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RE: Existing Buildings

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Will,

 

Get a copy of the IBC.  Chapter 34 is not as loose as your engineer friend has implied.  Structural additions and alterations are required to comply with the code with loads determined by ASCE 7.  There are exceptions, but you’d better read them to see if they apply to your building.  Also check to see if the IEBC [E is for existing] has been adopted in your area and whether new work triggers an applicable Appendix chapter; retrofit requirements are included in the IEBC for some types of buildings.

 

Nels Roselund, SE

njineer(--nospam--at)sbcglobal.net


From: Will Haynes [mailto:gtg740p(--nospam--at)gmail.com]
Sent: Thursday, January 11, 2007 2:58 PM
To: seaint(--nospam--at)seaint.org
Subject: Existing Buildings

 

We have done some additions to existing buildings and checked adequacy of floors for increases in loadings many times before. But I always checked the existing building's original structural drawings against current codes when making decisions, along with conducting some site visits for some verification of construction.

 

Today I got into a discussion with an engineer that has done a lot of rehab work. He states that since there is no existing building code, you can use whatever analysis and design methods you choose (obviously you should still meet statics) and that no codes apply. The only provisions in the IBC are in chapter 34 which he said has a provision that allows you to completely diregard the building codes and standards that are intended for new buildings when looking into the capacity of an existing building.

 

For instance, if there is an existing flat plate reinforced concrete slab that is being analyzed to carry up to 50% more capacity than it was originally designed for under ACI 318. If enough cores are taken to justify the actual concrete strength, the existing reinforcing strength is  known, and the locations of all the rebar are verified you can completely disregard ACI 318 and use whatever redistribution of moments is required to get the slab to work, disregard all ACI's phi factors, and use tension rings or whatever other method you can come up with to show that the slab works.

 

Does anyone here have experience in checking the capacity of existing designs in this manner, with total disregard to the building codes? Is this typical practice when substantial verifications of the existing construction can be accomplished?

 

 

 

Will Haynes, P.E.