Compare sections 1-1 and 2-2, Pn
23.37 kips. The allowable load is: P
P /
23.37/2.22
10.53 kips a n This compares with the tensile strength of each sheet for tension member design: P
A F
[4  11/16](3/16)  33
20.50 kips n n sy The allowable load is: P
P /
20.50/1.67
12.28 kips a n Use Pa
10.53 kips. The minimum distance between a bolt center and adjacent bolt edge or sheet edge is for Case 1: e
P/F t
(9.72/2) / (48  3/16)
0.54 in u e
e
0.54  2
1.08 in min For Case 2: e
(10.53/2) / (48  3/16)
0.59 in e
0.59  2
1.18 in min The bearing strength Pn per bolt of the 3/16-in-thick steel sheet is: P
F dt
(3  48)  5/8  3/16
16.88 kips n p The allowable bearing load for two bolts: P
2P /
2  16.88/2.22
15.21 kips  10.53 kips O.K. a n Using the A325 bolts with threads not excluded from the shear plane, the allowable shearing strength of each bolt is: P
A F /
(5/ 2 8)  0.7854  54/ 2.4
6.9 kips s b nv For two bolts, the allowable load is: P
2  6.9
13.8 kips  10.53 kips O.K. a In summary, the allowable loads for Cases 1 and 2 are 9.72 kips and 10.53 kips, respectively. The shear capacity of bolts should also be checked. FIGURE 8.12 Tapping screws. NOTE: A blank space does not signify necessarily that the type of screw cannot be used for this purpose; it denotes that the type of self-tapping screw will not generally give the best results in this type of material. (Parker-Kalon Corp., Emhart Corp., Campbellsville,

Standby Pay. In many union contracts, a requirement is imposed on contractors for standby pay for workers who may not actually be engaged in installing materials or performing work because of a requirement that members of the union be assigned to stand by for certain purposes. Examples of standby pay are pay for temporary water (plumbers), for temporary electric standby to maintain temporary power and lighting (electricians), and for steamfitters or electricians to maintain temporary heat. Standby pay is usually considered a normal part of the construction process, if in the union agreement, and must be allowed for by the contractor in cost estimates. Prevailing Wages. Contracts for construction for governmental agencies often require that the labor on a job be paid prevailing wages. These are defined as the wages received by persons normally performing that trade in the locality where the job is being performed. Prevailing wages in localities where there is a strong union usually are the union wages paid to labor in that area. Also considered part of prevailing wages are all fringe benefits and allowances usually paid in addition to hourly wages. If a contractor enters into an agreement that provides for payment of prevailing wages, the contractor may also be responsible for a subcontractor who fails to pay prevailing wages. Labor Recruitment. A contractors labor recruitment takes many forms. Most importantly, the work force comes from a following of labor that has previously worked with the contractor. These workers are summoned by telephone or by word of mouth when they are needed on the job site. In instances in which the usual labor force must be vastly expanded, the contractor can resort to advertising in newspapers or recruitment by advising local labor-union officials that workers are

In most buildings, the superstructure structural system consists of floor and roof decks, horizontal members that support them, and vertical members that support the other components. The horizontal members are generally known as beams, but they also are called by different names in specific applications. For example: Joists are closely spaced to carry light loads. Stringers support stairs. Headers support structural members around openings in floors, roofs, and walls. Purlins are placed horizontally to carry level roof decks. Rafters are placed on an incline to carry sloping roof decks. Girts are light horizontal members that span between columns to support walls. Lintels are light horizontal beams that support walls at floor levels in multistory buildings or that carry the part of walls above openings for doors and windows. Girders may be heavily loaded beams or horizontal members that support other beams (Fig. 1.3). Spandrels carry exterior walls and support edges of floors and roofs in multistory