Inputs in this page are basically required for wind load and seismic load calculation according to ASCE 7-05. There are three ways to enter/calculate time period:
- Direct Input
- Mass Table
- Program Calculated
| Setting | Description |
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| Time Period Calculation |
Select the method you want to use for determining the time period.
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| Setting | Description |
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< Previous
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Steps the Wizard to the previous step.
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Next >
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Proceeds the Wizard to the next step.
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Cancel
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Exits the Wizard without creating a new Vertical Vessel Footing job.
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Direct Input
| Setting | Description |
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Fundamental Period (T)
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Specify the fundamental time period of the vessel.
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Mass Table
The time period is calculated using Von Mises Theorem equation:
Where:
- H = Overall height in feet,
- D = Diameter of each section in feet,
- w = Distributed weight per foot of each section,
- W = Weight of each concentrated mass,
- t = Shell thickness of each section in inches,
- E = Modulus of elasticity for each section in millions of psi,
- a,b and g = Are coefficient for a given level depending on hi/H(the ratio of height of the level above grade to the overall height). Da and Dg are the difference in the values of a and g,from the top to the bottom of each section of uniform weight, diameter and thickness. b is determined for each concentrated mass.
| Setting | Description |
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| Units |
Specify the values of Length, Force/Length, and Force used in both tables on this page to describe the mass of the vessel. |
| Distributed Mass table |
This table is used to describe how the mass is distributed over one or more vertical sections of the vessel. | Setting | Description |
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| Mass/Length |
Specify a mass per unit of vertical height for this section of mass. |
| Height (Top / Bot) |
Specify the top and bottom heights, respectively, above base of this section of mass. |
| Diameter |
The diameter of the vertical vessel for this section. |
| Thickness |
The wall thickness of the vessel for this section. |
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| Concentrated Mass table |
This table is used to specify point masses in the vessel, such as ladders, platforms, etc.. | Setting | Description |
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| Mass |
Specify the amount of lumped mass. |
| Height |
The height above base where the lumped mass is centered. |
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Calculate Time Period
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The program calculates the Fundamental Period and enters this value for the Fundamental Period (T) (non-editable). |
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Program Calculated
Fundamental Period is calculated by using formula as described below,
Where:
- w = Weight of the structure, kips
- L = Length of the structure, inch
- E = Modulus of Elasticity, ksi
- I = Moment of Inertia, in4
- g = Gravitational acceleration
| Setting | Description |
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Long-Period Transition Period
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Long-period transition period (TL), in seconds, determined in ASCE Section 11.4.5 |
