# Getting started
GSA is a program for structural analysis, and it is assumed the user has a knowledge of structural engineering concepts. The GSA help is aimed at explaining the features and use of the program but not the structural concepts expressed in the program. A new user to GSA should refer to the Getting started (opens new window) manual which gives a worked example on the use of GSA.
# Design & analysis layers
An engineer normally thinks of a structure in terms or beams and columns, and slabs and walls. These are represented in GSA as members which form the structural model and live in the Design layer. These are a convenient way to describe the basic structure. The members may or may not be connected, so normally there will be a discrete connection between beams and columns, but there may be an implied connection where a secondary connects to a primary beam part-way along its length. In order to analyse the model the 1D members need to be properly connected and 2D members need to be meshed with finite elements. GSA provides a tool to handle this mapping and create an analysis model on the Analysis layer.
It is encouraged to use the Design layer to define the structure as this makes it easier to adjust the analysis model, but there is nothing that prevents the engineer from building the model directly in the Analysis layer.
# Data modules
Data in GSA is held in modules that can (in most cases) be thought of as tables. So, for example, a simple model may have a nodes module, an elements module, a beam sections module and some load modules. The data for these tables can be entered directly via Table views. However it is usually better to use some more convenient (and less error prone) methods of entering data.
This section is concerned with the construction of the geometrical model (nodes, elements and properties) and does not consider the loading.
There is no one correct way of building a model. The most appropriate method will depend on the shape and complexity of the model. Familiarity with other programs, such as spreadsheets and CAD packages will affect the approach, as will the availability of the geometric data in other formats.
# Data generation
The simplest way of constructing a model is to use the Data generation wizard. Templates are offered for typical structural forms. The structure is specified by selecting a template and defining a few key parameters.
Since this method is so quick and easy it is sometimes useful to generate from a template even if it is known that the resulting geometry will have to be edited to arrive at the desired geometry.
# Sculpting models
Sculpting is the term used for graphical editing of the model via a Graphic view. The clear visual feedback makes this method popular for all shapes, sizes and complexities of structure.
The mesh generation option in GSA makes sculpting a powerful tool for the meshing of irregular areas with 2D elements.
Sculpting is covered in more detail in the 'Working with the program' section under Working with graphic views.
# Spreadsheets & CAD
For some structures there is a regularity which lends itself to definitions of the structure in a spreadsheet. In other cases the structure can be defined in terms of a number of parameters that are subject to change, so spreadsheets give the flexibility to quickly generate variations on complex models. Data that is generated in a spreadsheet can either be read as a text file, or included directly in tables using cut and paste.
Structural models that exist in CAD packages may be transferred to GSA via the DXF and DWG file formats (provided the information can be saved as a DXF file in the CAD package). This is useful both when the geometric form has been defined by others and supplied in a CAD format and when it is felt that CAD is the most appropriate tool for defining the geometry.
Models assembled in BIM packages can be imported into GSA either via an Industry Foundation Classes (IFC) file or from the GSA/Revit link.