RELIABILITY-ANALYSIS OF CONCRETE CHIMNEYS UNDER WIND LOADING

A reliability analysis of tall reinforced-concrete chimneys under wind loads is presented. The safety criteria, i. e. , excessive deflection at the top of the chimney and exceedence of the ultimate moment capacity of the chimney cross-section at any level, are used to evaluate the risk in terms of the probability of failure. The ultimate moment capacity is estimated using the ultimate stress method based on a second-order stress-strain relationship for concrete. The formulation of wind-induced load effects, in both the alongwind and acrosswind directions, is based on probabilistic structural dynamics. A Covariance Integration Method is used to formulate a spectral description of fluctuating wind load effects on chimneys. Both load effects and structural resistance parameters are treated as random variables. A tall reinforced-concrete chimney, designed in accordance with the ACI Code, is used to illustrate the methodology presented herein.