ENGV 425
SHORT COLUMN AND SLENDER COLUMN TEMPLATE
1. A 16 in. square column is reinforced with four No. 11 (No. 36) bars, one in each corner, with
cover distances 3 in. to the steel center in each direction. Material strengths are f c? = 5000 psi
and f y = 60, 000 psi . Construct the interaction diagram relating axial strength Pn and flexural
strength Mn. Bending will be about an axis parallel to one face. Calculate the coordinates for Po,
Pb, and at least three other representative points on the curve.
2. Starting with the column in Problem 1, perform enough additional calculations to determine
the effects of increasing f c? from 5000 to 8000 psi on column capacity at both high and low axial
loads. Assuming that a compressive strength of 8000 psi is appropriate for the lower stories of a
high-rise structure, would you recommend using concrete with fc? = 8000 psi for the columns
supporting all stories within the building? Use your analysis to support your answer.
3. The short column shown in Fig. P9.4 will be subjected to an eccentric load causing uniaxial
bending about the Y axis. Material strengths are fy = 60 ksi and f c? = 4 ksi .
(a) Construct the nominal strength interaction curve
for this column, calculating no fewer than five
points, including those corresponding to pure
bending, pure axial thrust, and balanced failure.
(b) Compare the calculated values with those
obtained using Graph A.10 in Appendix A.

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