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[Civil] A Singular Error Occurs in the Plate Element

Question

A Singular Error occurs in the plate element.

 

Answer-1

Connect the plate element with a Rigid Link.

Plate elements have 5 degrees of freedom (DOF) excluding the Rz rotation, while beam elements have 6 DOF (Dx, Dy, Dz, Rx, Ry, Rz). When different elements are connected, you need to be aware of the mismatch in degrees of freedom.

If a torsional load is applied to the beam element connected vertically to the plate element, the plate element cannot resist the z-axis rotation, causing the beam element to rotate freely. This condition can lead to a Singular Error.

To transmit the torsional load to the beam element, you should connect a Rigid Link as shown in the diagram below. The Rigid Link transforms the torsion into an in-plane load.

The area where you connect the Rigid Link should extend to the region where displacements are restrained in the actual structure. For example, you can use the area of a column section, foundation footing area, or support area.

 

Answer-2

When creating plate elements, check the "with Drilling DOF" option.

By default, plate elements do not have the torsional (drilling) degree of freedom. However, in midas Civil, plate elements with all 6 degrees of freedom are available. When creating plate elements, there is an option called "with Drilling DOF," which allows you to consider all 6 degrees of freedom.

This option is called " Select whether to consider normal directions of freedom", and when checked, it creates a plate element with all six degrees of freedom.

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