×
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

BEARING PRESSURE

BEARING PRESSURE

BEARING PRESSURE

(OP)
WHAT IS THE ALLOWABLE BEARING PRESSURE FOR HOLLOW CONCRETE BLOCK
SOME BOOKS SHOW DIFFERENT NUMBERS

RE: BEARING PRESSURE

There are two practical answers to this question:

1.  Check the local building code for the allowable load capacity.

2.  Call your nearest block supplier and ask for a copy of one of his test reports to verify the tested load capacity and use it with an appropriate factor of safety.

Good luck.

RE: BEARING PRESSURE

Blocks are manufactured having a wide range of strengths.  Here in UK, the weakest in the code is 2.8N/sq mm (400 psi) and they go up to '35 or greater' N/sq mm (5000 psi).  The allowable bearing stress depends on the block strength and the mortar mix you choose, and then you have to consider things like slenderness of the wall or column, eccentricity of the load, factors of safety depending on block manufacturing standards, workmanship standards and so on.  So it isn't that simple - get hold of a copy of your local code!
R

RE: BEARING PRESSURE

High bearing pressures occur at high localised stresses, for example where lintels bear onto masonry. These stresses disperse quickly through the masonry at 45 degrees. This is recognised in the codes some of which allow an increase in the value of local design compressive stresses.
BS5628 considers 3 types of bearings: type 1 & 2 where the element applying the load is rigid, or provided with a stiff spreader, the difference between 1&2 being the "area of bearing of the load and its proximity to the end of the wall". Type 3 bearing comprises a spreader beam located at the end of a wall and spanning in its plane.
Based on this this the stress value under each bearing type must not exceed (1.25comp strength of masonry, fk/safety factor for material strength,Ym) for type 1 bearing; 1.5fk/Ym for type 2 condition; 2fk/Ym for type 3.
The additional factors of safety are applied to the loads acting on masonry (c.f steel, concrete), and also to the materials of construction, as masonry is a site assembled material, and the finished strength of the material is related to the degree of workmanship involved in its assembly (i.e. skill of the bricklayer), the factor of safety for materials takes into account the degree of supervision given to the work.

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