×
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

Fixing to Top of Unreinforced Masonry Wall

Fixing to Top of Unreinforced Masonry Wall

Fixing to Top of Unreinforced Masonry Wall

(OP)
Hi all,

Here in Western Australia, there is a plethora of residential buildings of unreinforced double brick construction (2 leafs separated by a 50mm cavity). The roof to wall detail typically consists of fixing rafters to a timber plate which is on top of internal leaf, which is strapped down into wall (900, 1200mm down etc..) with light gauge G.I. Straps. Further more either bolts into top of brickwork (top fixed, not face fixed) or nails into mortar joints are used to locate plate on wall (sorry scanner not working, will get sketch up as soon as I can). In my opinion this detail provides an unreliable mechanism in resisting In-plane and Out-of-Plane actions at the plate/wall interface. I personally don't get involved in the design of these types of houses and was seeking others opinions on this detail. The main reason I ask, is a client is looking at putting a timber framed second storey addition on a double brick house - my immediate concern is shear transfer in-plane of the walls from framed shear walls above and from timber floor diaphragm between the two types of construction. Has anyone dealt with this before? If so any information/opinion would be greatly appreciated.

Thanks in advance
Toby
P.S. - My initial concept was to bear joists/blocking on top of existing brickwork and then brick up between to "wedge" them in.

RE: Fixing to Top of Unreinforced Masonry Wall

Is there a rim board or blocking between joists? Definitely post a detail.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Fixing to Top of Unreinforced Masonry Wall

(OP)
Here is typical detail discussed - opinions appreciated.

As far as the upper storey extension goes, configuration of lower storey wall openings is changing considerably from original, so I have just opted to remove outer leaf and inset steel bracing frame fixed to new floor over.

Thanks
Toby

RE: Fixing to Top of Unreinforced Masonry Wall

The nailing provides a load path for both in plane and out of plane action st the plate interface so I guess it just comes down to whether or not the per nail capacity is sufficient. Do you have a method available to you to assess the per nail capacity? I don't know of one off hand.

I'm not sure that I understand the steel frame bracing scheme but it sound as though you've solved your immediate problem.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Fixing to Top of Unreinforced Masonry Wall

(OP)
Thanks KootK
Yes, nailing would provide load path, but as you mention, a method to reliably assess its capacity does not appear readily available - Anyone?

RE: Fixing to Top of Unreinforced Masonry Wall

Not sure what the exterior covering is on the addition is but if I were to put a second story on this I wouldn't feel very good about bearing on a single wythe. It the grouting between the wythes is sufficient I would have them remove the top two courses of the interior wythe, put a wood plate down to bear on both wythes and drill and epoxy all thread rods into the mortar below and have a rim joist for the floor joist to attach into at the edge of the wood plate and attach it down to the wood plate w/ framing angles. and have the decking and stud wall above it. This is all assuming the architect is not trying to carry the exterior wythe up to the 2nd floor roof as an exterior covering.

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