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jerbaroo / bridge-sim

Python library for concrete slab bridge simulation.
MIT License
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Unequal node spacing at bottom of pier #189

Closed jerbaroo closed 4 years ago

jerbaroo commented 4 years ago

While working on a PR with the msl parameters set to 10 (very very coarse mesh) the following issue was raised:


bottom_node_coords
array([[ 43.725   ,  -3.5     , -13.5     ],
       [ 43.725   ,  -3.5     , -12.771849],
       [ 43.725   ,  -3.5     , -12.771358],
       [ 43.725   ,  -3.5     , -12.67365 ],
       [ 43.725   ,  -3.5     , -12.673159],
       [ 43.725   ,  -3.5     , -11.7     ]])
jerbaroo commented 4 years ago

This is because of where the material properties change.

Consider one wall of pier 0. The Z positions of nodes at the top of the wall are -14.433, -12.95, -12.949, -12.75, -12.749, -10.767. To determine the position of nodes at the bottom of the pier, an interpolant is calculated to determine Z positions in the range [-13.5, -11.7] from the original range [-14.433, -10.767].

You will notice that some Z positions at the top of the wall are fairly close together. These positions are calculated with the following algorithm: First some required Z positions 'RZ' are determined, positions of loads and abutments etc.. After that a number of Z positions are calculated between each pair of adjacent Z positions 'RZ_i' and 'RZ_j', such that the maximum distance between Z positions does not exceed 'bridge.base_mesh_deck_max_z'. (In this case there are no additional positions added because the bridge mesh is so coarse)

More specifically each of the positions are from...