Fitness Center (Gymnasium) Live Loads & Associated Live Load Reductions for Columns and Girders

[trence76]

Scenario:
I'm analyzing an existing structure that is a 3-story high-end fitness club. For example, the club has a pool area on the lower level, and has squash courts, one full size basketball court (no seating), large open areas for various lifting equipment on the upper floors. Drawings state a design LL of 100psf was used. There is no indication that vibration was a consideration in the design.

Questions:
1) Is a "fitness center" a "gymnasium"?
2) What is the most appropriate live load to use for fitness centers? I feel that 100psf is adequate and that local checking is required for heavy equipment loads based on other eng-tips forums(squat racks, etc).
3) Do you consider fitness centers as "assembly" areas or uses?
4) Related to question 3), what about live load reduction for girders and columns? Per ASCE 7-16, live loads that exceed 100psf shall not be reduced (4.7.3). In this case, I am not exceeding 100psf so I should be able to reduce the live loads at least for columns supporting multiple floors. It may prove to not be conservative to implement for floor beams, or even girders, based on heavy localized areas of equipment. However, per ASCE 7-16, live loads shall not be reduced in assembly uses (4.7.5). Further, ASCE 7-16, Table 4.3.1 for gymnasiums it states live load reduction and multiple-story live load reduction is NOT permitted.

 

[r13]

Consider the more densified equipment on a floor, and more people involved, I don't think directly picking the live load specified for the gymnasium is justifiable, though similar. I might consider 125 psf - 150 psf, depending on the type and density of the equipment layout. You can sum the weight of all equipment proposed, plus the users, and compare to see which number comes closer. I wouldn't consider live load reduction, as the uncertainty is very high.

 

[trence76]

Thanks retired13! Really good insight.

After doing a load takedown, I'm not sure how the foundations and columns were designed if live load reduction was not used. Everything appears to be well over stressed if live load reduction is not considered.

 

[r13]

Note, did you estimate the area occupied by the equipment? The floor live load should apply on the free space only. It is difficult and impractical to impose loads on the exact manner, I think it is suffice to sum the equipment load and the live load, then take average. Start with 100 psf live load, see what happens.

 

[dhengr]

Trence76:
Along with any LL reductions, I would pay some special attention to floor deflection and vibration, since so much of that type of activity is done in unison, and by large groups. These both need special attention, some good experience and engineering judgement, as they are not so cut-n-dried as to be covered in a couple code sentences. The further you get away from these loaded areas, the more sense it makes to allow some load reduction, since all areas aren’t loaded that same way, all at the same time. Columns and footings seem to make sense, but be careful of that first adjacent large beam or girder, if its primary loading is one of these types of loadings.