When you have finished setting up your structure and its restraints and loading, you use the Analyse menu to carry out structural analysis on the structure. A progress bar will be displayed while the analysis is in progress.

Multiframe will check the structure prior to analysis and alert you if there are any problems.  For example: You must have specified the section type for all of the members.  If you have missed any members, Multiframe will alert you with a dialog and will select all of the undefined members in the Frame window.  You will also be alerted if there are any mechanisms or there are unrestrained degrees of freedom.  In each case the offending part of the structure will be selected in the Frame window.

Different analysis types are available dependent on the version you are using. This is summarised in the table below. Click on the links on the left for more information about the specific analysis type.

Also see:

Viewing Results on page 115.

Chapter 4 Multiframe Analysis on page 193 for information on the calculation methods used in Multiframe and sign conventions etcetera.

The solver will automatically switch from double precision to single precision arithmetic if there is not enough memory.  Single precision arithmetic is less precise than double (it has about 7 digits of precision as opposed to 15 digits for double), but has the advantage of requiring less storage space for the stiffness matrix.  This allows you to solve larger problems or have more load cases for the same amount of memory.  The only problem that can arise from the use of single precision arithmetic, is that if the stiffness matrix is badly conditioned, round-off errors may accumulate during analysis and may make results less accurate.  Multiframe will warn you if it switches to single precision and give you the option of analysing using single precision or cancelling the analysis.

The solver includes error checking routines to detect problems with the structure.  If you have drawn any members that are not connected to the rest of the structure, Multiframe will alert you to this fact.  The section properties of all the sections will also be checked to ensure that they are non-zero where appropriate.

The Reporting group at the bottom of the Analysis dialog contains three buttons for selecting the level of reporting to be output to the Report Window during an analysis.  Reporting is only used for a nonlinear analysis for which convergence and iteration data are output to the Report Window in addition to any warnings and error messages in relation to the analysis.  The Full report also includes the displacement and force norms at the end of each iteration.

A progress indicator is displayed while analysis is in progress.  To cancel analysis

§     Hit the escape key, or

§    Press cancel in the progress dialog

The cursor will change to a watch and analysis will be terminated.

You can switch from Multiframe to another program while analysis is in progress.