I am using a floating lane layout on a simple span 5 steel girder bridge.
Once I run the analysis I want to verify that all Roadways are being considered.
I am using the "Lane Load Details" window to check this. However, when selecting the "Mz positive" Influence Surface Group, it shows that Roadway 1 is the worst Roadway for all of my girders. I am finding this confusing as I was expecting different roadways to cause the maximum moments in different beams. Namely, how are both exterior girders seeing the maximum moment from the same Roadway: Roadway 1 which is a truck shifted all the way to one side of the bridge (as seen in the images below)?
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In the FLoat Option, as in the Mirror Option, the maximum number of 12 foot lanes is computed from the travelway width (referred to as the roadway. At the user's selection the process starts from the left edge of deck or right edge of deck. The initial lane (roadway) position aligns the left edge of the rightmost lane with the left edge of deck as shown below.
Live load analysis is performed at this lane (roadway) position. The lanes are moved to the right, or Floated according to the max lateral step value entered by the user. Live load analysis is again performed for this position and repeats in a similar manner for each subsequent carriageway position until the right edge of the leftmost lane aligns with the right edge of the deck as shown below.
The maximum results considering all roadway positions are computed and reported in the respective live load reports and diagrams.
In the mirror option there are two options for defining the live load vehicle path in each lane. The Center of lane options positions the vehicle in the center of each lane for live load analysis. The Left, center and right within lane option positions the vehicle successively in the left of lane, center of lane and right of lane as shown above in the Live Load distribution figure.
Please check the LBS help option which gives detailed explanation related to Lane Setup Dialog,
For more information related to lane load details in LBS program please check the wiki articles in the below mentioned Bentley Communities link.
https://communities.bentley.com/products/bridge_design___engineering/w/bridge_design_and_engineering__wiki/52121/lane-load-details-location-of-vehicle-and-udl
Please let me know if this is the information you are looking for.
Please let me know if you need any additional information.
Vinay,
I have my floating lanes setup using the steps you outlined above, thanks for confirming that.
So, my question remains regarding the Lane Load Details Window. It displays that Roadway 1 is the worst Roadway for moment for both of my exterior girders. This should not be possible. Why is this?