Plane Stress Element for Web of an I section

[Sapuser]

Dear All,
I have to model an I section beam 11 meters in length by using Sap2000. The beam have three spans and have fixed support at first and last nodes while the in between two supports have spring supports (K = 100000 KN/m).
I have to use Frame element for both the flanges while Plane stress element for the web in one model. The beam is lying on a soil foundation and I have given two spring supports. While in the second model, I have used FRAME elements for both web and flanges. My deflection at both the spring nodes in both the models are almost same, except that in the first model I also have some TRANSLATION. I do not know whether my modelling is correct or not? I am uploading my models if someone can check my PLANE stress element model; especially my RESTRAINT conditions. My moments values are also weird and I can not interpret them.
Thanking you all in advance.

 

[WARose]

I don't have SAP.....ergo, I assume that is why I am unable to open the link you gave. Is there anyway you can post the edit/command file in a post here? (I.e. where it will contain Joint Coordinates, Member Incidences, Member Properties, Loads, support locations and conditions, etc). Even from one code to another, you can generally figure it out by seeing that. I could probably model it quickly on a program I use and give you feedback.

 

[MotorCity]

If your beam is supported by the soil, wouldn't you have a continuously support elastic or spring supported foundation? Why are you designing it as a 3 span beam with only 2 interior supports?

 

[Sapuser]

@Motorcity, Thanks for the reply. This is a case study and not a real life problem. I have also to look out for different cases of beam settlement by varying the stiffness of both the springs i.e. free settlement and pinned supports instead of springs etc.

My deflections and joint reactions are coming the same for both models. And my stress variation pattern also looks good. I have refined my model. Attached is a refined version. I am worried about my constraints here. I fixed all the nodes in the plane stress element and when I add up all the translational force in the Z direction, it is equal to the model 1 value i.e. 48.10 KN for left most support i.e. fixed in both models.
Does fixing all the nodes as fixed one induce stiffness in the beam especially upper fibers and this can lead to higher stresses than actual?
Any suggestions will be welcomed.