John C's Communities Activities

Deflection value of sloped beams - STAAD

John C — Thu, 30 Jun 2022 22:35:04 GMT

Hi, I have a series of sloped beams loaded with the same trapezoidal load showing snow drift but the global deflection value I get for each beam appears to be different. I don't think I should I be using local deflection in this case but I'm not sure. The local values are fairly close even though I'd expect them to be exactly the same.

Please I am not referring to the deflection check using DJ1 and DJ2 rather I'm referring to the actual member deflection. This is the deflection I'm referring to

Please assist. Thanks!

column deflection

John C — Tue, 26 Apr 2022 22:03:36 GMT

Hi,

I have a question regarding column deflection and sway in STAAD. The below picture shows the deformed shape of a column subjected to lateral forces in a frame.

I know the maximum sway/drift in STAAD is gotten from the node displacement value (translation) at the top node in any direction needed (please correct me if I'm wrong) but my confusion is in obtaining the deflection value of the column member itself.

I have used the DFF parameter for deflection check and have set the DJ1 and DJ2 parameters to the top node and bottom nodes.

I'd like to know if the deflection value given by STAAD design output considers or includes the lateral translation of the top node or is it based on the assumption that the top and bottom nodes did not move (similar to beam bending). What is the best value to use for the column deflection? The STAAD output value or the nodal displacement close to the middle of the column?

Thanks.

Frame modelling

John C — Fri, 15 Apr 2022 09:19:36 GMT

Hi there, please I am working on a steel frame design that includes OWSJ in the model. I have tried various forms of releases for the joist members like assigning truss parameter to the diagonals and verticals, releasing moments at the ends etc. but when I run the analysis I get the following errors – member design failed for member xxx, Load case xxx has infinite or nan values and it doesn’t show utilization results too

I have looked through the forum and it looks like it has to do with the member releases but I’m still not able to solve this. Can you please look through my attached model to see if I’m doing anything wrong? Your response will be very much appreciated. Thanks.

The attached model has not been run yet as it takes some time to run but maybe you could take a look at my code file (loading, releases etc.) prior to running to see if I missed anything.

communities.bentley.com/.../Frame-model-release-variation1.STD

Girts in staad

John C — Fri, 11 Mar 2022 17:45:30 GMT

Hi there,

I'm modelling a steel frame in STAAD and looking to include c channel girts in the model. The girts (red lines) are to be located on the front face of the column with wall panels (green line) attached as shown below. I plan on using meshed plates for the wall panel and channels from section database as the girts. My question is how do I model both the girts and channel so they are on the face of the column and channel respectively.

Thanks.

Roof diaphragm

John C — Fri, 04 Mar 2022 21:58:22 GMT

Hi,

I am modelling a steel frame and I have a sloped low roof made of steel deck and beams. I want to apply loading on the deck to be distributed to the supporting beams and also account for the lateral stiffness due to the deck. How can I do this?

My first thought was to use the floor diaphragm option in node specification but as per the STAAD technical reference manual it is not applicable to sloped roof. What options are available for me to model the deck and get this diaphragm effect in STAAD.

Thanks.

Plate corner stresses vs plate center stresses

John C — Mon, 17 Jan 2022 20:57:45 GMT

Hi all, I am wondering which one to use between plate center stresses and corner stresses in plate post-processing results and when we should use them. I am modeling a dome shape, cylindrical wall and base slab.

Corner stresses seems to be higher than center stresses and the logical thing might be to go with the more conservative/higher corner stress values but in a case where someone is checking an existing design it may or may not be logical to go with the higher value (corner stresses).

Please assist. Thanks.

Horizontal member load at an angle

John C — Wed, 01 Dec 2021 00:57:11 GMT

Hi all, is there a way to apply concentrated member loads as shown in the image below using STAAD? This is a plan view of a cylinder, the blue marks show each beam division and each beam is 1m deep by 0.5m wide. Please advise. Thanks.

Plate modeling

John C — Thu, 11 Nov 2021 00:04:18 GMT

Hi there,

I am modeling a circular tank with sloped base slab in STAAD (note the base slab has an opening in the middle and the slope is towards the opening). The internal diameter of the tank is 60m and the height is 6.2m.

To create the geometry, I used the section wizard to create a cone shape for the base slab and also cylinder for the wall. On completion, I merged the prototypes into STAAD Pro and then generated plate mesh for each surface. The problem is that whenever I run the analysis I get this error message: WARNING* PLATE NO. 2411(JOINTS 3257 - 3256 - 3277 - 3278) IS BADLY SHAPED, WARPED, NOT CONVEX, OR NOT NUMBERED COUNTER-CLOCKWISE. Note I get a lot of them and not just one plate.

I looked in the forum and found this solution error message comes. "IS BADLY SHAPED, WARPED, NOT CONVEX OR NOT NUMBERED COUNTER CLOCKWISE". What can i do to solve this?. I have renumbered the plates, checked for duplicate nodes and warped plates as per the solution but still when I run the analysis the error doesn't go away. I have tried generating plate mesh with both polygonal and quadrilateral meshing and I still get the same error. Can anyone help with this please?

This is a screenshot of the model prior to meshing. Thanks.

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