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Stabilizers are basically STM Elements that are required to avoid ill-conditioned structure stiffness matrix in
the truss analysis. The member forces in Stabilizers are always zero. CAST
identifies and assigns Stabilizers during truss analysis; however, you must
always create a stable strut-and-tie model. See Q
& A #9 for more detail information about how to create a
stable Strut-and-Tie Model. Stabilizers are not included in
dimensioning STM Nodes.
An example of CAST's strut-and-tie model that requires Stabilizers can be seen in
Figure 4.1. In
this CAST model, two Stabilizers are required to avoid mechanism
to occur. STM Element E10 is
needed to make the truss stable internally, and STM Element E6
is required to make the truss stable externally. Since the element force of
these two STM
Elements is zero, they are assigned by CAST as Stabilizers. As also
can be seen in Figure
4.2, these Stabilizers are not included in the construction of STM Nodes
N1, N2, and N4.
Figure 4.1 Example of CAST's Strut-and-Tie
Model that Uses Stabilizers
Figure 4.2 Nodal Zones
N1, N2, and
N4 of Figure 4.1's Strut-and-Tie
Model
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Q & A