Example 1 1.8m wall 4.75m Using our formula we simply multiply the length (4.75m) by the height (1.8m) to produce our area in m2 (or square metres). So our calculation to work out the area of our wall would look like this: 4.75 x 1.8 = 8.55m2 The total wall area is 8.55m2 . Now just multiply 8.55 by the number of bricks to a square metre (60) and weve got the number of bricks for our wall. Dont forget to add an amount for wastage. Simple! So what about linear measurements? As the name suggests, linear measurements involve working with dimension along a line. Sometimes an overall dimension is split up into smaller parts. Example 2 gap wall wall 900mm 2100mm 1950mm Adding these together produces the overall linear measurement: 2100 + 900 + 1950 = 4950mm The overall linear measurement is 4950mm. Notice these dimensions are written as millimetres. This is usual practice in construction working drawings. To convert millimetres to metres we simply move the decimal point three places to the left.

Cold-formed shapes invariably cost more per pound than hot-rolled sections. They will be found to be more economical under the following circumstances: 1. Where their use permits a substantial reduction in weight compared to hotrolled sections. This occurs where relatively light loads are to be supported over short spans, or where stiffness rather than strength is the controlling factor in the design. 2. In special cases where a suitable combination of standard hot-rolled shapes would be heavy and uneconomical. 3. Where quantities required are too small to justify the investment necessary to produce a suitable hot-rolled section. 4. In dual-purpose panel work, where both strength and coverage are desired. Cold-formed shapes are usually made from hot-rolled sheet or strip steel, which costs less per pound than cold-rolled steel. The latter, which has been cold-rolled to desired thickness, is used for thinner gages or where, for any reason, the surface finish, mechanical properties, or closer tolerances that result from cold-reducing is desired. Manufacture of cold-formed shapes from plates for use in building construction is possible but is done infrequently. 8.1.1 Plate, Sheet, or Strip The commercial distinction between steel plates, sheet, and strip is principally a matter of thickness and width of material. In some sizes, however, classification depends on whether the material is furnished in flat form or in coils, whether it is carbon or alloy steel, and, particularly for cold-rolled material, on surface finish, type of edge, temper or heat treatment, chemical composition, and method of production. Although the manufacturers classification of flat-rolled steel products by size is subject to change from time to time, that given in Table 8.1 for carbon steel

Systems with large numbers of variables may sometimes be optimized by a process called simulation, which involves trial and error with the actual system or a model. In simulation, the properties of the system or model are adjusted with a specific input or range of inputs to the system, and outputs or performance are measured until an optimum result is obtained. When the variables are quantifiable and models are used, the solution usually can be expedited by use of computers. The actual system may be used when it is available and accessible and changes in it will have little or no effect on construction costs. For example, after installation of air ducts, an air-conditioning system may be operated for a variety of conditions to determine the optimum damper position for control of airflow for each condition. Suboptimization is a trial-and-error process in which designers try to optimize a system by first optimizing its subsystems. It is suitable when components influence each other in series. For example, consider a structural system consisting only of roof, columns, and footings. The roof has a known load (input), exclusive of its own weight. Design of the roof affects the columns and footings, because its output equals the load on the columns. Design of the columns loads only the footings. Design of the footings, however, has no effect on any of the other structural components. Therefore, the structural components are in series and they may be designed by suboptimization to obtain the minimum construction cost or least weight