Reinforced concrete chimneys

Plastics provide different performance requirement in providing protective liners in many different applications such as building foundations, pipe and tank liners containing corrosive liquids, etc. As an example Fig. 4-13 shows an RP stack liner being inspected prior to installation in a 682 ft. high reinforced concrete chimney (background) of the 1,500-megawatt Intermountain Power Project near Delta, Utah (1985). 

The paper presents a method for the rational design of reinforced concrete chimneys or cement silos, towers for warm liquids and cooling towers subject to the effects of thermal gradients. The loads acting on the structure are divided into general loads and local loads. The effects of these loads on the concrete, the vertical reinforcement, and the horizontal (annular) reinforcement are studied with the aid of tables to obtain the significant stresses. A numerical example is given. 8 refs, cited. 

For most utility and large industrial chimney applications, reinforced concrete chimney shells have been specified because of their relatively low costs of initial construction and subsequent maintenance. In chimneys where a fairly large outer shell diameter s required (10 to 12 ft.), the cost of a cast-in-place concrete structure is typically less than field welded steel. Since this chapter must necessarily limit itself to that approach most popularly specified, it will describe in further detail only the cast-in-place reinforced concrete outer shell without further consideration of steel or radial brick. (See Figures 48-4 and 48-5). 

In summary, there has been a great deal of research and analysis pertaining to the concrete chimney shell. All known effects have been studied thoroughly and can be incorporated in design. Both the owner and consulting engineer can feel confident that, when properly constructed, the exterior shell of a reinforced concrete chimney will provide a long and trouble-free service life. 

Kilic, S.A. and Sozen, M.A. (2003) "Evaluation of Effect of August 17, 1999, Marmara Earthquake on Two Tall Reinforced Concrete Chimneys". ACI Structural Journal 100 (3), pp.357-364. 

Strengthening of reinforced concrete chimneys, columns, beams and retrofits... 

Ballinger C, Maeda T, Hoshijima T, Strengthening of reinforced concrete chimneys, columns and beams with carbon fiber reinforced plastics, American Concrete Institute Report, SP 138-15, 233-248. 

Vertical safety nets have solved the problem of protection against falls on large reinforced concrete chimneys, but materials must then be hoisted inside the chimney instead of outside. 

Figure 48-5 Chimney construction-Jump-form technique. The jump-form technique of concrete chimney construction has been in use since the turn of the century and has been refined to a remarkably efficient construction method. Specially designed steel forms are raised in regular increments for each pour. The forms are raised by the crew using chain falls connected to overhead beams on the derrick—a structure that incorporates a work deck and is hung by cables from the inside of the concrete chimney. For each new pour, the derrick is raised using chain falls and reattached by cables to the concrete structure. Then the outside forms are raised, as one piece. Reinforcing steel is secured and the Inside forms are raised, again as one piece. After alignment and plumb are checked, the concrete is poured. Taper and wall thickness are adjusted by changing the circumference of the forms.

The cheapest and least durable chimney is the guyed steel stack. Self-supporting metal stacks and those of reinforced concrete come next. Radial and hollow brick stacks, properly designed, are cheaper than those of common brick of equal excellence. 

Galvanized-steel rebars can be used as a preventative measure to control corrosion in reinforced concrete structures exposed to carbonation or mild contamination with chlorides, such as chimneys, bridge substructures, tunnels and coastal buildings. 

The Japanese are also active in the application of fibre reinforced plastics to reinforced concrete structures to improve their earthquake resistance. Kabatake et al [22] reported on 14 cases in which chimneys were retrofitted with fibre reinforced plastics and were judged by the Building Disaster Prevention Association of Japan to be one of the most effective retrofitting methods. In this retrofitting programme, carbon fibre tapes impregnated with an epoxy resin were wound and adhered to the exterior of the chimney. Sumida et al [ 23] have described experiences with aramid reinforced... 

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