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  • 1.  Stone Foundation

    Posted 03-09-2019 07:35 PM
    Edited by Tirza Austin 03-09-2019 07:34 PM
    Hi all,

    Is there any feedback in minimum design building code (ASCE 7-10) on how to retrofit concrete buildings with stone or rock foundation, or any guideline, or any important experience to be shared?

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    Sayed Maqsood
    Oakland CA
    (510)395-4361
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  • 2.  RE: Stone Foundation
    Best Answer

    Posted 03-10-2019 12:59 PM
    Edited by Sayed Maqsood 03-25-2019 05:12 PM
    When dealing with old stone foundation, I strongly recommend that your design work avoid modification of the loads on the stone foundation. As long as the foundations are performing acceptably, I generally assume that they can continue to do so, as long as the loaded conditions are not changed.

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    Andrew Holmes
    Consulting Engineer
    Melbourne FL
    (859)3969628
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    Original Message


  • 3.  RE: Stone Foundation

    Posted 03-10-2019 12:59 PM
    Edited by Tirza Austin 03-10-2019 12:59 PM
    Sayed, have you revised the FEMA 356 (Prestandard and commentary for the seismic rehabilitation of buildings)? Maybe your concern could be solved through Chapter 4 reading. Regards, 

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    Andres Guzman Ing.,Ing.,M.ASCE
    UNIVERSIDAD DEL NORTE
    Barranquilla
    573004284680
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    Original Message


  • 4.  RE: Stone Foundation

    Posted 03-10-2019 06:19 PM
    Edited by Tirza Austin 03-10-2019 06:18 PM
    Andres,

    Thank you for the info. Fema 356, chapter 4 was helpful for the seismic rehabilitation of stone buildings.

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    Sayed Maqsood
    Oakland CA
    (510)395-4361
    ------------------------------

    Original Message


  • 5.  RE: Stone Foundation

    Posted 03-10-2019 06:19 PM
    Edited by Tirza Austin 03-10-2019 06:19 PM
    Are you required to comply with the International Building Code or the International Existing Building code? There is a 10% limit on load increases for the lateral load resisting system and a 5% trigger on the gravity system, in addition to a few other requirements (for example, a change in occupancy, or the size of the addition relative to the original building). If you exceed these, you would need to bring the existing structure up to code.

    On a renovation project where we did change occupancy and we had an old stone foundation, I made an attempt to quantify the original capacity of the stone foundation. What I discovered was that even if that foundation "worked" in some locations <g class="gr_ gr_3831 gr-alert gr_spell gr_inline_cards gr_run_anim ContextualSpelling ins-del" id="3831" data-gr-id="3831">for bearing</g>,  the anchorages of structure to the foundations could not meet even minimal seismic requirements in a low-seismic zone. We even ran some specialized pull tests to check capacity and determine if we could add anchors, <g class="gr_ gr_2533 gr-alert gr_gramm gr_inline_cards gr_run_anim Punctuation only-ins replaceWithoutSep" id="2533" data-gr-id="2533">however</g> the stone foundation had zero capacity in tension. As we were planning to gut the building anyway (this review was done during schematic design), the decision was ultimately made to replace those foundations.

    As far as I <g class="gr_ gr_5040 gr-alert gr_gramm gr_inline_cards gr_run_anim Punctuation only-ins replaceWithoutSep" id="5040" data-gr-id="5040">know</g> there aren't any standard "historical" structural data related to stone foundations (at least in my area, and we consulted with another engineer I would consider an expert in this area locally). In theory you could create a testing program to determine capacity, however in <g class="gr_ gr_5263 gr-alert gr_gramm gr_inline_cards gr_run_anim Punctuation only-ins replaceWithoutSep" id="5263" data-gr-id="5263">reality</g> if you are increasing loads above the threshold limits you will be required to replace them entirely.

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    Stephanie Slocum P.E.
    Engineers Rising LLC
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    Original Message


  • 6.  RE: Stone Foundation

    Posted 03-12-2019 01:04 PM
    Edited by Tirza Austin 03-12-2019 01:30 PM
    Dear Stephanie,
    Thank you for valuable info. It's a historical concrete structure that's placed over stone foundation. The stone foundation is 5 ft down from the ground level. The structure is an old concrete, three story house with the concrete strength of 6000 psi. Say the rock can't take tension, however the structure experienced low seismic waves in the past and it's still withstand. That might be due to vacancies within the rocks. Definitely, it wouldn't adequate for high seismic waves, and that's the reason we are retrofitting it.

    Sayed Maqsood
    Oakland CA
    (510)395-4361



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