Most of the analysis parameters are entered via the Main Dialog box window. The user can see all of the required entries for each analysis type.
Figure 1: Main Dialog (with About Window)
The analysis type can be determined by making a number of major selections:
- Problem Type: User makes selection on the type of analysis problem:
- Single Analysis vs. Spectral Analysis
- General Properties:
- Mass [Kip.sec2/in]
- Damping [% of critical]
- P- D ratio, which is a positive number (between 0 and 1) defined as (P/L)/ K, where K is the gross stiffness of the system.
This represents the stiffness reduction due to P-D.
- Model Type: The nonlinear model to be used. Options are:
- Bilinear model
- Stiffness-degrading model
- Bilinear model with bidirectional interaction
- Nonlinear Properties:
- Model Type: Bilinear vs. Stiffness Degrading
- K2/K1 ratio, where K1 and K2 are the gross stiffnesses in directions 1 and 2 respectively
- Y2/Y1 ratio, where Y stands for Yield Strength (positive or negative)
- Yneg/Ypos ratio, where Yneg and Ypos are the positive and negative yield strengths respectively
- Model Properties: The user can specify the model properties individually for the two directions
- Stiffness K, the gross stiffness [Kips/in]
- Positive Yield Ypos [Kips]
- Negative Yield Yneg [Kips]
- Positive hardening ratio (Khpos/K), where Khpos is the hardening stiffness in the positive direction
- Negative hardening ratio (Khneg/K), where Khneg is the hardening stiffness in the negative direction
- Period/Frequency range for spectral analysis. The user specifies:
- The first value in the range
- The last value in the range
- The total number of values in the range
- Type of value: Period vs. Frequency
- How the intermediate values are obtained: Linear vs. Logarithmic generation
- Target Strength/Ductility range for nonlinear spectral analysis. The user specifies:
- The first value in the range
- The last value in the range
- The total number of values in the range
- Type of value: Absolute Strength [Kips], Normalized Strength, Constant R (Elastic Force/Yield Force) or Ductility m.
The normalized strength is eta = h = Absolute Strength / (Mass x PGA)
- How the intermediate values are obtained: Linear vs. Logarithmic generation
This dialog also has a few buttons that are:
