DEVELOPMENT OF SOFTWARE FOR DESIGN OF SMOKE STACKS

Abstract

The ever-increasing need to restrict pollution levels and the rapid increase in the number of large-scale industries has promoted the construction of large number of chimneys every year. Steel chimneys are extensively used in industry. The proper engineering of such structures require a study of environmental aspects, estimation of aerodynamic and seismic loads and evaluation of thermal stresses. Atmospheric regulations necessitate adoption of tall steel chimneys that require strengthening against the stresses induced by randomly varying time-dependant wind and seismic loads. Now a days, chimneys reaching a height 150 m or above are required to be self-supporting. However, the virtual absence of literature has made the present design trend rather crude. This thesis is intended to present a detail design and analysis methodology for steel chimneys reaching a height 150 m. Most of the recently published standard codes are incorporated to approximate real time loading conditions. Dispersion analysis is made through empirical relations that are found to be satisfactory in Indian context. Constrained optimization technique has been adopted and a program has been developed to design the structural shell of a self-supporting steel chimney. Examples are included to show that the optimization approach is quite feasible for cost-effective preliminary calculations in a standard design office.