Erection Engineering : Structural steel

[boobathims]

What is sercivebility limit for during erection and under what load combinations ( I am not asking
the codal requirements - but best practices in field)

In some case i have seen 0.6Dead +1Wind . Is thi is logically correct ? During erection stage only
self weight is under Dead laod. How come this will come to 60% of of actual weight.

Thanks in advance

REgards
M.S.Boobathi

 

[BUGGAR]

I don't know about the 60% value but I have seen erection calcs. that considered only the steel dead load for erection only, ignoring all the interior steel stud, gyp board, etc. loads that wouldn't be present with the steel frame. The last steel building I did had the structural steel framing coming in at about 8 psf. Comfortably below the actual dead load that we designed for.

 

[thaidavid40]

You can get all your loads and specific combinations for loads during construction (erection) from the ASCE 37-14 code. It gives a thorough description of all the proper loads to use, and what they represent, as well as their statistical likelihood.
Good luck -
Dave

Thaidavid

 

[mike20793]

The 0.6 on the dead load is essentially a factor of safety of 1.5 for overturning/sliding under lateral loading. Consider the following LRFD combination: 0.9DL+1.6WL for ASCE 7-05 or 0.9DL+1.0WL for ASCE7-10. The 0.9 factor on the dead load is because, for gravity loading, engineers will often overestimate the actual dead load. For lateral loading, this can be unconservative. The 1.5 factor of safety at the service limit state comes from 0.9/0.6=1.5.