Another thought:
Suspect 30 105 30 span arrangement is causing the negative moments over the interior supports to approach that of a fix end moment condition. You can study this behavior by increasing the first and last span and notice the moments at the interior support will decrease.
A...
Some thoughts:
Studies found the effects of the exclusion vehicles under estimated negative moments by by up to 80%. {AASHTO fig.C3.6.1.2.1-1.
The effect of two trucks for negative moments may be reduced by 90%. [AASHTO 3.6.1.3.1].
The 50 feet spacing refered to is a minimum, and a greater...