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Rigid Diaphragms

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Rigid diaphragms may be used instead of plate finite elements to model stiff in-plane actions such as concrete floors.  Internally, the program creates multiple in-plane rigid links for each diaphragm prior to static or frequency analysis.  A rigid link is simply a member with very large sectional properties that can be adjusted with the diaphragm stiffness factor (see Settings > Data Options).  The larger the diaphragm stiffness factor, the stronger the in-plane rigid diaphragm action is.  The presence of rigid links with large diaphragm stiffness factor (say 1E10) could create numerical difficulties during the solution if the 64-bit floating point solver is used.  However, the unique 128-bit floating point solver in ENERCALC 3D makes this problem nonexistent in that much larger diaphragm stiffness factor (say 1E20) may be used without creating numerical difficulties during the solution.

 

The program further provides the option to ignore the rigid diaphragm actions as an analysis option (Analysis > Analysis Options).

 

It is important to point out that rigid diaphragm action in the program does not use Equal Displacement Constraints.  

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