infrmFB and infrmFBPH

02-Getting started with the modelling
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karabi
Posts: 18
Joined: 21 Jul 2020, 12:46

infrmFB and infrmFBPH

Post by karabi »

Hello,
I have a query related to element class. In case of infrmFB the number of integration sections can be modified however in case of infrmFBPH the sections is fixed in two sections. Is there any procedure to get more number of sections in case of infrmFBPH? if no then how can I model the transverse reinforcement with lesser spacing near the supports compared to that in the middle(for ductile detailing). Also it is mentioned that infrmFBPH takes lesser time than infrmFB so I preferred infrmFBPH but not able to assign different sections. Please help.
thanking you,

with regards,
Karabi
huffte
Posts: 978
Joined: 22 Jul 2011, 10:19
Location: Cookeville, Tennessee, USA
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Re: infrmFB and infrmFBPH

Post by huffte »

It seems you should be able to subdivide into two elements. The FBPH element may consist of two separate sections. So you could make the appropriate end the ductile section for each of the two subdivided elements. That may sound a little confusing, but first subdivide into two equal elements in the Element Connectivity tab. Then specify the multiple ductile and non-ductile cross sections in the Element Classes tab definitions.
Tim Huff
karabi
Posts: 18
Joined: 21 Jul 2020, 12:46

Re: infrmFB and infrmFBPH

Post by karabi »

Hello Huff,
Thank you for your response and your valuable time. I shall implement your suggestions. However there are few more queries. when I take two element sections (total will be four incase of infrmFBPH) for a member, say a beam, do I use a structural node to connect these two elements? if yes, then will that connecting structural node behave as a joint(similar to that of a structural node at beam column joint). Or the connecting structural node will have no effect on the continuity of the beam?
Apart from this I just want to confirm that when I create nodes say two nodes at 4m apart then these nodes will represent the centre to centre distance of the frame. right?
thanking you,

with regards,
Karabi
huffte
Posts: 978
Joined: 22 Jul 2011, 10:19
Location: Cookeville, Tennessee, USA
Contact:

Re: infrmFB and infrmFBPH

Post by huffte »

As with typical structural analysis and design software, creating a node at the midpoint and subdividing an element will maintain a fully continuous condition across the joint unless you manually alter releases of the members coming into that joint. The intermediate will be a 'structural' node in Seismostruct. Note that if the elements coming into the node have mass, then the dynamic characteristics will be slightly different (presumably, more reflective of reality) than the original model without the intermediate node. Nodes are indeed typically assigned to be representative of centerline distances. Rigid offsets may be applied to account for joint rigidity when desired.

Best of luck in your work, karabi.
Tim Huff
karabi
Posts: 18
Joined: 21 Jul 2020, 12:46

Re: infrmFB and infrmFBPH

Post by karabi »

Thanks a lot for your guidance :)
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