ASCE 7 seismic reduction factor (R) for a crane supporting frame

[TTomaz]

Dear all,

I'm reviewing a design of a crane supporting frame (near 10 m high and 20 m in width) which is connected from one column side to the other by tension-only rods and a light-weight non-structural roof. In this direction, the foundation footings are connected by beams.

We're talking about a high seismic area.

I would like to have your opinion on the appropriate reduction seismic factor (R) for a similar structure. Our guess is that it lies between a Ordinary Moment Frame R=4 and an inverted pendulum R=2,5, but considering an inverted pendulum would be excessively conservative. Opinions are welcomed.

Best regards.

 

[driftLimiter]

You get to decide which R factor you choose based on how you detail the frame. If you feel that R = 2.5 is too conservative, then detail it as an OMF and use R=4. Some sketches or details of what your doing could help us guide you more.