高温会降低混凝土的极限强度。
寒冷天气下的混凝土浇筑
当混凝土在寒冷天气下浇筑时，通常有必要预先加热水、骨料或两者同时预热，以便使其初始温度能够保证混凝土的初凝并获得强度。对水进行预热是提供必要的温度最有效的方法。出于这一目的，蓄水池应该安装一个通有蒸气的蛇形管或将蒸气可以直接通到水中，这是可以使用多个排气口以提供良好的热量分布。
当混合料的温度已知，一些专用图可以用来计算混凝土的温度。一条直线穿过所有三种比例，通过任意两个已知温度，就可以确定出第三个温度。如果砂的表面干燥，则应使用实线计算混凝土的温度。然而，如果砂含有3%的水分，则应使用虚线。
规范通常要求新浇筑的混凝土在浇筑后应保持3天温度不低于70°F或5天不低于50°F。当预计有寒冷天气时必须提供一些适当的方法来保持要求的温度。
用于混凝土中的钢筋
与混凝土相比，钢是一种高强度材料。普通钢筋在抗拉和抗压时可以利用的强度，即屈服强度，约为普通的结构混凝土抗压强度的1.5倍，而且超过抗拉强度的100倍。另一方面，与混凝土相比，钢材的成本要高得多。所以，两种材
料最好的结合使用是混凝土用于抵抗压应力。因此，在钢筋混凝土梁内，混凝土抵抗压应力，纵向钢筋配置在靠近受拉面处以抵抗拉应力，通常还附加配有一些钢筋，抵抗梁内的剪应力所引起的斜向拉应力。然而，钢材也可以用于抵抗应力，主要是为了减小受压构件的截面尺寸，例如用于多层建筑的下部楼层柱。即使不存在这种必要性，所有受压构件也要配置最少数量的钢筋，以保证这些构件在偶然出现的小弯矩作用下的安全性，在这情况下，不加钢筋的混凝土构件可能会开裂，甚至破坏。
使配筋最有效的发挥作用的基本条件是钢筋和混凝土的变形要一致，即这两种材料间要有足够强的黏结力，以确保钢筋和其周围混凝土间不发生相对移动。这种黏结力是由钢筋-混凝土结合面上较强的化学粘合作用，热轧钢筋表面层的固有粗糙度，以及间距较小的肋形表面变形等所构成的。钢筋的边面并行为两种材料间提供了很高的咬合作用。
钢材以两种不同方式应用于混凝土中：普通钢筋和预应力钢筋。普通钢筋在浇筑混凝土之前先置于模板内。钢筋中的应力，与硬化混凝土中的应力一样，除了由收缩或类似原因造成的附加应力外，仅仅是由结构上作用的荷载引起的，比较起来，在预应力混凝土结构中，在钢筋与混凝土共同工作承受外部荷载之前，对钢筋已施加了很大的拉力。
最常见的钢筋的形式为圆棒状。现在可以使用的钢筋的直径范围很大，在一般的应用中从10到35毫米，两种大型钢筋的尺寸为44和57毫米。对这些钢筋表面进行了变形处理，其目的是增加钢筋与混凝土之间的抗滑能力。对这些变形的最低要求已经通过实验研究予以确定。不同的钢筋制造厂家采用不同的变形花纹，他们全部都能够满足这些要求。
为了对钢筋进行拼接，或者便于制作置于模板内的钢筋骨架所进行的焊接，可能会引起金相的变化而降低材料的强度和延性，因此，必须对所有钢材的类型和焊接规程加以特殊的限制。ASTM中的A706的条款是专门使用于焊接的。
长期以来，在钢筋混凝土领域明显的趋向于高强度材料，包括钢筋和混凝土。屈服强度为40KSI的钢筋，在20年前几乎是标准的盲目前大部分已由屈服强度为60钢筋所取代。因为后者更为经济，而且使用他们可以减少模板内钢筋的拥挤状况。
ACI规范允许使用强度FY=80KSI的钢筋。这类高强度钢筋通常是逐渐屈服的没有屈服平台。在这种情况下，ACI规范要求在规定的最小屈服强度时的总应变不应超过0.0035。这是将现行的设计方法应用于这类高强度钢筋时必须遵守的。现行的设计方法是按钢材突然屈服，而且有屈服平台的情况而制定的。ASTM 规范中没有关于屈服强度高于60KSI的变形钢筋的条款，但是在实际中可能使用这种钢筋，根据ACI规范，他们可以在根据上述的要求的情况下使用。在特殊情况下，例如高层建筑的下部楼层的柱子，使用这一高强度范围内的钢筋就非常适合。
在恶劣的环境田间下，例如受除冰化学剂侵蚀的荞麦内，要求使用镀锌或环氧树脂涂层的钢筋，以便使钢筋的腐蚀和随之发生的混凝土的剥落减至最小。
混凝土结构的修复
钢筋混凝土是非常耐用的结构材料，它需要的修复工作很少。然而，它的耐用性受很多因素的影响。这包括那些设计和施工的失误，使用劣质材料和在侵蚀性环境下暴露。修复的必要性主要取决于对破坏程度的诊断。如果某项工程不只需要作装饰性处理，好的工作技巧很重要。
1、修复系统的功能要求
通过对事故的仔细诊断并找到损坏的原因之后，下一步是考虑修复方法的要求，这样会我到一个解决问题的有效方法。
①耐久性
选择有相当耐久性的修复材料非常重要。修复工作所用的材料最起码也要像基层混凝土那样耐用。
②钢筋的保护
对加劲钢筋的保护机理取决于所使用的修复材料的类型。例如，粘性材料能促使混凝土碱性增加，其抑制作用能保护钢筋免受更深的侵蚀，而环氧树脂砂浆可防止氧气、水分和其它有害物的侵人。
③基片粘结
使用基片粘结可进行完整的修复，它可防止水分和大气从界面进人。大多数的修复材料，通过使用合适的粘合手段，其粘合性能已大大地改善了，如环氧树脂系统使用未填充的环氧底漆，普通水泥修复系统使用普通水泥稀浆加上任何一种乳胶添加剂。所要采用的预防措施是：对即将被粘结的表面，必须先清理其上面的疏松和易碎的物质。
④尺寸稳定性
在养护期间，材料的收缩要保持到最小，为了防止修复失败、材料的尺寸变化应与基层材料相当接近。
⑤对环境引起的损伤的早期防护
一些开始就暴露在外的情况会引起修复的过早损坏。例如，热天会阻碍水泥的水合作用从而使局部修复的普通水泥发生变质，为了防止发生这种情况，养护期间应对其作特别的保护。
⑥操作方便
材料应当易混合和方便使用，这样可以随时填到裂缝和孔隙里去，材料最好是不粘工具，用泥刀修平时不剥落，填筑后不坍塌。
⑦外观
修复材料与现有混凝土的匹配程度取决于所修补的结构和业主的要求。当外观很重要或钢筋的保护层很薄时，要求采用镶面处理。
2、修复方法的选择
适当的修复就是消除与结构使用有关的所有缺陷。认真考虑选择正确的方法和某一特定操作所用的材料，弄清到底是要满足强度、耐用性的特定要求还是满足其它的长期或短期的性能要求。这些因素包括：
1.损伤的性质
如果活动裂缝里填的是刚性材料，那么不但填补材料会断裂，而且旧裂缝周围也会产生新的裂缝，修复活动裂缝的方法是要么采用柔性材料以适应结构位移，要么在修复之前采取一定措施消除结构位移。
2．断裂的部位
依靠材料重力填充裂缝技术在水平面上裂缝修补中的成功率较高，但在竖直面上裂缝修补中效果很差。
3．环境
如果裂缝里有水气、水和杂物时，要先补好漏洞。如果结构还处于工作状态并且环境潮湿时，会使得堵住漏洞这一工作更加困难。
4.工艺
工人所采用的修复工艺是另一个与修复有关的因素，有时它意味着水久性修复或者修复材料过早损坏。
5．成本
与为修复工作提供通路、做准备工作和实际劳力的成本相比，所用的修复材料的成本是相当小的。
6.外观
修复部位的表面可能很难看，特别是当它处于建筑物显眼的地方时。在这种情况下，修复工作系统就要包括对整个表面进行某种处理。
华北电力大学科技学院 毕业设计（论文）附件 外文文献翻译 学号：121912020115姓名：彭钰钊 所在系别：动力工程系专业班级：测控技术与仪器12K1指导教师：李冰 原文标题：Infrared Remote Control System Abstract 2016 年 4 月 19 日
红外遥控系统 摘要 红外数据通信技术是目前在世界范围内被广泛使用的一种无线连接技术，被众多的硬件和软件平台所支持。红外收发器产品具有成本低，小型化，传输速率快，点对点安全传输，不受电磁干扰等特点，可以实现信息在不同产品之间快速、方便、安全地交换与传送，在短距离无线传输方面拥有十分明显的优势。红外遥控收发系统的设计在具有很高的实用价值，目前红外收发器产品在可携式产品中的应用潜力很大。全世界约有1亿5千万台设备采用红外技术，在电子产品和工业设备、医疗设备等领域广泛使用。绝大多数笔记本电脑和手机都配置红外收发器接口。随着红外数据传输技术更加成熟、成本下降，红外收发器在短距离通讯领域必将得到更广泛的应用。 本系统的设计目的是用红外线作为传输媒质来传输用户的操作信息并由接收电路解调出原始信号，主要用到编码芯片和解码芯片对信号进行调制与解调，其中编码芯片用的是台湾生产的PT2262，解码芯片是PT2272。主要工作原理是：利用编码键盘可以为PT2262提供的输入信息，PT2262对输入的信息进行编码并加载到38KHZ的载波上并调制红外发射二极管并辐射到空间，然后再由接收系统接收到发射的信号并解调出原始信息，由PT2272对原信号进行解码以驱动相应的电路完成用户的操作要求。 关键字：红外线；编码；解码；LM386；红外收发器。 1 绪论
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Optimum blank design of an automobile sub-frame Jong-Yop Kim a ,Naksoo Kim a,*,Man-Sung Huh b a Department of Mechanical Engineering,Sogang University,Shinsu-dong 1,Mapo-ku,Seoul 121-742,South Korea b Hwa-shin Corporation,Young-chun,Kyung-buk,770-140,South Korea Received 17July 1998 Abstract A roll-back method is proposed to predict the optimum initial blank shape in the sheet metal forming process.The method takes the difference between the ?nal deformed shape and the target contour shape into account.Based on the method,a computer program composed of a blank design module,an FE-analysis program and a mesh generation module is developed.The roll-back method is applied to the drawing of a square cup with the ˉange of uniform size around its periphery,to con?rm its validity.Good agreement is recognized between the numerical results and the published results for initial blank shape and thickness strain distribution.The optimum blank shapes for two parts of an automobile sub-frame are designed.Both the thickness distribution and the level of punch load are improved with the designed blank.Also,the method is applied to design the weld line in a tailor-welded blank.It is concluded that the roll-back method is an effective and convenient method for an optimum blank shape design.#2000Elsevier Science S.A.All rights reserved. Keywords:Blank design;Sheet metal forming;Finite element method;Roll-back method
A convection-conduction model for analysis of the freeze-thaw conditions in the surrounding rock wall of a tunnel in permafrost regions Abstract Based on the analyses of fundamental meteorological and hydrogeological conditions at the site of a tunnel in the cold regions, a combined convection-conduction model for air flow in the tunnel and temperature field in the surrounding has been constructed. Using the model, the air temperature distribution in the Xiluoqi No. 2 Tunnel has been simulated numerically. The simulated results are in agreement with the data observed. Then, based on the in situ conditions of sir temperature, atmospheric pressure, wind force, hydrogeology and engineering geology, the air-temperature relationship between the temperature on the surface of the tunnel wall and the air temperature at the entry and exit of the tunnel has been obtained, and the freeze-thaw conditions at the Dabanshan Tunnel which is now under construction is predicted. Keywords: tunnel in cold regions, convective heat exchange and conduction, freeze-thaw. A number of highway and railway tunnels have been constructed in the permafrost regions and their neighboring areas in China. Since the hydrological and thermal conditions changed after a tunnel was excavated，the surrounding wall rock materials often froze, the frost heaving caused damage to the liner layers and seeping water froze into ice diamonds，which seriously interfered with the communication and transportation. Similar problems of the freezing damage in the tunnels also appeared in other countries like Russia, Norway and Japan .Hence it is urgent to predict the freeze-thaw conditions in the surrounding rock materials and provide a basis for the design，construction and
Study on Project Cost Control of Construction Enterprises By: R. Max Wideman Abstract With the increasing maturity of construction market, the competition between construction enterprises is becoming fierce. The project profit is gradually decreasing. It demands that all construction enterprises enhance their cost control, lower costs, improve management efficiency and gain maximal profits. This paper analyses the existing problems on project cost control of Chinese construction enterprises, and proposes some suggestions to improve project cost control system. Key Words ：Construction enterprises, Project management, Cost control After joining the WTO, with Chinese construction market becoming integrated, the competition among architectural enterprises is turning more intense. Construction enterprises must continually enhance the overall competitiveness if they want to develop further at home and abroad construction market. Construction Enterprises basically adopt the "project management-centered" model, therefore, it is particularly important to strengthen project cost control. 1.The Current Domestic Project Cost Classification and Control Methods Cost refers to the consumption from producing and selling of certain products, with the performance of various monetary standing for materialized labor and labor-consuming. Direct and indirect costs constitute the total cost, also known as production cost or manufacturing cost. Enterprise product cost is the comprehensive indicator to measure enterprise quality of all aspects. It is not only the fund compensation scale, but also the basis to examine the implementation of cost plan. Besides, it can provide reference for product pricing According to the above-mentioned definition and current domestic cost classification, construction project cost can be divided into direct costs and indirect costs. Direct costs include material cost, personnel cost, construction machinery cost, material transportation cost, temporarily facility cost, engineering cost and other direct cost. Indirect costs mainly result from project management and company's cost-sharing, covering project operating costs (covering the commission of foreign projects), project's management costs (including exchange losses of
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。
外文翻译 原文 Foreign T rade o f China Material Source:W anfang Database Author:Hitomi Iizaka 1.Introduction On December11,2001,China officially joined the World T rade Organization(WTO)and be c a me its143rd member.China’s presence in the worl d economy will continue to grow and deepen.The foreign trade sector plays an important andmultifaceted role in China’s economic development.At the same time, China’s expanded role in the world economy is beneficial t o all its trading partners. Regions that trade with China benefit from cheaper and mor e varieties of imported consumer goods,raw materials and intermediate products.China is also a large and growing export market.While the entry of any major trading nation in the global trading system can create a process of adjustment,the o u t c o me is fundamentally a win-win situation.In this p aper we would like t o provide a survey of the various institutions,laws and characteristics of China’s trade.Among some of the findings, we can highlight thefollowing: ?In2001,total trade to gross domestic pr oduct(GDP)ratio in China is44% ?In2001,47%of Chinese trade is processed trade1 ?In2001,51%of Chinese trade is conduct ed by foreign firms in China2 ?In2001,36%of Chinese exports originate from Gu an gdon g province ?In2001,39%of China’s exports go through Hong Kong to be re-exported elsewhere 2.Evolution of China’s Trade Regime Equally remarkable are the changes in the commodity composition of China’s exports and imports.Table2a shows China’s annu al export volumes of primary goods and manufactured goods over time.In1980,primary goods accounted for 50.3%of China’s exports and manufactured goods accounted for49.7%.Although the share of primary good declines slightly during the first half of1980’s,it remains at50.6%in1985.Since then,exports of manufactured goods have grown at a much
文献出处：Thronson P. Toward Comprehensive Reform of America’s Emergency Law Regime [J]. University of Michigan Journal of Law Reform, 2013, 46(2). 原文 TOWARD COMPREHENSIVE REFORM OF AMERICA’S EMERGENCY LAW REGIME Patrick A. Thronson Unbenownst to most Americans, the United States is presently under thirty presidentially declared states of emergency. They confer vast powers on the Executive Branch, including the ability to financially incapacitate any person or organization in the United States, seize control of the nation’s communications infrastructure, mobilize military forces, expand the permissible size of the military without congressional authorization, and extend tours of duty without consent from service personnel. Declared states of emergency may also activate Presidential Emergency Action Documents and other continuity-of-government procedures, which confer powers on the President—such as the unilateral suspension of habeas corpus—that appear fundamentally opposed to the American constitutional order.
中英文资料对照外文翻译 Design phase of the project cost management Abstract Project cost management is the basic contents to determine reasonable and effective control of the project cost. Described the current stage of the project cost management situation on the strengthening of the various stages of construction cost management of the importance of and raised a number of key initiatives. Keywords：cost of the construction project cost management status investment decision phase of the design phase of the implementation phase of the cost management in a market economy, Even under the WTO and China's accession to the world community, China's construction industry how to effectively control construction cost of the construction and management of an important component part. However, the current budget for the construction projects - estimate, budget, Super budget accounts for the "super three" is still widespread and that eventually led to a serious loss of control of project investment. Project cost management is the basic contents to determine reasonable and effective control of the project cost. As the project cost to the project runs through the entire process, stage by stage can be divided into Investment Decision stage, the design and implementation phases. The so-called Project Cost effective control is the optimization of the construction plans and design programs on the basis of in the building process at all stages, use of certain methods and measures to reduce the cost of the projects have a reasonable control on the scope and cost of the approved limits.
南京理工大学 毕业设计(论文)外文资料翻译 教学点：南京信息职业技术学院 专业：电子信息工程 姓名：陈洁 学号： 014910253034 外文出处：《 Pci System Architecture 》 (用外文写) 附件： 1.外文资料翻译译文；2.外文原文。 指导教师评语： 该生外文翻译没有基本的语法错误，用词准确，没 有重要误译，忠实原文；译文通顺，条理清楚，数量与 质量上达到了本科水平。 签名： 年月日 注：请将该封面与附件装订成册。
附件1：外文资料翻译译文 64位PCI扩展 1.64位数据传送和64位寻址：独立的能力 PCI规范给出了允许64位总线主设备与64位目标实现64位数据传送的机理。在传送的开始，如果回应目标是一个64位或32位设备，64位总线设备会自动识别。如果它是64位设备，达到8个字节（一个4字）可以在每个数据段中传送。假定是一串0等待状态数据段。在33MHz总线速率上可以每秒264兆字节获取（8字节／传送＊33百万传送字／秒），在66MHz总线上可以528M字节／秒获取。如果回应目标是32位设备，总线主设备会自动识别并且在下部4位数据通道上（AD[31::00]）引导，所以数据指向或来自目标。 规范也定义了64位存储器寻址功能。此功能只用于寻址驻留在4GB地址边界以上的存储器目标。32位和64位总线主设备都可以实现64位寻址。此外，对64位寻址反映的存储器目标（驻留在4GB地址边界上）可以看作32位或64位目标来实现。 注意64位寻址和64位数据传送功能是两种特性，各自独立并且严格区分开来是非常重要的。一个设备可以支持一种、另一种、都支持或都不支持。 2.64位扩展信号 为了支持64位数据传送功能，PCI总线另有39个引脚。 ●REQ64#被64位总线主设备有效表明它想执行64位数据传送操作。REQ64#与FRAME#信号具有相同的时序和间隔。REQ64#信号必须由系统主板上的上拉电阻来支持。当32位总线主设备进行传送时，REQ64#不能又漂移。 ●ACK64#被目标有效以回应被主设备有效的REQ64#（如果目标支持64位数据传送），ACK64#与DEVSEL#具有相同的时序和间隔（但是直到REQ64#被主设备有效，ACK64#才可被有效）。像REQ64#一样，ACK64#信号线也必须由系统主板上的上拉电阻来支持。当32位设备是传送目标时，ACK64#不能漂移。 ●AD[64::32]包含上部4位地址／数据通道。 ●C/BE#[7::4]包含高4位命令/字节使能信号。 ●PAR64是为上部4个AD通道和上部4位C/BE信号线提供偶校验的奇偶校验位。 以下是几小结详细讨论64位数据传送和寻址功能。 3.在32位插入式连接器上的64位卡
翻译文献：INVESTIGATION ON DYNAMIC PERFORMANCE OF SLIDE UNIT IN MODULAR MACHINE TOOL （对组合机床滑台动态性能的调查报告） 文献作者：Peter Dransfield, 出处：Peter Dransfield, Hydraulic Control System-Design and Analysis of TheirDynamics, Springer-Verlag, 1981 翻译页数：p139—144 英文译文： 对组合机床滑台动态性能的调查报告 【摘要】这一张纸处理调查利用有束缚力的曲线图和状态空间分析法对组合机床滑台的滑动影响和运动平稳性问题进行分析与研究，从而建立了滑台的液压驱动系统一自调背压调速系统的动态数学模型。通过计算机数字仿真系统，分析了滑台产生滑动影响和运动不平稳的原因及主要影响因素。从那些中可以得出那样的结论，如果能合理地设计液压缸和自调背压调压阀的结构尺寸. 本文中所使用的符号如下： s1-流源，即调速阀出口流量； S el—滑台滑动摩擦力 R一滑台等效粘性摩擦系数： I1—滑台与油缸的质量 12—自调背压阀阀心质量 C1、c2—油缸无杆腔及有杆腔的液容； C2—自调背压阀弹簧柔度； R1, R2自调背压阀阻尼孔液阻， R9—自调背压阀阀口液阻 S e2—自调背压阀弹簧的初始预紧力； I4, I5—管路的等效液感 C5、C6—管路的等效液容： R5, R7-管路的等效液阻； V3, V4—油缸无杆腔及有杆腔内容积； P3, P4—油缸无杆腔及有杆腔的压力 F—滑台承受负载， V—滑台运动速度。本文采用功率键合图和状态空间分折法建立系统的运动数学模型，滑台的动态特性可以能得到显著改善。
提高塔式复合人工湿地处理农村生活污水的 脱氮效率1 摘要： 努力保护水源，尤其是在乡镇地区的饮用水源，是中国污水处理当前面临的主要问题。氮元素在水体富营养化和对水生物的潜在毒害方面的重要作用，目前废水脱氮已成为首要关注的焦点。人工湿地作为一种小型的，处理费用较低的方法被用于处理乡镇生活污水。比起活性炭在脱氮方面显示出的广阔前景，人工湿地系统由于溶解氧的缺乏而在脱氮方面存在一定的制约。为了提高脱氮效率，一种新型三阶段塔式混合湿地结构----人工湿地（thcw）应运而生。它的第一部分和第三部分是水平流矩形湿地结构，第二部分分三层，呈圆形，呈紊流状态。塔式结构中水流由顶层进入第二层及底层，形成瀑布溢流，因此水中溶解氧浓度增加，从而提高了硝化反应效率，反硝化效率也由于有另外的有机物的加入而得到了改善，增加反硝化速率的另一个原因是直接通过旁路进入第二部分的废水中带入的足量有机物。常绿植物池柏（Taxodium ascendens），经济作物蔺草（Schoenoplectus trigueter），野茭白（Zizania aquatica），有装饰性的多花植物睡莲（Nymphaea tetragona），香蒲（Typha angustifolia）被种植在湿地中。该系统对总悬浮物、化学需氧量、氨氮、总氮和总磷的去除率分别为89%、85%、83%、83% 和64%。高水力负荷和低水力负荷（16 cm/d 和32 cm/d）对于塔式复合人工湿地结构的性能没有显著的影响。通过硝化活性和硝化速率的测定，发现硝化和反硝化是湿地脱氮的主要机理。塔式复合人工湿地结构同样具有观赏的价值。 关键词： 人工湿地；硝化作用；反硝化作用；生活污水；脱氮；硝化细菌；反硝化细菌 １. 前言 对于提高水源水质的广泛需求，尤其是提高饮用水水源水质的需求是目前废水深度处理的技术发展指向。在中国的乡镇地区，生活污水是直接排入湖泊、河流、土壤、海洋等水源中。这些缺乏处理的污水排放对于很多水库、湖泊不能达到水质标准是有责任的。许多位于中国的乡镇地区的社区缺乏足够的生活污水处理设备。由于山区地形、人口分散、经济基础差等原因，废水的收集和处理是很成问题的。由于资源短缺，经济欠发达地区所采取的废水处理技术必须低价高效，并且要便于施用，能量输入及维护费用较低，而且要保证出水能达标。建造在城市中基于活性污泥床的废水集中处理厂，对于小乡镇缺乏经济适用性，主要是由于污水收集结构的建造费用高。 1Ecological Engineering，Fen xia ，Ying Li。
毕业设计（论文） 外文文献翻译 文献、资料中文题目：研究建设项目的工程造价 文献、资料英文题目： 文献、资料来源： 文献、资料发表（出版）日期： 院（部）： 专业：工程管理 班级： 姓名： 学号： 指导教师： 翻译日期： 2017.02.14
科技文献翻译 题目：研究建设项目的工程造价 研究建设项目的工程造价 摘要 在工程建设中，中国是拥有世界最大投资金额和具有最多建设项目的国家。它是一 项在建设项目管理上可以为广泛的工程管理人员进行有效的工程造价管理，并合理 确定和保证施工质量和工期的条件控制施工成本的重要课题。 在失去了中国建筑的投资和技术经济工程，分离的控制现状的基础上，通过建设成 本控制的基本理论为指导，探讨控制方法和施工成本的应用，阐述了存在的问题在 施工成本控制和对决心和施工成本的控制这些问题的影响，提出了建设成本控制应 体现在施工前期，整个施工过程中的成本控制，然后介绍了一些程序和应用价值工 程造价的方法在控制建设项目的所有阶段。 关键词：建设成本，成本控制，项目 1.研究的意义 在中国，现有的工程造价管理体系是20世纪50年代制定的，并在1980s.Traditional 施工成本管理方法改进是根据国家统一的配额，从原苏联引进的一种方法。它的特 点是建设成本的计划经济的管理方法，这决定了它无法适应当前市场经济的要求。 在中国传统建筑成本管理方法主要包括两个方面，即建设成本和施工成本控制方法 的测定方法。工程造价的确定传统的主要做法生搬硬套国家或地方统一的配额数量 来确定一个建设项目的成本。虽然这种方法已经历了20多年的改革，到现在为止，计划经济管理模式的影响仍然有已经存在在许多地区。我们传统的工程造价控制的
预测高速公路建设项目最终的预算和时间 摘要 目的——本文的目的是开发模型来预测公路建设项目施工阶段最后的预算和持续的时间。 设计——测算收集告诉公路建设项目，在发展预测模型之前找出影响项目最终的预算和时间，研究内容是基于人工神经网络(ANN)的原理。与预测结果提出的方法进行比较,其精度从当前方法基于挣值。 结果——根据影响因素最后提出了预算和时间，基于人工神经网络的应用原理方法获得的预测结果比当前基于挣值法得到的结果更准确和稳定。 研究局限性/意义——因素影响最终的预算和时间可能不同,如果应用于其他国家,由于该项目数据收集的都是泰国的预测模型,因此,必须重新考虑更好的结果。 实际意义——这项研究为用于高速公路建设项目经理来预测项目最终的预算和时间提供了一个有用的工具，可为结果提供早期预算和进度延误的警告。 创意/价值——用ANN模型来预测最后的预算和时间的高速公路建设项目,开发利用项目数据反映出持续的和季节性周期数据, 在施工阶段可以提供更好的预测结果。 关键词：神经网、建筑业、预测、道路、泰国 文章类型：案例研究 前言 一个建设工程项普遍的目的是为了在时间和在预算内满足既定的质量要求和其他规格。为了实现这个目标,大量的工作在施工过程的管理必须提供且不能没有计划地做成本控制系统。一个控制系统定期收集实际成本和进度数据,然后对比与计划的时间表来衡量工作进展是否提前或落后时间表和强调潜在的问题(泰克兹,1993)。成本和时间是两个关键参数，在建设项目管理和相关参数的研究中扮演着重要的角色，不断提供适当的方法和
工具，使施工经理有效处理一个项目，以实现其在前期建设和在施工阶段的目标。在施工阶段,一个常见的问题要求各方参与一个项目，尤其是一个所有者,最终项目的预算到底是多少?或什么时候该项目能被完成？ 在跟踪和控制一个建设项目时，预测项目的性能是非常必要的。目前已经提出了几种方法,如基于挣值技术、模糊逻辑、社会判断理论和神经网络。将挣值法视为一个确定的方法，其一般假设，无论是性能效率可达至报告日期保持不变，或整个项目其余部分将计划超出申报日期（克里斯坦森，1992；弗莱明和坎普曼，2000 ；阿萨班尼，1999；维卡尔等人，2000）。然而，挣值法的基本概念在研究确定潜在的进度延误、成本和进度的差异成本超支的地区。吉布利（1985）利用平均每个成本帐户执行工作的实际成本，也称作单位收入的成本，其标准差来预测项目完工成本。各成本帐户每月的进度是一个平均平稳过程标准偏差，显示预测模型的可靠性，然而，接受的单位成本收益在每个报告期在变化。埃尔丁和休斯（1992）和阿萨班尼（1999）利用分解组成成本的结构来提高预测精度。迪克曼和Al-Tabtabai（1992）基于社会判断理论提出了一个方法，该方法在预测未来的基础上的一组线索，源于人的判断而不是从纯粹的数学算法。有经验的项目经理要求基于社会判断理论方法的使用得到满意的结果。Moselhi等人（2006）应用“模糊逻辑”来预测潜在的成本超支和对建设工程项目的进度延迟。该方法的结果在评估特定时间状态的项目和评价该项目的利润效率有作用。这有助于工程人员所完成的项目时间限制和监控项目预算。Kaastra和博伊德（1996）开发的“人工神经网络”,此网络作为一种有效的预测工具，可以利用过去“模式识别”工作和显示各种影响因素的关系，然后预测未来的发展趋势。罗威等人（2006）开发的成本回归模型能在项目的早期阶段估计建筑成本。总共有41个潜在的独立变量被确定，但只有四个变量：总建筑面积，持续时间，机械设备，和打桩，是线性成本的关键驱动因素，因为它们出现在所有的模型中。模型提出了进一步的洞察了施工成本和预测变量的各种关系。从模型得到的估计结果可以提供早期阶段的造价咨询（威廉姆斯（2003））——最终竞标利用回归模型预测的建设项目成本。 人工神经网络已被广泛用在不同的施工功能中，如估价、计划和产能预测。神经网络建设是Moselhi等人（1991）指出，由Hegazy（1998）开发了一个模型，该模型考虑了项目的外在特征，估计加拿大的公路建设成本： ·项目类型 ·项目范围
204/JOURNAL OF BRIDGE ENGINEERING/AUGUST1999
JOURNAL OF BRIDGE ENGINEERING /AUGUST 1999/205 ends.The stress state in each cylindrical strip was determined from the total potential energy of a nonlinear arch model using the Rayleigh-Ritz method. It was emphasized that the membrane stresses in the com-pression region of the curved models were less than those predicted by linear theory and that there was an accompanying increase in ?ange resultant force.The maximum web bending stress was shown to occur at 0.20h from the compression ?ange for the simple support stiffness condition and 0.24h for the ?xed condition,where h is the height of the analytical panel.It was noted that 0.20h would be the optimum position for longitudinal stiffeners in curved girders,which is the same as for straight girders based on stability requirements.From the ?xed condition cases it was determined that there was no signi?cant change in the membrane stresses (from free to ?xed)but that there was a signi?cant effect on the web bend-ing stresses.Numerical results were generated for the reduc-tion in effective moment required to produce initial yield in the ?anges based on curvature and web slenderness for a panel aspect ratio of 1.0and a web-to-?ange area ratio of 2.0.From the results,a maximum reduction of about 13%was noted for a /R =0.167and about 8%for a /R =0.10(h /t w =150),both of which would correspond to extreme curvature,where a is the length of the analytical panel (modeling the distance be-tween transverse stiffeners)and R is the radius of curvature.To apply the parametric results to developing design criteria for practical curved girders,the de?ections and web bending stresses that would occur for girders with a curvature corre-sponding to the initial imperfection out-of-?atness limit of D /120was used.It was noted that,for a panel with an aspect ratio of 1.0,this would correspond to a curvature of a /R =0.067.The values of moment reduction using this approach were compared with those presented by Basler (Basler and Thurlimann 1961;Vincent 1969).Numerical results based on this limit were generated,and the following web-slenderness requirement was derived: 2 D 36,500a a =1?8.6?34 (1) ? ??? t R R F w ?y where D =unsupported distance between ?anges;and F y =yield stress in psi. An extension of this work was published a year later,when Culver et al.(1973)checked the accuracy of the isolated elas-tically supported cylindrical strips by treating the panel as a unit two-way shell rather than as individual strips.The ?ange/web boundaries were modeled as ?xed,and the boundaries at the transverse stiffeners were modeled as ?xed and simple.Longitudinal stiffeners were modeled with moments of inertias as multiples of the AASHO (Standard 1969)values for straight https://www.doczj.com/doc/c617958399.html,ing analytical results obtained for the slenderness required to limit the plate bending stresses in the curved panel to those of a ?at panel with the maximum allowed out-of-?atness (a /R =0.067)and with D /t w =330,the following equa-tion was developed for curved plate girder web slenderness with one longitudinal stiffener: D 46,000a a =1?2.9 ?2.2 (2) ? ? ? t R f R w ?b where the calculated bending stress,f b ,is in psi.It was further concluded that if longitudinal stiffeners are located in both the tension and compression regions,the reduction in D /t w will not be required.For the case of two stiffeners,web bending in both regions is reduced and the web slenderness could be de-signed as a straight girder panel.Eq.(1)is currently used in the ‘‘Load Factor Design’’portion of the Guide Speci?cations ,and (2)is used in the ‘‘Allowable Stress Design’’portion for girders stiffened with one longitudinal stiffener.This work was continued by Mariani et al.(1973),where the optimum trans-verse stiffener rigidity was determined analytically. During almost the same time,Abdel-Sayed (1973)studied the prebuckling and elastic buckling behavior of curved web panels and proposed approximate conservative equations for estimating the critical load under pure normal loading (stress),pure shear,and combined normal and shear loading.The linear theory of shells was used.The panel was simply supported along all four edges with no torsional rigidity of the ?anges provided.The transverse stiffeners were therefore assumed to be rigid in their directions (no strains could be developed along the edges of the panels).The Galerkin method was used to solve the governing differential equations,and minimum eigenvalues of the critical load were calculated and presented for a wide range of loading conditions (bedding,shear,and combined),aspect ratios,and curvatures.For all cases,it was demonstrated that the critical load is higher for curved panels over the comparable ?at panel and increases with an increase in curvature. In 1980,Daniels et al.summarized the Lehigh University ?ve-year experimental research program on the fatigue behav-ior of horizontally curved bridges and concluded that the slen-derness limits suggested by Culver were too severe.Equations for ‘‘Load Factor Design’’and for ‘‘Allowable Stress Design’’were developed (respectively)as D 36,500a =1?4?192(3)? ?t R F w ?y D 23,000a =1?4 ?170 (4) ? ? t R f w ?b The latter equation is currently used in the ‘‘Allowable Stress Design’’portion of the Guide Speci?cations for girders not stiffened longitudinally. Numerous analytical and experimental works on the subject have also been published by Japanese researchers since the end of the CURT project.Mikami and colleagues presented work in Japanese journals (Mikami et al.1980;Mikami and Furunishi 1981)and later in the ASCE Journal of Engineering Mechanics (Mikami and Furunishi 1984)on the nonlinear be-havior of cylindrical web panels under bending and combined bending and shear.They analyzed the cylindrical panels based on Washizu’s (1975)nonlinear theory of shells.The governing nonlinear differential equations were solved numerically by the ?nite-difference method.Simple support boundary condi-tions were assumed along the curved boundaries (top and bot-tom at the ?ange locations)and both simple and ?xed support conditions were used at the straight (vertical)boundaries.The large displacement behavior was demonstrated by Mi-kami and Furunishi for a range of geometric properties.Nu-merical values of the load,de?ection,membrane stress,bend-ing stress,and torsional stress were obtained,but no equations for design use were presented.Signi?cant conclusions include that:(1)the compressive membrane stress in the circumfer-ential direction decreases with an increase in curvature;(2)the panel under combined bending and shear exhibits a lower level of the circumferential membrane stress as compared with the panel under pure bending,and as a result,the bending moment carried by the web panel is reduced;and (3)the plate bending stress under combined bending and shear is larger than that under pure bending.No formulations or recommendations for direct design use were made. Kuranishi and Hiwatashi (1981,1983)used the ?nite-ele-ment method to demonstrate the elastic ?nite displacement be-havior of curved I-girder webs under bending using models with and without ?ange rigidities.Rotation was not allowed (?xed condition)about the vertical axis at the ends of the panel (transverse stiffener locations).Again,the nonlinear distribu-