Reliability analysis of concrete chimneys under wind loading: Fid-Bau Portal

Reliability analysis of concrete chimneys under wind loading

Kareem, A. / Hseih, J.

Abstract 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. These are broadly classified into three categories: (a) wind environment and meteorological data, (b) parameters reflecting wind—structure interactions, and (c) structural properties. A first-order second-moment (FOSM) approach is used to examine their uncertainties and a reliability analysis is presented. The general bounds on the probability of failure of the system expressed in terms of the probability of failure of individual modes are derived including closer bounds. A tall reinforced-concrete chimney, designed in accordance with the ACI Code, is used to illustrate the methodology presented herein.