×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

other options

other options

other options

(OP)
Hi, I have a 2 story building design in steel (moment frame) but with the increase of the steel cost the building is not giving the right numbers.  What other options can I consider.  Shear walls, combining concrete with steel???.  The building's architecture allows to have the first level in concrete and then to continue in steel also the sreal wall option is arch. acceptable.

 

RE: other options

Diagonal braces are the most cost effective if the architect will allow them.  Round threaded rods in an X alignment,(tension only), are the cheapest of the diagonal brace types.

RE: other options

How about a concrete flat slab structure ? i think its the most economical up to 6 stories.  

RE: other options

Currently we are involved in a multi-family residential project over a PT slab where the upper residential units are being redesigned from light gage steel studs with shear walls to wood frame with shear walls, all due to $$$ difference in materials.  No surprise with the steel costs...

Mike McCann
MMC Engineering

RE: other options

Yes, braces go from joint to joint, unless the members receiving the braces are designed to take the brace forces, in which case you are back to a moment frame of sorts.  Also, if the braces are tension only as civilperson suggested, you will need one with the opposite slope, but not necessarily in the same bay.

RE: other options

This is often the challenge of our work: selecting a bracing system that is economical and fits with the architectural requirements. Moment frames are not always the best solution. Search for walls that you can hide bracing in. The next best solution is to find a wall where you can work around the openings.

RE: other options

Typically braces go from joint to joint, but not necessarily, it depends on your analysis and assumptions too. For example K-type Bracing.

RE: other options

You may want to politely suggest small modifications to the architecture that will make considerable cost savings. Some things like exit doors can be relocated to allow for mbracing/better spacing of beams/columns/better alignment of members.

It is usually best to discuss these with the architect first so you dont tread on their toes.

RE: other options

The Moment Resistant Frame Solution isn't the best you can have due to its deformability (deformability check could coerce you to increase sections dimensions) and for huge detailing. But has a good ductility.

So you can choose a Braced Frame solution. If you go for CBF (Concentric Braced Frames) you will have small drift but less ductility if compared to MRF. And braces can occupy space needed by windows. But watch out, because you have:

-    X-brace;
-    K-brace,
-    Chevron-brace (V-shape);
-    Upside-down chevron-brace
-    Single diagonal brace;

so, pick one of these that fits well for your architecture.

But I would suggest you to go for EBF, Eccentric Braced Frames. You will occupy less space and the "links" will provide you global rigidity and ductility (benefits from both MRF and CBF). I will go for it: EBF shear-type link (short eccentricity).
 

RE: other options

CSD:

Some Architects stick their foot in their mouth so much, I never realized that they had toes!

noevil

Mike McCann
MMC Engineering

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources