AASHTO SHEAR CONNECTORS

[bigmig]

Does anyone know why the AASHTO LRFD 3rd Edition (PE Edition) Section 6.10.10.4.1 applies a load resistance factor of 0.85 to the value of a shear connector in composite steel design, while the AISC Section I5.3 (2nd edition, my 13th edition is at work) on page 6-214 says specifically that no factor is applied to shear connectors because the resistance factor associated with flexural strength "accounts for all sources of variability"?

Is AASHTO being overly conservative?

 

[civilperson]

AASHTO worries about fatigue.