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Nonlinear Modal Analysis of Structures with Rigid-End Offsets



Kevin K. Wong


The nonlinear modal analysis (NMA) methodology for analyzing moment-resisting framed structures is here extended to include frame elements with rigid-end offsets. Four keys components of the NMA methodology for conducting dynamic analysis of nonlinear framed structures include: (1) The force analogy method for material nonlinearity; (2) The stability functions for geometric nonlinearity; (3) The state space method for dynamic analysis; and (4) The modal superposition for computational efficiency. Under this NMA methodology, the nonlinear stiffness matrices capturing full panel zone rigidities and centroidal locations of plastic hinges in moment-resisting frames are completely derived in conjunction with satisfying global equilibrium, joint compatibility, and element force-displacement relationship. Nonlinear dynamic analysis of a 10-story steel frame with rigid-end offsets is then performed and results are compared with those obtained using Perform-3D (P3D) commercial software. Good agreement between NMA and P3D results indicate accuracy of the proposed methodology even though it is based on different assumptions.
Proceedings Title
43rd Structures Congress
Conference Dates
March 29-31, 2012
Conference Location
Chicago, IL


Wong, K. (2012), Nonlinear Modal Analysis of Structures with Rigid-End Offsets, 43rd Structures Congress, Chicago, IL (Accessed July 15, 2024)


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Created March 31, 2012, Updated February 19, 2017