LRFD load factor on elevator impact load?
LRFD load factor on elevator impact load?
(OP)
I'm designing an elevator pit that will be supported by steel beams and corner columns. Most elevator manufactures provide drawings with impact loads that area already doubled for impact, which takes care of ASCE 7-10 4.6.2 ("All elements subject to dynamic loads from elevators shall be designed for impact loads and delfection limits prescribed by ASME A17.1"). Well, ASME A17.1 doesn't say much about impact loads as far as I can tell. So my question is, is that doubling of the load acting as an LRFD load factor (meaning, it replaces the normal 1.6 multiplier), or do I still need to use the 1.6 factor on top of that? In ASCE 7-10, section 4.6 on Impact Loads also lists 20% and 50% increases for machinery, so that makes me think the 1.6 applies on top of these , since a 20 or 50% increase would be less than the normal 1.6.
Feedback will be appreciated,
Thanks.
Feedback will be appreciated,
Thanks.






RE: LRFD load factor on elevator impact load?
Also, just FYI, the two times factor is only appropriate in terms of elevators based on a long history of performance. All the newer "fancy" elevators are using higher factors, since the factor of two is appropriate for instantaneous applications without a drop in height. The factor I have seen is between two point five and three, due to a drop during the time between something going "wrong" and the safety gadgetry grabbing and arresting the fall of the cab.
RE: LRFD load factor on elevator impact load?