鋼製煙突の地震強度に対する一検討

概要

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This paper deals with an ananalysis of earthquake response of a steel stack by direct numerical integlation of the governing differential equations of motion. To simplify the analysis, the following assumptions are made. a) The distributed mass of the stack is concentrated at equidistant sections. b) The stack is regarded as an span continuous beam which is fixed on one end and is free on the other end. c) There is no foundation rotation. d) The stack is resisted only by the bending moment and there are no effects of damping forces and shearing forces. With these assumptions, regarding the stack as a 6 degree freedom system, the dynamic behaviour of the stack to strong-motion earthquake (recorded at EI Centre, California in 1940) is analyzed. The governing equations of motion of stack are defined by the following second order linear ordinary differential equations; [numerical formula] (i, j=1, 2,・・・・・・,6) where m_i, y_i and z represents the concentrated mass, the horizontal displacement of ith mass, and the earthquake acceleration respectively. Integrating the differential equations numerically, displacement and velocity of each mass, and the bending moment of each section are calculated. These resalts are compared with the dynamic behaviour of the same stack due to wind pressure. Furthermore equivalent horizontal seismic coefficients of each section of the stack are shown.
1962-10-30