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 EQUATION:
Fdy = 1.1Fy
(82)
The dynamic yield stresses in shear for different steels are presented in
paragraph 4.b.(2) of this section.
3.
BEAMS AND PLATES.
a.
Beams.
(1) Dynamic Flexural Capacity. The dynamic flexural capacity of a
steel section is related to its static flexural capacity by the ratio of the
dynamic to the static yield stresses of the material. For beams with design
ductility less than or equal to 3, and for a rectangular cross-sectional
beam with any design ductility ratio:
EQUATION:
Mp = Fdy(S + Z)/2
(83)
where S and Z are the elastic and plastic section moduli, respectively.
For beams with design ductility ratio greater than 3:
EQUATION:
Mp = FdyZ
(84)
(2) Resistance-Deflection Function. The resistance-deflection
functions for steel beams are the same as for concrete beams and are shown
in Figure 34. Formulas for determining the ultimate unit resistance and the
elastic and elasto-plastic unit resistances are shown in Tables 5 and 6
respectively. The elastic, elasto-plastic, and equivalent elastic
stiffnesses are shown in Table 7. For uniformly distributed loading on spans
which do not differ in length by more than 20 percent, the following
relationships can be used to define the resistance-deflection function.
1.
Two-span continuous beam:
EQUATION:
ru = 12Mp/L2
(85)
EQUATION:
KE = 163EI/L4
(86)
2.
Exterior span of continuous beams with 3 or more spans:
EQUATION:
ru = 11.7Mp/L2
(87)
EQUATION:
KE = 143EI/L4
(88)
2.08-132
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