re: 7 storeys mid- rise

[mronlinetutor]

I have completed a model of 7 stories mid-rise concrete moment frame.

Attached is my first report.

spacing of column
10'x10'

girder size
3'x4'

girder length
30'

room size
30'x30'

column size
3'x3'

concrete slab
10"

roof slab
12"

matt foundation
4'

shear wall
32"

Only the girder size and column size are checked.

Can you see anything wrong with it?

Thank you very much.

From

Stanley.


disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

Please note there is an update on girder length and room size.

 

[r13]

Seems reasonable but the 32" shear wall.

 

[MIStructE_IRE]

If you have shear walls why are you using a moment frame? 3’ x 3’ columns are massive for 7 storeys on a 10’ grid! They’re extremely heavily reinforced by the look of those graphics.

Is there supposed to be a plan layout we’re not seeing?

3’ columns on a 10’ grid... That’s going to look wrong!

Actually, you note columns on a 10’ grid but your beam span is 360”?

Why so many stirrups in the columns? You wont even fit a poker in there.

Why stirrups @ 4” crs in a 48” deep beam?

Why do beams need double layer rebar with an L/d ratio of 7.5 (Assuming the 30’ span) or an L/d ratio of about 2 assuming columns on a 10’ grid with 4’ dp beams..?!

Why do you need a 32” shear wall for only 7 storeys?

I’ll be honest, none of this makes any sense to me.

Is this a real project?

 

[r13]

The design was done on/by MIDAS, I believe.

 

[mronlinetutor]

The design was done by Midas Gen 2020.

I only check the girder and column size respected to
Dead Load 50psf,
LL 50psf,
RL, roof load=LL,
Wx, .7*Z*Z,
Wy, .7*Z*Z,
SL, snow load undefined,
RL, rain load undefined.
Ex, response spectrum scale=.5, modification factor R=4.0
Ey, response spectrum scale=.5, modification factor R=4.0

I haven't checked,
serviceability
capacity demand
punching shear
slab
matt
shear wall.

This is my first report by Midas Gen and I am going to verify by calculation.



disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[mronlinetutor]

Here is a picture of it.

I have not to check the weak beam strong column.
I have not to check the soft story.
I have not to check drift.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[mronlinetutor]

Here is a picture of the 1st floor with slab.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[mronlinetutor]

Here is another picture of the first floor with a

slab.



disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[r13]

I can see your advancement through the times you been on this forum, and admire your persistence albeit lack of real engineering experience/practice. What building code the design was based on? Where it is located? As IRE pointed out correctly, there are rooms for optimization, but much better than upsizing. However, you will lose a lot of money, if it is constructed as is, because of too much unnecessary wastes. It is time to get a structural engineer involved.

 

[BAretired]

Not a lot of room to move around in this building!

BA

 

[mronlinetutor]

Any building will collapse or severely damaged if you put it under time history analysis using El Centro as an input, the building would collapse.
I believe El Centro is an eight scale earthquake. Hence I cannot design the building. Vancouver is a high-risk earthquake zone where an eight scale quake could hit any time.

Therefore I use the response spectrum and scale it down by 50% which makes an eight-scale quake to a five-scale quake so that I can check and design the building.


disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[mronlinetutor]

The room has no interior columns. Only the shear wall and corridor has columns. There are double stairwells on the north, a four elevator shaft near the center, and another double stairwell on the south side. It takes me ten years to learn Midas Gen and I am still only halfway through all its functions, for example, pushover analysis which is not required for any building less than 10 storeys high. The ceiling is 16'. Other functions include construction stages management and different types of base-isolators. The model from Midas Gen can further input into Midas FEA NX for further analysis such as earthquake load in different locations and prestressing and post-tensioning. Still, furthermore, the model from Midas Gen can be input into Midas GTS NX for foundation soil analysis including seepage of groundwater and water table and soil settlement and time consolidation and subgrade reaction and resonance of the soil mass below the foundation due to simulated earthquake.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[r13]

As I'd feared, it is located at a region of seismic zone H!

 

[mronlinetutor]

There are no interior columns. Shear wall 32" with no column along the wall except at four corners. There are shear walls on all three sides with the south side has no shear wall and just for windows. There are columns 3'x3' at the four corners. There is a door opening 6'4" with a column relocated to the door jam.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[mronlinetutor]

The rooms have no interior columns. Only the corridor does. Here is a plane view.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[mronlinetutor]

I don't know whether it is permissible to lay a girder on top of a shear wall. The building is not exactly a post and beam construction. It is partly posts and partly designed with shear walls and columns at the corners and corners of the shear wall and door jams.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[r13]

You should try to put elevator shaft and stairwell in the middle as shear core, then eliminate the perimeter shear walls. If two stairwells are required, put them on opposite in long direction on the building.

 

[mronlinetutor]

Here are the locations of the columns. The circles represent the columns.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[mronlinetutor]

I am designing the building using the Canadian code. For structural purposes, Midas Gen is still using NBC 1995. The building members are not optimized yet but they will be.

However, for the shear wall checking and design, Midas Gen has to use the American Code back to 2011. Midas Gen does not support shear wall design and checking using the Canadian Code.

disclaimer: all calculations and comments must be checked by senior engineers before they are taken to be acceptable.

 

[phamENG]

Sometimes persistence is a virtue. Sometimes, it's an unhealthy obsession.

Sounds like you need to lose Midas, and probably hire a structural engineer who knows how to design this sort of building.