Library Seismic

[waldo459]

ASCE 7-02 gives the library live load as 150 psf for stack rooms. Section 9.5.3, definition of W, the effective weight of the structure including the total dead load and other loads listed below: In storage areas, a min of 25% of the floor live load. Actual partition weight or 10 psf, whichever is greater. Total operating weight of permanent equipment. 20% of flat roof snow if loads exceed 30 psf.

If library stack room is considered storage, then I would use 25% of 150 psf in the effective seismic weight. However, I can see that with the stacks full, this might be unconservative, especially if bolted to the floor. If classified as actual partition weight, then 100% of the stack weight would be used. Before I run loads on the building, I just want to be sure that I should include 100% of the live load for library stacks for the effective seismic weight. This will make a significant difference in the design, although I'm probably in SDC B.

 

[JAE]

Wow, this seems weird that the code would be so silent on library stack weights for seismic. In most libraries, the stacks are full (this doesn't mean that the stacks weigh the full amount used in gravity design when full).

I would be wary of only using 25%. Perhaps engineering judgement, and perhaps a study of what true weight is usually found on a full stack would be in order.

 

[steve1]

Perhaps you should give some to thought to considering the stacks to be dead load and not live load, since for the most part stacks in library rooms are usually full. The Massachusettes Building Code defines library stack loads as the greater of 150 psf or weight of stacks at 40 pcf. For a double stack at approximately 2 feet wide by 8 feet high the floor loading would be 320 psf under the stacks, and 150 psf between the stacks. The seismic load would then consist of 100 percent of the stack weight and 25 percent of the floor live load (150 psf) between the stacks, and in other areas of the room.