Lateral Restraint at the top of a Masonry Wall Query

[MattyG123]

Hey Guys

I've got a builder wanting to building a new blockwall (9m high) to the top of existing structural steel in a warehouse. I've been using Structural Toolkit in Australia about checking the masonry wall.

In the photos below, I am assuming an unreinforced masonry wall with a length of 3m (so I will have structural steel posts, either SHS or CHS at 3m center's vertically). If I attached the SHS or CHS at the top of the existing structural beam (supporting the warehouse roof), will this count as lateral restraint at ever 3 meters? Because it seems that for the top to be restrained it needs to be restrained continuously along the top edge (see photo highlighted in yellow).

In Structural Toolkit, I can assume the top edge to be free (F) but I feel this is too conservative and when I choose this option it says in the red text, "Unreinf'd: Too Slender (Comp)". But when I choose the top edge to be Simple Restraint, it works out ok.

Q1. Can I assume Simple (S) restraint at the top edge?

Q2. Whats governing this red text, "Unreinf'd: Too Slender (Comp)". I cant seem to find the reason for this? Is it a limit between the ratio of Height of Wall to Thickness of Masonry block (I am assuming a 290 thick block). So H/t (9000/290 = 31)?

Thanks for your help!
Matty

 

[Lomarandil]

Without an element across the top between parts, it is a free restraint condition. However...

While code provisions for unreinforced masonry vary.. most allow slenderness ratios around 16-20. So the wall wouldn't pass in the vertical direction, but having a ratio around 10 in the horizontal direction is (usually) enough.

Sorry, I'm not familiar with structural toolkit or the AS masonry code to offer anything more specific



----
just call me Lo.

 

[JLNJ]

Why are choosing 4-sided restraint? Doesn't the wall primarily span (horizontally) the 3m between vertical posts? I'd say to put the software aside and think about how the wall will act.

The more difficult thing to judge will likely be the compatibility of the the posts and details at the top of the wall with the horizontal and vertical deflections of the roof.

 

[MSUK90]

How posts are connected to top and bottom members?
How wall is connected to posts?
Footings safe for added load? As 9m height with 290mm thickness is a lot of additional load..