Seismic fragility assessment of a tall reinforced concrete chimney

Abstract

Summary In China, a considerable proportion of reinforced concrete (RC) industrial chimneys in operation was designed and constructed in accordance with less rigorous outdated seismic criteria during the end of 19th and early 20th century. However, few research works have been reported till date on a realistic overall assessment of the seismic performance of these existing aging RC chimney structures. Therefore, in this study, fragilities of existing RC chimney were studied. For this purpose, an existing 240 m tall RC chimney was selected and structurally modeled with a lumped mass beam (stick) model by means of the OpenSees analysis program. In order to capture the uncertainties in ground motion realizations, a series of 21 ground motions are selected from the Next Generation Attenuation database as the input motions. To develop the analytical fragility curves, nonlinear incremental dynamic analysis of the studied RC chimney was then carried out using the selected input motions, which were normalized to different excitation levels. The section curvature ductility ratio was considered as the damage index. Based on material strain and sectional analysis, four limit states (LSs) were defined for five damage state. The seismic responses of the all sections were utilized to evaluate the likelihood of exceeding the LSs. Then the peak ground acceleration (PGA)‐based seismic fragility curves of the structure were constructed assuming a lognormal distribution. Finally, under the light of these fragility curves, the damage risks in existing RC chimney were discussed. The analytical results indicated that for design level earthquake of PGA = 0.1 g (g is the gravitational acceleration) and the maximum considered earthquake of PGA = 0.22 g, the probabilities of exceeding the light damage state were around 1.5% and 44%, respectively, while the exceedance probabilities corresponding to moderate, extensive and complete damage states were approximately zero in both cases. On the other hand, fragility analysis revealed that the RC chimney structure had considerable ductility capacity and was capable to withstand a strong earthquake with some structural damages. Copyright © 2014 John Wiley & Sons, Ltd.

Seismic partitioned fragility analysis for high‐rise RC chimney considering multidimensional ground motion

“…The free‐standing RC chimney structure is 240 m high, and the inside diameter varies between 22.94 m at the base and 7.34 m at the top. The site soil is Class III according to new seismic code of China (China Ministry of Construction, 2010), and it is the equal of National Earthquake Hazards Reduction Program class D. The design peak ground acceleration (PGA) is 0.1 g, and maximum considered earthquake of PGA is 0.22 g. More detailed geometric parameters of the chimney structure are described in Zhou's paper …”

“…They found that the damage area of RC circular hollow high‐pier appears not only at the bottom of the pier but also in the middle of the pier and on the top of the pier in earthquake, and the vulnerability at the bottom of the pier is higher than that of other areas. Zhou et al studied the fragility of a 240‐m‐height RC chimney under one‐dimensional ground motion and obtained the damage probability of the chimney structure under a particular intensity of ground motion.…”

Combined Effect of Vertical and Horizontal Ground Motions on Failure Probability of RC Chimneys

“…e e ect of NFGMs along the vertical direction on the behaviors of other types of chimney structures (steel chimney and masonry chimney) should be studied. In order to reduce computation cost, a twodimensional model was created for the chimney structure as done in Zhou et al [8] in this work. In future research, it is suggested to create a three-dimensional model to simulate chimney structure to enhance the accuracy of calculation results.…”

“…Turkeli et al [7] studied the response of RC chimneys under wind and earthquake loads and showed that the opening at the body of the chimney can cause brittle failure. Zhou et al [8] evaluated the damage probability of a high-rise RC chimney with a height of 240 m under seismic loads through seismic fragility analysis (SFA), and some meaningful conclusions were obtained in their study. However, the influence of the vertical component of the ground motions was not considered.…”

Seismic Response and Safety Assessment of an Existing Concrete Chimney under Wind Load

“…Karaca et al [18] carried out the dynamic responses of chimneys after FRP strengthening. Zhou et al [19] revealed that the RC chimney structure had considerable ductility and could withstand a strong earthquake with some structural damage using fragility analysis. Gorski [20] investigated the influence of the three components mentioned above on the total cross-wind response of the chimney.…”