How can I define Moving Load Optimization for my bridge?

The bridge has 2 girders spaced 30ft apart with floor beams running from girder to girder. The bridge is on a 21-degree skew. The travel way is 26’-0” wide and is centred between the girders. I would like to use the “traffic lane optimization” commands to find the maximum moment & shear on the girders and on the floor beams.

However, I am not able to find the definitions of certain parameters in the help manual. For example, I am confused about the “Anal. Lane Offset” and “Margin” parameters. Can you please tell me what I need to enter into each of the “Traffic Lane Optimization Properties”?

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Answer:

About the moving load optimization, kindly refer to the image below. That would clarify what each option stands for.


So, for the vehicle positions and carriageway as posted by you, the following should be the input:
Optimization Lane: 26'
Lane Width: 12'
Anal. Lane Offset: 2'
Wheel Spacing: 6'
Margin: 0'
Offset distance to lane centre: The input here is the eccentricity of the centre of the carriageway from the reference element in accordance with which the lane is defined.