I have a Validation > Model > General > "Member collision" error. How do I resolve it?

Structural Members such as steel and concrete beams

A Member collision is a model validation error that can occur if two members have a common length in which their centerlines clash.

In the screenshot below, the Status window is reporting two members colliding. SB 1/A/1-1/B/1 -1 : SB 1/A/1-1/1/'29 -1

Double clicking this branch highlights both members in the active Scene view.

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Double clicking the individual members listed under this branch highlights each in turn. This perhaps provides a little more detail on the issue. One member extends between the columns while the other member only extends for part of the length. Both, however, have a common length such that they share the same physical space. This is impossible to achieve in reality.
 

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In a slightly different example shown in the screenshot below, the Status window is reporting two members colliding. SB 1/A/1-1/B/1 -1 : SB 1/A/1-1/B/1 -1

Note that the references are identical and hence this tells us that both individual members share exactly the same physical space in the model. This is because the reference relates to the intersection of the start and end locations of the member.
 

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To resolve the Member collision validation error you need to select one of the two members and use Delete to remove it from the model. This ensures that only one member occupies the physical 3D space.
 

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Once the member is removed from the model, if you run the Validate command again the issue should not be flagged.

Walls

The Member collision validation error will also occur if any type of beam is placed along the top of and in the plane of any kind of wall.  Though this is not prevented during modelling, it is not allowed and will cause the Member collision validation error.  This applies to all wall types; bearing, concrete (meshed and mid-pier) and general.

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The reason for this is that all wall types already have elements automatically created along their top in the solver model, so adding another member along the top of the wall (either partially or entirely) will cause a collision with these existing elements.    For more about the solver models for walls see the following topics:

• How bearing walls are represented in solver models
• How meshed walls are represented in solver models
• How mid-pier walls are represented in solver models

To resolve this error, the beam along the top of the wall must be removed as this situation of beam lying along the top of a wall - which we believe is uncommon - is beyond the current scope of the program. 

If you really must model this kind of geometry, some manual modelling will be required e.g. if the beam is along the top of a bearing wall, a bearing wall cannot be used.  You could alternatively retain the beam you wish to lie along the wall top, then manually replicate the bearing wall solver model vertical elements - we would suggest by using regularly spaced columns of a general material with appropriate releases.