The unit-price technique is frequently used for preparation of cost estimates. It can be used for any level of estimate but does require that some design be performed. Data for the technique are obtained from commercially available handbooks of unit prices, which are usually updated at least once a year. The industry approach to development of preliminary or higher-level cost estimates for a warehouse using the unit-price technique usually proceeds as follows: The warehouse is divided into categories, for example, loading dock, storage facilities, aisles, restrooms, and offices. The special equipment required, such as cranes, crane rails, and docks, is listed. Then, the estimator looks up in a unit-price book the cost of each of the items specified above. For each category, the unitprice book gives the total cost of materials, labor, and equipment to construct an item. For instance, for a loading dock, the unit price would be specified as either the cost per linear foot or the cost per truck accommodated by the dock; for rest rooms, the unit price would be specified as the total cost of all the fixtures needed or as the total cost per square foot. Finally, the estimator sums the preceding costs to arrive at the total cost of the warehouse. The discipline approach to development of a preliminary or higher-level cost estimate for a warehouse using the unit-price technique typically proceeds as follows: From the design documents, the estimator determines the ground area the building occupies (the footprint of the building). The costs of grading and the building floor slab are obtained from a unit-price handbook. With information from the contract documents, the estimator calculates the amount and cost of the structural materials and finishes needed. The unit cost of illumination and air-conditioning are also obtained from a unit-price handbook. Finally, the estimator adds the preceding costs to arrive at the total costs. Crew Development Technique. This is used to prepare the estimate based on the costs for the specific personnel and equipment that would be needed to complete each item during each phase of construction. The crew development technique differs from the unit-price technique, where the activity is priced without assignment of specific workers and equipment. For a specific project, the size and mix of crew selected depend on project needs. If early completion is the key consideration, a large crew working multiple shifts and much overtime might be advisable. If access to a site is difficult, a small crew might be necessary. Size and mix of crew can also vary during the course of construction. For example, for a typical high-rise structure, construction may start with personnel and equipment that provides the lowest cost per unit of production. As work progresses and access to work areas grows more difficult, a smaller crew using more equipment may be used. In the final construction stages, when the investment in the building is large and interest costs are high, the contractor may employ a large crew working shifts and overtime to finish as soon as possible, thereby minimizing total project costs. Estimators tend to use the crew development technique for high-level estimates, the definitive and above. Unlike the unit-price technique, the crew development technique is based on the way the facility actually will be erected. Consequently, it is the most accurate of the estimating techniques. Hence, it is the principal technique for fixed-price estimates; where accuracy is critical. The crew development technique is based on data from production handbooks. These may be organized in accordance with the use of a facility or by building

Link. A link, with reference to horizontal wiring, includes the workstation outlet, the horizontal cabling, and the communications-closet patch panel. (Compare to definition of channel.) NFPA. National Fire Protection Administration, a code-making body. NEC. National Electrical code, NFPA 70 (often referred to as The Code), that most jurisdictions follow for electrical and communications work. NIC. Network interface cards are installed in PCs so that the PC may be connected to the LAN by patch cable. OTDR. Optical time domain reflectometer, a fiberoptic cable test tool that locates fiber breaks and can determine loss per connection, splice, or segment. OC. Optical carrier, a definition of optical transmission rate for SONET. The OC-1 transmission rate is 52 Mbps. The OC-3 transmission rate is 156 Mbps. Patch Cable. The cable used to connect PCs to wall jack or system furniture jack. They are also used to connect network gear to patch panels in the communications closets. Patch Panel. A rack-mounted panel of 12, 24, or 48 jacks. Cables from wall or system furniture outlets are terminated on the back. Patch cables are used to connect the patch panel directly to network gear or to the network gear patch

V    dA dx 2G where v  shearing unit stress G  modulus of rigidity A  cross-sectional area Truss Deflections. The dummy unit-load method may also be adapted for the determination of the deformation of trusses. As indicated by Eq. (5.30), the strain energy in a truss is given by which represents the sum of the strain energy for all the members of the truss. S is the stress in each member caused by the loads. Applying Castiglianos first theorem and differentiating inside the summation sign yield the deformation: d   (5.98) AE P The partial derivative in this equation is the rate of change of axial stress with the load P. It is equal to the axial stress u in each bar of the truss produced by a unit load applied at the point where the deformation is to be measured and in the direction of the deformation. Consequently, Eq. (5.98) can also be written Sul d   (5.99) AE To find the deflection of a truss, apply a vertical dummy unit load at the panel point where the deflection is to be measured and substitute in Eq. (5.99) the stresses in each member of the truss due to this load and the actual loading. Similarly, to find the rotation of any joint, apply a dummy unit moment at the joint, compute the stresses in each member of the truss, and substitute in Eq. (5.99). When it is necessary to determine the relative movement of two panel points, apply dummy unit loads in opposite directions at those points. It is worth noting that members that are not stressed by the actual loads or the dummy loads do not enter into the calculation of a deformation. As an example of the application of Eq. (5.99), let us compute the deflection of the truss in Fig. 5.53. The stresses due to the 20-kip load at each panel point are shown in Fig. 5.53a, and the ratio of length of members in inches to their crosssectional area in square inches is given in Table 5.5. We apply a vertical dummy unit load at L2, where the deflection is required. Stresses u due to this load are shown in Fig. 5.53b and Table 5.5. The computations for the deflection are given in Table 5.5. Members not stressed by the 20-kip loads or the dummy unit load are not included. Taking advantage of the symmetry of the truss, we tabulate the values for only half the truss and double