Moment-Interaction Diagram
- Gokhan Alkan (Unlicensed)
- Seda Ozdemir (Unlicensed)
The moment interaction diagram is created axial forces versus moments, and is used to show the interaction of the applied forces compared to the M-N interaction failure envelope.
Part of the “Column Design Lines” includes also “Axial Force Moment Design” in BDS.
To verify this feature, several examples from “StructurePoint (SP)” software are utilized.
The sample problems including interaction diagram generation to verify solutions of “spColumn” feature are employed to compare the results obtained from BDS with that of i) SP Column feature, ii) hand calculations and iii) from a Reference. All these three items are collected under the title” spColumn” against BDS results.
Example #1: Interaction Diagram - Tied Reinforced Concrete Column (ACI 318-14)
Problem definition:
Develop an interaction diagram for the square tied concrete column shown in the figure below about the x-axis. Determine seven control points on the interaction diagram and compare the calculated values in the Reference and with exact values from the complete interaction diagram generated by spColumn engineering software program from StructurePoint.
Comparison of Results:
Control Point | M (kip.ft) | φM (kip.ft) | P (kips) | φP (kips) | ||||
|---|---|---|---|---|---|---|---|---|
BDS | spColumn | BDS | spColumn | BDS | spColumn | BDS | spColumn | |
Pure compression |
|
|
|
| 1534 | 1534 | 997.1 | 997 |
εs=0 | 252 | 261 | 164 | 170 | 975 | 957 | 634 | 622 |
fs= -0.5fy | 340 | 339 | 221 | 220 | 654 | 649 | 426 | 422 |
fs= -fy* (balanced) | 376 | 386 | 244 | 251 | 440 | 417 | 286 | 271 |
εs=-0.005 | 323 | 320 | 291 | 288 | 199 | 195 | 179 | 175 |
Pure bending | 232 | 238 | 210 | 214 |
|
|
|
|
Pure tension |
|
|
|
| -480 | -480 | -432 | -432 |
Note that intermediate values obtained from BDS are interpolated.