...
What
...
are
...
E
...
c (S),
...
E
...
c (D),
...
and
...
E
...
c (V)
...
in
...
composite
...
beam
...
design?
...
Answer:
...
Values
...
for
...
E
...
c (S),
...
E
...
c (D),
...
and
...
E
...
c (V)
...
are
...
given
...
as
...
follows:
...
- Ec (S)
...
- is
...
- the
...
- modulus
...
- of
...
- elasticity
...
- for
...
- strength
...
- design.
...
- For LRFD,
...
- E
...
- c (S)
...
- is
...
- taken
...
- directly
...
- as
...
- the
...
- modulus
...
- of
...
- elasticity
...
- of
...
- the
...
- material
...
- assigned
...
- to
...
- the
...
- composite
...
- section.
...
- For ASD,
...
- E
...
- c (S)
...
- is
...
- calculated
...
- as
...
- 33
...
- *
...
- gamma
...
- c
...
- 1.
...
- 5 *
...
- √f
...
- '
...
- c (ksi),
...
- where
...
- gamma
...
- c
...
- is
...
- the
...
- weight
...
- per
...
- unit
...
- volume
...
- (kips/in
...
- 3
...
- )
...
- of
...
- the
...
- material
...
- assigned
...
- to
...
- the
...
- composite
...
- section.
...
- Ec (D)
...
- is
...
- the
...
- deflection
...
- modulus
...
- of
...
- elasticity,
...
- given
...
- as
...
- E
...
- c (S)
...
- /
...
- (creep
...
- factor),
...
- where
...
- the
...
- creep
...
- factor
...
- is
...
- specified
...
- in
...
- the
...
- Preference
...
- menu.
...
- Ec (V)
...
- is
...
- the
...
- vibration
...
- modulus
...
- of
...
- elasticity,
...
- given
...
- as
...
- 1.35
...
- *
...
- E
...
- c (S).
...
- This
...
- amplification
...
- coefficient
...
- is
...
- suggested
...
- in
...
- AISC
...
- Guide
...
- 11,
...
- page
...
- 12.
...
Since
...
these
...
modular
...
ratio
...
are
...
different,
...
transformed
...
inertia
...
varies
...
between
...
strength,
...
deflection,
...
and
...
vibration
...
analysis.
...