SAP2000 modell : Slabless + Cantilevered from RC wall reduced thickness stair

[Luk]

I have in my official projekt a slabless stair : 3 flyings and 2 landings , 120cm width , Riser = 17cm and Tread = 30cm , but thickness 15cm.

I wish to reduce the thickness to 10cm . You can see my stair dimensions in attached pictures .

First and third flying have 6 x 30cm treads , and the second flying have 5 x 30cm treads.

I have the SAP2000 v24 modell .

Can someone to check the attached SAP2000 v24 modell if it's correct or not , and if can be reduced the thickness of stair to 10cm ?

I'm interested about Load Combination : 1.35 x ( Self Weight + Finish Weight ) + 1.5 x ( Live Load )

Live Load = 3kN/m2

Finish Weight = 0.5kN/m2

In attached images are screenshots from a book , and that formulas are in attached Excell spreadsheet .

I wish to check the SAP2000 modell will give me the same results that one from Excel spreadsheet ?

In Section 2-2 the stair it's sustained from side beam just 107.5cm by both of landing , because there are 180cm window also .

Can you someone help me to check the slabless stair if it can be reduced to 10cm thickness ? ( cantilevered sustain from RC wall + longitudinally sustain . Right now it's brick wall in side of Section 1-1 and 3-3 , but i can make RC wall instead of brick to sustaing the slabless stair cantilevered together with longitudinally )

For flying 1 and 3 , ( Section 1-1 and 3-3 ) i can make to have cantilever sustain also from RC wall from the side of flying.

Flying 2 ( Section 2-2) can't be made it with cantilever sustain because there it's a window.

For Section 1-1 and 3-3 i wish that all Riser to be a cantilever beam : 27cm x 10cm x 120cm

Live Load 3kN/m2 , concrete 20N/mm2 ( C25/30 concrete but with 1.5 safety factor = 20N/mm2 ) and rebar 430N/mm2 ( 500N/mm2 but with 1.15 safety factor = 430N/mm2 )

 

I wish to make the stair just like in belove link , but just 10cm thickness instead of 15cm that i have right now in my official projekt , and the longitudinally sustains to be with stirrup loops from 8mm rebars .

Cantilevered sustain from RC wall rebars will depends of what bending moments will get ( logitudinally , transversal and twisting bending moments ) - maybe 4 x 16mm in top and 4 x 10mm rebar in bottom for every tread ?

Or 2 x 12mm rebars in top + 1 x 12mm of every Riser and 2 x 12mm in bottom + 1 x 12mm of every Riser ?

 

For 10cm thickness the stirrup loops must to have 6cm width and 2 x 2cm concrete cover .

Tread stirrup = 36cm x 6cm ( 30cm tread + 10cm thickness = 40cm - 2 x 2cm concrete cover = 36cm )

Riser stirrup = 23 x 6cm ( 17cm riser + 10cm thickness = 27cm - 2 x 2cm concrete cover = 23cm )

 

I have the stair projekt in .dwg form also , so if anyone can help me , i can send them in .dwg form also .

 

Cypress – Cantilevered concrete stair - Vancouver - STUDIO-TM
https://studio-tm.com/constructionblog/?p=1754

Sap2000_Modell.rar SLABLESS STAIR-1_My_Projekt-modificat_Update1.xlsx

[Luk]

Someone can make footfall analisys in SAP2000 ? Dynamic modal analisys , for the above reinforced concrete slabless open well stair analisys 

[UmarMakhzumi]

Hi Luk,

Thanks for explaining your question. It is interesting. I did try to look at the model but I wasn't able to load it in SAP2000.

You have a tricky situation. Without being able to look at your model, all I can say is that please do give thought to seismic considerations. If your stairs are supported on Masonry walls, attention should be paid to the connection and anchorage requirements and stability.

Good luck.

Thanks.

[Luk]

2 hours ago, UmarMakhzumi said:

Hi Luk,

Thanks for explaining your question. It is interesting. I did try to look at the model but I wasn't able to load it in SAP2000.

You have a tricky situation. Without being able to look at your model, all I can say is that please do give thought to seismic considerations. If your stairs are supported on Masonry walls, attention should be paid to the connection and anchorage requirements and stability.

Good luck.

Thanks.

Please look the belove video tutorial how to open the sap2000 file in an older version of software :

Tutorial Sap2000 - Open a newer file of Sap2000 in older version
https://www.youtube.com/watch?v=o2Do1ag5jdM

[G_Farooq]

I do not have SAP2000 v24, but reviewed your excel file. Your design seems to be ok. I have designed/used these type of stairs in various projects, the recent one in Karachi. But always from an RCC wall. Just make sure that ring spacing provided and anchor bar length in wall is as per seismic detailing rules.

[Luk]

4 minutes ago, G_Farooq said:

I do not have SAP2000 v24, but reviewed your excel file. Your design seems to be ok. I have designed/used these type of stairs in various projects, the recent one in Karachi. But always from an RCC wall. Just make sure that ring spacing provided and anchor bar length in wall is as per seismic detailing rules.

It can be opened Sap2000 v24 with and older version of sap2000 also .

Please look the belove video tutorial how to open the sap2000 file in an older version of software :

Tutorial Sap2000 - Open a newer file of Sap2000 in older version
https://www.youtube.com/watch?v=o2Do1ag5jdM