Application of wall membranes should he started at the bottom of one end of the wall and the strips of fabric or felt laid vertically. Preparation of the surfaces and laying of the membrane proceed much as they do with floor membranes. The surfaces to which the membrane is attached must be dry and smooth, which may require that the faces of masonry walls be leveled with a thin coat of grout or mortar. The plies of the wall membrane should be lapped into those of the floor membrane. If the outside method of application is used and the membrane is faced with masonry, the narrow space between the units and the membrane should be filled with mortar as the units are laid. The membrane may be terminated at the grade line by a return into the superstructure wall facing. Waterstops in joints in walls and floors containing a bituminous membrane should be the metal-bellows type. The membrane should be placed on the exposed face of the joint and it may project into the joint, following the general outline of

Mu  required flexural strength, kip-in calculated for primary bending and P- effects cPn  design compressive strength (Art. 7.19.3) bMn  design flexural strength (Art. 7.20.2) Mu may be determined for the factored loads from a second-order elastic analysis. The AISC LRFD specification, however, permits Mu to be determined from Eq. (7.60) with the variables in this equation determined from a first-order analysis. M  B M  B M (7.60) u 1 nt 2 lt where Mnt  required flexural strength, kip-in, with no relative displacement of the member ends; for example, for a column that is part of a rigid frame, drift is assumed prevented Mlt  required flexural strength, kip-in, for the effects only of drift as determined from a first-order analysis B1  magnification factor for Mnt to account for the P- effects  Cm 1  P /P u e Cm  reduction factor defined for Eq. (7.57) B2  magnification factor for Mlt to account for the P- effects B2 may be calculated from either Eq. (7.61) or (7.62), the former usually being the simpler to evaluate.

When the upper column is of such dimension that its finished end does not wholly bear on the lower column, one of two methods must be followed: In Fig. 7.56c, stresses in a portion of the upper column not bearing on the lower column are transferred by means of flange plates that are finished to bear on the lower column. These bearing plates must be attached with sufficient single-shear bolts to develop the load transmitted through bearing on the finished surface. When the difference in column size is pronounced, the practice is to use a horizontal bearing plate as shown in Fig. 7.56d. These plates, known as butt plates, FIGURE 7.56 Slip-critical bolted column splices. may be attached to either shaft with tack welds or clip angles. Usually it is attached to the upper shaft, because a plate on the lower shaft may interfere with erection of the beams that frame into the column web. Somewhat similar are welded column splices. In Fig. 7.57a, a common case, holes for erection purposes are generally supplied in the splice plates and column flanges as shown. Some fabricators, however, prefer to avoid drilling and punching of thick pieces, and use instead clip angles welded on the inside flanges of the columns, one pair at diagonally opposite corners, or some similar arrangement, Figure 7.57b and c corresponds to the bolted splices in Fig. 7.56c and d. The shop and field welds for the welded butt plate in Fig. 7.57c may be reversed, to provide erection clearance for beams seated just below the splice. The erection clip angles would then be shop welded to the underside of the butt plate, and the field holes would pierce the column web. The butt-weld splice in Fig. 7.57d is the most efficient from the standpoint of material saving. The depth of the bevel as given in the illustration is for the usual column splice, in which moment is unimportant. However, should the joint be subjected to considerable moment, the bevel may be deepened; but a 1/8-in minimum shoulder should remain for the purpose of landing and plumbing the column. For full moment capacity, a complete-penetration welded joint would be required. A clear understanding of what the fabricator furnishes or does not furnish to the erector, particularly on fabrication contracts that may call for delivery only, is all- FIGURE 7.57 Welded column splices. importantand in many instances fabricated steel is purchased on delivery basis