An additional feature of many of Structural Engineering Library calculation modules is automatic selection of sizes that satisfy your specified design criteria.
Note: If you turned off the option to have the program automatically perform unbalanced Live load placement in the previous topic, please click back to the Span Loads tab now and make sure the option for Auto Unbalanced Live Load Placement is selected once again.
Click the Calculations tab as shown below:
When the screen displays the Calculations environment, the Summary Results tab will be displayed by default as shown below:
Take a look at the stress and deflection ratios indicted in the screen capture below:
We can see that our 6.75" x 30" size guess works, but may not be an optimum use of the section. It would be interesting to see if we could find a more efficient section. Rather than manually trying other sizes from the database, we will use the Automatic Design function to select an optimum member size for us. Click the [Auto Select] button on the Beam Span Data tab shown below:
The Wood Member Design dialog is displayed, and it allows you to set the design criteria:
On the Wood Member Design dialog, click the [Glu-Lam - Western] section type, set the Maximum Stress Ratio to 1.0, and the Minimum Total Deflection Ratio to 180, then click the [Start Design] button.
The software will automatically search the built-in Wood Section Database for all sections that satisfy this criteria using the beam span, stress grade, and loading you have specified. In a few moments the following dialog will be displayed:
Notice how the listed members can be sorted in different orders based on: Weight, Bending Ratio, Shear Ratio, LL Deflection Ratio,Total Deflection Ratio, Depth, etc. This allows you to review the beam sizes that pass your criteria in different ways.
Click on the 5.125 x 27 beam and then click the [Select] button. The Summary Results tab now appears like this: