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floor Slab to Wall Connection.

  • 1.  floor Slab to Wall Connection.

    Posted 06-01-2017 02:01 PM

    Hello Everybody,

    I am back to existing buildings. According to my experience most of the existing building that were built more than 100 years ago are stone masonry buildings. In the most cases the floor slabs are Fox and Barrett structure or wood structure.

    The situation with one of the project is as follows. The building is approximately 150 years old and has historical value. The walls are exterior stone masonry and floor slabs are wood structure. Interior walls are mostly wood structure.

    Our assignment was to design the repair of all exterior walls. The repair gradually translated into exterior wall rebuilding.

    The interior walls are not connected to exterior walls. The wood floor slabs appear to be randomly supported on the exterior and interior walls. The distance between floor beam supports is from 10 feet to 20 feet. The floor sheathing is not connected to walls. According to accepted contemporary practice there is no proper connection between walls and floor slabs. Simple hand calculation shows that existing connections of floor slabs to walls are not adequate to transfer out-of-plane wind loads. But building existed for 150 years and there is no visual sign of any distress in the walls or floors.

    It is our opinion that in any case floors have to be connected to walls. Because there is no sign of the distress the owner does not agree to do it.

    There is International Existing Building Code. According to this code, if building survived for many years then no strengthening is needed.

    I would like to have an opinion of the engineers dealing with existing buildings. What would you do in such case? Would you insist on connecting floors to walls? What would be your argument? Or would you agree with the owner and do nothing?

    Thank you for your help and advice.


    Jane Krisanova, P.Eng.

    Senior Structural Engineer
    Ojdrovic Engineering Inc.
    4195 Dundas St. West, Suite 233, Toronto, ON  M8X 1Y4

    T: 416-925-0333x224, F 416-925-3980, M 416-856-6584


  • 2.  RE: floor Slab to Wall Connection.

    Posted 06-02-2017 11:00 AM

    You should post a photo or sketch of this 150 year old building to get more meaningful response.  I assume your building is box shaped.
    For your information in NYC buildings in the early 1900's did not require wind loading for building less than 100 foot high.  this is in part due to the mass of the old masonry and stone transitional buildings being much greater than the wind loads.

    Martin Fradua P.E., F.ASCE
    Vice President
    Huntington NY

  • 3.  RE: floor Slab to Wall Connection.

    Posted 06-05-2017 09:46 AM
    I agree with Martin.  Photos and or sketches would be helpful.  Also, you did not mention the thickness of the wall or the height of the building.

    Joseph Buongiorno P.E., M.ASCE
    Building Infrastructure Consulting Services
    Hopatcong NJ

  • 4.  RE: floor Slab to Wall Connection.

    Posted 06-05-2017 09:49 AM
    Hi Jane
    I read your post and comments relative to interesting project.
    All suggestions to you are valid; however,
    1. Due to environment impact you might like to be much careful with your design.
    2. What type of building occupancy is involved?
    3. Do you have soil report as of 150 years to 2017? It is critical for the area that is cold and I think has freezing factor for building over 100 years has been built.
    4. The recent soil and earthquake consideration certainly apply for wind factor.
    I personally, do not assume old buildings are settled and steady for any occupancy in 21 st century.
    Please, post additional information it is broad for specific design.

    Sent from my iPad

  • 5.  RE: floor Slab to Wall Connection.

    Posted 06-02-2017 01:34 PM
    Generally, in my experience in Florida and the Existing Building Code, you are required to bring elements of the structure up to current codes IF the renovation, addition, or repairs are over a certain financial amount or a percentage of the area of the structure. However, some codes do require action if there is a "dangerous condition" or other such verbiage, and this is usually defined in terms of stress/strength and loading requirements.

    Though I do agree with what I understand you are trying to do from a structural engineering standpoint, if it is not required by your building codes specifically, than the owner is correct legally. Florida is full of old buildings not designed or built for hurricanes and somehow they have survived - but that should not be the reason(s) we are using to justify structural improvements, IMO. Otherwise you would have to go around the world spending trillions improving every building not properly designed and built for modern wind, seismic, snow, etc etc....

    Andrew Kester P.E., M.ASCE
    KSE, LLC
    Deland FL

  • 6.  RE: floor Slab to Wall Connection.

    Posted 06-06-2017 11:22 AM
    I agree with Martin.  Not knowing where the building is located, it's original construction most likely pre-dated any building codes at that time.  Assuming the exterior stone masonry walls are quite thick, the building has been resisting wind by its sheer weight.  However there is no mention whether the roof diaphragm is attached to the walls. 
    Have you checked IBC 2012, Section 3404 for alterations made to the building or part 3404.4, to see if you fall within the 10% exception rule.  But the key part is that the building doesn't appear to have any "existing" structural elements carrying lateral load other than the exterior walls themselves.  What does the local Building Official say?   
    You don't mention what the building's future occupancy is.  Assuming it will be habitable then bringing it up to code so that it's safe would meet the "standard of care".  Distress or not, I would connect the floors to the walls so I could sleep at night.  Sometimes all it requires is a couple SImpson connectors.

    Raymond Kovachik P.E., M.ASCE
    Structural Engineer
    Elliott LeBoeuf & McElwain
    Centreville VA

  • 7.  RE: floor Slab to Wall Connection.

    Posted 06-07-2017 10:03 AM
    Hi Raymond,
    Well expressed. We are moving forward to engage discussion for real engineering aspect for Jane's project.
    How many building codes are available for building design?
    Thank you
    Soussan Bathaee M.ASCE-SEI

    Sent from my iPad

  • 8.  RE: floor Slab to Wall Connection.

    Posted 06-06-2017 03:38 PM
    It seems to me that there are a number of issues. I will comment on only one.
    (1) Public welfare and safety. if you believe in your professional opinion that the situation is unsafe then I think that I would try to ensure that the owner understands that the situation is unsafe. I would do that in writing. I do not believe you are under any obligation to substantiate it by analysis unless you wish to or are retained to do so. For the sake of your relationship, I would try to be very clear but very diplomatic - maybe get your marketing people involved.
    Archie B. Wainright, PE, M. ASCE

    Archie Wainright P.E., M.ASCE
    Wainright Engineering & Consulting
    St Augustine FL

  • 9.  RE: floor Slab to Wall Connection.

    Posted 06-08-2017 12:38 PM
    Hi Archie
    Well said, I think owner of the project is the valid source for any contracts.
    Soussan Bathaee M.ASCE-SEI

    Sent from my iPad

  • 10.  RE: floor Slab to Wall Connection.

    Posted 06-09-2017 01:05 PM

    Thank you everybody who responded. I was reading every mail with great interest.

    The sketches were attached because the question was in general. Is wall-to-floor connections require by default?

    The building is 3 stories high. Plan dimensions are 145'x63'. Height is 43'. Exterior walls are 2' to 3' thick stone masonry. Interior walls are wood structure. Floor slabs are wood structure. Floor slabs and roof structure have simple supports on the walls. Supports are spaced at approximately 10'. No anchorage at beam supports exists.

    The scope of job did not include seismic evaluation of the building. The seismic activity in the region is low. Occupancy – offices.

    There is no significant structural damage to any structural elements. Exterior walls deteriorated due to weather and aging.

    No code existed at the time of the construction.

    In Canada, we do not have any code on existing buildings. In USA, you have International Existing Building Code.

    Our opinion on necessity of floor-to-wall and roof-to-wall connection was presented at each meeting with the client and owner. Our opinion was also included in the report.

    The owner accepted exterior wall rebuilding. The owner refused to accept structural drawings showing slabs-to-wall connections.

    On the owner request we prepared list of codes that require wall-to-slab connection. But all these codes are valid only for new construction.

    According to IEBC 2015, the wall rebuilding shall be treated as "Repair". It means that no reinforcement of the structural members or connections are required.

    We agreed to remove wall-to-slab connections but asked the owner to send us letter saying that the owner will accept full responsibility for this decision.

    Discussion with authority is not the option. The building is federal property and the owner does not have obligation to follow national or provincial codes. The federal standards are focused mostly on preservation of historical value by means of minimal interventions.


    The conclusion is that at this time in North America there is no official requirement to connect walls to floor and roof slabs for existing building if building does not have structural damage. I am talking about buildings where seismic evaluation is not required by owner.

    It is our team opinion that wall-to-floor connection is a must for the buildings even if seismic evaluation is not required by the owner. In this case the only our tool is rhetoric.

    The building survived for 150 years. Does it mean that the building will survive the next 50 years?

    How predictable is behavior of the existing buildings where walls rely on their thickness and mass?

    Best regards,

    Jane Krisanova Aff.M.ASCE
    Senior Structural Engineer
    Ojdrovic Engineering Inc
    Toronto ON

  • 11.  RE: floor Slab to Wall Connection.

    Posted 06-13-2017 09:40 AM
    Hi Jane,
    Your project and your communication is the best process for collaboration practice among architect and engineers.
    1. Seismic evaluation, I think it is the necessity of the international building code comply evaluation, no matter building is not in specific zone.
    2. The building is Federal or private property, owner for the people protection would be in safer side of humanity protection to assure the IBC apply for future complication.
    3. I think in Canada or any place in the globe first rule of law is humane and living system safety. The architects, engineers, construction contractors, ....are responsible to design and build infrastructure facilities securing life of humane protection from any unknown man made or naturals disasters.
    4. I do respect to your opinion, but I think in 21st century building of 150 years, can stand for another 50 years, is too far for assumption.
    5. Best challenging project for discussion.

    Please, ensure to verify soil engineers takes a sample for analysis for the environment impact. In the region. It seems that owner and client are able to have soil engineer on board.
    I appreciate your attention, I will review your given information for further study.
    Thank you

    Soussan Bathaee M.ASCE-SEI
    Sent from my iPad