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RE: Masonry lap splice (fwd)

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I posed your question to someone that I know on the MSJC and below is his
response.  I have removed names to "protect the innocent", except
mine...since I am not so innocent.  <grin>


Ypsilanti, MI

---------- Forwarded message ----------
Date: Wed, 29 Oct 2003 16:01:32 -0500
To: 'Scott Maxwell' <smaxwell(--nospam--at)>
Subject: RE: Masonry lap splice

To not much surprise, this has been a hotly debated item within various code

It started (innocently enough) with a request from the seismic design
community questioning whether 48 bar diameters was long enough for all
applications where ductility was an issue.  When this topic was researched,
a mode of failure (a virtual splitting of the masonry along the length of
the lap) was identified that was not considered in the development of the
48db equation (which is primarily based on the bond strength between the
reinforcement and the grout).  The research however focused on laps
subjected to direct tensile loading (not flexural as is a more common design
case).  A full copy of the research report can be downloaded at <>

My personal feeling is that the longer lap lengths may be justified when:
1)       the laps are subjected to direct tensile loads
2)       large inelastic deformations are anticipated (i.e., plastic hinge
3)       no confining reinforcement is present (which may preclude this
splitting phenomenon seen in the research)

The debate on this topic is far from over - and will likely result in
substantial reductions in the required length of lap (as a function of one
or more of the above items).

Hope this helps.  Feel free to share this with your email list.

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