Lateral forces staircase

[injonil]

I am in the process of assembling a straight steel staircase that will be installed along the gable of a garage to reach the attic.

I am building a platform at the top which the staircase will be attached to. Down below, I am pouring a solid concrete foundation that the staircase will be attached to. The platform will rest on 4 pieces of 95x95 wood posts with footings.

The steel staircase itself is quite heavy, about 4-500kg.

Will the platform/posts be subjected to lateral forces?

My guess is that the platform will be subjected to forces slanting downwards, which therefore means both lateral forces and downward forces. I would need to counteract the lateral forces, for example, by attaching an inner post to the garage and an outer post with a brace against the garage. Or am I thinking incorrectly?

 

[justusandersson]

If you can integrate two of the posts with the stairs and its foundation, you don't need to worry about lateral forces.

 

[injonil]

If you can integrate two of the posts with the staircase and its foundation, you don't have to worry about lateral forces.

Thanks for the response! I was kind of thinking about that from the start, that there shouldn't be any lateral forces, but now I'm getting unsure. Yes, the staircase will be well anchored to the platform, which in turn is well anchored to the posts. And as mentioned, the staircase will also be securely screwed into the concrete foundation at the bottom.

Do you have the possibility to explain why there wouldn't be any lateral forces, just forces going straight down into the posts with this construction? Not that I doubt you, but just because I want to understand. I found an image that I attach which supports your statement; the construction in the image doesn't seem to handle any lateral forces.

 

[injonil]

I think I understand how it works now! The lateral forces are absorbed by the staircase's attachments to the foundation and the platform/posts. Have I got that right?