B  (7.61) 2 1  (Pu /HL) oh 1 B  (7.62) 2 1  P /P u e where Pu  sum of the axial-load strengths, kips, of all the columns in a story Pe  AgFy /c2 Ag  gross area of member, in2 Fy  specified yield stress, ksi c  Kl Fy Kl Fy    r E r 286,220 K  effective column length factor in the plane of bending, to be determined by structural analysis, but not to exceed unity in calculation of B1 and not to be less than unity in calculation of B2 r  governing radius of gyration, in, about the plane of buckling oh  drift, in, of the story in which the column is located L  story height, in H  sum of all the horizontal forces on the story that cause oh For ASD, members subject to both axial tension and bending stresses should be proportioned to satisfy Eq. (7.55), with b and Fb, respectively, as the computed and allowable bending tensile stress. But the compressive bending stresses must not exceed the values given in Art. 7.20.1. LRFD for Tension and Bending. Symmetric members subject to both axial tension and bending stresses should be proportioned to satisfy either Eq. (7.58) or Eq. (7.59), whichever is applicable. FIGURE 7.37 Steel-concrete composite-beam construction: (a) and (b) with welded-stud shear connectors; (c) with encasement in concrete. In composite construction, rolled or built-up steel shapes are combined with reinforced concrete to form a structural member. Examples of this type of construction include: (a) concrete-encased steel beams (Fig. 7.37c), (b) concrete decks interactive with steel beams (Fig. 7.37a and b), (c) concrete encased steel columns, and (d) concrete filled steel columns. The most common use of this type of construction is for composite beams, where the steel beam supports and works with the concrete slab to form an economical building element. Design procedures require that a decision be made regarding the use of shoring for the deck pour. (Procedures for ASD and LRFD differ in this regard.) If shoring is not used, the steel beam must carry all dead loads applied until the concrete hardens, even if full plastic capacity is permitted for the composite section afterward. The assumed composite cross section is the same for ASD and LRFD procedures. The effective width of the slab is governed by beam span and beam spacing or edge distance (Fig. 7.37a and b). Slab compressive stresses are seldom critical for interior beams but should be investigated, especially for edge beams. Thickening the slab key and minimum requirements for strength of concrete can be economical. FIGURE 7.38 Steel-concrete composite-beam construction with formed steel decking: (a) ribs parallel to beam; (b) ribs transverse to beam [refer to (a) for applicable requirements]. Connector Details. In composite construction, shear connectors welded to the top flange of the steel beam are typically used to ensure composite action by transferring shear between the concrete deck and steel beam. Location, spacing, and size limitations for shear connectors are the same for ASD and LRFD procedures. Connectors, except those installed in ribs of formed steel decks, should have a minimum lateral concrete cover of 1 in. The diameter of a stud connector, unless located directly over the beam web, is limited to 2.5 times the thickness of the beam flange to which it is welded. Minimum center-to-center stud spacing is 6 diameters along the longitudinal axis, 4 diameters transversely. Studs may be spaced uniformly, rather than in proportion to horizontal shear, inasmuch as tests show a redistribution of shear under high loads similar to the stress redistribution in large bolted joints. Maximum spacing is 8 times the slab thickness. Formed Steel Decking. Concrete slabs are frequently cast on permanent steel decking with a ribbed, corrugated, cellular, or blended cellular cross section (see Sec. 8). Two distinct composite-design configurations are inherent: ribs parallel or ribs perpendicular to the supporting beams or girders (Fig. 7.38) The design procedures, for both ASD and LRFD, prescribed for composite concrete-slab and steelbeam construction are also applicable for systems utilizing formed steel decking, subject to additional requirements of the AISC Specification for Structural Steel for Buildings and as illustrated in Fig. 7.38. Shear and Deflection of Composite Beams. In ASD and LRFD, shear forces are assumed to be resisted by the steel beam. Deflections are calculated based on composite section properties. It should be noted that, because of creep of the concrete, the actual deflections of composite beams under long-term loads, such as dead load, will be greater than those computed. 7.26.1 ASD of Encased Beams Two design methods are allowed for encased beams. In one method, stresses are computed on the assumption that the steel beam alone supports all the dead load applied prior to concrete hardening (unless the beam is temporarily shored), and the composite beam supports the remaining dead and live loads. Then, for positive bending moments, the total stress, ksi, on the steel-beam bottom flange is M M  D  L  0.66F (7.63) b S S y t where Fy  specified yield stress of the steel, ksi MD  dead-load bending moment, kip-in ML  live-load bending moment, kip-in S  section modulus of steel beam, in3 St  section modulus of transformed section, in3. To obtain the transformed equivalent steel area, divide the effective concrete area by the modular ratio n (modulus of elasticity of steel divided by modulus of elasticity of concrete). In computation of effective concrete area, use effective width of concrete slab (Fig. 7.37a and b) The stress 0.66Fy is allowed because the steel beam is restrained against lateral

Design requirements for engineered brick structures given in this section are taken from Building Code Requirements for Engineered Brick Masonry, promulgated by the Brick Institute of America, 11490 Commerce Park Drive, Reston, 11.2.1 General Requirements of Design Standard Building Code Requirements for Engineered Brick Masonry provides minimum requirements predicated on a general analysis of the structure and based on generally accepted engineering analysis procedures. The standard contains a requirement for architectural or engineering inspection of the workmanship to ascertain, in general, if the construction and workmanship are in accordance with the contract drawings and specifications. Frequency of inspections should be such that an inspector can inspect the various stages of construction and see that the work is being properly performed. The standard requires reduced allowable stresses and capacities for loads when such architectural or engineering inspection is not provided. Engineered brick bearing-wall structures do not require new techniques of analysis and design, but merely application of engineering principles used in the analysis and design of other structural systems. The method of analysis depends on the complexity of the building with respect to height, shape, wall location, and openings in the wall. A few conservative assumptions, however, accompanied by proper details to support them, can result in a simplified and satisfactory solution for most bearing-wall structures up to 12 stories high. More rigorous analysis for bearingwall structures beyond this height may be required to maintain the economics of this type of construction. 11.2.2 Materials for Masonry Construction Strength (compressive, shearing, and transverse) of brick structures is affected by the properties of the brick and the mortar in which they are laid. In compression, strength of brick has the greater effect. Although mortar is also a factor in compressive strength, its greater effect is on the transverse and shearing strengths of masonry. For these reasons, there are specific design requirements for and limitations on materials used in engineered brick structures. Brick. These units must conform to the requirements for grade MW or SW, ASTM Standard Specifications for Building Brick, C62. In addition, brick used in load-bearing or shear walls must comply with the dimension and distortion tolerances specified for type FBS of ASTM Standard Specifications for Facing TABLE 11.1 Mortar Requirements of Masonry Kind of masonry Types of mortar Masonry in contact with earth:

The major purposes of plumbing are: (1) to convey water and heating gas, if desired, from sources outside a building to points inside where the fluid or gas is needed, and (2) to collect wastewater and storm water in the building, on the roof, or elsewhere on the site and convey the liquid to sewers outside the building. For these purposes, plumbing requires fixtures for collecting discharged water and wastes; pipes for supply and disposal; valves for controlling flow; drains, and other accessories. For more details, see Sec. 14. Heating, Ventilation, and Air-Conditioning (HVAC). Part of the environmental control systems within buildings, along with lighting and sound control, HVAC is often necessary for the health and comfort of building occupants. Sometimes, however, HVAC may be needed for manufacturing processes, product storage, or operation of equipment, such as computers. HVAC usually is used to control temperature, humidity, air movement, and air quality in the interior of buildings. Ventilation is required to supply clean air for breathing, to furnish air for operation of combustion equipment, and to remove contaminated air. Ventilation, however, also can be used for temperature control by bringing outside air into a building when there is a desirable temperature difference between that air and the interior