Multiframe allows you to specify a member as Tension only or Compression only. Tension only members will resist forces in the structure only when the member is in axial tension. Similarly, compression only members will resist forces in the structure only when the member is in axial compression. These types of members have been implemented in a general sense and changing a member to tension or compression only does not alter the member end releases. If a tension or compression only member is not required to resist moments then the appropriate member end releases should be applied.

Tension only and compression only members are taken into account by a nonlinear analysis. These types of members are removed or reinstated to the structure at the end of each iteration based upon the axial deformation of the member. The Tension only and compression only aspects of members are ignored in static linear, modal or time history analyses – they are treated as normal members in these cases.

To set the member type

§    Select the member or members to be modified

§    Choose Member Type from the Frame menu

A dialog box will appear with radio buttons indicating the types of members.

§    Click on the radio button corresponding to the type of member you require

§    Click on the OK button