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sarif.muhammed
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Joined: 20 Jul 2009
Posts: 7
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 Posted: Sun Jul 21, 2019 4:31 amPost subject: Single stair steel stringer beam at centre |
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Dear All,
What are the precautions or checks we need to do in order to design a steel stair case withsteel stringer beam atcenter as shown in images,
Does I section is a viable solution for this?
Thanks
Sarif
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sakumar79
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Joined: 18 Apr 2008
Posts: 708
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| Posted: Tue Jul 23, 2019 10:57 amPost subject: |
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Dear Er Sarif,
In addition to typical design for DL+LL, the stringer beam has to be designed for DL+Half LL assuming the half LL is fully on one side of the beam. This will result in UDT on the girder and hence ISMB sections may not be most suitable. Rectangular Tubes, Double ISMC as Box sections or a tube built up with plates may be more economical.
Hope that helps
S Arunkumar |
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dgupta
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Joined: 07 Sep 2009
Posts: 32
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| Posted: Fri Jul 26, 2019 10:11 amPost subject: |
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| You may want to check for vibration as well. |
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abhio
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Joined: 08 Mar 2010
Posts: 545
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| Posted: Fri Sep 06, 2019 1:41 pmPost subject: |
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Please also consider lateral load on the handrail as per IS: 875 (Part - II).
The toughened glass/ acrylic balustrade is interesting. I suppose it requires very strict deflection control to prevent cracking. |
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logeshcivil
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Joined: 07 Aug 2017
Posts: 34
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| Posted: Mon Aug 29, 2022 5:41 amPost subject: |
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Dear sefians
If i were to design Staircase as shown in the figure.How should i go about it.What would be the ideal thickness of the plate?
What are the points should i consider for the design?
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vikram.jeet
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Joined: 26 Jan 2003
帖子:3699
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| Posted: Mon Aug 29, 2022 10:27 amPost subject: |
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| sakumar79 wrote: |
Dear Er Sarif,
In addition to typical design for DL+LL, the stringer beam has to be designed for DL+Half LL assuming the half LL is fully on one side of the beam. This will result in UDT on the girder and hence ISMB sections may not be most suitable. Rectangular Tubes, Double ISMC as Box sections or a tube built up with plates may be more economical.
Hope that helps
S Arunkumar |
Yes , very nicely enlightened . Stair one one side loaded will give torsional moment at supports .and Box pipe / double channels welded together in box shape are more suitable. |
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sakumar79
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Joined: 18 Apr 2008
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| Posted: Wed Aug 31, 2022 3:33 amPost subject: |
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| logeshcivil wrote: |
Dear sefians
If i were to design Staircase as shown in the figure.How should i go about it.What would be the ideal thickness of the plate?
What are the points should i consider for the design? |
Dear Er Logesh,
If you look carefully, you can see a central tapered plate below the tread. Hence,
1. Design the tread as a double cantilever for foot fall load. Normal Live Load as UDL should not be considered and instead point loads close to edge will be more critical. Deflection check may also be critical in this case
2. Design the vertical tapered plate as a cantilever from the wall
3. Design the weld connection for transfer of bending stresses from the vertical plate to the plate along wall edge
4. Design the stringer plate and bolts to transfer the bending stress from the plate to the wall
Other sefians may point out any step/check I missed
Hope that helps
Arunkumar |
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vikram.jeet
General Sponsor
Joined: 26 Jan 2003
帖子:3699
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| Posted: Wed Aug 31, 2022 7:43 amPost subject: |
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| sakumar79 wrote: |
| logeshcivil wrote: |
Dear sefians
If i were to design Staircase as shown in the figure.How should i go about it.What would be the ideal thickness of the plate?
What are the points should i consider for the design? |
Dear Er Logesh,
If you look carefully, you can see a central tapered plate below the tread. Hence,
1. Design the tread as a double cantilever for foot fall load. Normal Live Load as UDL should not be considered and instead point loads close to edge will be more critical. Deflection check may also be critical in this case
2. Design the vertical tapered plate as a cantilever from the wall
3. Design the weld connection for transfer of bending stresses from the vertical plate to the plate along wall edge
4. Design the stringer plate and bolts to transfer the bending stress from the plate to the wall
Other sefians may point out any step/check I missed
Hope that helps
Arunkumar |
Nice response fm Er Arun.
Only reg supporting wall -
In case wall is rcc , it seems OK as it can take bending moments .
In case of bk wall ( without stringer rcc beam sandwiched in masonry )
Regarding check of stresses in wall ,if stair loaded fully , moment from stringer plate , transfered to wall and causing bending Tensile stresses in masonry be checked .
Just to illustrate : stair width = 1.0m
Point load of 130 kg at tip of cantilever may cause Mo in wall along vertical direction
= 130x1.0= 130 kgm / tread width of say 30cm
(这130公斤pt早些时候按负载是875,but if revised same value may be taken as per rev)
Taking tread width as 30cm, bk wall 23 cm th
BM =130x100= 13000 kgcm per 30 cm , thisBM is caused in vertical direction of wall
If all steps are loaded , the bending Tensile stress in bk masonry
= 130x100 x6 / (30x23^2)
= 4.91 kg/cm2
Direct comp stress due to masonry wt
And considering wall section at lowermost step level
This section is subjected to uniform BM of 130 kgm/ 30cm , the vertical BM from upper steps get transfered at base section
Taking F/F ht
Direct comp stress = 3.0m
Masonry wt = 500x3.0 = 1500 kg / m run
Comp stress at wall bottom = 1500 /(23x100) = 0.65 kg/cm2
Hence n
Tensile stress ,net = 4.91 -0.65 = 4.26 Tensile Not OK * cf 0.7 kg/cm2 for 1:6 bkwork
(*由于松口bk masonry sandwiched between rcc slab at floor level can be taken to some extent but bk masonry stress is far off from permitted )
Rcc wall would suit otherwise 345 th wall can be tried
Just a rough illustration but engineers can further refine. |
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