Insertion Points / Cardinal Points 3

[theshearstud]

Is it possible to change the cardinal point of an area element?

When modeling concrete beams and slabs, if only the beam insertion point is adjusted (say to top center), the overall depth of the beam+slab floor system will be (+ slabdepth/2) larger than intended to be modeled.

Thanks

 

[stressed]

You can assign the frame insertion point to be anything you like using the frame offsets from cardinal points at the bottom of the insertion point dialogue. If you want to move your beams down 6", for example, type -6" in the I and J fields.

Area elements have a similar feature in which you assign area thickness overwrites to "move" the area in its local +3 or -3 direction. If you have a large area, meshed or unmeshed, select and assign thickness overwrites using the "user defined joint offsets by points" and specify the joint offsets (local 3 to the area) for each of the 4 corner joints. SAP2000 automatically knows the 4 corner joint labels, so you just input the offset 4 times, once for each corner.

 

[theshearstud]

Thanks for the response stressed. This definitely provides an answer to my question. Follow up question:

Is it possible to specify the joint offset for an area element with one command? The model I am currently working on is a relatively large floor system with a fine mesh (vibrational analysis for sensitive equipment). It is not practical to go though each node and change the joint offset. Also, the slab changes depth throughout the floor, so just changing the frame member offset will not quite give an accurate representation for the entire floor.

I am trying to see if there is a way to expedite the process.

Thanks again.

 

[stressed]

aggie, you shouldn't have to select each individual shell element one at a time. Select one entire floor or area of the floor even if it's 100's or 1,000's of elements.. and SAP2000's "user defined joint offsets by points" should default to "multiple" to assign the offset to all the selected areas. The different slab depths can be dealt with by assigning different section properties and assigning offsets to different areas on the floor.

 

[johnbridge231]

Be careful when assigning this property, as it may result in the presence of axial forces in beams for example.

Analysis and Design of arbitrary cross sections
Reinforcement design to all major codes
Moment Curvature analysis

http://www.engissol.com/cross-section-analysis-design.html

 

[theshearstud]

stressed/johnbridge

When I assign the area joint offsets to a group of shell elements, the "multiple" for joint ID does appear. But, only one joint for each area element is offset. Have you encountered this before? Do you know what it going on?

Even when I try to assign an area joint offset to one shell element, I am not given the option to toggle through different joints.

Thanks

 

[theshearstud]

I'm sorry I didn't even realize the toggle button was next to the joint offset and not the joint ID. I found the answer to my questions. Thanks again guys!

 

[Tweety3]

Hi john .. Would you please give me more details regarding what you say of presence of axial forces in beams if the offset property for beams and slabs is used..