×
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

Masonry Strength Design - LRFD

Masonry Strength Design - LRFD

Masonry Strength Design - LRFD

(OP)
I was designing a CMU Lintel Beam as a flexural member recently and decided to compare the results using the tradional elastic analysis (ASD) approach (which I have always used) and the ultimate strength design (LRFD) approach now allowed by code which considers Whiteney's stress block.

I was startled to see that there was a huge difference between the ASD and LRFD approaches.  The stress ratios I was calculating using LRFD were significantly lower than the ASD approach (more than 40%). I expected the LRFD results would yield somewhat smaller stress ratios (perhaps 10-20% difference)since it is considering the true ultimate state, but I didn't expect the difference to be so pronounced.

Has anyone else noticed large differences in design using ASD & LRFD for masonry??   

RE: Masonry Strength Design - LRFD

Can you post your calcs as an attachment?

RE: Masonry Strength Design - LRFD

I have noticed you get a big advantage using ultimate strength design with masonry.  I think this is because the assumptions for allowable stress design of masonry are so conservative--triangular compressive stress block, low allowable compressive stress, low allowable steel stress, etc.

DaveAtkins

RE: Masonry Strength Design - LRFD

I have also noted large advantages when using Ultimate Strength Design of masonry.  I noted it on this forum a few months back without much discussion on 2 different posts (kind of related to the same question).

http://www.eng-tips.com/viewthread.cfm?qid=252182&page=1

http://www.eng-tips.com/viewthread.cfm?qid=252451&page=1

I verified all of my calculations by and with the NCMA computer program... so I hope they are correct
 

RE: Masonry Strength Design - LRFD

(OP)
OK, thanks guys.

I just needed a sanity check.  It seems absurd that a code would present two different methods with such differing results.

Does anyone know when strength design was introduced in the masonry code?
 

RE: Masonry Strength Design - LRFD

2002 was the first ACI 530 to introduce strength design.

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