Masonry Seismic Design Question

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    Mitulkumar Patel

    1st of all DO NOT study from 2006 IBC, 2015 IBC is a different ball game. You want to practice looking up codes in the 2015 version if you want a shot as passing the test.

    What you have highlighted says you when you design your masonry veneer system, it must be in a way that during an earthquake it does not add more load on the primary structure. Essentially it is telling you to use adjustable ties and not corrugated or rigged ties so when the wall starts moving, the veneer doesn't pull and push structural members around. 

    Hope it helps, and good luck!

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    Drake

    Thanks Mitulkumar and this help a lot. Based on what you explained, I did some research. Some of the resources do mention to use adjustable anchors to help balance the deflection in an earthquake.

    So I guess the conclusion is we want to avoid rigidly fastening the masonry to the primary structure in seismic design while allowing them 2 to move differently?

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    Mitulkumar Patel

    form my understanding (very little in seismic) it's ok if things move, you don't want the movement to affect your primary structure. 

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    Joseph Petrarca

    I heard about someone who had a very similar question regarding this:  What non-structural masonry will be affected by seismic design?  The two choices that were contenders were A. interior load-bearing masonry walls must be isolated from structure.  And...B. the masonry brick veneer is installed with adjustable ties to the backup wall

     

    And like you, I'm thinking..."how the heck can you have reinforced masonry interior walls that are isolated from structure?"  that's not reasonable even aside from seismic design. They have to be attached to structure somehow. Considering seismic, if you have a standing masonry wall not attached to anything, that is definitely a hazard in an earthquake.  I don't know what the official answer is but the interior masonry being isolated from structure makes no sense to me in the real world. But...this isn't the real world. 

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    Drake

    Appreciate it. I would also assume it wants to move separately otherwise the shear plane in the masonry might crack itself easily if it is rigidly connected.

    But hopefully someone can weigh in more thoughts here too..

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    Elif Bayram

    Drake, you can refer to FEMA Chapter 9, for design strategies of non structural building elements too. The idea behind of isolating non structural members from the main structure is to avoid extra loads on the system, especially considering that how masonry is heavy. In general, in seismic design, the lighter the building the better. It is because Newton’s second Law F=MA,. The more the more mass (M) of an object, the more the forces that are acting on that object. In this case that forces are seismic forces and Mass is your building.

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    Drake

    Hi Elif, what you have mentioned in Chapter 9 and the Newton's Law are great. Acutally they help explain some of the very basic rule of thumbs in a simple way. Now I need to dive into these. Appreciate this great guide! 

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    Elif Bayram

    Glad to help Drake. Good luck with studying!

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