Progressive Collapse design examples in UFC_4_023_03

[cmrdata]

I appreciate comments from anyone who has gone through this design guide and its illustrative design example in appendix E (for a steel frame structure) regarding the calculation of the m factors.
Please see attached.
Thank you.

 

[haynewp]

Kind of late but I have used this UFC before and I couldn't figure out where they are getting the difference either. I would get a spreadsheet going and see if the values are coming from one of the other formula limits in the Partially Restrained Simple Connections (Flexible). Please post if you have already figured it out.

 

[cmrdata]

Thank you, haynewp, for taking the time looking into this.
No, as of now, I haven't figured out how they came up with those values.

I ran into the similar problem when I tried to duplicate their "a", "b", and "c" values in Table E-7 (p.146) for W24x68, etc.

 

[wannabeSE]

The W24x62 have different connection m-factors because some are improved WUF with bolted web moment connections while others are simple shear connections. I am not familiar with detailing WUF connections, so I can not comment further.

On the beam/girder m-factors, the b_f/2t_f and h/t_w values in your calculations are not consistent with the values in the Steel Construction Manual. For a W24x68, b_f/2t_f = 7.66, and h/t_w = 52.0