Unlike most other analysis options derived results from a response spectrum analysis cannot be derived from the basic response spectrum results. Instead the derived modal results must be calculated and then these combined.
A pseudo response spectrum analysis is based on mode shapes arrived at by static analysis. In order to combine these for a response spectrum analysis the modal information must be supplied.
Two possible methods of performing a the GSBridge Analysis are available, as described in the Step-by-Step Guide, and the Dialog deals with these differently:
Buckling is an eigenanalysis to find the load factors and modes of buckling.
This page confirms that all the data required for the analysis is present.
The use of analysis envelopes is described in the Step-by-Step Guide.
This page defines the analysis parameters. If no modal dynamic analysis results are present, this option is disabled and this page cannot be opened.
Definition
This page defines the analysis parameters and the output requirements. If no modal dynamic analysis results are present, this option is disabled and this page cannot be opened. The load is assumed to vary as
This page defines the analysis parameters for linear time history analysis. If no modal dynamic analysis results are present, this option is disabled and this page cannot be opened.
A mass analysis calculates the mass and mass distribution in the structure.
This information is required when the “Individual component buckling” option has been selected.
For both a modal dynamic and modal dynamic p-delta analysis the user is brought to this page.
Nonlinear static analysis uses dynamic relaxation to allow for nonlinear effects and large displacements.
This page defines the analysis parameters for periodic load analysis. If no modal dynamic analysis results are present, this option is disabled and this page cannot be opened.
The progress of an analysis can be viewed in a progress report and Graphic view that are opened at the start of the analysis. The Graphic view shows the deflection of the model as the analysis progresses.
This option is required when 'automatic load increment analysis' has been selected. The limits set here control the automatic load increment option and can be used to define the 'capacity' of the model.
The basic response cases are set up in the data. This page confirms which output is required. If no modal results are present the user is warned: “There are no modal results present. This analysis will terminate”.
A Ritz analysis is similar to a modal analysis but is specified in terms of Ritz vectors.
The soil-structure analysis is a static analysis of a single analysis case including soil structure interaction.
Definition
All analysis options are controlled from the analysis wizard and depend on the selected solver option.
This is where the loading associated with the analysis case is specified. In the simplest case each analysis case will have a single, unfactored load case (e.g. case A1, description L1). For a P-delta or other nonlinear analysis results should not be combined post analysis so the factored and combined loads must be specified for the analysis case (e.g. case A1, description 1.4L1+1.6L2 or 1.5A3 or1.6C1).
Definition
With the exception of simple linear static analysis, the Analysis Wizard is used to set up the data required for an analysis – both the task and case information. The wizard hides the complexity of the inter-relationship between these from the user.