Smart questions
Smart answers
Smart people
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Member Login
Remember Me
Forgot Password?
Join Us!

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips now!
  • 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!
Join Eng-Tips
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

LINK TO THIS FORUM!

Add Stickiness To Your Site By Linking To This Professionally Managed Technical Forum.
Just copy and paste the
code below into your site.

Eng-Tips LinkedIn® Group

Partner With Us!

"Best Of Breed" Forums Add Stickiness To Your Site
Partner Button
(Download This Button Today!)

Feedback

"...your web site's great! I've been using this system for almost a year now and find it really, really helpful. The people have been helpful in answering just about any question you post in the forums..."
More...

Geography

Where in the world do Eng-Tips members come from?
Click Here To Find Out!

Eng-Tips Shirts!

Get Eng-Tips Swag
Get your
Eng-Tips Forums
SWAG here!
Home > Forums > Structural Engineers > Activities > Structural engineering other technical topics Forum

Load factors in ACI 318 1971

thread507-325368
Read More Threads Like This One
dcceecy (Structural)
6 Jul 12 14:49
we are checking a concrete floor built in 1974.
The current load combination is 1.2DL+1.6LL from ACI 318.
I am wondering what they used in 1974. 1.4DL+1.7LL?
we do no have a copy for ACI318 1971. Can anyone help me out?
Thanks.
BAretired (Structural)
6 Jul 12 15:38
I have ACI 318-63 but I don't know if that would have still been in effect in 1974. It specified:

U = 1.5D + 1.8L
or
U = 1.25(D + L + W)
or
U = 0.9D + 1.1W

BA

BAretired (Structural)
6 Jul 12 15:47
I believe you can purchase ACI 318-71 online for $25.

BA

hokie66 (Structural)
6 Jul 12 19:02
Be aware that some of the capacity reduction factors may have changed as well.
woodman88 (Structural)
7 Jul 12 11:00
Or you can pay $163.50 (http://www.cement.org/buildings/resources.asp?cat2...) and get all from 1908 tom 1999.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

JedClampett (Structural)
7 Jul 12 17:27
If you can wait until Wednesday, I have ACI 318-71 in my office. But I'm on vacation now.
dcceecy (Structural)
7 Jul 12 18:29
JedClampett
Thank you. Please let us know the load factors and the reduction factor of ACI 318 1971
dcceecy (Structural)
9 Jul 12 9:37
I did some research online and found a paper talking about the load reduction factors of earlier days.
Please see the attached pdf.
According to the paper (to calculate the overall or global factor of safety, line 12-18), we can solve these two equations to find the load factors
a*D+b*D (=L) = 1.72*0.9*2*D
a*D+b*D/2 (=L) = 1.67*0.9*1.5*D

then a=1.4, b=1.7

Somebody please verify those load factors if you have ACI318 1971. Thanks.
PT999 (Structural)
9 Jul 12 10:32
ACI 318-71
U = 1.4D + 1.7L
msquared48 (Structural)
9 Jul 12 10:48
YUP. That's what mine says too. Absolutely amazing!

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
dcceecy (Structural)
9 Jul 12 11:08
Thank you for the verification.
I am very curious now. why are those load factors used in cocnrete (in such earlier days) while ASD were used for almost all other materails?
Does that come from a tradition or the ACI 318 committee just adopted some research paper using load factors? Does anybody know the particular reason?
Sorry, too many questions.

Thanks.
JedClampett (Structural)
10 Jul 12 21:42
My guess is that the failure mechanisms of concrete used with LRFD were:
1) Easier to calculate
2) Easier to match with test data
3) Someone had to be first.
Read More Threads Like This One

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!

Back To Forum

Back To Structural engineering other technical topics

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close