Abstract: Seismic design criteria based on performance of
structures have recently been adopted by practicing engineers in
response to destructive earthquakes. A simple but efficient
structural-analysis tool capable of predicting both the strength and
ductility is needed to analyze reinforced concrete (RC) structures
under such event. A three-dimensional lattice model is developed in
this study to analyze torsions in high-strength RC members.
Optimization techniques for determining optimal variables in each
lattice model are introduced. Pure torsion tests of RC members are
performed to validate the proposed model. Correlation studies
between the numerical and experimental results confirm that the
proposed model is well capable of representing salient features of the
experimental results.