The ULS Design Spreadsheet has now been updated to Version 2.16, which can be downloaded from:
The main new feature is the option to design for prestress loads applied to circular tanks. Due to axi-symmetric effects, when circumferential prestress is applied to a circular tank structure this generates a uniform axial stress across the cross section, in spite of the eccentric position of the prestress cables. This is handled by applying a virtual reaction moment, equal and opposite to the moment due to the eccentricity of the prestress. Use of this feature is illustrated in the screenshots below (click any image for full-size view):
If the “Adjust for circular tank loading” is set to “False”, or left blank, the section capacity is calculated in the usual way, allowing for the eccentricity of the prestress force:
If the option is set to True, the virtual moment is applied to the section, reducing the section capacity:
The correction for the circular tank effect is shown in the function output:
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