Raft
Raft
(OP)
There is about 8 silos spaced out equally over a rectangle shaft of 10 x 20 meter. I want to calculate ULS and SLS for worst case scenerio, which would include loading half of silos in one side of the raft. So, I want to consider to case: flexible and rigid raft. I know u can treat the raft as a beam in case of flexible raft. Can any body shed some light on this??? I have looked into Elastic solution by davis and poulos, but not sure how to deal with this.!!!!





RE: Raft
1) soil/rock description & strength
2) silo height
3) Mat foundation embedment & thickness and
4) Seismic region concerns.
RE: Raft
RE: Raft
Allowable bearing capacity would not be critical due to the large mat area. So your problem now becomes limiting total settlement, checking for the large stress bulb at the mat perimeter, and checking for differential settlement between edge and center of the tank.
You can use BOEF equations in Roark's formulas for stress and strain book. Given the 0.45 m mat thickness, you are likely to have a flexible beam but you may get semi rigid beam if mat thickness is closer to 0.6 m.
RE: Raft
RE: Raft
RE: Raft
RE: Raft
RE: Raft
Please note that you didnt create worst load scenario.
Only first or only last horiziontal row would create worst scenario since they would create moment around weaker axis (smaller H^3)
Guys one question, I know its a long shot but calculating raft fondation on ground, can it be done "by hand" and not using computer analysis?
RE: Raft
Im looking for some tips on beam-raft design process.
Basicly I have few question and would love to get some assistence from more experienced people of this forum.
1) Should downstead beams and slab be poured at once, or is it ok to first cast beams, detail reinforcement overlaping from beam to slab, and then cast a slab.
2.)When defining a perimetar ground beam on top of wich is a bearing wall. Should the width of the beam be determined as it was a strip footing so that bearing capacity under the perimetar beam is always less then actual ground capacity. I dont know if this is maybe conservative because we are delaing with a raft foundation and not with a strip footing.
I hope you guys can spread some light. I thank you very much.
Ana
RE: Raft
RE: Raft
Will do.