The Earthquake Engineering Online Archive

A refined physical theory model for predicting the seismic behavior of braced steel frames

Ikeda, Kiyohiro; Mahin, Stephen A.

UCB/EERC-84/12, Earthquake Engineering Research Center, University of California, Berkeley, 1984-07, 180 pages (530/I41/1984R)

A state-of-the-art model for inelastic response analysis of braced steel structures is presented. The model combines analytical formulations describing plastic hinge behavior with empirical formulas developed based on a study of experimental data. It is suitable for studying the inelastic cyclic behavior of individual elements as well as the dynamic response of relatively large structural systems. Analytical expressions for the axial force versus axial deformation behavior of the brace are derived as a solution of the basic beam-column equation based on specified assumptions. While these expressions form the basis of the new model, several empirical behavioral characteristics are implemented in the modeling to achieve better representation of observed cyclic inelastic behavior. Verification of the model is performed based on quasistatic analyses of individual struts and dynamic response analyses of a three-story, x-braced steel frame representative of offshore platforms. The model is applied to the study of the design of a full-scale, six-story K-braced steel frame. Conclusions are offered regarding the inelastic behavior of braces. The reliability and practicability of the above analytical approach for modeling brace behavior are discussed.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-84-12.pdf (11 MB)