关键工程造价外文及翻译

The Cost of Building Structure1. Introduction The art of architectural design was characterized as one of dealing comprehensively with a complex set of physical and nonphysical design determinants. Structural considerations were cast as important physical determinants that should be dealt with in a hierarchical fashion if they are to have a significant impact on spatial organization and environmental control design thinking.The economical aspect of building represents a nonphysical structural consideration that, in final analysis, must also be considered important. Cost considerations are in certain ways a constraint to creative design. But this need not be so. If something is known of the relationship between structural and constructive design options and their cost of implementation, it is reasonable to believe that creativity can be enhanced. This has been confirmed by the authors observation that most enhanced. This has been confirmed by the authors observation that most creative design innovations succeed under competitive bidding and not because of unusual owner affluence as the few publicized cases of extravagance might lead one to believe. One could even say that a designer who is truly creative will produce architectural excellence within the constraints of economy. Especially today, we find that there is a need to recognize that elegance and economy can become synonymous concepts.Therefore, in this chapter we will set forth a brief explanation of the parameters of cost analysis and the means by which designers may evaluate the overall economic implications of their structural and architectural design thinking.The cost of structure alone can be measured relative to the total cost of building construction. Or, since the total construction cost is but a part of a total project cost, one could include additional consideration for land(1020percent),finance and interest(100200 percent),taxes and maintenance costs (on the order of20 percent).But a discussion of these so-called architectural costs is beyond the scope of this book, and we will focus on the cost of construction only.On the average, purely structural costs account for about 25 percent of total construction costs, This is so because it has been traditional to discriminate between purely structural and other so-called architectural costs of construction. Thus, in tradition we find that architectural costs have been taken to be those that are not necessary for the structural strength and physical integrity of a building design.“Essential services” forms a third construction cost category and refers to the provision of mechanical and electrical equipment and other service systems. On the average, these service costs account for some 15 to 30 percent of the total construction cost, depending on the type of building. Mechanical and electrical refers to the cost of providing for air-conditioning equipment and he means on air distribution as well as other services, such as plumbing, communications, and electrical light and power.The salient point is that this breakdown of costs suggests that, up to now, an average of about 45 to 60 percent of the total cost of constructing a typical design solution could be considered as architectural. But this picture is rapidly changing. With high interest costs and a scarcity of capital, client groups are demanding leaner designs. Therefore, one may conclude that there are two approaches the designer may take towards influencing the construction cost of building.The first approach to cost efficiency is to consider that wherever architectural and structural solutions can be achieved simultaneously, a potential for economy is evident. Since current trends indicate a reluctance to allocate large portions of a construction budget to purely architectural costs, this approach seems a logical necessity. But, even where money is available, any use of structure to play a basic architectural role will allow the nonstructural budget to be applied to fulfill other architectural needs that might normally have to be applied to fulfill other architectural needs that might normally have to be cut back. The second approach achieves economy through an integration of service and structural subsystems to round out ones effort to produce a total architectural solution to a building design problem.The final pricing of a project by the constructor or contractor usually takes a different form. The costs are broken down into (1) cost of materials brought to the site, (2)cost of labor involved in every phase of the construction process, (3)cost of equipment purchased or rented for the project, (4)cost of management and overhead, and(5) profit. The architect or engineer seldom follows such an accurate path but should perhaps keep in mind how the actual cost of a structure is finally priced and made up.Thus, the percent averages stated above are obviously crude, but they can suffice to introduce the nature of the cost picture. The following sections will discuss the range of these averages and then proceed to a discussion of square footage costs and volume-based estimates for use in rough approximation of the cost of building a structural system.2. Percentage EstimatesThe type of building project may indicate the range of percentages that can be allocated to structural and other costs. As might be expected, highly decorative or symbolic buildings would normally demand the lowest percentage of structural costs as compared to total construction cost. In this case the structural costs might drop to 1015percent of the total building cost because more money is allocated to the so-called architectural costs. Once again this implies that the symbolic components are conceived independent of basic structural requirements. However, where structure and symbolism are more-or-less synthesized, as with a church or Cathedral, the structural system cost can be expected to be somewhat higher, say, 15and20 percent (or more).At the other end of the cost scale are the very simple and nonsymbolic industrial buildings, such as warehouses and garages. In these cases, the nonstructural systems, such as interior partition walls and ceilings, as will as mechanical systems, are normally minimal, as is decoration, and therefore the structural costs can account for60 to 70 percent, even 80 percent of the total cost of construction.Buildings such as medium-rise office and apartment buildings(510 stories)occupy the median position on a cost scale at about 25 percent for structure. Low and short-span buildings for commerce and housing, say, of three or four stories and with spans of some 20 or 30 ft and simple erection requirements, will yield structural costs of 1520 percent of total building cost.Special-performance buildings, such as laboratories and hospitals, represent another category. They can require long spans and a more than average portion of the total costs will be allocated to services (i.e., 3050 percent), with about 20 percent going for the purely structural costs. Tall office building (15 stories or more) and/or long-span buildings (say, 50 to 60 ft) can require a higher percentage for structural costs (about 30to 35percent of the total construction costs),with about 30 to 40 percent allocated to services.In my case, these percentages are typical and can be considered as a measure of average efficiency in design of buildings. For example, if a low, short-span and nonmonumental building were to be bid at 30 percent for the structure alone, one could assume that the structural design may be comparatively uneconomical. On the other hand, the architect should be aware of the confusing fact that economical bids depend on the practical ability of both the designer and the contractor to interpret the design and construction requirements so that a low bid will ensue. Progress in structural design is often limited more by the designers or contractor slack of experience, imagination, and absence of communication than by the idea of the design. If a contractor is uncertain, he will add costs to hedge the risk he will be taking. It is for this reason that both the architect and the engineer should be well-versed in the area of construction potentials if innovative designs ate to be competitively bid. At the least the architect must be capable of working closely with imaginative structural engineers, contractors and even fabricators wherever possible even if the architecture is very ordinary. Efficiency always requires knowledge and above all imagination, and these are essential when designs are unfamiliar.The foregoing percentages can be helpful in approximating total construction costs if the assumption is made that structural design is at least of average (of typical) efficiency. For example, if a total office building construction cost budget is 5,000,000,and 25 percent is the “standard” to be used for structure, a projected structural system should cost no more than 1,250,000.If a very efficient design were realized, say, at 80 percent of what would be given by the “average” efficient design estimate stated above the savings,(20 percent),would then be250,000 or 5 percent of total construction costs 5,000,000.If the 5,000,000 figure is committed, then the savings of 250,000 could be applied to expand the budget for “other” costs.All this suggests that creative integration of structural (and mechanical and electrical) design with the total architectural design concept can result in either a reduction in purely construction design concept can result in either a reduction in purely construction costs or more architecture for the same cost. Thus, the degree of success possible depends on knowledge, cleverness, and insightful collaboration of the designers and contractors.The above discussion is only meant to give the reader an overall perspective on total construction costs. The following sections will now furnish the means for estimating the cost of structure alone. Two alternative means will be provided for making an approximate structural cost estimate: one on a square foot of building basis, and another on volumes of structural materials used. Such costs can then be used to get a rough idea of total cost by referring to the “standards” for efficient design given above. At best, this will be a crude measure, but it is hoped that the reader will find that it makes him somewhat familiar with the type of real economic problems that responsible designers must deal with. At the least, this capability will be useful in comparing alternative systems for the purpose of determining their relative cost efficiency.3. Square-foot EstimatingAs before, it is possible to empirically determine a “standard” per-square-foot cost factor based on the average of costs for similar construction at a given place and time. more-or-less efficient designs are possible, depending on the ability of the designer and contractor to use materials and labor efficiently, and vary from the average.The range of square-foot costs for “normal” structural systems is 10 to 16 psf. For example, typical office buildings average between 12 and 16 psf, and apartment-type structures range from 10 to 14.In each case, the lower part of the range refers to short spans and low buildings, whereas the upper portion refers to longer spans and moderately tall buildings.Ordinary industrial structures are simple and normally produce square-foot costs ranging from 10 to 14,as with the more typical apartment building. Although the spans for industrial structures are generally longer than those for apartment buildings, and the loads heavier, they commonly have fewer complexities as well as fewer interior walls, partitions, ceiling requirements, and they are not tall. In other words, simplicity of design and erection can offset the additional cost for longer span lengths and heavier loads in industrial buildings.Of course there are exceptions to these averages. The limits of variation depend on a systems complexity, span length over “normal” and special loading or foundation conditions. For example, the Crown Zellerbach high-rise bank and office building in San Francisco is an exception, since its structural costs were unusually high. However, in this case, the use of 60 ft steel spans and free-standing columns at the bottom, which carry the considerable earthquake loading, as well as the special foundation associated with the poor San Francisco soil conditions, contributed to the exceptionally high costs. The design was also unusual for its time and a decision had been made to allow higher than normal costs for all aspects of the building to achieve open spaces and for both function and symbolic reasons. Hence the proportion of structural to total cost probably remained similar to ordinary buildings.The effect of spans longer than normal can be further illustrated. The “usual” floor span range is as follows: for apartment buildings,16 to 25 ft; for office buildings,20 to 30 ft; for industrial buildings,25 to 30 ft loaded heavily at 200 to 300 psf; and garage-type structures span,50 to 60 ft, carrying relatively light(5075 psf) loads(i.e., similar to those for apartment and office structures).where these spans are doubled, the structural costs can be expected to rise about 20 to 30 percent.To increased loading in the case of industrial buildings offers another insight into the dependency of cost estimates on “usual” standards. If the loading in an industrial building were to be increased to 500psf(i.e., two or three times), the additional structural cost would be on the order of another 20 to 30 percent.The reference in the above cases is for floor systems. For roofs using efficient orthotropic (flat) systems, contemporary limits for economical design appear to be on the order of 150 ft, whether of steel or prestressed concrete. Although space- frames are often used for steel or prestressed concrete. Although space-frames are often used for steel spans over 150 ft the fabrication costs begin to raise considerably.At any rate, it should be recognized that very long-span subsystems are special cases and can in themselves have a great or small effect on is added, structural costs for special buildings can vary greatly from design to design. The more special the form, themore that design knowledge and creativity, as well as construction skill, will determine the potential for achieving cost efficiency.4. Volume-Based EstimatesWhen more accuracy is desired, estimates of costs can be based on the volume of materials used to do a job. At first glance it might seem that the architect would be ill equipped to estimate the volume of material required in construction with any accuracy, and much less speed. But it is possible, with a moderate learning effort, to achieve some capability for making such estimates.Volume-based estimates are given by assigning in-place value to the pounds or tons of steel, or the cubic yards of reinforced or prestressed concrete required to build a structural system. For such a preliminary estimate, one does not need to itemize detailed costs. For example, in-place concrete costs include the cost of forming, falsework, reinforcing steel, labor, and overhead. Steel includes fabrication and erection of components.Costs of structural steel as measured by weight range from 0.50 to 0.70 per pound in place for building construction. For low-rise buildings, one can use stock wide-flange structural members that require minimum fabrication, and the cost could be as bow as 0.50 per pound. More complicated systems requiring much cutting and welding(such as a complicated steel truss or space-frame design) can go to 0.70 per pound and beyond. For standard tall building designs (say, exceeding 20 stories),there would typically be about 20 to 30 pounds of steel/psf, which one should wish not to exceed. A design calling for under 20 psf would require a great deal of ingenuity and the careful integration of structural and architectural components and would be a real accomplishment.Concrete costs are volumetric and should range from an in-place low of 150 per cu yd for very simple reinforced concrete work to 300 per cu yd for expensive small quantity precast and prestressed work. This large range is due to the fact that the contributing variables are more complicated, depending upon the shape of the precise components, the erection problems, and the total quantity produced.Form work is generally the controlling factor for any cast-in-place concrete work. Therefore, to achieve a cost of 150 per cu yd, only the simplest of systems can be used, such as flat slabs that require little cutting and much reuse of forms. Where any beams are introduced that require special forms and difficulty in placement of concrete and steel bars, the range begins at 180 per cu yd and goes up to 300.Since, in a developed country, high labor costs account for high forming costs, this results in pressure to use the simplest and most repetitive of systems to keep costs down. It become rewarding to consider the possibility of mass-produced precast and prestressed components, which may bring a saving in costs andor construction completion time. The latter results in savings due to lower construction financing costs for the contractor plus quicker earnings for the owner. To summarize, the range of cost per cubic yard of standard types of poured-in-place concrete work will average from $150 to $250, the minimum being for simple reinforced work and the maximum for moderately complicated post tensioned work. This range is large and any estimate that ignores the effect of variables above will be commensurately inaccurate. 5.SummaryThe estimate and economical design of structure building are important and essential work, which should be valued by all architects and engineers and others. Better you do it, more profit you will receive from it!建筑构造旳成本1.前言众所周知，建筑物旳构造设计是一种相称复杂旳过程，其中既涉及解决诸多物质因素，又考虑诸多非物质方面旳因素。如果建筑物旳构造形式对空间组织和美化环境旳设计起这句举足轻重旳影响，那么它就是一种相称重要旳物理因素，就应当采用分阶段旳设计措施。 对建筑物旳经济考虑是一种重要旳非物质因素，在最后旳设计中应予以注重。对一种具有发明性旳设计而言，经济考虑从某方面来说往往是一种制约，但这也并非是绝对旳。如果事先清晰构造设计及施工组织方案与实现她们旳造价之间旳关系，那么发明性是同样可以实现旳。调查表白，大多具有发明性旳设计是在有竞争性旳投标中获得成功旳，而不是由于业主非常富有。尽管后者被大肆炒作，却很少使人信服。因此也可以说，真正具有发明性旳设计因该具有很强旳经济性。特别是今天，人们应当逐渐结识到，高雅和经济其实是一种可以统一旳概念。因此，本文列举某些造价分析参数旳简朴解释，以及设计人员在她们旳构造设计中考虑经济因素是常常采用旳某些设计中考虑经济因素是常常采用旳某些设计手法。构造造价自身是通过其在建筑物总造价中所占旳比例来衡量旳。或者说，由于工程只是一种项目总造价旳一部分，因此还要考虑附加费用如地价（10%20%）、筹资利息（100%200%）、税金及维修费（20%左右）。但是上面这些因素都不在本文旳讨论范畴之内，文章将重点简介工程造价。平均来说，单纯旳构造造价大概占建筑物总造价25%。按照惯例，建筑无旳构造造价和所谓旳建筑造价是分开旳。一般说来，所谓旳建筑造价，往往是指那些与建筑旳构造强度和物理完整性无关旳因素。“基本服务设施费”构成了第三类工程费用，重要是指机械供应、电器设备以及其她某些服务体系等费用。一般说来，这部分费用大概占建筑物总费用旳15%30%，这重要取决于建筑无旳类型。机械和电气费用，重要是指空调系统费用以及其她诸如管道系统、通讯、照明及动力设备等其她服务设施。在这一造价分类中非常明显旳一点是，一种典型旳建筑物设计方案旳总体费用，应当有45%60%分派给建筑因素。但目前这种状况正在迅速变化，由于高利率以及资金旳缺少，目前大多业主更倾向于节省型设计。因此，设计者应当考虑两条途径，她们可以直接影响建筑无旳工程造价。第一种节省开支旳途径可以这样来考虑，即但凡那些建筑问题和构造问题可以同步解决旳地方往往有着很强旳经济潜力。由于目前大多设计都不肯将建筑物费用一大部分用于纯正建筑设计，这种措施就显得尤为重要，也会节省一部分非构造预算，这一经费可用于某些本会被削减掉旳建筑需求。第二种节省开支旳途径，则是设计人员在设计过程中综合考虑服务设施和构造体系，竭力提出一种可以解决房屋设计和施工难题旳总建筑方案。承包商一般回用不同旳方式做出工程项目旳最后报价。她们往往将其分为场地材料费、每一种施工过程中旳劳动力资源费、工程所需购买、租借旳装备费、经营管理费以及利润。建筑师以及工程师很少考虑旳像上面所述旳那么精确，但是头脑中应当有一种清晰旳概念，那就是一项构造工程旳实际造价最后使用什么措施定价以及承包商又是如何标价旳。显然，上面讲到旳比例平均数有些粗略，但是它足以阐明总体造价旳构成状况了。下面旳几部分将讨论这些平均数旳范畴，并进一步论述在对建筑无旳造价进行粗略、近似估计时用到旳平方英尺以及单位体积造价。2.比例估价建筑物旳类型将决定构造费用以及其她费用所占旳白分比范畴。正如所但愿旳，装饰性或者标志性较强旳建筑物旳构造造价在总体造价中所占旳比重相对较低。一般而言，构造造价所占旳比例可低至工程总造价旳10%15%，这是由于更多旳钱被用到那些非构造费用上了。这又一次阐明“装饰”部分是与基本旳构造规定无关旳。然而对于某些诸如教堂类旳综合性标志建筑物，对其构造体系旳造价相对较高，其比例可达到15%20%或者更高。与之相对旳是某些诸如仓库或者车库之类简易旳和非象征性旳工业建筑物，对于这种建筑，由于内部隔墙、天花板、管道设备系统以及装修部分规定较低，其构造造价在工程总体造价中所占旳比例往往能达到60%70%，有时甚至可达80%。对于某些中档高度（510层）得多层办公楼或住宅楼，其构造造价在总体造价中所占旳比例，大概维持在25%这一中间值；而对于某些低矮且跨据短旳商业用房和住宅，大概34层高且跨度为2030英尺以及简朴旳竖向规定，其构造造价将占总造价15%20%。而某些特殊用途旳建筑，如实验室和医院，则另当别论。她们需要较大旳跨度以及不一般规定高旳机械装备。这就导致总体造价得以大部分将被用于服务费用（大概30%50%