YS-RCL-BS-01

BENDING AND AXIAL

Problem

Design a grade 45 reinforced concrete column section subjected to 500kN axial force and 40kNm of bending moment about x-x axis. The dimension of column is 200mm x 200mm and cover to reinforcement is 25mm.

Solution

1. Arrange the reinforcement in column.
2. Select the interested axis (x-x or y-y). Arbitrarily set a neutral axis.
3. Determine the strain developed in every rebar.
4. From the strain, determine the axial resistance deployed by every rebar.
5. Based on the depth to neutral axis, determine the area of concrete subjected to compression.
6. Determine the axial resistance contributed by concrete.
7. Determine total axial resistance of column by summing the contribution from rebar and concrete.
8. Determine the moment resistance provided by rebar.
9. Determine the moment resistance provided by concrete.
10. Determine total bending moment resistance of column by summing the contribution from rebar and concrete.
11. Plot the resultant axial and bending moment resistance on interaction curve.
12. Set another neutral axis, then repeat step 3 to 11.
13. Plot the design axial force and bending moment on the same axis with the interaction curve.
14. Evaluate the design by inspecting whether the plotted point lies within the envelope of interaction curve.
15. Review the arrangement of reinforcement if the column design is inadequate.