土木建筑工程
中英文资料外文翻译文献
外文翻译
Abstract:To study the application of continuum structural topology optimization methods to real engineering structures,an optimization method for an optimal topology design of multistory steel frame bracing systems is presented.On a sensitivity analysis,an element removal criterion for continuum structures with stress and multi-displacement constraints under multiple lateral loading conditions is proposed.A concept of mean thickness of a design domain is provided to ensure the reasonableness of optimal results.In the proposed optimization method,the optimal design of an unbraced steel frame without displacement constraints is performed firstly,and then the optimal topology of a bracing system for the multistory steel frame considering displacement constraints is obtained by using evolutionary structural optimization and the given removal criterion,and finally the optima layout of the bracing system is interpreted as bracing members.An example of 3-bay 12-story plane steel frame shows that it is effective for the given optimization method in the optimal design of bracing systems for multistory steel frames.
Key words:steel frame;bracing system;continuum;topology optimization;evolutionary structural optimization
1．Reinforced Concrete
Plain concrete is formed from a hardened mixture of cement ,water ,fine aggregate, coarse aggregate (crushed stone or gravel),air, and often other admixtures. The plastic mix is placed and consolidated in the formwork, then cured to facilitate the acceleration of the chemical hydration reaction lf the cement/water mix, resulting in hardened concrete. The finished product has high compressive strength, and low resistance to tension, such that its tensile strength is approximately one tenth lf its compressive strength. Consequently, tensile and shear reinforcement in the tensile regions of sections has to be provided to compensate for the weak tension regions in the reinforced concrete element.
It is this deviation in the composition of a reinforces concrete section from the homogeneity of standard wood or steel sections that requires a modified approach to the basic principles of structural design. The two components of the heterogeneous reinforced concrete section are to be so arranged and proportioned that optimal use is made of the
materials involved. This is possible because concrete can easily be given any desired shape by placing and compacting the wet mixture of the constituent ingredients are properly proportioned, the finished product becomes strong, durable, and, in combination with the reinforcing bars, adaptable for use as main members of any structural system.
The techniques necessary for placing concrete depend on the type of member to be cast: that is, whether it is a column, a bean, a wall, a slab, a foundation. a mass columns, or an extension of previously placed and hardened concrete. For beams, columns, and walls, the forms should be well oiled after cleaning them, and the reinforcement should be cleared of rust and other harmful materials. In foundations, the earth should be compacted and thoroughly moistened to about 6 in. in depth to avoid absorption of the moisture present in the wet concrete. Concrete should always be placed in horizontal layers which are compacted by means of high frequency power-driven vibrators of either the immersion or external type, as the case requires, unless it is placed by pumping. It must be kept in mind, however, that over vibration can be harmful since it could cause segregation of the aggregate and bleeding of the concrete.
Hydration of the cement takes place in the presence of moisture at temperatures above 50°F. It is necessary to maintain such a condition in order that the chemical hydration reaction can take place. If drying is too rapid, surface cracking takes place. This would result in reduction of concrete strength due to cracking as well as the failure to attain full chemical hydration.
It is clear that a large number of parameters have to be dealt with in proportioning a reinforced concrete element, such as geometrical width, depth, area of reinforcement, steel strain, concrete strain, steel stress, and so on. Consequently, trial and adjustment is necessary in the choice of concrete sections, with assumptions based on conditions at site, availability of the constituent materials, particular demands of the owners, architectural and headroom requirements, the applicable codes, and environmental reinforced concrete is often a site-constructed composite, in contrast to the standard mill-fabricated beam and column sections in steel structures.
A trial section has to be chosen for each critical location in a structural system. The trial section has to be analyzed to determine if its nominal resisting strength is adequate to carry the applied factored load. Since more than one trial is often necessary to arrive at the required section, the first design input step generates into a series of trial-and-adjustment analyses.
The trial-and –adjustment procedures for the choice of a concrete section lead to the
convergence of analysis and design. Hence every design is an analysis once a trial section is chosen. The availability of handbooks, charts, and personal computers and programs supports this approach as a more efficient, compact, and speedy instructional method compared with the traditional approach of treating the analysis of reinforced concrete separately from pure design.
2. Earthwork
Because earthmoving methods and costs change more quickly than those in any other branch of civil engineering, this is a field where there are real opportunities for the enthusiast. In 1935 most of the methods now in use for carrying and excavating earth with rubber-tyred equipment did not exist. Most earth was moved by narrow rail track, now relatively rare, and the main methods of excavation, with face shovel, backacter, or dragline or grab, though they are still widely used are only a few of the many current methods. To keep his knowledge of earthmoving equipment up to date an engineer must therefore spend tine studying modern machines. Generally the only reliable up-to-date information on excavators, loaders and transport is obtainable from the makers.
Earthworks or earthmoving means cutting into ground where its surface is too high ( cuts ), and dumping the earth in other places where the surface is too low ( fills). Toreduce earthwork costs, the volume of the fills should be equal to the volume of the cuts and wherever possible the cuts should be placednear to fills of equal volume so as to reduce transport and double handlingof the fill. This work of earthwork design falls on the engineer who lays out the road since it is the layout of the earthwork more than anything else which decides its cheapness. From the available maps ahd levels, the engineering must try to reach as many decisions as possible in the drawing office by drawing cross sections of the earthwork. On the site when further information becomes available he can make changes in jis sections and layout,but the drawing lffice work will not have been lost. It will have helped him to reach the best solution in the shortest time.
The cheapest way of moving earth is to take it directly out of the cut and drop it as fill with the same machine. This is not always possible, but when it canbe done it is ideal, being both quick and cheap. Draglines, bulldozers and face shovels an do this. The largest radius is obtained with the dragline,and the largest tonnage of earth is moved by the bulldozer, though only over short distances.The disadvantages of the dragline are that it must dig below itself, it cannot dig with force into compacted material, it cannot dig on
steep slopws, and its dumping and digging are not accurate.
Face shovels are between bulldozers and draglines, having a larger radius of action than bulldozers but less than draglines. They are anle to dig into a vertical cliff face in a way which would be dangerous tor a bulldozer operator and impossible for a dragline. Each piece of equipment should be level of their tracks and for deep digs in compact material a backacter is most useful, but its dumping radius is considerably less than that of the same escavator fitted with a face shovel.
Rubber-tyred bowl scrapers are indispensable for fairly level digging where the distance of transport is too much tor a dragline or face shovel. They can dig the material deeply ( but only below themselves ) to a fairly flat surface, carry it hundreds of meters if need be, then drop it and level it roughly during the dumping. For hard digging it is often found economical to keep a pusher tractor ( wheeled or tracked ) on the digging site, to push each scraper as it returns to dig. As soon as the scraper is full,the pusher tractor returns to the beginning of the dig to heop to help the nest scraper.
Bowl scrapers are often extremely powerful machines;many makers build scrapers of 8 cubic meters struck capacity, which carry 10 m 3heaped. The largest self-propelled scrapers are of 19 m 3 struck capacity ( 25 m 3 heaped )and they are driven by a tractor engine of 430 horse-powers.
Dumpers are probably the commonest rubber-tyred transport since they can also conveniently be used for carrying concrete or other building materials. Dumpers have the earth container over the front axle on large rubber-tyred wheels, and the container tips forwards on most types, though in articulated dumpers the direction of tip can be widely varied. The smallest dumpers have a capacity of about 0.5 m 3, and the largest standard types are of about 4.5 m 3. Special types include the self-loading dumper of up to 4 m 3 and the articulated type of about 0.5 m 3. The distinction between dumpers and dump trucks must be remembered .dumpers tip forwards and the driver sits behind the load. Dump trucks are heavy, strengthened tipping lorries, the driver travels in front lf the load and the load is dumped behind him, so they are sometimes called rear-dump trucks.
3. Safety of Structures
The principal scope of specifications is to provide general principles and computational methods in order to verify safety of structures. The “ safety factor ”, which according to modern trends is independent of the nature and combination of the materials used, can usually be defined as the ratio between the conditions. This ratio is also proportional to the
inverse of the probability ( risk ) of failure of the structure.
Failure has to be considered not only as overall collapse of the structure but also as unserviceability or, according to a more precise. Common definition. As the reaching of a “ limit state ” which causes the construction not to accomplish the task it was designed for. There are two categories of limit state :
(1)Ultimate limit sate, which corresponds to the highest value of the load-bearing capacity. Examples include local buckling or global instability of the structure; failure of some sections and subsequent transformation of the structure into a mechanism; failure by fatigue; elastic or plastic deformation or creep that cause a substantial change of the geometry of the structure; and sensitivity of the structure to alternating loads, to fire and to explosions.
(2)Service limit states, which are functions of the use and durability of the structure. Examples include excessive deformations and displacements without instability; early or excessive cracks; large vibrations; and corrosion.
Computational methods used to verify structures with respect to the different safety conditions can be separated into:
(1)Deterministic methods, in which the main parameters are considered as nonrandom parameters.
(2)Probabilistic methods, in which the main parameters are considered as random parameters.
Alternatively, with respect to the different use of factors of safety, computational methods can be separated into:
(1)Allowable stress method, in which the stresses computed under maximum loads are compared with the strength of the material reduced by given safety factors.
(2)Limit states method, in which the structure may be proportioned on the basis of its maximum strength. This strength, as determined by rational analysis, shall not be less than that required to support a factored load equal to the sum of the factored live load and dead load ( ultimate state ).
The stresses corresponding to working ( service ) conditions with unfactored live and dead loads are compared with prescribed values ( service limit state ) . From the four possible combinations of the first two and second two methods, we can obtain some useful computational methods. Generally, two combinations prevail:
(1)deterministic methods, which make use of allowable stresses.
(2)Probabilistic methods, which make use of limit states.
The main advantage of probabilistic approaches is that, at least in theory, it is possible to scientifically take into account all random factors of safety, which are then combined to define the safety factor. probabilistic approaches depend upon :
(1) Random distribution of strength of materials with respect to the conditions of fabrication and erection ( scatter of the values of mechanical properties through out the structure );
(2) Uncertainty of the geometry of the cross-section sand of the structure ( faults and imperfections due to fabrication and erection of the structure );
(3) Uncertainty of the predicted live loads and dead loads acting on the structure;
(4)Uncertainty related to the approximation of the computational method used ( deviation of the actual stresses from computed stresses ).
Furthermore, probabilistic theories mean that the allowable risk can be based on several factors, such as :
(1) Importance of the construction and gravity of the damage by its failure;
(2)Number of human lives which can be threatened by this failure;
(3)Possibility and/or likelihood of repairing the structure;
(4) Predicted life of the structure.
All these factors are related to economic and social considerations such as：
(1) Initial cost of the construction;
(2) Amortization funds for the duration of the construction;
(3) Cost of physical and material damage due to the failure of the construction;
(4) Adverse impact on society;
(5) Moral and psychological views.
The definition of all these parameters, for a given safety factor, allows construction at the optimum cost. However, the difficulty of carrying out a complete probabilistic analysis has to be taken into account. For such an analysis the laws of the distribution of the live load and its induced stresses, of the scatter of mechanical properties of materials, and of the geometry of the cross-sections and the structure have to be known. Furthermore, it is difficult to interpret the interaction between the law of distribution of strength and that of stresses because both depend upon the nature of the material, on the cross-sections and upon the load acting on the structure. These practical difficulties can be overcome in two ways. The first is to apply different safety factors to the material and to the loads, without necessarily adopting the probabilistic criterion. The second is an approximate probabilistic method which introduces some simplifying assumptions ( semi-probabilistic methods ) .
2. 中文翻译
摘要：为了研究连续型拓扑优化理论在实际工程中的应用，该文给出了一种多层钢框架支撑体系连续型拓扑优化设计方法。基于灵敏度分析，探讨了连续体结构在多工况荷载作用下、同时受应力和多位移约束的拓扑优化删除准则。为保证拓扑优化结果的合理性，提出了设计区域平均厚度的概念。在该文给出的优化设计方法中，首先在不考虑位移约束的情况下对无支撑钢框架进行优化设计，然后在有位移约束的条件下采用渐进结构优化算法和删除准则对支撑体系进行连续型拓扑优化设计，并将获得的支撑最优拓扑构形转化成相应的杆件。通过一个3跨12层钢框架支撑体系的拓扑优化设计实例验证了该文给出的钢框架支撑体系连续型拓扑优化设计方法的有效性。
关键词：钢框架；支撑体系；连续型；拓扑优化；渐进结构优化
1. 钢筋混凝土
素混凝土是由水泥、水、细骨料、粗骨料（碎石或；卵石）、空气，通常还有其他外加剂等经过凝固硬化而成。将可塑的混凝土拌合物注入到模板内，并将其捣实，然后进行养护，以加速水泥与水的水化反应，最后获得硬化的混凝土。其最终制成品具有较高的抗压强度和较低的抗拉强度。其抗拉强度约为抗压强度的十分之一。因此，截面的受拉区必须配置抗拉钢筋和抗剪钢筋以增加钢筋混凝土构件中较弱的受拉区的强度。
由于钢筋混凝土截面在均质性上与标准的木材或钢的截面存在着差异，因此，需要对结构设计的基本原理进行修改。将钢筋混凝土这种非均质截面的两种组成部分按一定比例适当布置，可以最好的利用这两种材料。这一要求是可以达到的。因混凝土由配料搅拌成湿拌合物，经过振捣并凝固硬化，可以做成任何一种需要的形状。如果拌制混凝土的各种材料配合比恰当，则混凝土制成品的强度较高，经久耐用，配置钢筋后，可以作为任何结构体系的主要构件。
浇筑混凝土所需要的技术取决于即将浇筑的构件类型，诸如：柱、梁、墙、板、基础，大体积混凝土水坝或者继续延长已浇筑完毕并且已经凝固的混凝土等。对于
梁、柱、墙等构件，当模板清理干净后应该在其上涂油，钢筋表面的锈及其他有害物质也应该被清除干净。浇筑基础前，应将坑底土夯实并用水浸湿6英寸，以免土壤从新浇的混凝土中吸收水分。一般情况下，除使用混凝土泵浇筑外，混凝土都应在水平方向分层浇筑，并使用插入式或表面式高频电动振捣器捣实。必须记住，过分的振捣将导致骨料离析和混凝土泌浆等现象，因而是有害的。
水泥的水化作用发生在有水分存在，而且气温在50°F以上的条件下。为了保证水泥的水化作用得以进行，必须具备上述条件。如果干燥过快则会出现表面裂缝，这将有损与混凝土的强度，同时也会影响到水泥水化作用的充分进行。
设计钢筋混凝土构件时显然需要处理大量的参数，诸如宽度、高度等几何尺寸，配筋的面积，钢筋的应变和混凝土的应变，钢筋的应力等等。因此，在选择混凝土截面时需要进行试算并作调整，根据施工现场条件、混凝土原材料的供应情况、业主提出的特殊要求、对建筑和净空高度的要求、所用的设计规范以及建筑物周围环境条件等最后确定截面。钢筋混凝土通常是现场浇注的合成材料，它与在工厂中制造的标准的钢结构梁、柱等不同，因此对于上面所提到的一系列因素必须予以考虑。
对结构体系的各个部位均需选定试算截面并进行验算，以确定该截面的名义强度是否足以承受所作用的计算荷载。由于经常需要进行多次试算，才能求出所需的截面，因此设计时第一次采用的数值将导致一系列的试算与调整工作。
选择混凝土截面时，采用试算与调整过程可以使复核与设计结合在一起。因此，当试算截面选定后，每次设计都是对截面进行复核。手册、图表和微型计算机以及专用程序的使用，使这种设计方法更为简捷有效，而传统的方法则是把钢筋混凝土的复核与单纯的设计分别进行处理。
2. 土方工程
由于和土木工程中任何其他工种的施工方法与费用相比较，土方挖运的施工方法与费用的变化都要快得多，因此对于有事业心的人来说，土方工程是一个可以大有作为的领域。在1935年，目前采用的利用轮胎式机械设备进行土方挖运的方法大多数还没有出现。那是大部分土方是采用窄轨铁路运输，在这目前来说是很少采用的。当时主要的开挖方式是使用正铲、反铲、拉铲或抓斗等挖土机，尽管这些机械目前仍然在广泛应用，但是它们只不过是目前所采用的许多方法中的一小部分。因此，一个工程师为了使自己在土方挖运设备方面的知识跟得上时代的发展，他应当花费一些时间去研究现代的机械。一般说来，有关挖土机、装载机和运输机械的唯一可靠而又最新的资料可以从制造厂商处获得。
土方工程或土方挖运工程指的是把地表面过高处的土壤挖去（挖方），并把它倾卸到地表面过低的其他地方（填方）。为了降低土方工程费用，填方量应该等于
挖方量，而且挖方地点应该尽可能靠近土方量相等的填方地点，以减少运输量和填方的二次搬运。土方设计这项工作落到了从事道路设计的工程师的身上，因为土方工程的设计比其他任何工作更能决定工程造价是否低廉。根据现有的地图和标高，道路工程师应在设计绘图室中的工作也并不是徒劳的。它将帮助他在最短的时间内获得最好的方案。
费用最低的运土方法是用同一台机械直接挖方取土并且卸土作为填方。这并不是经常可以做到的，但是如果能够做到则是很理想的，因为这样做既快捷又省钱。拉铲挖土机。推土机和正铲挖土机都能做到这点。拉铲挖土机的工作半径最大。推土机所推运的图的数量最多，只是运输距离很短。拉铲挖土机的缺点是只能挖比它本身低的土，不能施加压力挖入压实的土壤内，不能在陡坡上挖土，而且挖。卸都不准确。
正铲挖土机介于推土机和拉铲挖土机的之间，其作用半径大于推土机，但小于拉铲挖土机。正铲挖土机能挖取竖直陡峭的工作面，这种方式对推土机司机来说是危险的，而对拉铲挖土机则是不可能的。每种机械设备应该进行最适合它的性能的作业。正铲挖土机不能挖比其停机平面低很多的土，而深挖坚实的土壤时，反铲挖土机最适用，但其卸料半径比起装有正铲的同一挖土机的卸料半径则要小很多。
在比较平坦的场地开挖，如果用拉铲或正铲挖土机运输距离太远时，则装有轮胎式的斗式铲运机就是比不可少的。它能在比较平的地面上挖较深的土（但只能挖机械本身下面的土），需要时可以将土运至几百米远，然后卸土并在卸土的过程中把土大致铲平。在挖掘硬土时，人们发现在开挖场地经常用一辆助推拖拉机（轮式或履带式），对返回挖土的铲运机进行助推这种施工方法是经济的。一旦铲运机装满，助推拖拉机就回到开挖的地点去帮助下一台铲运机。
斗式铲运机通常是功率非常大的机械，许多厂家制造的铲运机铲斗容量为8 m 3，满载时可达10 m3。最大的自行式铲运机铲斗容量为19立方米（满载时为25 m 3），由430马力的牵引发动机驱动。
翻斗机可能是使用最为普遍的轮胎式运输设备，因为它们还可以被用来送混凝土或者其他建筑材料。翻斗车的车斗位于大橡胶轮胎车轮前轴的上方，尽管铰接式翻斗车的卸料方向有很多种，但大多数车斗是向前翻转的。最小的翻斗车的容量大约为0.5立方米，而最大的标准型翻斗车的容量大约为4.5m3。特殊型式的翻斗车包括容量为4 m3的自装式翻斗车，和容量约为0.5 m3的铰接式翻斗车。必须记住翻斗车与自卸卡车之间的区别。翻斗车车斗向前倾翻而司机坐在后方卸载，因此有时被称为后卸卡车。
3. 结构的安全度
规范的主要目的是提供一般性的设计原理和计算方法，以便验算结构的安全度。就目前的趋势而言，安全系数与所使用的材料性质及其组织情况无关，通常把它定义为发生破坏的条件与结构可预料的最不利的工作条件之比值。这个比值还与结构的破坏概率（危险率）成反比。
破坏不仅仅指结构的整体破坏，而且还指结构不能正常的使用，或者，用更为确切的话来说，把破坏看成是结构已经达到不能继续承担其设计荷载的“极限状态”。通常有两种类型的极限状态，即：
（1）强度极限状态，它相当于结构能够达到的最大承载能力。其例子包括结构的局部屈曲和整体不稳定性；某此界面失效，随后结构转变为机构；疲劳破坏；引起结构几何形状显著变化的弹性变形或塑性变形或徐变；结构对交变荷载、火灾和爆炸的敏感性。
（2）使用极限状态，它对应着结构的使用功能和耐久性。器例子包括结构失稳之前的过大变形和位移；早期开裂或过大的裂缝；较大的振动和腐蚀。
根据不同的安全度条件，可以把结构验算所采用的计算方法分成：
（1）确定性的方法，在这种方法中，把主要参数看作非随机参数。
（2）概率方法，在这种方法中，主要参数被认为是随机参数。
此外，根据安全系数的不同用途，可以把结构的计算方法分为：
（1）容许应力法，在这种方法中，把结构承受最大荷载时计算得到的应力与经过按规定的安全系数进行折减后的材料强度作比较。
（2）极限状态法，在这种方法中，结构的工作状态是以其最大强度为依据来衡量的。由理论分析确定的这一最大强度应不小于结构承受计算荷载所算得的强度（极限状态）。计算荷载等于分别乘以荷载系数的活载与恒载之和。
把对应于不乘以荷载系数的活载和恒载的工作（使用）条件的应力与规定值（使用极限状态）相比较。根据前两种方法和后两种方法的四种可能组合，我们可以得到一些实用的计算方法。通常采用下面两种计算方法：
确定性的方法，这种方法采用容许应力。
概率方法，这种方法采用极限状态。
至少在理论上，概率法的主要优点是可以科学的考虑所有随机安全系数，然后将这些随机安全系数组合成确定的安全系数。概率法取决于：
（1）制作和安装过程中材料强度的随机分布（整个结构的力学性能数值的分散性）；
（2）截面和结构几何尺寸的不确定性（由结构制作和安装造成的误差和缺陷而引起的）；
对作用在结构上的活载和恒载的预测的不确定性；
所采用的近似计算方法有关的不精确性（实际应力与计算应力的偏差）。
此外，概率理论意味着可以基于下面几个因素来确定允许的危险率，例如：建筑物的重要性和建筑物破坏造成的危害性；
（2）由于建筑物破坏使生活受到威胁的人数；
（3）修复建筑的可能性；
（4）建筑物的预期寿命。
所有这些因素均与经济和社会条件有关，例如：
（1）建筑物的初始建设费；
（2）建筑物使用期限内的折旧费；
（3）由于建筑物破坏而造成的物质和材料损失费；
（4）在社会上造成的不良影响；
（5）精神和心理上的考虑。
就给定的安全系数而论，所有这些参数的确定都是以建筑物的最佳成本为依据的。但是，应该考虑到进行全概率分析的困难。对于这种分析来说，应该了解活载及其所引起的盈利的分布规律、材料的力学性能的分散性和截面的结构几何尺寸的分散性。此外，由于强度的分布规律和应力的分布规律之间的相互关系是困难的。这些实际困难可以采用两种方法来克服。第一种方法对材料和荷载采用不同的安全系数，而不需要采用概率准则；第二种方法是引入一些而简化假设的近似概率方法（半概率方法）。
Inventory management Inventory Control On the so-called "inventory control", many people will interpret it as a "storage management", which is actually a big distortion. The traditional narrow view, mainly for warehouse inventory control of materials for inventory, data processing, storage, distribution, etc., through the implementation of anti-corrosion, temperature and humidity control means, to make the custody of the physical inventory to maintain optimum purposes. This is just a form of inventory control, or can be defined as the physical inventory control. How, then, from a broad perspective to understand inventory control? Inventory control should be related to the company's financial and operational objectives, in particular operating cash flow by optimizing the entire demand and supply chain management processes (DSCM), a reasonable set of ERP control strategy, and supported by appropriate information processing tools, tools to achieved in ensuring the timely delivery of the premise, as far as possible to reduce inventory levels, reducing inventory and obsolescence, the risk of devaluation. In this sense, the physical inventory control to achieve financial goals is just a means to control the entire inventory or just a necessary part; from the perspective of organizational functions, physical inventory control, warehouse management is mainly the responsibility of The broad inventory control is the demand and supply chain management, and the whole company's responsibility. Why until now many people's understanding of inventory control, limited physical inventory control? The following two reasons can not be ignored: First, our enterprises do not attach importance to inventory control. Especially those who benefit relatively good business, as long as there is money on the few people to consider the problem of inventory turnover. Inventory control is simply interpreted as warehouse management, unless the time to spend money, it may have been to see the inventory problem, and see the results are often very simple procurement to buy more, or did not do warehouse departments . Second, ERP misleading. Invoicing software is simple audacity to call it ERP, companies on their so-called ERP can reduce the number of inventory, inventory control, seems to rely on their small software can get. Even as SAP, BAAN ERP world, the field of
转型衰退时期的土木工程研究 Sergios Lambropoulosa[1], John-Paris Pantouvakisb, Marina Marinellic 摘要 最近的全球经济和金融危机导致许多国家的经济陷入衰退，特别是在欧盟的周边。这些国家目前面临的民用建筑基础设施的公共投资和私人投资显著收缩，导致在民事特别是在民用建筑方向的失业。因此，在所有国家在经济衰退的专业发展对于土木工程应届毕业生来说是努力和资历的不相称的研究，因为他们很少有机会在实践中积累经验和知识，这些逐渐成为过时的经验和知识。在这种情况下，对于技术性大学在国家经济衰退的计划和实施的土木工程研究大纲的一个实质性的改革势在必行。目的是使毕业生拓宽他们的专业活动的范围，提高他们的就业能力。 在本文中，提出了土木工程研究课程的不断扩大，特别是在发展的光毕业生的潜在的项目，计划和投资组合管理。在这个方向上，一个全面的文献回顾，包括ASCE体为第二十一世纪，IPMA的能力的基础知识，建议在其他：显著增加所提供的模块和项目管理在战略管理中添加新的模块，领导行为，配送管理，组织和环境等；提供足够的专业训练五年的大学的研究；并由专业机构促进应届大学生认证。建议通过改革教学大纲为土木工程研究目前由国家技术提供了例证雅典大学。 1引言 土木工程研究（CES）蓬勃发展，是在第二次世界大战后。土木工程师的出现最初是由重建被摧毁的巨大需求所致，目的是更多和更好的社会追求。但是很快，这种演变一个长期的趋势，因为政府为了努力实现经济发展，采取了全世界的凯恩斯主义的理论，即公共基础设施投资作为动力。首先积极的结果导致公民为了更好的生活条件（住房，旅游等）和增加私人投资基础设施而创造机会。这些现象再国家的发展中尤为为明显。虽然前景并不明朗（例如，世界石油危机在70年代），在80年代领先的国家采用新自由主义经济的方法（如里根经济政策），这是最近的金融危机及金融危机造成的后果（即收缩的基础设施投资，在技术部门的高失业率），消除发展前途无限的误区。 技术教育的大学所认可的大量研究土木工程部。旧学校拓展专业并且新的学校建成，并招收许多学生。由于高的职业声望，薪酬，吸引高质量的学校的学生。在工程量的增加和科学技术的发展，导致到极强的专业性，无论是在研究还是工作当中。结构工程师，液压工程师，交通工程师等，都属于土木工程。试图在不同的国家采用专业性的权利，不同的解决方案，，从一个统一的大学学历和广泛的专业化的一般职业许可证。这个问题在许多其他行业成为关键。国际专业协会的专家和机构所确定的国家性检查机构，经过考试后，他们证明不仅是行业的新来者，而且专家通过时间来确定进展情况。尽管在很多情况下，这些证书虽然没有国家接受，他们赞赏和公认的世界。 在试图改革大学研究（不仅在土木工程）更接近市场需求的过程中，欧盟确定了1999博洛尼亚宣言，它引入了一个二能级系统。第一级度（例如，一个三年的学士）是进入
Statistical hypothesis testing Adriana Albu，Loredana Ungureanu Politehnica University Timisoara,adrianaa@aut.utt.ro Politehnica University Timisoara,loredanau@aut.utt.ro Abstract In this article,we present a Bayesian statistical hypothesis testing inspection, testing theory and the process Mentioned hypothesis testing in the real world and the importance of, and successful test of the Notes. Key words Bayesian hypothesis testing; Bayesian inference;Test of significance Introduction A statistical hypothesis test is a method of making decisions using data, whether from a controlled experiment or an observational study (not controlled). In statistics, a result is called statistically significant if it is unlikely to have occurred by chance alone, according to a pre-determined threshold probability, the significance level. The phrase "test of significance" was coined by Ronald Fisher: "Critical tests of this kind may be called tests of significance, and when such tests are available we may discover whether a second sample is or is not significantly different from the first."[1] Hypothesis testing is sometimes called confirmatory data analysis, in contrast to exploratory data analysis. In frequency probability,these decisions are almost always made using null-hypothesis tests. These are tests that answer the question Assuming that the null hypothesis is true, what is the probability of observing a value for the test statistic that is at [] least as extreme as the value that was actually observed?) 2 More formally, they represent answers to the question, posed before undertaking an experiment,of what outcomes of the experiment would lead to rejection of the null hypothesis for a pre-specified probability of an incorrect rejection. One use of hypothesis testing is deciding whether experimental results contain enough information to cast doubt on conventional wisdom. Statistical hypothesis testing is a key technique of frequentist statistical inference. The Bayesian approach to hypothesis testing is to base rejection of the hypothesis on the posterior probability.[3][4]Other approaches to reaching a decision based on data are available via decision theory and optimal decisions. The critical region of a hypothesis test is the set of all outcomes which cause the null hypothesis to be rejected in favor of the alternative hypothesis. The critical region is usually denoted by the letter C. One-sample tests are appropriate when a sample is being compared to the population from a hypothesis. The population characteristics are known from theory or are calculated from the population.
零售企业营销策略中英文对照外文翻译文献(文档含英文原文和中文翻译)
译文： 零售企业的营销策略 Philip Kotlor 今天的零售商为了招徕和挽留顾客，急欲寻找新的营销策略。过去，他们挽留顾客的方法是销售特别的或独特的花色品种，提供比竞争对手更多更好的服务提供商店信用卡是顾客能赊购商品。可是，现在这一切都已变得面目全非了。现在，诸如卡尔文·克连，依佐和李维等全国性品牌，不仅在大多数百货公司及其专营店可以看到，并且也可以在大型综合商场和折扣商店可以买到。全国性品牌的生产商为全力扩大销售量，它们将贴有品牌的商品到处销售。结果是零售商店的面貌越来越相似。 在服务项目上的分工差异在逐渐缩小。许多百货公司削减了服务项目，而许多折扣商店却增加了服务项目。顾客变成了精明的采购员，对价格更加敏感。他们看不出有什么道理要为相同的品牌付出更多的钱，特别是当服务的差别不大或微不足道时。由于银行信用卡越来越被所有的商家接受，他们觉得不必从每个商店赊购商品。 百货商店面对着日益增加的价格的折扣店和专业商店的竞争，准备东山再起。历史上居于市中心的许多商店在郊区购物中心开设分店，那里有宽敞的停车场，购买者来自人口增长较快并且有较高收入的地区。其他一些则对其商店形式进行改变，有些则试用邮购盒电话订货的方法。超级市场面对的是超级商店的竞争，它们开始扩大店面，经营大量的品种繁多的商品和提高设备等级，超级市场还增加了它们的促销预算，大量转向私人品牌，从而增加盈利。 现在，我们讨论零售商在目标市场、产品品种和采办、服务以及商店气氛、定价、促销和销售地点等方面的营销策略。 一、目标市场 零售商最重要的决策时确定目标市场。当确定目标市场并且勾勒出轮廓时，零售商才能对产品分配、商店装饰、广告词和广告媒体、价格水平等作出一致的决定。如沃尔玛的目标市场相当明确：
吉林化工学院理学院 毕业论文外文翻译English Title（Times New Roman ，三号） 学生学号：08810219 学生姓名：袁庚文 专业班级：信息与计算科学0802 指导教师：赵瑛 职称副教授 起止日期：2012.2.27～2012.3.14 吉林化工学院 Jilin Institute of Chemical Technology
1 外文翻译的基本内容 应选择与本课题密切相关的外文文献（学术期刊网上的），译成中文，与原文装订在一起并独立成册。在毕业答辩前，同论文一起上交。译文字数不应少于3000个汉字。 2 书写规范 2.1 外文翻译的正文格式 正文版心设置为：上边距：3.5厘米，下边距：2.5厘米，左边距：3.5厘米，右边距：2厘米，页眉：2.5厘米，页脚：2厘米。 中文部分正文选用模板中的样式所定义的“正文”，每段落首行缩进2字；或者手动设置成每段落首行缩进2字，字体：宋体，字号：小四，行距：多倍行距1.3，间距：前段、后段均为0行。 这部分工作模板中已经自动设置为缺省值。 2.2标题格式 特别注意：各级标题的具体形式可参照外文原文确定。 1．第一级标题（如：第1章绪论）选用模板中的样式所定义的“标题1”，居左；或者手动设置成字体：黑体，居左，字号：三号，1.5倍行距，段后11磅，段前为11磅。 2．第二级标题（如：1.2 摘要与关键词）选用模板中的样式所定义的“标题2”，居左；或者手动设置成字体：黑体，居左，字号：四号，1.5倍行距，段后为0，段前0.5行。 3．第三级标题（如：1.2.1 摘要）选用模板中的样式所定义的“标题3”，居左；或者手动设置成字体：黑体，居左，字号：小四，1.5倍行距，段后为0，段前0.5行。 标题和后面文字之间空一格（半角）。 3 图表及公式等的格式说明 图表、公式、参考文献等的格式详见《吉林化工学院本科学生毕业设计说明书（论文）撰写规范及标准模版》中相关的说明。
外文文献： Project Cost Control: The Way it Works By R. Max Wideman In a recent consulting assignment we realized that there was some lack of understanding of thewholesystem of project cost control, how it is setup and applied. So we decided to write up adescription ofhow it works. Project cost control is not that difficult to follow in theory. First you establish a set of reference baselines. Then, as work progresses, you monitor the work, analyzethe findings, forecast the end results and compare those with the reference baselines. If the end resultsare not satisfactory then you make adjustments as necessary to the work in progress, and repeat the cycleat suitable intervals. If the end results get really out of line with the baseline plan, you may have tochange the plan. More likely, there will be (or have been) scope changes that change the referencebaselines which means that every time that happens you have to change the baseline plan anyway. But project cost control is a lot more difficult to do in practice, as is evidenced by the number of projectsthat fail to contain costs. It also involves a significant amount of work, as we shall see, and we might aswell start at the beginning. So let us follow the thread of project cost control through the entire projectlife span. And, while we are at it, we will take the opportunity to point out the proper places for several significantdocuments. These include the Business Case, the Request for (a capital) Appropriation (for execution),Work Packages and the Work Breakdown Structure, the Project Charter (or Brief), the Project Budget orCost Plan, Earned Value and the Cost Baseline. All of these contribute to the organization's ability toeffectively control project costs. Footnote I am indebted to my friend Quentin Fleming, the guru of Earned Value, for checking and correcting mywork on this topic. The Business Case and Application for (execution) Funding It is important to note that project cost control is most effective when the executive managementresponsible has a good understanding of how projects should unfold through the project life span. Thismeans that they exercise their responsibilities at the key decision points
农村社会养老保险的现状、问题与对策研究社会保障对国家安定和经济发展具有重要作用，“城乡二元经济”现象日益凸现，农村社会保障问题客观上成为社会保障体系中极为重要的部分。建立和完善农村社会保障制度关系到农村乃至整个社会的经济发展，并且对我国和谐社会的构建至关重要。我国农村社会保障制度尚不完善，因此有必要加强对农村独立社会保障制度的构建，尤其对农村养老制度的改革，建立健全我国社会保障体系。从户籍制度上看，我国居民养老问题可分为城市居民养老和农村居民养老两部分。对于城市居民我国政府已有比较充足的政策与资金投人，使他们在物质和精神方面都能得到较好地照顾，基本实现了社会化养老。而农村居民的养老问题却日益突出，成为摆在我国政府面前的一个紧迫而又棘手的问题。 一、我国农村社会养老保险的现状 关于农村养老，许多地区还没有建立农村社会养老体系，已建立的地区也存在很多缺陷，运行中出现了很多问题，所以完善农村社会养老保险体系的必要性与紧迫性日益体现出来。 （一）人口老龄化加快 随着城市化步伐的加快和农村劳动力的输出，越来越多的农村青壮年人口进入城市，年龄结构出现“两头大，中间小”的局面。中国农村进入老龄社会的步伐日渐加快。第五次人口普查显示：中国65岁以上的人中农村为5938万，占老龄总人口的67.4%.在这种严峻的现实面前，农村社会养老保险的徘徊显得极其不协调。 （二）农村社会养老保险覆盖面太小 中国拥有世界上数量最多的老年人口，且大多在农村。据统计，未纳入社会保障的农村人口还很多，截止2000年底，全国7400多万农村居民参加了保险，占全部农村居民的11.18%，占成年农村居民的11.59%.另外，据国家统计局统计，我国进城务工者已从改革开放之初的不到200万人增加到2003年的1.14亿人。而基本方案中没有体现出对留在农村的农民和进城务工的农民给予区别对待。进城务工的农民既没被纳入到农村养老保险体系中，也没被纳入到城市养老保险体系中，处于法律保护的空白地带。所以很有必要考虑这个特殊群体的养老保险问题。
项目成本控制 一、引言 项目是企业形象的窗口和效益的源泉。随着市场竞争日趋激烈，工程质量、文明施工要求不断提高，材料价格波动起伏，以及其他种种不确定因素的影响，使得项目运作处于较为严峻的环境之中。由此可见项目的成本控制是贯穿在工程建设自招投标阶段直到竣工验收的全过程，它是企业全面成本管理的重要环节，必须在组织和控制措施上给于高度的重视，以期达到提高企业经济效益的目的。 二、概述 工程施工项目成本控制，指在项目成本在成本发生和形成过程中，对生产经营所消耗的人力资源、物资资源和费用开支，进行指导、监督、调节和限制，及时预防、发现和纠正偏差从而把各项费用控制在计划成本的预定目标之内，以达到保证企业生产经营效益的目的。 三、施工企业成本控制原则 施工企业的成本控制是以施工项目成本控制为中心，施工项目成本控制原则是企业成本管理的基础和核心，施工企业项目经理部在对项目施工过程进行成本控制时，必须遵循以下基本原则。 3.1 成本最低化原则。施工项目成本控制的根本目的，在于通过成本管理的各种手段，促进不断降低施工项目成本，以达到可能实现最低的目标成本的要求。在实行成本最低化原则时，应注意降低成本的可能性和合理的成本最低化。一方面挖掘各种降低成本的能力，使可能性变为现实；另一方面要从实际出发，制定通过主观努力可能达到合理的最低成本水平。 3.2 全面成本控制原则。全面成本管理是全企业、全员和全过程的管理，亦称“三全”管理。项目成本的全员控制有一个系统的实质性内容，包括各部门、各单位的责任网络和班组经济核算等等，应防止成本控制人人有责，人人不管。项目成本的全过程控制要求成本控制工作要随着项目施工进展的各个阶段连续 进行，既不能疏漏，又不能时紧时松，应使施工项目成本自始至终置于有效的控制之下。 3.3 动态控制原则。施工项目是一次性的，成本控制应强调项目的中间控制，即动态控制。因为施工准备阶段的成本控制只是根据施工组织设计的具体内容确
顾客满意策略与顾客满意营销 原文来源：《Marketing Customer Satisfaction 》自20世纪八十年代末以来, 顾客满意战略已日益成为各国企业占有更多的顾客份额, 获得竞争优势的整体经营手段。 一、顾客满意策略是现代企业获得顾客“货币选票”的法宝随着时代的变迁, 社会物质财富的极大充裕, 顾客中的主体———消费者的需求也先后跨越了物质缺乏的时代、追求数量的时代、追求品质的时代, 到了20世纪八十年代末进入了情感消费时代。在我国, 随着经济的高速发展,我们也已迅速跨越了物质缺乏时代、追求数量的时代乃至追求品质的时代, 到今天也逐步迈进情感消费时代。在情感消费时代, 各企业的同类产品早已达到同时、同质、同能、同价, 消费者追求的已不再是质量、功能和价格, 而是舒适、便利、安全、安心、速度、跃动、环保、清洁、愉快、有趣等,消费者日益关注的是产品能否为自己的生活带来活力、充实、舒适、美感和精神文化品位, 以及超越消费者期望值的售前、售中、售后服务和咨询。也就是说, 今天人们所追求的是具有“心的满足感和充实感”的商品, 是高附加值的商品和服务,追求价值观和意识多元化、个性化和无形的满足感的时代已经来临。 与消费者价值追求变化相适应的企业间的竞争, 也由产品竞争、价格竞争、技术竞争、广告竞争、品牌竞争发展到现今的形象竞争、信誉竞争、文化竞争和服务竞争, 即顾客满意竞争。这种竞争是企业在广角度、宽领域的时空范围内展开的高层次、体现综合实力的竞争。它包括组织创新力、技术创新力、管理创新力、产业预见力、产品研发力、员工向心力、服务顾客力、顾客亲和力、同行认同力、社会贡献力、公关传播沟通力、企业文化推动力、环境适应力等等。这些综合形象力和如何合成综合持久的竞争力, 这就是CSft略所要解决的问题。CS寸代,企业不再以“自己为中心”,而是以“顾客为中心”；“顾客为尊”、“顾客满意”不再是流于形式的口号, 而是以实实在在的行动为基础的企业经营的一门新哲学。企业不再以质量达标, 自己满意为经营理念, 而是以顾客满意, 赢得顾客高忠诚度为经营理念。企业经营策略的焦点不再以争取或保持市场占有率为主, 而是以争取顾客满意为经营理念。因此, 营销策略的重心不再放在竞争对手身上而是放在顾客身上, 放在顾客现实的、潜在的需求上。当企业提供的产品和服务达到了顾客事先的期望值, 顾客就基本满意；如果远远超越顾客的期望值, 且远远高于其他同行, 顾客才真正满意；如果企业能不断地或长久地令顾客满意, 顾客就会忠诚。忠诚的顾客不仅会经常性地重复购买, 还会购买企业其它相关的产品或服务；忠诚的顾客不仅会积极向别人推荐他所买的产品, 而且对企业竞争者的促销活动具有免疫能力一个不满意的顾客会将不满意告诉16-20个人, 而每一个被告知者会再传播给12-15个人。这样, 一个不满意者会影响到二、三百人。在互联网普及的今天, 其影响则更大。据美国汽车业的调查, 一个满意者会引发8笔潜在的生意, 其中至少有一笔会成交。而另一项调查表明, 企业每增加5%的忠诚顾客, 利润就会增长25%-95%。一个企业的80%的利润来自20%的忠诚顾客；而获取一个新顾客的成本是维持一个老顾客成本的6倍。所以,美国著名学者唐?佩 珀斯指出: 决定一个企业成功与否的关键不是市场份额, 而是在于顾客份额。 于是, 企业纷纷通过广泛细致的市场调研、与消费者直接接触、顾客信息反馈等方式来了解顾客在各方面的现实需求和潜在需求。依靠对企业满意忠诚的销售、服务人员, 定期、定量地对顾客满意度进行综合测定, 以便准确地把握企业经营中与“顾客满意” 目标的差距及其重点领域, 从而进一步改善企业的经营活动。依靠高亲和力的企业文化、高效率的人文管理和全员共同努力, 不断地向顾客提供高附加值的产品, 高水准的亲情般的服
软件专业毕业论文外文文献中英文翻译 Object landscapes and lifetimes Tech nically, OOP is just about abstract data typing, in herita nee, and polymorphism, but other issues can be at least as importa nt. The rema in der of this sect ion will cover these issues. One of the most importa nt factors is the way objects are created and destroyed. Where is the data for an object and how is the lifetime of the object con trolled? There are differe nt philosophies at work here. C++ takes the approach that con trol of efficie ncy is the most importa nt issue, so it gives the programmer a choice. For maximum run-time speed, the storage and lifetime can be determined while the program is being written, by placing the objects on the stack (these are sometimes called automatic or scoped variables) or in the static storage area. This places a priority on the speed of storage allocatio n and release, and con trol of these can be very valuable in some situati ons. However, you sacrifice flexibility because you must know the exact qua ntity, lifetime, and type of objects while you're writing the program. If you are trying to solve a more general problem such as computer-aided desig n, warehouse man ageme nt, or air-traffic con trol, this is too restrictive. The sec ond approach is to create objects dyn amically in a pool of memory called the heap. In this approach, you don't know un til run-time how many objects you n eed, what their lifetime is, or what their exact type is. Those are determined at the spur of the moment while the program is runnin g. If you n eed a new object, you simply make it on the heap at the point that you n eed it. Because the storage is man aged dyn amically, at run-time, the amount of time required to allocate storage on the heap is sig ni fica ntly Ion ger tha n the time to create storage on the stack. (Creat ing storage on the stack is ofte n a si ngle assembly in structio n to move the stack poin ter dow n, and ano ther to move it back up.) The dyn amic approach makes the gen erally logical assumpti on that objects tend to be complicated, so the extra overhead of finding storage and releas ing that storage will not have an importa nt impact on the creati on of an object .In additi on, the greater flexibility is esse ntial to solve the gen eral program ming problem. Java uses the sec ond approach, exclusive". Every time you want to create an object, you use the new keyword to build a dyn amic in sta nee of that object. There's ano ther issue, however, and that's the lifetime of an object. With Ian guages that allow objects to be created on the stack, the compiler determines how long the object lasts and can automatically destroy it. However, if you create it on the heap the compiler has no kno wledge of its lifetime. In a Ianguage like C++, you must determine programmatically when to destroy the
The significance of control construction costs manages on entire process First, The necessary of control construction costs manages on entire process Talk about the management and the control on construction costs, that the field we are just accustomed to is thought of is a project advance in final account. Indeed , right away at present system and reality,what the job of that the management and the control on construction costs is advance in final account. Be that in advance, the people who work on final account according that already be ascertaied of the working drawing to calculate project amounts，apply a quota mechanically, the meter mechanically fetching cost, or designing that according to the drawing sheet and construction organization after construction is over as well as the scene construction visa takes notes weaves the final account being completed. This is necessary , useful no doubt. But we must see that when pre-final accounts personnel weave working drawing budget or the final account being completed, the construction plan and the design paper already determined. But construction being to take according to picture as principle, so then in advance, job done by final account personnel is only the change secretly scheming against cost produced by design alteration and prevents upvaluation from calculating boldly. But suppose the project is unreasonable on economy, there is a fault in decision-making; suppose designing a scheme feasible or be not optimum on the technology; the final account
专业资料 学院： 专业：土木工程 姓名： 学号： 外文出处：Structural Systems to resist (用外文写) Lateral loads 附件：1.外文资料翻译译文；2.外文原文。
附件1：外文资料翻译译文 抗侧向荷载的结构体系 常用的结构体系 若已测出荷载量达数千万磅重，那么在高层建筑设计中就没有多少可以进行极其复杂的构思余地了。确实，较好的高层建筑普遍具有构思简单、表现明晰的特点。 这并不是说没有进行宏观构思的余地。实际上，正是因为有了这种宏观的构思，新奇的高层建筑体系才得以发展，可能更重要的是：几年以前才出现的一些新概念在今天的技术中已经变得平常了。 如果忽略一些与建筑材料密切相关的概念不谈，高层建筑里最为常用的结构体系便可分为如下几类： 1.抗弯矩框架。 2.支撑框架，包括偏心支撑框架。 3.剪力墙，包括钢板剪力墙。 4.筒中框架。 5.筒中筒结构。 6.核心交互结构。 7. 框格体系或束筒体系。 特别是由于最近趋向于更复杂的建筑形式，同时也需要增加刚度以抵抗几力和地震力，大多数高层建筑都具有由框架、支撑构架、剪力墙和相关体系相结合而构成的体系。而且，就较高的建筑物而言，大多数都是由交互式构件组成三维陈列。 将这些构件结合起来的方法正是高层建筑设计方法的本质。其结合方式需要在考虑环境、功能和费用后再发展，以便提供促使建筑发展达到新高度的有效结构。这并
不是说富于想象力的结构设计就能够创造出伟大建筑。正相反，有许多例优美的建筑仅得到结构工程师适当的支持就被创造出来了，然而，如果没有天赋甚厚的建筑师的创造力的指导，那么，得以发展的就只能是好的结构，并非是伟大的建筑。无论如何，要想创造出高层建筑真正非凡的设计，两者都需要最好的。 虽然在文献中通常可以见到有关这七种体系的全面性讨论，但是在这里还值得进一步讨论。设计方法的本质贯穿于整个讨论。设计方法的本质贯穿于整个讨论中。 抗弯矩框架 抗弯矩框架也许是低，中高度的建筑中常用的体系，它具有线性水平构件和垂直构件在接头处基本刚接之特点。这种框架用作独立的体系，或者和其他体系结合起来使用，以便提供所需要水平荷载抵抗力。对于较高的高层建筑，可能会发现该本系不宜作为独立体系，这是因为在侧向力的作用下难以调动足够的刚度。 我们可以利用STRESS，STRUDL 或者其他大量合适的计算机程序进行结构分析。所谓的门架法分析或悬臂法分析在当今的技术中无一席之地，由于柱梁节点固有柔性，并且由于初步设计应该力求突出体系的弱点，所以在初析中使用框架的中心距尺寸设计是司空惯的。当然，在设计的后期阶段，实际地评价结点的变形很有必要。 支撑框架 支撑框架实际上刚度比抗弯矩框架强，在高层建筑中也得到更广泛的应用。这种体系以其结点处铰接或则接的线性水平构件、垂直构件和斜撑构件而具特色，它通常与其他体系共同用于较高的建筑，并且作为一种独立的体系用在低、中高度的建筑中。