The
Column Design Section in Strunet contains two main parts: Charts to
develop strength interaction diagrams for any given section, and
readymade Column Interaction Diagrams, for quick design of a given
column.
Concrete
column is one of the most interesting members in concrete structural
design application. A structural design of a concrete column is quite
complicated procedures. Evaluation, however, of a given column section and
reinforcement is straightforward process. This is due to the fact that
pure axial compression is rarely the case in column analysis. Some value
of moment is always there due to end restraint, or accidental eccentricity
due to out of alignment. ACI established the minimum eccentricity on a
concrete column, regardless of the structural analysis proposed for the
column, which is defined as the maximum axial compression load that a
column can be designed for.
Column
Design Charts in Bullets:
One
of the demanding aspects in concrete column design is to define the
controlling points on strength interaction diagram. The column strength
interaction diagram is a curve plot of points; where each point has two
ordinates. The first ordinate is bending moment strength and the second is
the corresponding axial force. Both ordinates are linked with
eccentricity. The shape of the curve, or the strength interaction diagram,
can be defined by finding the ordinates of major seven points. Each point
has specific requirement, as established by the code, and thus evaluating
the requirement of this point will result of calculating the ordinates.
The points and their respective requirements are as follows:
 Point
1: axial compression at zero moment.
 Point
2: maximum axial compression load permitted by code at zero eccentricity.
 Point
3: maximum moment strength at the maximum axial compression load permitted
by code.
 Point
4: compression and moment strength at zero strain in the tension side
reinforcement.
 Pont
5: compression and moment strength at 50% strain in the tension side
reinforcement.
 Point
6: compression and moment strength at balanced conditions.
 Point 7: moment strength at zero axial force.
