Building Load Combinations

[1969grad]

I work in the oil and gas area and need to upgrade our specs for pre-engineered metal buildings used for compressor buildings, meter buildings, etc.

If we specify IBC instead of UBC does this code specify the load combinations for design? Or do we need to reference the metal building specs for load combinations?

Also, does the IBC reference ASCE 7 for wind, etc. loads or do we need to add a reference to ASCE 7?

Most of our facilities are out in the middle of nowhere. Hence we could normally specify either IBC or UBC although I do have a statement to the effect of ahereing to all local codes. I have noticed on recent quotes that the building vendors prefer IBC.

Seems that our management decided to reduce the scope of our IHC subscribtion as a cost saving measure which prompts this question as I cannot look up the answers. Recent lay offs have also reduced our structural engineering capabilities in this area such that I do not get a warm and fuzzy feeling from the guys left on the above issues.

 

[JedClampett]

IBC has load combinations similar to UBC. It uses ASCE 7 for wind. As far as referencing it, that's tough. You really don't need to, it's already referenced in the IBC. When you get down to it, there's any codes referenced in UBC (ACI, AISC, etc.) and you don't re-reference them, do you?

 

[ERV]

A reference to local codes generally means whatever code that your state has adopted. Access your state government through the internet and search building codes. The 97 UBC uses ASCE 7-95 and the 2000 IBC uses ASCE 7-98, there is a difference as far as wind loads are concerned and if applicable seimic requirements differ.

 

[1969grad]

If IBC, for example, references ASCE 7 for wind loads then I would not reference it in my specification.

The way I approach writting specifications is to write a text portion which would be applicable to any project and then add a data sheet which is site and project specific.

My initial plan was to write the text of the spec with IBC as the primary code and then state that any local codes would apply. I think this gives me an out in case the local county has any funny requirements or wants UBC and makes the vendor responsible for the research.

The above is based on my assumption that IBC is sufficient. My post is partly to determine if I have to supplement it with design load combination requirements or the basis of determining wind, snow, seismic, etc. loads.

In today's super competitive environment the goal is to work with the building vendor's standard design as opposed to creating requirements for 100% custom design.

 

[ERV]

Correct. If using IBC or UBC you do not have to reference ASCE 7 separately.

 

[NigelB]

There are three structural performance issues to address in your documents. The first is design loading. We require the design to be based on the prevailing Code (most frequently the IBC 2000). Then we list the loading, including live load, collateral dead load, wind design criteria (speed, exposure, importance, etc.) and seismic design criteria. We list the required load combinations, to avoid arguement. The second is allowable deflection. This includes vertical deflection for frames and purlins, lateral deflection of frames and girts, and special deflection limits for wind girts for masonry cladding. The third is dimensional limits, such as maximum column sizes and maximum frame depths. Require the supplier to submit calculations, and check that they have satisfied the specified criteria.