01-08-2013, 03:55 PM
I just had a brief look I see for now 2 issues in the analysis model.
1. The variable section modeling technique
According to extruded view vs. drawings the beam and the column don't have eccentricity.
In sap (I see it's done in sap) you can change the insertion point to get that. I don't like this solution it can lead to wrong results.
Instead I would draw the frame lines along the section center line.
See Finite Element Design of Concrete Structures By Rombach first or second edition page 24-25
The bending moments in frame should increase after doing so. The shear at base (used for foundation design) should increase a little also.
I'll provide later a model, a comparison, between a frame like this one done with shells and with frames.
2. Bracings in roof plane 20mm diameter I guess.
In pdf at page 28 I can see that they have both compression and tension. I believe these are rods for tension only. If that's true we should be seeing there only tension.
The simplest way to get that in sap would be to assign releases for axial force to bracings in compression and leave only those in tension active, unreleased.
This means that from an X bracing only one will work /, while the other will be buckled.
so |X|X|X|X| becomes |/|/|\|\|
Possibly after doing so you'll see a double value for axial force. Also you'll see some increase in axial force in purlins.
I see an improvement the connection column-beam can be moved more to the middle.
I design for transport limitations of 3m width and 12m length for the steel part.
So you could move the connection away from the column closer to where bending moment is 0 in gravity loading.
1. The variable section modeling technique
According to extruded view vs. drawings the beam and the column don't have eccentricity.
In sap (I see it's done in sap) you can change the insertion point to get that. I don't like this solution it can lead to wrong results.
Instead I would draw the frame lines along the section center line.
See Finite Element Design of Concrete Structures By Rombach first or second edition page 24-25
The bending moments in frame should increase after doing so. The shear at base (used for foundation design) should increase a little also.
I'll provide later a model, a comparison, between a frame like this one done with shells and with frames.
2. Bracings in roof plane 20mm diameter I guess.
In pdf at page 28 I can see that they have both compression and tension. I believe these are rods for tension only. If that's true we should be seeing there only tension.
The simplest way to get that in sap would be to assign releases for axial force to bracings in compression and leave only those in tension active, unreleased.
This means that from an X bracing only one will work /, while the other will be buckled.
so |X|X|X|X| becomes |/|/|\|\|
Possibly after doing so you'll see a double value for axial force. Also you'll see some increase in axial force in purlins.
I see an improvement the connection column-beam can be moved more to the middle.
I design for transport limitations of 3m width and 12m length for the steel part.
So you could move the connection away from the column closer to where bending moment is 0 in gravity loading.