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SAFE- Foundation Design

SAFE- Foundation Design

SAFE- Foundation Design

%Hello Colleagues,

Im fairly new to using SAFE for foundation design and would like to know what approach the rest of you take when designing a foundation in SAFE.

When exporting the ground floor from ETABS to SAFE, the column loads are brought in as point loads, and any wall load resting on the ground floor is brought in as a deep beam element (CSI mentions that the deep beam elements are used to mimic the highly stiffened area under the wall).

1)Other than making sure my material properties and soil properties are assigned properly, do we need to add anything else to the model prior to running it? for example, drawing the column element on the slab, deleting the deep beam element and drawing a wall above, etc. I ask this because i feel like it would to simple to just export and click run. I feel like im missing something.

2)i have noticed that i get very weird results when in comes to design a mat/footing for a stair shaft and/or an elevator shaft. When i say "weird" i mean that when i check the required reinforcement in the mat, about 90% of the mat is okay with 1 in^2/ft of rebar, then there are the shaft corners where i have specks that require 15 in^2/ft and above. This is very odd to me and i typically ignore these high requirements since they are small specks, but then there are times where these specks are about 1 sqft of area. Have you guys encountered similar issues? Could this be a result of my ETABS wall mesh? I Typically dont mesh my walls. What i do instead is, if i have a 30feet long wall, i would break it into (3) 10 feet long walls and mesh each individual section to be split at the middle.

3)I have ran footings/mat files where i have turned the deep beam element into a none beam,I get much less rebar requirements but i feel like this approach is not correct since it disregards any rigidity in the mat/footing under the wall. has anyone done this as well?

4)All of the problems above rise from exporting and ETABS' ground floor into SAFE for foundation design. What if i did not have an ETABS model to export? What if i just had some columns and walls with loads and i wanted to design a mat/footing in SAFE? Would i still draw in only the point load and not a column element in SAFE? Must i draw a deep beam element, and not a wall above the mat?

Do your thoughts, do you guys have any recommendations?

RE: SAFE- Foundation Design

1) * Make sure you assign the correct rebar material for slab elements design, SAFE assigns a default rebar material.
Select Slab Elements -- Design -- Slab Design Overwrites
*Make sure to revise the design preferences as needed (Design Code, Min Cover, etc)
*Make sure to delete any loads from any drop panels as SAFE adds the loads from drop panels to the existing slab loads and not replace them as ETABS does
*Make sure to revise the existing combinations

As for the rest i typically draw a Stiff area with the wall width under the wall beam elements and joints to take this area of high stress out of my consideration when viewing the design results

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