Assuming you want to model the roof as a flexible or semi-rigid diaphragm (able to resist and transmit in-plane loads by deforming and unable to resist out-of-plane loads), you can use a meshed plate with different membrane, bending and shear thicknesses. To do this: -Create a plate, where you want the roof diaphragm. -While editing the plate, expand the advanced options and set the membrane thickness to 1 1/2" -The bending and shear thicknesses to a much smaller value, say 10% of the membrane thickness, e.g. 1/8". -Before analysis, make sure to mesh the plate. This will give you a plate which is stiff in-plane, but has only notional stiffness out-of-plane. The notional out-of-plane stiffness comes from the bending and shear thicknesses, which are required only to stabilize the nodes in the meshed plate for out-of-plane deformations and rotations. You might need to experiment with the values of these thicknesses to (i) get a stable model & (ii) minimize the out-of-plane deformations.
Appreciate the video explanation of rigid diaphragm option for plate members. Will try using this to simplify plywood skins used as shear panels. Would be interested in any thoughts regarding steel roof decks and "semi-rigid diaphragms as mentioned in the comment below. Thank-you.
Seems unfortunate that rigid diaphragms can not share a common node. Tried creating two rigid diaphragms at 90-deg to each other simulating the way two plywood shear panels might meet at a corner. S3D lets me create the two rigid diaphragms but throws error messages when I try to solve.... dang. Perhaps I am not using the feature properly.
Assuming you want to model the roof as a flexible or semi-rigid diaphragm (able to resist and transmit in-plane loads by deforming and unable to resist out-of-plane loads), you can use a meshed plate with different membrane, bending and shear thicknesses. To do this: -Create a plate, where you want the roof diaphragm. -While editing the plate, expand the advanced options and set the membrane thickness to 1 1/2" -The bending and shear thicknesses to a much smaller value, say 10% of the membrane thickness, e.g. 1/8". -Before analysis, make sure to mesh the plate. This will give you a plate which is stiff in-plane, but has only notional stiffness out-of-plane. The notional out-of-plane stiffness comes from the bending and shear thicknesses, which are required only to stabilize the nodes in the meshed plate for out-of-plane deformations and rotations. You might need to experiment with the values of these thicknesses to (i) get a stable model & (ii) minimize the out-of-plane deformations.
Hi! Will it also be possible to specify a semi-rigid diaphragm, like in the case of a steel deck at roof?
Assuming you want to model the roof as a flexible or semi-rigid diaphragm (able to resist and transmit in-plane loads by deforming and unable to resist out-of-plane loads), you can use a meshed plate with different membrane, bending and shear thicknesses.
To do this:
-Create a plate, where you want the roof diaphragm.
-While editing the plate, expand the advanced options and set the membrane thickness to 1 1/2"
-The bending and shear thicknesses to a much smaller value, say 10% of the membrane thickness, e.g. 1/8".
-Before analysis, make sure to mesh the plate.
This will give you a plate which is stiff in-plane, but has only notional stiffness out-of-plane. The notional out-of-plane stiffness comes from the bending and shear thicknesses, which are required only to stabilize the nodes in the meshed plate for out-of-plane deformations and rotations. You might need to experiment with the values of these thicknesses to (i) get a stable model & (ii) minimize the out-of-plane deformations.
Appreciate the video explanation of rigid diaphragm option for plate members. Will try using this to simplify plywood skins used as shear panels. Would be interested in any thoughts regarding steel roof decks and "semi-rigid diaphragms as mentioned in the comment below. Thank-you.
Seems unfortunate that rigid diaphragms can not share a common node. Tried creating two rigid diaphragms at 90-deg to each other simulating the way two plywood shear panels might meet at a corner. S3D lets me create the two rigid diaphragms but throws error messages when I try to solve.... dang. Perhaps I am not using the feature properly.
Assuming you want to model the roof as a flexible or semi-rigid diaphragm (able to resist and transmit in-plane loads by deforming and unable to resist out-of-plane loads), you can use a meshed plate with different membrane, bending and shear thicknesses.
To do this:
-Create a plate, where you want the roof diaphragm.
-While editing the plate, expand the advanced options and set the membrane thickness to 1 1/2"
-The bending and shear thicknesses to a much smaller value, say 10% of the membrane thickness, e.g. 1/8".
-Before analysis, make sure to mesh the plate.
This will give you a plate which is stiff in-plane, but has only notional stiffness out-of-plane. The notional out-of-plane stiffness comes from the bending and shear thicknesses, which are required only to stabilize the nodes in the meshed plate for out-of-plane deformations and rotations. You might need to experiment with the values of these thicknesses to (i) get a stable model & (ii) minimize the out-of-plane deformations.
Hey Mark,
We will look into this aspect of Rigid Diaphragms and get back to you. Thanks for the feedback.