Area Of Wheel Load On Plate

Question:

Dear Sir/Madam,

When applying wheel load on plate elements, is the load:

(1) Applied as a concentrated load at the middle of the plate element regardless of the actual wheel position in relation to the defined traffic lane?
(2) Applied as a concentrated load at a point on the plate element depending on the actual wheel position in relation to the defined traffic lane?
(3) Applied as an uniform area load over the area of the plate element?
(4) Applied as an uniform area load over the area of 300 mm X 300 mm of the plate element?
(5) Applied otherwise than the above?

In item (4) above, can I change the wheel load area of 300 mm X 300 mm? What happen if the wheel load area is larger than the plate element?

In Midas, how can I consider the dispersal of wheel load in the vertical direction as allowed in, for example, 6.2.6 and 6.3.3 of Appendix A, BD 37/01?

Thanks,



Answer:

Hello,

The wheel load is transferred to nearby nodes in proportion to the distance of the load from the nodes and it applied as concentrated load there.  This can be checked quite easily by using the moving load tracer.  Just write the load to file and add this file as static load case to model using MCT command shell.  Kindly note that the model would have to be re-analysed after doing that.
Generally the dispersion is not considered for plate modelling.  If it is required, then the loads would have to be applied manually.
Kindly let us know if further assistance would be required.

Regards,
Nandeep
Technical Manager, MIDAS


Nandeep,

Let's say there is a quadrilateral plate element of the size 350 mm X 350 mm positioned with its centre located 600 mm perpendicularly from and one of its edge parallel to the centre line of the traffic lane. If the wheel spacing is 1000 mm with 4 wheels per axle, a wheel load will be at 100 mm away from the plate centre (measured in the direction perpendicular to the centre line of the traffic lane).

When applying the wheel load on the plate element, is the load:

(1) Applied as a concentrated load at the middle of the plate element regardless of the actual wheel position in relation to the defined traffic lane?
(2) Applied as a concentrated load at a point on the plate element depending on the actual wheel position in relation to the defined traffic lane?
(3) Applied as an uniform area load over the area (350 mm X 350 mm) of the plate element?
(4) Applied as an uniform area load over the area of 300 mm X 300 mm of the plate element?
(5) Applied otherwise than the above?

In item (4) above, can I change the wheel load area of 300 mm X 300 mm? What happen if the wheel load area is larger than the plate element?

Thanks,




Hello,

I couldn't quite understand the dimensions provided.  
However, I'll begin by saying that we can't control the wheel area.  The load is considered as nodal load.  Kindly refer the image below for better understanding.  For simplification, I've considered a square plate mesh structure.
In the image above, W/2 is the wheel load located on any plate.  a, b, c, d, e, f and L are distances.  The wheel load is simply distributed following simple engineering mechanics formulation.  The 'X' mark shows the final load which is applied on the plate nodes representing the two wheel loads.
I hope the method is clear.  Kindly let us know if further assistance would be required.

Regards,
Nandeep
Technical Manager, MIDAS
Creation date: 10/17/2018 9:42 PM (dklee@midasit.com)      Updated: 10/18/2018 7:12 AM (dklee@midasit.com)
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