|
a
|
=
|
depth
of equivalent rectangular stress block, in.
|
|
ab
|
=
|
depth
of equivalent rectangular stress block at balanced condition, in.
|
|
Ag
|
=
|
gross
area of column, in2.
|
|
As
|
=
|
area
of reinforcement at tension side, in2.
|
|
A’s
|
=
|
area
of reinforcement at compression side, in2.
|
|
A’st
|
=
|
Total
area of reinforcement in column cross section, in2.
|
|
b
|
=
|
column
width dimension, in.
|
|
c
|
=
|
distance
from extreme compression fiber to neutral axis, in.
|
|
cb
|
=
|
distance
from extreme compression fiber to neutral axis at balanced
condition, in.
|
|
Cc
|
=
|
compression
force in equivalent concrete block.
|
|
Cs
|
=
|
compression
force in tension-side reinforcement, if any.
|
|
C’s
|
=
|
compression
force in compression-side reinforcement.
|
|
d
|
=
|
distance
from extreme compression fiber to centroid of tension-side
reinforcement
|
|
d’
|
=
|
distance
from extreme compression fiber to centroid of compression-side
reinforcement
|
|
e
|
=
|
eccentricity,
in.
|
|
eb
|
=
|
eccentricity
at balanced condition, in.
|
|
Es
|
=
|
modulus
of elasticity of reinforcement, psi.
|
|
f’c
|
=
|
specified
compressive strength of concrete, psi.
|
|
fy
|
=
|
specified
tensile strength of reinforcement, psi.
|
|
fs
|
=
|
stress
in tension-side reinforcement at strain es
, ksi.
|
|
f’s
|
=
|
stress
in compression-side reinforcement at strain e's , ksi.
|
|
h
|
=
|
overall
column depth, in.
|
|
Mb
|
=
|
nominal
bending moment at balanced condition.
|
|
Mn
|
=
|
nominal
bending moment at any point.
|
|
Po
|
=
|
nominal
axial load strength at zero eccentricity.
|
|
Pb
|
=
|
nominal
axial force at balanced condition.
|
|
Plim
|
=
|
limit
of nominal axial load value at which low or high axial compression
can be defined in accordance with ACI 9.3.2.2.
|
|
Pn
|
=
|
nominal
axial load strength at any point.
|
|
T
|
=
|
tension
force in tension-side reinforcement.
|
|
b1
|
=
|
factor
as defined by ACI 10.2.7.3.
|
|
es
|
=
|
strain
in tension-side reinforcement at calculated stress fs
|
|
e's
|
=
|
strain
in compression-side reinforcement at calculated stress f’s
|
|
ey
|
=
|
yield
strain of reinforcement.
|
|
f
|
=
|
strength
reduction factor
|
