2. Increases resistance to corrosion 3. Improves machinability in free-cutting steels Silicon (Si) 2%  (9% with 18.5% (not much changed by carbon) Hardens with loss in plasticity (Mn  Si  P) Increases hardenability moderately Negative (graphitizes) Sustains hardness by solid solution 1. Used as generalpurpose deoxidizer 2. Alloying element for electrical and magnetic sheet 3. Improves oxidation resistance 4. Increases hardenability of steel carrying nongraphitizing elements 5. Strengthens lowalloy steels Titanium (Ti) 0.75% (1%  with 6%  (less with lowered temp) Provides agehardening system in high Ti-Fe alloys Probably increases hardenability very strongly as dissolved. The carbide effects reduce hardenability Greatest known (2% Ti renders 0.50% carbon steel unhardenable) Persistent carbides probably unaffected. Some secondary hardening 1. Fixes carbon in inert particles a. Reduces martensitic hardness and hardenability in

4. Raises hot and creep strength, red hardness 5. Enhances corrosion resistance in stainless steel 6. Forms abrasionresisting particles Nickel (Ni) Unlimited 10% (irrespective of carbon content) Strengthens and toughens by solid solution Increases hardenability mildly, but tends to retain austenite with higher carbon Negative (graphitizes) Very little in small percentages 1. Strengthens unquenched or annealed steels 2. Toughness pearlitic-ferric steels (especially at low temperatures) 3. Renders highchromium iron alloys austenitic Steel* (Continued) TABLE 4.19 Effects of Alloying Elements in Steel* (Continued) Element Solid solubility In gamma iron In alpha iron Influence on ferrite Influence on austenite (hardenability) Influence exerted through carbide Carbideforming tendency Action during tempering Principal functions Phosphorus (P) 0.5% 2.8% (irrespective of carbon content) Hardens strongly by solid solution Increases hardenability Nil 1. Strengthens lowcarbon

where M
bending moment, in-lb R
radius of curvature at centerline of member, in b
width of cross section, in d
depth of cross section, in When M is in the direction tending to decrease curvature (increase the radius), tensile stresses occur across the grain. For this condition, the allowable tensile stress across the grain is limited to one-third the allowable unit stress in horizontal shear for southern pine for all load conditions, and for Douglas fir and larch for wind or earthquake loadings. The limit is 15 psi for Douglas fir and larch for other types TABLE 10.12 Bearing Area Factors Cb Bearing length, in 0.50 1.00 1.50 2.00 3.00 4.00 6 or more Bearing area factor 1.75 1.38 1.25 1.19 1.13 1.10 1.00 of loading. These values are subject to modification for duration of load. If these values are exceeded, mechanical reinforcement sufficient to resist all radial tensile stresses is required. When M is in the direction tending to increase curvature (decrease the radius), the stress is compressive across the grain. For this condition, the allowable stress is limited to that for compression perpendicular to grain for all species. (K. F. Faherty and T. G. Williamson, Wood Engineering and Construction Handbook, and D. E. Breyer, Design of Wood Structures, 2d ed., McGraw-Hill Publishing Company, New York.) 10.5.10 Form Factor Design values for bending Fb for beams with a circular cross section may be multiplied by a form factor C
1.18. For a flexural member with a square cross section loaded in the plane of the diagonal (diamond-shape cross section), C may