What is the most efficient way you use in your office to design the concrete beam? 1

[sea2003]

Hi Everyone,

my question seems simple, but I get confused when I found the consultant offices design the concrete beam in a different manner
and the resultant is completely different.

Here are the most common ways that I notice :

consultant type 1
1- After applying the building load on the 3D model and applying the crack modifier as per code, they design the concrete beam using the software design report ( i.e ETAB software) without any enhancement

Consultant type 2

Define the slab as a membrane element instead of a shell element and design the beam accordingly based on beam force.


Consultant type 3

Using manual calculation ( I surprised when I found an international consultant follow that way)

Consultant type 4
Modifying the slab crack factor to get a load on the beam similar to manual calculation they design the beam using an excel file and force obtain from 3d model.

 

[BAretired]

To each his own. I have always used manual calculation and wouldn't know how to do it otherwise. But then, I am not doing it any more.

BA

 

[271828]

It has been a while, but the last time I designed concrete beams, we were "Consultant Type 5": use an individual beam design program like

https://www.cesdb.com/spbeam.html

That's a pretty efficient approach IMO.

 

[dik]

I use excel spreadsheets all the time for this... I generally only use computer programs to give me the design output, I then size by hand... a bit of a dinosaur in that regard.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[KootK]

I've been known to pick a few off of the shelf from the CRSI manual.

 

[WARose]

I've typically used Alex's spreadsheets.

 

[sea2003]

I totally agree with you if we have a small building we can design the beam manually or even use computer programs to give you the design member force and then design the member using an excel sheet.

But when we have a complex structure like a mall, the number of beams is massively huge, it will consume a long time if we design the beams manually or even using an excel sheet.

What do you think?

 

[dik]

I'd do it the same way... I did the Cornwall Centre in Regina, by hand about 40 years back... no Excel at the time... and there are a large number of repeats. Today, there are numerous programs that will give you the design values, and then you selectively pick the members you want to design... if memory serves, there were hundreds of composite W14x22 with 10' tributary load spanning 25', with single clip angle bolted/welded connections (first project where I used them)... Lower floor simple span construction, and roof plastic design.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[271828]

"I totally agree with you if we have a small building we can design the beam manually or even use computer programs to give you the design member force and then design the member using an excel sheet.

But when we have a complex structure like a mall, the number of beams is massively huge, it will consume a long time if we design the beams manually or even using an excel sheet."

The gap in required time isn't as large as it might seem.

I think the design team can go whichever way it likes better.

Enormous buildings with little repetition have been designed with tables, manual calcs, and individual beam design spreadsheets or programs. Similar beams are grouped into one calculation. A practical design has lots of grouping to keep things simple.

With the alternative of fully automated design, there is still a lot of checking and grouping of designs. Also, inevitably, the program won't be able to design all members. There is the advantage of easier redesign when necessary, however.

 

[mtu1972]

Having started my career with a slide rule, everything was done by hand. Moments from 2D moment distribution. Shears from member statics. Design was an iterative process. Members were grouped and designed accordingly. Calculators did not change much.

With computer programs, I developed a spreadsheet and used the forces from the 2D or 3D programs. I let the computer design steel members, but still used my spreadsheet for concrete beams and girders.

Input require width, depth (d), shear, moment, and steel and concrete strengths; which rarely were changed. Rebar area was calculated and the required number of each bar size was shown for me to choose.

Shear required me to input the area and spacing of the stirrups so some iterations may have been required.

The last 13 years I used IES and know I let it design the reinforcing in the grouped members. Some iterations were inevitably required to eliminate member failures and reinforcing choices.

gjc