yes, but you'll pay for having to strengthen the floor members and connections, plus making the brace work in both compression and tension.

symmetry = cheap.

there are other bracing options besides 'X'.

Thank you eL for the info. I just found out x bracing not always a best solution, for example in earthquake. The frequently direction changed loading will cause some braces to fail. Not quite sure what it means, but it is in writing.

"I just found out x bracing not always a best solution, for example in earthquake. The frequently direction changed loading will cause some braces to fail."

i've never heard this; the same argument could be used against shear walls then. the direction that loads are not analyzed will challenge any bracing system. look up the story about the citibank building in ny.

I also found out that we don't need to Use braced system for all walls. It could be two walls use BF, other two walls use moment frame. Am I right, guys?

ask your engineer how they feel about two different system rigidities in a high-rise.

You need to watch the Video about the Citicorp Building in New York City where the building was not designed for high wind loads. It is a real eye opener. I kind of figured they made every student sit thru that video. You know one of the more well known architects Hugh Stubbins and the best of American Engineers (I can't recall his name but it has a french twist). Anyhow it is an amazing story and even a more amazing repair which was kept on the hush while being done because of the potential fear factor. They even used the parshioners from the church which sits under the structure to do a massive survey of how many people might actually live within the fall radius of the tower. They thought they were doing a survey for something else, but its actual purpose was to get a head count of people in a specific area.

Here is an article about it.....Sit down when your reading this one.

http://www.duke.edu/~hpgavin/ce131/citicorp1.htm

Moment frames and shear walls, or braced frames and shear walls can be easily combined together to resist lateral forces. Shear walls are typically separated from frames so they don't alter the response of the frames.

Braced frames and moment frames can be combined to resist lateral forces although it's a more complicated combination. Part of the loads are resisted by the moment frame and part of the loads are resisted by the braced frame.

Braced frames can be concentric or eccentric, but eccentrically braced frames perform in a more ductile manner similar to moment frames. Moment frames deflect more than braced frames and could cause nonstructural component damage during an earthquake.

earthquake bracing is over-rated

snook: Thanks for the clarification.

urbanity: Your explanation is thorough. Do you have pictures?

el: the follwing two buildings should be using two lateral resistance system in the perimeter.


[img]https://lh4.googleusercontent.com/-wUgdhoRna6c/TXlMHPreP3I/AAAAAAAAADo/jEqIP8lqYU8/s1600/chicago+tower.jpg

Yes. As long as the building doesn't fall down.

HA! i was going to say that the diagonal bracing youre talking about would expose the slabs to higher torsion i think, but if you compensate for that they can be equally effective. And then i look and youve posted an image of a project i worked on for a long time which uses that diagonal type bracing you mentioned... not the SOM building, but the tower in the back ground and to the right. Its called Leatop Plaza, and in fact, construction is nearly complete