Amir Kalasheh's Activities

Concrete Slab bearing on Steel Beams using STAAD.Pro V8i SELECTseries 6

Amir Kalasheh — Fri, 01 Jul 2016 00:44:17 GMT

I am trying to perform an analysis on an existing two-way concrete slab supported on each side by deep concrete grade beams using STAAD.

Background Info:

As part of a rehab project, a large section of the two-way slab needs to be cut-out and replaced; but the floor needs to remain operational during repairs. As such, steel beams will be placed directly underneath the bottom of the slab around the cut-out and connected to the deep concrete grade beams. In order to make the repairs easier and cheaper, the slab will sit directly on-top of the steel beams without any attachments between the two to resist negative (upward) bending of the slab.

STAAD Model Info:
I have modeled the concrete grade beams and the steel beams as well as 1'x1' plate elements (XZ Plane) representing the 12" thick slab. I used the offset command to set the top of the steel beams equal to the top of the concrete beams. Each beam has a node every 1' which sits directly underneath a corresponding plate/slab node. All of the slab/plate element nodes are 6" above the beam nodes in the Global Y direction to represent the center of slab elevation.

Is it possible to connect the concrete slab plate nodes to the steel beam nodes using the Master-Slave Command in the FY direction?

I am concerned about using this command because the slab is only bearing on the steel. I do not want the STAAD analysis to assume a composite connection with studs that would cause the steel beam to bend upwards with the slab in regions of negative moment. I only want the master-slave command to function in the (-)FY direction. Possible?

Would the appropriate master-slave command be RIGID to connect the existing slab which is doweled into the existing grade beams?

Plate Girder Bridge - Neutral Axis to Calculate Moment at Midspan

Amir Kalasheh — Fri, 03 Feb 2017 17:17:16 GMT

Please see the attached STAAD model as a reference.

I am modeling a bridge with four 72" deep plate girders + 10" thick concrete deck on top. I have modeled everything using plate elements and I'm in the process of calculating the midspan moments due to dead load by summing (Sx * Plate Area * Distance to Neutral Axis) for each flange plate and web plate at midspan.

The plate girders are supported in the model at the bottom flange node to mimic the actual bridge seat condition.

1) For my moment calculation, should I consider the neutral axis to be located at the bottom flange node since this is where the support is modeled? Or should I consider the neutral axis to be located at the centroid of the plate girder even though the support is at the bottom flange?

2) Does it matter which node is assigned the master and which node is assigned the slave? In my model, I set the deck node as the master and the corresponding girder node as the slave. communities.bentley.com/.../72in-Plate-Girder-Bridge.std

change commnad

santhosh kumar — Fri, 13 May 2016 14:42:50 GMT

After check code command, can i use perform analysis and change command for another set of load combination.?

How to model Property for Structural Roof Deck Diaphragm

Amir Kalasheh — Fri, 13 May 2016 15:28:57 GMT

I am trying to accurately model a gable roof with a structural metal roof deck that acts as a diaphragm. Ultimately, I'd like to take forces from my STAAD model to design the structural metal roof deck diaphragm. I only want to consider metal roof deck, with no concrete topping.

I plan to model the structural metal roof deck using plate elements made of steel. What is the best way to define the Property for the structural metal roof deck?

Should I assign a very thin (1/8") thickness to the plate elements? Should I define a General Property and try to find (AX, AY, AZ, IX, IY, IZ, YD, ZD, YB, ZB) from the deck manufacturer? Should I create a user-table to define the property?

Please any advice you can offer on how to model the Property for the structural metal roof deck would be greatly appreciated!! I have a sloped roof so I cannot use the master-slave command.

Thank you!

Master-Slave for Pitched Gable Roof Diaphragm

Amir Kalasheh — Tue, 09 Feb 2016 14:54:41 GMT

For a flat roof that lays in the XZ plane: I would normally assign one of the nodes in the center of the roof as the master and slave all of the other roof nodes in the XZ direction.

Would this methodology still be applicable for a pitched gable roof (slope = 5 degrees)? It does not seem correct to only assign one master node and slave all of the other roof nodes when the roof is not flat. It also does not seem correct to use the XZ slave direction because the roof is sloped so it is technically not in the global XZ plane.

How can I properly model the roof diaphragm for a pitched gable roof? Should I have two master nodes, one for each side of the gable roof? Would I still use the XZ slave direction?

Any insight that can be offered would be greatly appreciated!!

Optimize composite steel beams in STAAD.Pro

Amir Kalasheh — Tue, 09 Feb 2016 18:15:48 GMT

Will STAAD.Pro optimize composite steel beams? I was initially designing my floor as non-composite and using STAAD.Pro to optimize the steel member sizes. Now, I need to check what the steel member sizes would be if I had a composite deck. I've never tried to optimize composite steel beams in STAAD.pro before so I am unsure.

Thanks for any insight you can offer, it is greatly appreciated!!!