AISC LRFD 1.pdf

For P u 0.4P yR v = 0.60F y d c t w (K1-9)Sect. K1.] FLANGES AND WEBS WITH CONCENTRATED FORCES 75whereand = 0.90324twEFRn=hyw(K1-8)When the pair of concentrated compressive forces to be resisted is applied at a distancefrom the member end that is less than d/2, R n shall be reduced by 50 percent.When transverse stiffeners are required, they shall either bear on or be welded to theloaded flange to develop the force transmitted to the stiffener. The weld connectingtransverse stiffeners to the web shall be sized to transmit the unbalanced force in thestiffener to the web. Also, see Section K1.9.Alternatively, when doubler plates are required, see Section K1.10.7. Web Panel-Zone ShearEither doubler plates or diagonal stiffeners shall be provided within the boundariesof the rigid connection of members whose webs lie in a common plane when therequired strength exceeds R v ,where = 0.90and R v is determined as follows:(a) When the effect of panel-zone deformation on frame stability is not consideredin the analysis,For P u > 0.4P y⎛ P ⎞uRv = 0.60Fd y ctw1.4 −⎜P ⎟⎝ y ⎠(K1-10)(b) When frame stability, including plastic panel-zone deformation, is consideredin the analysis:For P u 0.75P y23bcftcfRv = 0.60Fd y ct⎛w1+⎞⎜ ddt ⎟⎝ b c w ⎠(K1-11)For P u > 0.75P yLRFD Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTION