Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

RE: Site Class E question

[Subject Prev][Subject Next][Thread Prev][Thread Next]

You will need to check all 4 eqn’s of ASCE ch. 9.5.5.  Compute period T on the approx method, T = ct hn x .  The Cs coeff. should be based on 9.5.5.2.1-1, but need not be greater than 9.5.5.2.1-2.

 

David A. Topete, SE

Structural Engineer

 

GFDS Engineers

543 Howard St., First Floor

San Francisco, CA 94105

v : (415) 512-1301 x21

f : (415) 512-1302

dtopete(--nospam--at)gfdseng.com

www.gfdseng.com

 


From: Anantha Narayan C.K. [mailto:anant_27(--nospam--at)yahoo.com]
Sent: Tuesday, January 16, 2007 7:12 AM
To: seaint(--nospam--at)seaint.org
Subject: Site Class E question

 

Greetings,

 

I have a question pertaining to designing for site class E. My Ss = 1.71 g and S1 =0.68 g

 

Refer Tables 9.4.1.2.4 a and b. Fa for site class E with Ss > 1.25 g, the Fa value is 0.9 as compared to 1.0 for site class B,C,D and E and Fv is 2.4 for S1 > 0.5

 

Cs for a structure whose time period is computed is given as Cs = Sds / (R/I). This I assume means a structure whose T is computed based on highest modal mass participation in either direction.

 

It is my understanding that the site class E is worse than D and hence, intuitively I am expecting a higher base shear. But the Cs value would be lower for site class E than for site class D. Could anyone please help me understand the difference in designing for site class E than for site class D.

 

Also is Cs = Sd1/ T*(R/I) only used when the Time period (T) is computed based on emperical values given in ASCE 7-02?

 

Thanks

Anantha

 

VTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVTVT

 

ANANTHA NARAYAN, E.I.

Structural Engineer

Bliss and Nyitray Inc.

Miami, FL - 33134

 


All New Yahoo! Mail – Tired of unwanted email come-ons? Let our SpamGuard protect you.