Tension and curvature capacity check

1. Purpose

Perform a capacity check for a combination of curvature and tension.

2. Description

The capacity is calculated using a simple utilization equation, ISO12628-5:2009 , Helica.

3. Required results

To estimate the capacity, the element forces and curvature need to be stored from the simulation.
These time series will be used to calculate environmental loads.

4. Description of input parameters

The following user input is required.

4.1. Input for capacity check

  • Type of check (Tension and curvature/Tension/Curvature)

  • Load factors for tension and curvature, \(\gamma_{t,f}\) and \(\gamma_{c,f}\) (read only, may be overridden)

  • Material factors for tension and curvature, \(\gamma_{t,m}\) and \(\gamma_{c,m}\)(read only, may be overridden)

The number of factors are dependent on the type of check.
The tension capacity and maximum curvature, \(R_{t,k}\) and \(R_{c,k}\), are inputs on the cross section.

4.1.1. Statistics

The response extreme value are estimated using either

  • observed maximum

  • use distribution fitting for a given return period

4.1.2. Analysis Time Window

The time window can be set using

  • start time

  • end time

4.1.3. Output

Option to add intermediate results.

The intermediate results are stored together with the element results.

5. Calculation of capacity

5.1. Tension and curvature

The capacity can be expressed by the utilization factor, \(u\):

\[u = \frac{S_{t,d}\cdot\gamma_{t,f}}{\frac{R_{t,k}}{\gamma_{t,m}}} +\frac{S_{c,d}\cdot\gamma_{c,f}}{\frac{R_{c,k}}{\gamma_{c,m}}} \text{ where } u < 1\]

  • \(S_{t,d}\), is the characteristic environmental tension

  • \(S_{c,d}\), is the characteristic environmental curvature

The default values for the load and material factors are all set to 1.0. The equation is then given as

\[u = \frac{S_{t,d}}{R_{t,k}} +\frac{S_{c,d}}{R_{c,k}}\]

5.2. Tension

The capacity can be expressed by the utilization factor, \(u\):

\[u = \frac{S_{t,d}\cdot\gamma_{t,f}}{\frac{R_{t,k}}{\gamma_{t,m}}} \text{ where } u < 1\]

  • \(S_{t,d}\), is the characteristic environmental tension

5.3. Curvature

The capacity can be expressed by the utilization factor, \(u\):

\[u = \frac{S_{c,d}\cdot\gamma_{c,f}}{\frac{R_{c,k}}{\gamma_{c,m}}} \text{ where } u < 1\]

  • \(S_{c,d}\), is the characteristic environmental curvature