The Earthquake Engineering Online Archive

Generalized plastic hinge concepts for 3D beam-column elements

Chen, Paul Fu-Song; Powell, Graham H.

UCB/EERC-82/20, Earthquake Engineering Research Center, University of California, Berkeley, 1982-11, 274 pages (555.6/C4755/1982)

In the "section" type of model, inelastic behavior is defined for the cross section as a whole, rather than for individual fibers. Action-deformation relationships for the cross section must be devised, considering the stress-strain characteristics of the cross section material. Models of this type are less accurate than fiber models, but more efficient computationally. This report presents the theory and computational techniques for the section-type model and analyzes five example structures. In developing the model, inelastic interaction among bending moments, torque, and axial force has been considered by means of yield interaction surfaces and a flow-rule type of plasticity theory. Emphasis has been placed on the ability to consider arbitrary loading-unloading cycles of the type likely to be induced by an earthquake. Both stable hysteretic action-deformation characteristics and relationships involving stiffness degradation are considered. Three inelastic beam-column elements have been developed for the computer program(s) WIPS and/or ANSR: an element with distributed plasticity and nondegrading stiffness suitable for modeling inelastic behavior in piping systems; an element with lumped plasticity and nondegrading stiffness suitable for modeling inelastic steel beams and columns in buildings; an element, suitable for modeling inelastic reinforced concrete beams and columns in buildings, with lumped plasticity and degrading stiffness.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-82-20.pdf (46 MB)