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TR.22.3 Element Ignore Stiffness

Structural units like glass panels or corrugated sheet roofs are subjected to loads like wind pressures or snow loads. While these units are designed to carry those loads and transmit those loads to the rest of the structure, they are not designed to provide any additional stiffness to the structure. One way to handle the situation is to not input the unit as part of the structural model, and apply the load using load generation techniques like AREA LOAD or FLOOR LOAD.

STAAD provides another way of handling such units. This is through the help of the ELEMENT IGNORE STIFFNESS command. To use this feature, the glass panel or roof unit must be defined using plate elements. The IGNORE STIFFNESS command enables one to consider the unit just for the purpose of application of ELEMENT LOAD commands, while its stiffness will not be considered during the assembly of the stiffness matrix. In other words, it is like an INACTIVE member which is active for ELEMENT LOAD command application but INACTIVE for stiffness. Like the INACTIVE command, the plates listed here will become active at the next CHANGE command. To keep them inactive, re-enter this data after each CHANGE.

The SELFWEIGHT, ELEMENT WEIGHT, TEMPERATURE, and mass of the plates listed here will still be ignored.

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