There are two benchmark problems which AISC has adopted to find whether an analysis method meets the needs of a rigorous second-order analysis adequate for use in the Direct Analysis Method (DAM). Article C2.1 in the Commentary of the Specification (pp 16.1-273 through 16.1-277) describes in detail these two benchmark problems.
The closed form solutions for Δ max and Mmax are given on page 16.1-276 for several axial loads. Figure C-C2.2 summarizes the results for the first benchmark problem and Figure C-C2.3 summarizes the second. Conduct second order analyses for both benchmark cases, using MASTAN or any other structural analysis software you choose.
Perform:
• Apply a uniform load of 0.2 k/ft on the first benchmark problem (in the Commentary of the Specificatiok).
• Apply a horizontal wind load of 1.0 kips on the second benchmark problem (in the Commentary of the Specificatio).
• While holding these forces constant, run a series of load cases varying the axial force from 0 kips to 450 kips in increments of 50 kips (a total of 10 load cases to run) for the first benchmark problem and from 0 kips to 200 kips in increments of 20 kips (a total of 11 load cases).
• Repeat this for a 1, 10, and 20 element model for each of the two benchmark problems.
final output :
1. A table for each for the three models showing the load case, Δmax, Mmax, both from the computer solutions and the exact, closed form solution, and the percent difference between the solutions (the solutions should agree within 3% for moment and 5% for deflection per the article).
2. Plots of P vs. Δ and M vs. Δ from your computer results for each of the three models.