Analysis and Design of RC Chimney in STAAD-PRO

Reinforced chimneys are used in Power plants to take the hot and poisonous flue gas to a great height designed mainly to resist the lateral forces like wind and earthquake as well the thermal stresses of the flue gas. An attempt is made to understand the variation of lateral deflection at the top of the chimney, by varying the height of chimney above 275 m. A total of five models are selected for five different heights i.e 275m, 285m, 295m, 305m & 315m and the analysis is done. All the models were analyzed and the lateral deflection regarding is calculated. Code of practice for design of reinforced concrete chimney (Third revision of IS 4998:1992 [Part I]) is used for the referance analysis. STAAD PRO software is used to do the analysis. Further an attempt is made to understand the variation of lateral deflection at the top of the chimney for different heights.

Non-Destructive Testing of Technical Conditions of RC Industrial Tall Chimneys Subjected to High Temperature

Non-destructive tests of reinforced concrete chimneys, especially high ones, are an important element in assessing their condition, making it possible to forecast their safe life. Industrial chimneys are often exposed to the strong action of acidic substances, They are negatively exposed to the condensation of the flue gases. Condensate affects the inside of the thermal insulation and penetrates the chimney wall from the outside. This is one reason for the corrosion of concrete and reinforcing steel. Wet thermal insulation settles, and drastically reduces its insulating properties. This leads to an increase in temperature in the reinforced concrete chimney wall and creates additional large variations in temperature fields. This consequently causes a large increase in internal forces, which mainly increase tensile and shear stresses. This results in the appearance of additional cracks in the wall. The acid condensate penetrates these cracks, destroying the concrete cover and reinforcement. Thermographic studies are very helpful in monitoring the changes in temperature and consequently, the risk of concrete and reinforcement corrosion. This simple implication between changes in temperature of the chimney wall and increasing inner forces as shown in this article is particularly important when the chimney cannot be switched off due to the nature of the production process. Methods for interpreting the results of thermovision tests are presented to determine the safety and durability of industrial chimneys.

Comparative approach to seismic vulnerability of an elevated steel tank within a reinforced concrete chimney

This study provides a framework for investigating the seismicresponse of an elevated steel water tank within a reinforcedconcrete chimney, to assist optimal tank placement and analysedifferent tank geometries. Elevated tank design procedures indifferent guidelines and codes are adequate for specific cases,none of which meets the exact requirements of this case study,in which the supporting structure mass is large relative to thestorage tank. The tank is located at an elevation 63 m belowthe mid-height of the 200 m chimney, resulting in a differentbehavior than a simple cantilever. Furthermore, for certainH/R ratios, coupling effects may exist between the fundamentalperiod of the chimney and that of the sloshing wave. An equivalentmodel is examined that is simple enough yet able to accuratelyproduce the design acceleration, dynamic amplification,damping and torsional effects at the chosen tank location, andto capture site effects. An analysis of the tank at ground level isconducted according to AWWA D100-11. Then, the tank at elevation63 m is analysed within the framework of three existingmethods using code spectra and site-specific spectra. A novelfourth method is then proposed which, contrary to the existingmethods, can accurately capture the conditions of this casestudy by combining the benefits of all methods. The workflowdescribed here can be readily applied to other cases of elevatedtanks for which the standard procedures are inadequate.