D1.L.1.1.4 Bending Stress
Allowable bending stress for tension and compression for a structural member, as given in XVII-2214 of NF-3000 1974 is:
Along Major Axis:
For Compact Sections, tension and compression on extreme fibers of compact hot rolled or built-up members symmetrical about and loaded in the plane of their minor axes and meeting the requirements of Subsection NF shall result in a maximum bending stress:
Fb = 0.66×Fy
If meeting the requirements of this member of:
Width-thickness ratio of un-stiffened projecting elements of the compression flange shall not exceed 52.2/√Fy.
Width-thickness ratio of stiffened elements of the compression flange shall not exceed 190/√Fy.
The depth-thickness ratio of the web shall not exceed
d/t = (412/√Fy)[1 - 2.33(Fa/Fy)]
except that it need not be less than 257/√Fy.
The laterally unsupported length of the compression flange of members other than box-shaped members shall not exceed the value of 76bf/√Fy nor 20000/(d/Af)Fy.
For noncompact and slender elements, clause XVII-2214.2 and XVII-2214.5 of NF-3000 1974 are followed respectively.
For box-type flexural members, maximum bending stress is:
Fb = 0.60×Fy
Along Minor Axis:
For doubly symmetrical members (I shaped) meeting the requirements of XVII-2214.1(a) and (b) of NF-3000 1974, maximum tensile and compressive bending stress shall not exceed:
Fb = 0.75×Fy