Mass Code 7th Ed Chapter 34

[papaaj]

The new version (7th Ed) of the Massachusetts Building Code, Chapter 34 (Section 3408) classifies work related to alterations to existing buildings into different levels of work. Level 2 work includes several different types of alterations, as defined in Section 3408.4.3, one of which is this:

"4. Increase in effective seismic weight, with or without structurally attached additions, up to a lifetime limit of 10% of the effective seismic weight of the building..."

If the alterations fall into the Level 2 classfication, the engineer is required to analyze the building for certain lateral loads per Section 3408.7.3.

My concern is that this seems to be a particularly stringent requirement. Interpreting the code literally, if we add so much as one small piece of equipment to the structure, we are therefore increasing the seismic weight, so we would fall into Level 2 Work. And that means we would have to do a lateral analysis of the existing building, which could be a significant effort depending on the structure.

The preceding version of the Mass Code (6th ed) did not require a lateral analysis of the building if the weight increased by less than 10% (Sect 3408.4.3.2) and the alterations to the building do not reduce the lateral load capacity of the structure (Sect 3408.3.5).

So my questions are: Am I interpreting this provision in the 7th edition of the Mass. Code correctly? Is there any wiggle room to this provision, so I can avoid performing a lateral analysis of the building? What have other people been doing in situations like this?

Here is a link to chapter 34 of the Mass Code 7th edition:

http://www.mass.gov/Eeops/docs/dps/inf/780CMR-1/780034.pdf

And here is a link to chapter 34 of the Mass Code 6th edition:

http://www.mass.gov/Eeops/docs/dps/BuildingCode/780034.pdf

Thanks in advance for your help!

 

[MiketheEngineer]

I think it is saying you can add up to 10% of the weight of the building without doing analyis.. Similiar to IBC.

Not familiar with the MA code - so I may be wrong..

 

[papaaj]

Mike - I know what you're saying, relative to what IBC says. The previous version of the Mass Code had a similar provision. But in the new version of the Mass Code, I don't read it that way. As I quoted above, it says "an increase...up to 10%" of the seismic weight pushes you into what they call Level 2 Work. And once you're in Level 2, you have to show that the building can resist some minimum lateral loads.

 

[MiketheEngineer]

Try calling your local building dept -- maybe they can shed some on light on it and they have to to buy into what you do anyway....