How are tension-only members modeled during response-spectrum analysis?

Answer: Tension-only and compression-only behavior are nonlinear effects which should be evaluated using nonlinear time-history analysis. Response-spectrum analysis (RSA) is a linear method which does not consider nonlinear assignments during formulation. Links represent another nonlinear assignment which does not affect RSA. RSA uses effective stiffness and effective damping according to the stiffness used in the corresponding modal analysis case. Stiffness may be based on zero initial conditions or that at the end of the nonlinear case. These options are shown in Figure 1:

Figure 1 - Stiffness

Nonlinear time-history analysis should be run to consider complete nonlinear behavior.

See Also

• Tension and compression limits article

• Tension-only elements in ETABS article