DYNAMIC EFFECTS DUE TO WIND.

There are two distinct types of dynamic effects due to wind on tall structures. The along-wind dynamic response is due to turbulent wind and random in nature. It can be taken care of in practical designs by the gust factor approach. The gust factors obtained by different authors are examined and their applicability to Indian conditions are studied. The cross-wind dynamic excitation is due to vortex shedding and has a definite periodicity. The principles underlying the behavior of tall structures under such a harmonic lateral loading are explained. Available information on the quantitative value of Strouhal number lift coefficient and critical damping ratio is reviewed and compared. Reduction of lateral force on tapered stacks is discussed.