Archie_M_notes

SV loads, a little more

The SV vehicles are very wide and have widely spaced wheels on the axle. This means that, with shallow fill depth, the action of the two wheels do not overlap. The distribution within Archie was built on the assumption (reasonable for all other loads) that the distributions do overlap. The distribution width is worked out as Axle track +1.5m + depth from wheel to extrados.

There is a further complication in this because the rules in BD21 sa that the load can be treated as a UDL across the full width once the loads are combined. Load transfer due to centrifugal action is thus cancelled. If that assumption is invalid, the effect must be taken into account. As with railway loading, the simplest way to deal with this is to treat wheel loads rather than axle loads. I will therefore build a set of SV load files based on wheels instead of axles, but users must then be sure to restrict the "bridge width" used appropriately for half a vehicle.

SV Loads

It has been pointed out to me that the rules for SVloads are different from HB loads and therefore the load files need modifying.

New files can be downloaded here, but please note that they are only valid (for the time being) if there is enough fill at the critical poisition to ensure that the two wheels on an axle act together. That means 1.15m of fill at about 1/4 span. If this isn't the case it may be necessary to use a resticted bridge width to make sure the load is sufficient.