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shri shanmuga nandini A SEFI Member
Joined: 21 Nov 2022 Posts: 1
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Posted: Mon Nov 21, 2022 12:30 pmPost subject: SUPPORT CONDITION |
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what support should we assign for UC Column base support in staad pro? when we have to consider fixed, pinned and fixed but (release moment in one direction )? |
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vikram.jeet General Sponsor
Joined: 26 Jan 2003 帖子:3699
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Posted: Tue Nov 22, 2022 3:51 amPost subject: |
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Not clear on what UC represents -
Column of buildings
Support Condition : If strata Rocky, Hard soil -take Fixed
Medium or soft strata - hinged is appropriate for gravity loading , but in eartquake fixity is available , in software it is not possible to include separate conditions,, hence fixed can be adopted..
For single col masts and towers - Fixed irrespective of strata
Gravity loading moments at base are result of compatibility, and even slight rotation due to weak strata, cause this moment to cease.
However for equilibrium moments caused by wind EQ, especially on single column masts, there is no escape as str stability depend totally on this moment to be resisted. |
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satishkemkar General Sponsor
Joined: 23 Nov 2012 Posts: 38
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Posted: Tue Nov 22, 2022 6:49 amPost subject: |
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UC represents universal column steel according to British standard In staad , option "Fixed But " is available where you can release moment or force according to your choice
Thanks
Satish |
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spsvasan ...
Joined: 18 Dec 2008 Posts: 374
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Posted: Sun Dec 11, 2022 7:20 amPost subject: |
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vikram.jeet wrote: |
Not clear on what UC represents -
Column of buildings
Support Condition : If strata Rocky, Hard soil -take Fixed
Medium or soft strata - hinged is appropriate for gravity loading , but in eartquake fixity is available , in software it is not possible to include separate conditions,, hence fixed can be adopted..
For single col masts and towers - Fixed irrespective of strata
Gravity loading moments at base are result of compatibility, and even slight rotation due to weak strata, cause this moment to cease.
However for equilibrium moments caused by wind EQ, especially on single column masts, there is no escape as str stability depend totally on this moment to be resisted. |
Dear Er.Shri ShanmugaNandini
I fully agree with Er.Vikram Jeet. Further, if the column is supported by 3 or more piles I will adopt fixed support condition. For single piles I adopt hinged condition. For double piles I adopt fixity along the pilecap and will release the base moment in the perpendicular direction
S.P.Srinivasan |
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vikram.jeet General Sponsor
Joined: 26 Jan 2003 帖子:3699
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Posted: Sun Dec 11, 2022 9:15 amPost subject: |
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spsvasan wrote: |
vikram.jeet wrote: |
Not clear on what UC represents -
Column of buildings
Support Condition : If strata Rocky, Hard soil -take Fixed
Medium or soft strata - hinged is appropriate for gravity loading , but in eartquake fixity is available , in software it is not possible to include separate conditions,, hence fixed can be adopted..
For single col masts and towers - Fixed irrespective of strata
Gravity loading moments at base are result of compatibility, and even slight rotation due to weak strata, cause this moment to cease.
However for equilibrium moments caused by wind EQ, especially on single column masts, there is no escape as str stability depend totally on this moment to be resisted. |
Dear Er.Shri ShanmugaNandini
I fully agree with Er.Vikram Jeet. Further, if the column is supported by 3 or more piles I will adopt fixed support condition. For single piles I adopt hinged condition. For double piles I adopt fixity along the pilecap and will release the base moment in the perpendicular direction
S.P.Srinivasan |
Very rightly stated by Er SPSrinivasan saheb.
The above observation from my end were for isolated footings only without tie beams. In presence of tie beams in both dir, condition is fixed in all situations. For Raft foundations the condition is fixed irrespective of strata Similarily for Pile foundations -col to pile cap is fixed in all situations
Single pile case is very rightly pointed out by Sri SPS saheb. 如果领带在桩帽梁水平没有,,needs to be hinged in dir where no tie beam run. Twin pile cap - nicely explained
Further I feel that even in presence of plinth beams,, the compatibility moments at footing level are small,, and hence a fixed option is more close,, even if foundation tie beams are not present in isolated footings. |
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