When it comes to elasticity analysis, load combination has always been an important post-processing step. Unlike design software that can automatically generate load combinations, general finite element software currently requires manual load combination, which is a simple process for those who are familiar with APDL. It involves a combination of several APDL commands, such as Lcdef, Lcase, and Lcoper.
However, if you are using Workbench, in addition to inserting APDL commands, more often than not, you’ll use the Solution Combination function. This article will explain how to use it.
Before performing load combination, each individual load should be analyzed step by step. What are individual loads? For example, a floor slab can be subject to both dead and live loads. When performing static analysis, you should set up two load steps: the first load step calculates the dead load, and the second load step calculates the live load. Of course, seismic response spectrum analysis also requires a separate calculation, as shown below.
This example mainly combines dead load, live load, and response spectrum analysis. Therefore, two types of analysis were performed first: static analysis and response spectrum analysis. In static analysis, the dead and live loads were calculated separately, with two load steps set up. The first load step considered the self-weight, horizontal lateral force, and uniform additional dead load of the floor slab, while the second load step considered the live load of the floor slab.
Next, we’ll use the Solution Combination function to perform load combination.
Go back to the Model module, click the Solution Combination button in the upper right corner, or right-click to insert this module.
First, let’s get to know this toolbox. The list shows the basic individual loads to be combined, and the rows represent the combination coefficients. Under the column labeled Time/Frequency, you can select the load step to be included in the load combination according to the type of analysis you are performing. For example, if you set up two loads, labeled time=1 and time=2, when you input a value of 1 for time, it represents the first load, which defaults to Endtime, or the last individual load, but you can input your own value.
Combinaiton1, 2, 3, 4, etc. represent the specific combination numbers, and the values subsequently filled in are the combination coefficients for each individual load.
In this case, two combinations were performed:
The toolbox was set up as follows:
After setting up the toolbox values, right-click and insert the type of results you want to view, such as the displacement in the Z direction, and then solve directly.
Note that you can set the results for different combination numbers on the right-hand side of the result viewer, which defaults to the last combination number.