2  A 
max  (5.322) x 1.2avg where max  the maximum displacement at level x and avg  the average of the displacement at the extreme points of the structure at level x The torsional amplification factor, Ax, is not required to exceed 3.0. The more severe loading for each element shall be considered for design. Overturning. The building shall be designed to resist overturning effects caused by the seismic forces. At any story, the increment of overturning moment in the story under consideration shall be distributed to the various vertical force-resisting elements in the same proportion as the distribution of the horizontal shears to those elements. The overturning moments at level x, Mx shall be determined from the following formula: n M    F (h  h ) (5.323) x ii x ix where Fi  the portion of the seismic base shear V, induced at Level i, hi and hx  the height from the base to level i or x,   the Overturning Moment Reduction Factor The Overturning Moment Reduction Factors are 1.0 for the top 10 stories, 0.8 for the 20th story from the top and below, and value between 1.0 and 0.8 determined by a straight line interpolation for stories between the 20th and 10th stories below the top. Story Drift Determination. The design story drift shall be computed as the difference of the deflections at the center of mass at the top and bottom of the story under consideration. Where allowable stress design is used. shall be computed using earthquake forces without dividing by 1.4. For structures assigned to Seismic Design Category C, D, E, or F having plan irregularity types 1a or 1b of Table 5.12, the design story drift shall be computed as the largest difference of the deflections along any of the edges of the structure at the top and bottom of the story under consideration. The deflections of level x, x, shall be determined in accordance with following

A wide variety of manufactured products are produced from concrete and used in building construction. These include such items as concrete brick, concrete block or tile, concrete floor and roof slabs, precast wall panels, precast beams, and cast stone. These items are made both from normal dense concrete mixes and from mixes with lightweight aggregates. Concrete blocks are made with holes through them to reduce their weight and to enable masons to grip them. Nominal size (actual dimensions plus width of mortar joint) of hollow concrete block usually is 8  8  16 in. Solid blocks often are available with nominal size of 4  8  16 in or 4  21/2  8 in. For a list of modular sizes, see Standard Sizes of Clay and Concrete Modular Units, ANSI A62.3. Properties of the units vary tremendouslyfrom strong, dense, load-bearing units used under exposed conditions to light, relatively weak, insulating units used for roof and fire-resistant construction. Many types of concrete units have not been covered by adequate standard specifications. For these units, reliance must be placed upon the manufacturers specifications. Requirements for strength and absorption of concrete brick and block established by ASTM for Type I, Grades N-I and S-I (moisture-controlled), and Type II, Grades N-II and S-II (non-moisture-controlled), units are summarized in

Efflorescence. White fleecy deposit on the face of plastered walls, caused by salts in the sand or backing; also referred to as whiskering or saltpetering. Egg and Dart. Ornamentation used in cornices consisting of an oval and a dart alternately. Eggshelling. Plaster chip-cracked concave to the surface, the bond being partly destroyed. Enrichments. Any cast ornament that cannot be executed by a running mold. Expanded Metals. Sheets of metal that are slit and drawn out to form diamondshaped openings. Fat. Material accumulated on a trowel during the finishing operation of plaster and used to fill in small imperfections. Also denotes a mortar that is not too stiff, too watery, or oversanded. Feather Edge. A beveled-edge wood tool used to straighten reentrant angles in the finish plaster coat. Fines. Aggregate capable of passing through a No. 200 sieve. Finish Coat. Last and final coat of plaster; also denotes a thin coat of joint treatment to reduce variations in surface texture and suction. Finisher. A tradesman with skill in finishing of gypsumboard joints. Fire Taping. Taping of gypsumboard joints without subsequent finishing coats, usually used where esthetics is not important. Fisheyes. Spots in plaster finish coat about 1/4 in in diameter, caused by lumpy lime because of age or insufficient blending of material. Float. A tool shaped like a trowel, with a handle braced at both ends and wood base for blade, used to straighten, level, and texture finish plaster coats. Floating Angles (Corner Floating). Unrestrained surfaces intersecting at about 90
, usually with fasteners omitted near the intersection (Fig. 11.28). Foil Back. A gypsumboard with a reflective aluminum-foil composite laminated to its back surface. Furring. Strips that are nailed over studs, joists, rafters, or masonry to support lath or gypsumboard. This construction permits free circulation of air behind the plaster or gypsumboard. Gaging. Mixing of gaging plaster with lime putty to acquire the proper setting time and initial strength. Also denotes type of plaster used for mixing with the