Second-order inelastic analysis of steel frames using element with midspan and end springs
W. F. Chen1 and S. L. Chan2
1George E. Goodwin Distinguished Prof. and Head of Struct. Engrg., School of Civ. Engrg., Purdue Univ., West Lafayette, IN 47907-1284.
2Reader, Dept. of Civ. and Struct. Engrg., Hong Kong Polytechnic Univ., Hung Hom, Kowloon, Hong Kong.
Published: 18 August 1995
ABSTRACT:
An efficient method for elastoplastic large-deflection analysis of steel frames using an element with plastic hinges at midspan and two ends is proposed. The need in conventional methods to divide a member into two or more elements to model the distributed loads, and the need to allow for a plastic hinge at its span is eliminated. The formation of plastic hinges is simulated as gradually softening springs. This approach prevents the overestimation of the capacity of a steel frame and also reduces the complexity in data handling. Because the element stiffness matrix is explicitly derived, the additional computational effort for forming the element matrix only involves a few algebraic calculations and is therefore minimal. The saving in the overall computer time and data input and output efforts is considerable since a single element can be used to model one beam member in the ultimate analysis of most practical structures. Most importantly, the linear structural model can be directly used for a second-order inelastic analysis, leading to a convenience and consistency in extending a linear analysis to a nonlinear analysis.