Centrifugal Loading Using AASHTO

Question:

I am following up on the email below.

Has the vertical effect on wheel loads due to centrifugal loading been implemented for AASHTO live loading in recent versions of Midas? If so, are there are tutorials or documentation on how to implement this loading?

Thanks,


Answer:
Hi,

New feature about centrifugal loads has been implemented in Civil 2018 (v2.1) as shown below.


Using this feature, the vertical effect on wheel loads due to centrifugal loading can be taken into account for particular elements selected by the user.

Here is the procedure. For example, the maximum positive moment of the j-end of element no. 444 is 1749.1 k-ft and we want to find the corresponding centrifugal loads.
Step 1. Perform moving load analysis. Maximum positive moment due to live load = 1749.1 k-ft.

Step 2. Go to Moving Load Tracer and find the vehicle position which gives maximum positive moment for the element no. 444.



Step 3. Hit the 'Write Min/Max Load to File' button and check on the 'Centrifugal Forces' option in the dialog below. Click OK.


The MCT file will be generated.


Step 4. Copy and paste the text in the MCT file into MCT Command Shell. Click Run.


Vertical live load and corresponding centrifugal load will be generated as a static load.



The generated centrifugal loads are applied to the pavement level as shown below. We need to move the loads to the upper direction by 6 ft.



Step 5. Go to the 'Element Beam Load' table and assign 6 ft of eccentricity to the centrifugal load cases. Note that this step will be done by the program in the next release.



Centrifugal loads are applied to the beam elements with the eccentricity of 6 ft in the global Z axis.



Step 6. Check the moment at the j-end of element 444 due to centrifugal loads. It is 185.6 k-pf.



I hope this may be helpful for your work.

Regards,
DK Lee
Creation date: 6/27/2018 12:19 PM (dklee@midasit.com)      Updated: 6/27/2018 9:54 PM (dklee@midasit.com)
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Ramp-E_Spans_6&7_Proposed Condition.mcb