Curved staircase Design Clarification

[Thulz]

Link - 1

https://www.eng-tips.com/viewthread.cfm?qid=439014

Link - 2

https://www.eng-tips.com/viewthread.cfm?qid=430210

Link - 1

Hi all,
Presently am working in analysis and design of curved steel staircase.
Staircase details :
Outer Curve Span - 11.4m
Inner Curve Span - 6.3m
Height of Stair - 3.3m
Rise - 150mm , Tread - 1.5m width , Varying size (approx 710mm at outer side & 330mm at inner side)
Stringer Beam - Plate of depth 350mm and 16mm thick
Tread Plate - 8mm thick Plate
Tread Plate Supports at both side - Plate 50mm wide and 8mm thick
Handrails load is taken as Nodal load of Fy= - 0.18kN (Separate analysis done)
Loading :
Live Load - 4 kN/m[sup]2[/sup]
stone Finish Load - 0.84 kN/m[sup]2[/sup] (maximum value taken)
Supports:
Both End fixed, If I go for one end fixed and other end hinged, resulting in higher reactions and even higher deflection.
So, I considered both end fixed. Knowing that I have to release moment at one end, assigned both end fixed to reduce deflection.

I have analysed in Staad pro.
Considering Stringer beam as Plate element, found with higher deflection.
If i consider Stringer beam as beam element , found with lesser deflection.
Still the deflection not in limit.

Need Clarification on Support condition and which element I have to consider for analysis? either beam element or plate element.

Link - 2
Curved Stair Sanity Check
The above link is similar to my project.

Since the post has been closed , I replied as separate thread without adding subject and content.(thread507-430210)

[have you checked the deflection??
How does it works??]

Am new to this forum and of-course my first language is not English, is there any problem bcoz of that??

Thanks for all of your comments.

 

[JedClampett]

This wins the award for the worst thread of May 17, 2018. No title, a reference and a question that must relate to the original thread.
Is there a black star we can give it?

 

[TehMightyEngineer]

No black stars but we do have red flags.

I'd star your reply as an attempt at an "anti-star" Jed but something tells me this will get deleted post-haste anyway.

Original poster; I assume English is not your first language. I'd suggest make a new topic and try to explain your questions as clearly as possible with lots of detail.

Ian Riley, PE, SE
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[JedClampett]

Well, the kind of funny thing is that the OP was his, so the question is, "Why not just put the question as a reply?"

 

[MotorCity]

And you received answers in your previous thread, have provided no new information, and simply re-asked the same question.
No black star, but how about a "C'mon man!!"

 

[bones206]

They were trying to ask a follow up question to the closed thread, because the topic of that thread was related to theirs.

 

[Thulz]

@bones206
Exactly.

 

[racookpe1978]

Right. So ask your specific question.

As it is written now: No. We cannot clearly determine what the problem is, much less guess an accurate, adequate, safe answer to that problem.

 

[bones206]

For the boundary conditions, as with any structure, use your judgement and try to idealize the actual support condition as accurately as possible, while always staying on the conservative side. When there is uncertainty, I usually analyze a range of BC’s to envelope the design of members and connections.

For the stringers, you may be seeing higher slightly higher deflection in the plates because of shear deflection. There may be other degrees of freedom in STAAD plate elements that are treated differently in equivalent frame elements. The user manual may shed more light on that.