4.13 Meshing problems Three examples are given:
1. A circular slab. 2. Rectangular slab with small indentations (architectural features). 3. Rectangular slab resting on a rectangular column.
Here are possible solutions to the three slabs:
1. What if we want a node in the centre of the slab (in this example, the maximum deflection will be in the centre)? Without modifying the mesh size, we can force Sumo to place a node there by using Constraint Lines. 2. Small architectural features will complicate the mesh and inevitably introduce triangular shell elements. We can modify the mesh size (e.g. 0.2m) but this may be costly in terms of time and computing power if the slab forms part of a larger structure. Furthermore, a 100mm indentation in the slab’s edge won’t affect the analysis considering that the slab’s thickness is 300mm. We can have a more accurate analysis with a mesh with better quality if we remove the indentations. 3. There are several ways to improve on the quality of the mesh. Here are three options: i) We can always decrease the mesh size. ii) Use Constraint Lines to force the mesh around the column’s footprint. iii) Most importantly, we should always improve on the quality of the modelling. Although this example looks nice in a 3D view, the analytical model is what’s important for analysis. It would be wise to simply move the column’s analytical li ne to the edge of the slab to simplify the mesh. 4.14 Monolithic beam results Interpreting monolithic beam results. For a detailed discussion, download the following document on our website: Monolithic Beam White Paper. 4.15 Convergence of shear in shells Compare the shear force results in a slab with varying mesh sizes to results in a beam. Shear force is usually the last component in the convergence chain. That means that a finer mesh will produce more accurate results. 5. Modelling exercise The final part of this course will offer students the opportunity to apply the skills learned throughout this course by building a Sumo model from 2D drawings.
The attached drawings contain all the information needed to create the model. You need to run a successful linear analysis and see if your results correlate to those of your classmates and colleagues.
Sumo Workshop Training Manual
Page 4
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