Addition to Existing Structure
Addition to Existing Structure
(OP)
Regarding the evaluation of an existing building for the force increase in an existing building or element that is part of the existing LFRS:
How do you evaluate this increase:
1. Analyze the existing building with current design loads and determine forces in existing members of the LFRS.
2. Analyze the existing building and addition with current design loads and determine the new forces in the existing members of the LFRS.
3. Compare increase to 10% allowed by IBC.
or
1. Analyze the existing building with original design loads and determine forces in existing members of the LFRS.
2. Analyze the existing building and addition with current design loads and determine the new forces in the existing members of the LFRS.
3. Compare increase to 10% allowed by IBC.
Why?
Thanks!!
How do you evaluate this increase:
1. Analyze the existing building with current design loads and determine forces in existing members of the LFRS.
2. Analyze the existing building and addition with current design loads and determine the new forces in the existing members of the LFRS.
3. Compare increase to 10% allowed by IBC.
or
1. Analyze the existing building with original design loads and determine forces in existing members of the LFRS.
2. Analyze the existing building and addition with current design loads and determine the new forces in the existing members of the LFRS.
3. Compare increase to 10% allowed by IBC.
Why?
Thanks!!






RE: Addition to Existing Structure
RE: Addition to Existing Structure
Essentially The IBC states that if lateral force increase in the existing member is less than 10% than it can be considered OK// as is.
What I'm getting at is a situation where you have an older building not designed for seismic and you want to put a small addition on it. So using the above procedure you may have the following outcome when evaluating an existing masonry shear wall:
1. current code wind 8kip ,current code seismic 10kip
2. current code wind w/ addition 8.2kip, current seismic w/ addition 10.5kip
3. 3.5%, 5% - OK//
1. old code wind 7.8 kip wind, NA (seimic not in old code)
2. current code wind w/ addition 8.2kip, current seismic w/ addition 10.5kip
3. 5.1%, 33% - NG//
EIT
www.HowToEngineer.com
RE: Addition to Existing Structure
You check the gravity loads for the existing structural elements that are supporting the addition. If you are increasing the loads (I use the current code loads requirements) to the existing structural elements more than 5%, you need to provide calculations to show the existing structural elements works under the current code or you need to provide a repair for those structural elements to the current code.
You do the same for the lateral loads, but with a 10% increase allowed.
The assumption is that the existing building was designed and built per the original building code requirements. You are only checking the design capability of the existing structural elements that are being effected by the addition. But this means that all the additional loads (from the addition) are going into just the effected structural elements. So, in the case of seismic, you can not take the existing building base shear value and compare it to the existing building plus addition base shear value for the increase.
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: Addition to Existing Structure
RE: Addition to Existing Structure
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: Addition to Existing Structure
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Addition to Existing Structure
Thanks guys!
EIT
www.HowToEngineer.com
RE: Addition to Existing Structure
or just locally analyze the new cantilever beam and connection?
RE: Addition to Existing Structure
EIT
www.HowToEngineer.com