1、14 Computer-Aided Design for Construction,A building is of course an assembly of some in situ construction and many premanufactured standard components. 一座建筑当然由一些现场制作的构件和很多工厂预制的标准构件组成的。,When we consider the vast number of components included in a typical building, the essential aim of design documen
2、tation is to identify in each case which component is required, and its precise intended location. 当我们考虑一座典型的建筑中采用的数不胜数的构件时，设计文件资料的必不可少的目的是确定各种情况下需要哪个构件，以及这个构件预期的准确位置。,We are rarely designing the components themselves. Normally their exact 3-D form does not matter too much and does not have to be sh
3、own in much detail. 我们很少只设计构件本身。正常情况下，这些构件确切的三维形状无关紧要，也不必要将它们显示得多详细。,So it is conventional to represent little more than the shape of the component outline in plan provided that this makes the item reasonably recognizable. For example, a wash hand basin only requires its outline shape, and a suggest
4、ion of the bowl, in plan view. 所以，常规上总是仅仅用平面图描述构件的轮廓形态，只要能识别出来即可。例如：一个洗手盆只需要它的轮廓形状，加上有点盆的样子，画在平面上即可。,1. 建议, 意见；2. 细微的迹象；3. 使人作（尤其是不好的事情的）推测的理由；4. 暗示；联想,If the outline is accurate in size, then the component can be placed on a building plan with reasonable confidence that it will not clash with other
5、 elements in the vicinity. 如果轮廓尺寸精确，那么构件就可以很有把握地置于建筑图中，而不与相邻构件相冲突。,When a CAD system is in use, the components in a building are rarely so tightly packed that a 2-D, or perhaps box geometry, representation is going to lead to many problems of clashing components. 使用ACD系统时，很少会将一个建筑中的构件摆放得如此紧密，使二维、或也许
6、立体示意图中会出现很多构件冲突的问题。,Full 3-D representation might be more necessary in the design of a car where component shapes are more critical. But for buildings, 3-D representation for everything might prove to be wasteful in design effort. 在设计小轿车时，构件形状较为关键，就需要全三维的示意图了。但是，对于建筑物，每个部位都用三维视图表示，这样的设计可能过于浪费了。,The
7、building designer is well able to think in 3-D and eventually the results of his work must be a series of 2-D drawings for the contractor. It does help, however, if the manufacturers name or other descriptive material can be attached to graphical components within the computer data model, to facilit
8、ate the printing of bills of materials. 建筑设计师可以很好地进行三维思维，提供给承包商的最终设计结果应该是一系列的二维图纸。然而，如果制造商的名称或其它描述性资料可以作为附件与计算机数据模型中的图件一块提供，使材料清单易于打印，也确是很有益的。,It is not possible to generalize too much, however. An exception to the above view occurs when the building is dominated by very highly standardized componen
9、ts, and the component density is high. 但是，也不能一概而论。当一个建筑中主要由高度标准化的构件组成，而且构件布置又很密集时，就会与上述情况不同。,For example, hospitals with their high services content can fall into this category. If time and trouble is taken to build up a database containing full 3-D descriptions of the range of standard components t
10、o be used, the benefits of being able to design in full 3-D may repay the initial effort. 例如，医院具有很多服务性很强的设施，就属于这种情况。如果人们花费时间和精力，来建立一个包括全部要采用的标准件的全三维描述材料的数据库，能进行三维设计的好处就是可以回报当初的努力。,The designer can achieve a higher degree of optimization simply by rearranging components in different ways, and viewing
11、 the results from different viewpoints. 设计者只需要通过不同方式重新布置构件，以不同的角度考察结果，就可以将设计更进一步优化。,It is cheaper to deal with impractical layouts and clashing of tightly packed components on a screen, compared with making alterations with the actual components later on site. 在屏幕上处理不切实际的设计及由于布置过于紧密而发生的冲突，要比日后在现场改换实
12、际构件便宜得多。,A characteristic of buildings is that there are typically tens of thousands of components, although many are similar items repeated many times over at different locations. So when CAD methods are employed, keys to success are： 建筑物的一个特点就是，它总由有成千上万个构件构成，尽管其中许多构件都相似，而且在不同部位多次重复使用。因此，采用CAD时，成功的
13、关键因素就是：,Simple representation (frequently symbols are adequate) 简单表达（常常是用符号就足够了） Very rapid positioning of components 构件快速定位 Accurate positioning of components 构件准确定位 Ease of copying components 构件易于复制 Ease of moving previous placed components 先前布置的构件易于移位,Use of parameterized shapes, i.e. the same ba
14、sic components that occur in different sizes, for example, steel sections, pipes, ducts, radiators. 使用参数化模型，也就是说，以不同尺寸出现的同一基本构件，如钢件，管件，槽孔，散热器。,In some CAD system the act of copying a component each time involves the duplication of its entire graphical data within the database, as well as storing the
15、 new position. In use for building design, such databases rapidly become large, cumbersome and use up much computer power. 在某些CAD系统中，每次拷贝一个构件，都要在数据库中复制这个构件的全部图形数据，再存储到一个新的位置。如在建筑设计中使用，这样的数据库就会变得很庞大，很笨重，消耗很多计算机资源。,Systems more suitable for building design would merely store the new component position
16、 together with a reference pointer back to the original single set of graphical data. This is much more concise. 更适于建筑设计的系统，应仅储存构件的新位置数据和构件一组原始图形数据的参考点数据。这样就会简洁得多。,The large number of components and the variety of disciplines makes a sophisticated layering or component selection system very necessar
17、y. 由于构件数量很多，对构件的要求也多种多样，就很有必要设置复杂的分层系统或者设置构件选择系统。,When a designer works on a drawing board, he may be working either on a general arrangement at small scale, or on details at large scale. 当设计者在绘图板上工作时，他可能在进行小比例尺的总体布置，也可能在进行大比例的细化。,Large components tend to be shown on the general arrangement but the
18、joints between them are on detail drawings. What tends to get missed out in this process, only to reappear as headaches on site, are the problems of fit between different items. 大型构件应在总体布置中表示，而大型构件间的结点应该用详图表示。不同构件的配合问题，可能容易在这个过程中被遗漏，而在现场却一定会重现，这是令人头痛的问题。,口语化？,However in CAD operation the concept of
19、drawings and scale tends to remain rather in the background until after the design is basically finished and the drawing sheets have to be plotted. Before that time it is the date model that rules. 然而，在设计基本完成而且要将那些绘制的图件打印出来之前，在CAD操作中，绘图和比例的概念一直处于后台，都是数据模型起控制作用。,In 2-D workings this may be an entire
20、floor with all construction and components. In box geometry it is the whole building. So element after element can be placed with considerable precision. 在二维作品中，这可能是一个包括全部结构和构件的整体楼板。在立体图形中，它可能就是整个建筑。这样，人们就可以相当精准地将构件一个一个布置好。,If there are large precast concrete cladding panels, then these can be place
21、d side by side with the correct space left for jointing and tolerances. This of course is how it is attempted manually with the GA drawing. 如果有大型预制混凝土盖板，就可以将它们顺序排放，并为接头和容许误差留有合适的空隙。当然，这是人们致力于手工绘制总体布置图时采用的方法。,But now the designer can zoom in as much as he likes with a screen to explore the problems o
22、f fit between unlike components placed perhaps at different times by different designers. So the gulf between general arrangement design and detail design is rather less apparent. This is a major benefit. 但现在设计者可以在屏幕上随心所欲缩放，以研究也许由不同设计者、不同时间置放的不同构件之间的配合问题。因而，总体布置设计和详图设计间的差异是不大明显的。这是很大的优点。,Some though
23、t needs to be given to how certain detail will ultimately be presented on drawings. At small scale little may be shown of any item or component apart from an outline. On large scale drawings, more detail may be required. 对于图件终究要绘制得多详细，还需要作些说明。小比例尺图件上可能只看到一点构件的轮廓，大比例尺图件上可能要求更详细。,Presentation for each
24、 instance can be made easier if the more limited graphics is included in one category or layer, and the greater detail in another. Then the choice for particular drawings can be made simply by the user turning on the relevant categories for each display or plot. 如果某个域或某一图层包含有较有限的图形，而另一个域或另一层包含有较详细的细节，任何一个案例都可以被较轻松展现。那么，专门图件的选择就可以通过使用者在每次显示或绘图时打开相关的域而完成。,
