【正文】 ree or four stories and with spans of some 20 or 30 ft and simple erection requirements, will yield structural costs of 15～20 percent of total building cost.Specialperformance 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 (., 30～50 percent), with about 20 percent going for the purely structural costs. Tall office building (15 stories or more) and/or longspan 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, shortspan and nonmonumental building were to be bid at 30 percent for the structure alone, one could assume that the structural design may be paratively 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 designer’s or contractor’ slack of experience, imagination, and absence of munication 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 wellversed in the area of construction potentials if innovative designs ate to be petitively 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, 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 be﹩250,000 or 5 percent of total construction costs ﹩5,000, the ﹩5,000,000 figure is mitted, 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 paring alternative systems for the purpose of determining their relative cost efficiency.3. Squarefoot EstimatingAs before, it is possible to empirically determine a “standard” persquarefoot cost factor based on the average of costs for similar construction at a given place and time. moreorless 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 squarefoot costs for “normal” structural systems is ﹩10 to ﹩16 psf. For example, typical office buildings average between ﹩12 and ﹩16 psf, and apartmenttype structures ra