Freedom Tower's foundation in Manhattan with new high strenght steel

[Mick28]

Hello,

I've seen an article on special beams for the Freedom Tower in NYC, see below:

http://www.constructalia.com/en_EN/n...4&idCat=250663

This kind of high strenght steels are more and more used (I heard for sustainability), does anybody knows the other advantages of these new steel grades??

Thanks

[Kelvin]

High strength steels have been around for decades and are economical when the use of a higher yield steel saves material. Thus, if the member is governed by strength - a HS steel will allow you to use a smaller section (and save weight) to do the same job. If however, the member is being governed by stability or serviceability, additional yield strength is not much use because E and kL are unaffected by Fy.

[scalziand]

Originally Posted by Kelvin

High strength steels have been around for decades and are economical when the use of a higher yield steel saves material. Thus, if the member is governed by strength - a HS steel will allow you to use a smaller section (and save weight) to do the same job. If however, the member is being governed by stability or serviceability, additional yield strength is not much use because E and kL are unaffected by Fy.

I was bummed to learn that while higher strength steels can withstand a higher load(stress) than lower strength steel, they will deflect the same amount as the lower strength steel under a given load because all steel has the same modulus of elasticity(E), thus making higher strength steels not so useful for dimension critical applications, like Kevin said.