Field measurements of amplitude-dependent damping in a 79-storey tall building and its effects on the structural dynamic responses

This paper describes some results obtained from full-scale measurements of wind effects on a super-tall building, Di-Wang Tower, located in Shenzhen, China. This tall building has 79-storeys with a height of approximately 324 m. Field measurements including wind speed, wind direction and wind-induced acceleration responses have been made. The amplitude-dependent characteristics of damping are obtained by using the random decrement technique from the detailed analysis of the field acceleration measurements. The main objective of this paper is to present detailed investigations into the effects of nonlinear damping on the dynamic responses of the tall building subjected to various types of applied loads based on the measured amplitude-dependent damping characteristics. The predicted dynamic responses of the building obtained by using the measured damping characteristics were compared with those computed by using constant damping parameters assumed by the structural designers. It is concluded from the investigations that knowledge of actual damping characteristics are very important in the accurate prediction of the dynamic responses of a tall building when the major harmonic components of the applied loads overlap with the lowest natural frequencies of the building. The design damping level for tall building structures currently used by structural engineering practitioners appears to be high and not conservative.