This project is supported under the Research Initiation Awards (RIA) Program, FY 91. The objective of this research is to perform a 3- D study of reinforced concrete (R/C) structures on the adverse effects of nonproportional deformations on the inelastic response of R/C members. A finite element model which includes an assemblage of inelastic solid elements to model the concrete and elastic-plastic bar elements representing the reinforcing steel will be used to study the complex interaction between the axial and lateral deformations. As a case study, the response of ICS Building during the Imperial Valley Earthquake of Oct. 15, 1979 will be evaluated. Further parametric study at the elements level will be also performed to advance the knowledge and to satisfy the need for detailed information on the force-displacement response of R/C columns under uncoupled fluctuation of axial and lateral loads. The results of this project are expected to improve the understanding of the cyclic behavior of R/C structures and members, and to impact the seismic design practices of R/C structures.