緑 堀田’s scientific contributions

A numerical method for the nonlinear analysis of steel space frames subjected to cyclic loading is presented. It is a kind of plastic hinge method, and plastic deformations in the plastic hinge are obtained by integration of generalized plastic strains (axial plastic strain ερo, biaxial plastic curvatures φρy and φρz and warping plastic curvature φρω) of the member along the assumed length lρ of elasticplastic region respect to the member axis. The non-stationary hysteretic stress-strain relation of material and the effects of large deflection "are taken into account. In the present paper the fundamental theory of the method is given in detail showing a few analytical results to examine propriety of the basic concept of the method on (1) ultimate load behavior of curved I-beams; (2)inelastic behavior of wide flange beam-columns under constant vertical and tow-dimensional alternating horizontal loads

The fundamental theory of a new plastic hinge method for the nonlinear analysis of steel space frames was presented previously. The purpose of this paper is to describe the method to reduce total number of the elements for entire structre. It is done by evaluating the imaginary length lp of elastic-plastic region of the yield element using the nodal forces. Adopting the above procedure, the size of the master stiffness matrix becomes nearly as small as conventional plastic hinge method. The accuracy of this improved method is examined by several examples