Page 324 - Civil Engineering Formulas

Maximum unbraced length l b , in (mm) 2200(M 1 /M u )]r y F y A f 20,000 F y d d F y /608

[3600 ________________________________ and d/t w exceed 75% of the limits for these ratios, the following flange thickness, in (mm).

Design Criteria for Symmetrical Flexural Sections for Load-Factor Design of Bridges
Web minimum thickness t u , in (mm) d 2 F y 608 h 150

Flange minimum thickness t f , in (mm) b 2 F y 65.0 b 2 F y 69.6 See AASHTO specification *Straight-line interpolation between compact and braced noncompact moments may be used for intermediate criteria, except that t w 1064 b d 9.35 F yf t f

bending strength M u , in kip (mm kN) F y Z F y S ___________________________________
Maximum should be maintained as well as the following: For compact sections, when both b /t f is the yield strength of the flange, ksi (MPa); t w is the web thickness, in (mm); and t f

TABLE 10.3 Type of section Compact* Braced noncompact † Unbraced interaction equation applies: where F yf

257