Load Case Data Form

Before defining load cases, define any load patterns or functions that will be needed; see the Define Load Patterns topic for more information. Click the Analysis > {Type} > New command to display the Load Case Data form for the type of load case selected.

• Load Case Name. Accept the default or enter a name for the load case being defined. It should be unique among all load cases of all types.

• Set Def Name button. Click the Set Def Name button to allow the program to automatically create a name based on the load type.

• Notes - Modify/Show button. Click this button to access the Load Case Notes form. Use that form to add Load Case Notes to the model file.

• Design button. Click this button to access the Design Load Type form. Choose Program Determined, or User Specified and then a design type from the drop-down list. Design load types are used in creating automatic design load combinations.

• Show Load Case Tree button. Click this button to access the Load Case Tree form. The form lists the various load cases that have been defined for the model.

• Load Case Type drop-down list. CSiBridge accommodates many types of load cases. Most broadly, analyses are classified as linear or nonlinear, depending on how the structure responds to the loading. Select the primary loads case type, then select the available analysis types (e.g., Linear or Nonlinear). These options will be different for different load case types.

The remaining data on the form depends on the chosen type of load case.

Click on the appropriate link for the type of load you are defining:

• Static:

• Linear. The most common type of analysis. Loads are applied without dynamic effects.

• Nonlinear. Loads are applied without dynamic effects. May be used for cable analysis, pushover analysis, and other types of nonlinear problems.

• Nonlinear Staged Construction. The definition of a nonlinear direct-integration time-history load case for staged construction.

• Multi-Step Static. Linear static analysis for multi-stepped load cases, such as moving loads and wave loads. A separate output step is produced for each step of the given loads.

• Modal. Calculation of dynamic modes of the structure using the Eigenvector or Ritz-vector method. Loads are not actually applied, although they can be used to generate Ritz vectors.

• Response Spectrum. Statistical calculation of the response caused by acceleration loads. Requires response-spectrum functions.

• Time History:

• Time History.  Time-varying loads are applied. Requires time-history functions. The solution may be by modal superposition or direct integration methods.

• Linear Modal

• Linear Direct Integration

• Nonlinear Time History.  Time-varying loads are applied. Requires time-history functions. The solution may be by modal superposition or direct integration methods.

• Nonlinear Modal

• Nonlinear Direct Integration

• Moving Load. Calculation of the most severe response resulting from vehicle live loads moving along lanes on the structure. Uses defined vehicle loads and defined lanes rather than the load patterns that are used by other analysis types.

• Buckling. Calculation of buckling modes under the application of loads.

• Steady State. A steady-state load case solves for the response of the structure due to cyclic (harmonic, sinusoidal) loading at one or more frequencies of interest.

• Power Spectral Density. A power spectral density load case solves for the response of the structure resulting from cyclic (harmonic, sinusoidal) loading over a range of frequencies, and then integrates the resulting spectrum weighted by a probabilistic power-spectral-density function to get a root-mean-square (RMS) expected response.

• Hyperstatic. A hyperstatic load case calculates the linear response of the structure with all supports removed and loaded only by the reactions from another linear static load case. This is typically used to calculate the secondary forces under prestress loading.