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Currently, the overly conservative thermal design forces are obtained on the basis of simplified assumptions made about the temperature gradient across the containment wall. Using the method presented in this paper, a more rational and better estimate of the design forces can be obtained. Herein, the outside temperature is considered to consist of a constant mean on which yearly and daily harmonic changes plus a randomly varying part are superimposed. The random part is modeled as a stationary random process. To obtain the stresses due to random and harmonic temperatures, the complex frequency response function approach has been used. Numerical results obtained for a typical containment show that the higher frequency temperature variations, though of large magnitude, induce relatively small forces in a containment. Therefore, in a containment design, a rational separation of more effective, slowly varying temperatures, such as seasonal cycle from less effective but more frequently occuring daily and hourly changes, is desirable to obtain rational design forces.

The wind pressure distribution and dynamic behavior of hyperbolic cooling towers are significantly different from those of simple slender structures. Therefore, the gust response factors developed for design of these simple structures may not be applicable to cooling towers. A method which considers the dynamic interaction of the wind and tower is presented to obtain the gust factors for cooling tower design. Wind pressure distribution measurements made on model towers in wind tunnels are used. Simplifying assumptions are made concerning the correlation characteristics of wind pressure on a tower surface. Effect of change in wind and tower parameters on gust factors is examined.

When measurements of stress-strain in a prestressed concrete structure are made, extraneous strains due to creep and shrinkage of concrete and relaxation of steel are also recorded. In the presence of these extraneous strains, the significance of making the measurements for surveillance of grouted tendon containment structures is critically examined from a statistical standpoint. The discriminating power of stress-strain measurement schemes to unmistakably detect the occurrence of abnormal losses in prestress due to various causes, including corrosion, is expressed in terms of power functions. The measurements of stress or strain by meters cannot be relied upon for detection of abnormal situations which may arise due to excessive corrosion of tendon steel. Elaborate instrumentation for the purpose of surveillance seems unnecessary.

Acceleration floor spectra curves are commonly used as seismic design inputs for light equipment and other secondary systems. Earlier the writer had presented a method for generation of floor spectra directly from prescribed ground spectra. Further complementary developments in this method are made. These are: (1)The development of the method for generation of floor spectra at structural frequencies (an important resonance case); and (2)evaluation of nonstationarity of earthquake motions on floor spectra curves. Also, some approximations made in earlier work are further evaluated. As a result of these developments and evaluations, a comprehensive procedure based on stochastic principles is presented in the paper for definition of seismic design inputs for secondary systems. This procedure avoids the use of often used and recently criticized spectrum-consistent time history as seismic input for generation of floor spectra curves.