Soldier- beveled or no?

[BeanAnimal]

Re: Soldier- beveled or no?

In the past, we used to go to Gobblers Knob and watch Phil while drinking beer. Much has changed with the event over the years and it, for lack of better words, is just not much fun anymore

I hope to start the foundadtion this coming week if the weather holds. Due to the heavy clay, I need to be able to dig the footers, pour, stack and backfill without rain or my excavation will fill with water and NEVER drain unless I pump it out

[Cheesesteak]

Re: Soldier- beveled or no?

It may help for those having trouble with the physics to take a simple cross section of the dome, through its peak. You end up with an arch. The dome is (for the most part) an arch rotatated around an axis and the forces act in the same manner with regard to the legs and base. The strenght of the vertical legs must be sufficient to prevent the arch from spreading or toppling the legs. Any joint in the arch or legs should be at an angle (or of sufficient strength if not) that resists the forces acting upon them.

When the leg and/or joint is of sufficient strength to be static, then the force is counteracted and the load (mass) is transfered to the bearing surface. The difference between the truncated dome and the perfect half sphere are somewhat ambiguos in this case, as the entire dome is made of stacked chains of brick. The angled joint atop the soldier course does help to counteract the outward thurst of the arch, so long as the soldier course is held in place and prevent from sliding outward.

In any case, I don't see many failed domes, so the entire subject would appear to be more academic than important to our projects

I agree with most of what you have here - except that the loads are transferred vertically. The arch load pushes down and out. See here for a basic illustration: Arch Loading

If the arch simply pushed "down," there would be no need to mortar the "soldier" course in place. The reason it needs to be mortared to to provide some resistance against the outward force caused by the arch. The bigger (higher, heavier) the arch - the more buttressing needed.

Buttressing . . .

[lwood]

Re: Soldier- beveled or no?

Nice example Cheese. Agreed, it's primarily academic. We can use my 60" low-dome as a test case. No buttressing, red clay fire-brick and a solider course extending 2" above the hearth, covered with 4 inches of 5-1 unexpanded perlite.

My feeling is that the red clay fire-brick would fail long before the aluminized fire-brick. so mine should be the worst case. This discussion has gotten me nervous about my dome, especially anyone climbing on it. I don't worry, so much, about the static forces. It's any sudden loads may be a problem. No cracks so far, so good. I need to add another layer of vermiculite before finishing. So am going to be careful. It did support one small Filipino mason during the insulation layer installation.

I think the insulation layer itself also provides some structural support.

Overall, I think the idea of buttressing is a good idea over say 42" dia. But less than that it's a bit over-kill.

[BeanAnimal]

Re: Soldier- beveled or no?

I don't disagree at all cheese... If my explanation implied differently then it was due to poor wording on my part