Trapezoidal Load on Beam Element

 Posts: 41
 Joined: Mon Aug 03, 2020 5:38 pm
Trapezoidal Load on Beam Element
Sir, How can I apply Trapizoidal/Triangular load in STKO Opensees. I am able to find the option for applying Uniformly Distributed Load but unable to find for the Trapezoidal Load and Triangular Load. Kindly help.
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Re: Trapezoidal Load on Beam Element
Unfortunately OpenSees does not have a triangular or trapezoidal eleLoad (that is, a load distributed in closed form over a single finite element).
However this can be done in STKO using the load>EdgeForce, using the option Mode=function. In this way you can define a custom Python function (of x, y, and z global coordinates).
Keep in mind, however, that in this way you can define any kind of function (triangular, trapezoidal or whatever... ) but since there is no equivalent eleLoad, STKO will convert this distributed EdgeForce into a set of equivalent (lumped) nodal loads.
This means that you need to discretize the beam/column with more that 1 finite element.
However this can be done in STKO using the load>EdgeForce, using the option Mode=function. In this way you can define a custom Python function (of x, y, and z global coordinates).
Keep in mind, however, that in this way you can define any kind of function (triangular, trapezoidal or whatever... ) but since there is no equivalent eleLoad, STKO will convert this distributed EdgeForce into a set of equivalent (lumped) nodal loads.
This means that you need to discretize the beam/column with more that 1 finite element.

 Posts: 41
 Joined: Mon Aug 03, 2020 5:38 pm
Re: Trapezoidal Load on Beam Element
Thank you so much STKO Team ...
If possible kindly attach the file that you made because I have done the same in STKO as you said but I am not able to see any loads in the Opensees TCL files after I write them.
If possible kindly attach the file that you made because I have done the same in STKO as you said but I am not able to see any loads in the Opensees TCL files after I write them.
Re: Trapezoidal Load on Beam Element
Here is a sample file with the same triangular load (EdgeForce) applied to 4 beams.
Each beam has been subdivided (meshed) into a different number of elements.
In cases such as this one, i.e. a custom distributed load that is not available in OpenSees, you can still use this feature in STKO, but STKO will convert that load to a set of equivalent (lumped) nodal loads. Now, since they are nodal loads, you need to discretize your element to see internal deformations.
Here is the file:
And here is an example of how to mesh edges with different numbers of subdivision (use the EdgeSeed command)
Here I used 1, 2, 4, and 8 subdivisions, of course the best result is obtained with the beam with more subdivisions:
These are the equivalent nodal loads written in TCL:
Each beam has been subdivided (meshed) into a different number of elements.
In cases such as this one, i.e. a custom distributed load that is not available in OpenSees, you can still use this feature in STKO, but STKO will convert that load to a set of equivalent (lumped) nodal loads. Now, since they are nodal loads, you need to discretize your element to see internal deformations.
Here is the file:
And here is an example of how to mesh edges with different numbers of subdivision (use the EdgeSeed command)
Here I used 1, 2, 4, and 8 subdivisions, of course the best result is obtained with the beam with more subdivisions:
These are the equivalent nodal loads written in TCL:

 Posts: 41
 Joined: Mon Aug 03, 2020 5:38 pm
Re: Trapezoidal Load on Beam Element
Great work sir ....Thank you so much