Frequent Asked Questions
Most frequent questions and answers
PolyStringer is an inevitable tool for design of concrete diaphragms with hollow-core slabs.
- Insert geometry, loads and reactions
Insert Geometry and loads in the governing load combinations. Reactions can either be defined manually, if they are determined elsewhere, which often would be the case for rigid diaphragms. Otherwise the reactions can be determined directly in PolyStringer, this leads to a solution suited for more flexible diaphragms.
- Check shear fields
Check to see if the shear forces exceed the capacity of the diaphragm, which is often 20-25kN/m for hollow-core slabs. If this is the case insert an upper limit for the shear forces, PolyStringer will then try to redistribute the forces, learn more in “How to Smoothen out shear forces?”.
- Determine stringer reinforcement
Click the button “Auto Reinforce” to let PolyStringer insert the necessary stringer reinforcement. Afterwards the amounts and sizes can be adjusted.
- Go to “Modelling”
- Select the stringer
- Choose “Stringers” and then “Compression only”
This is done by inserting “Shear Field Limits”.
- Go to “Reactions and Shear Forces”
- Select the shear fields, where you want to limit the shear force
- Add the shear fields to a new shear field limit group
- Enter the shear force limit for the group
- Press “Calculate”
PolyStringer then try to redistribute the internal forces to satisfy the new limits.
You have the option to see both the initial- and the modified results. Only the modified results are used for further calculations.
In cases with large size differences in the model, the scaling function can be used to give a better overview of the whole model. This is done by moving the “Scale” slider, which is found above the “Calculate” button.
Unscaled stringer model
Scaled stringer model
In “Export Settings” it is possible to change the resolution of the stringer model images which are used for the pdf. This is done by changing the values for “image size (W x H)”. Larger values lead to a higher resolution of the pdf export. It is also possible to change the ratio between width x height and thereby get a pdf with less whitespace. This is done by adjusting the values to correspond better with the stringer model size.
Image size 1000 x 500px
Image size 1600 x 800px