The response of slender structures to turbulent wind loads

One of the most challenging issues in the modern design of tall buildings is related to the evaluation of the response to wind actions, which is in many cases more demanding if compared to the response to design seismic forces. Moreover, the simplified methodologies provided by current codes are not adequate for complex structures. Here two different procedures are considered: the first exploits the wind tunnel pressure recordings as external forces applied to the structure in a deterministic context; the second estimates the response to gust buffeting through a stochastic approach. Both methodologies are addressed by means of a Direct Frequency Domain (DFD) approach, which allows to obtain a more refined modeling of complex structures, and exploits the same numerical solution algorithm, based on efficient implementations of iterative projection methods. A criterion is also described fully exploiting, when available, the wind tunnel data to integrate the parameters of the stochastic model. Moreover, low frequency vortex shedding is accounted for through equivalent static forces computed with experimental parameters. Real-life examples are reported, showing the effectiveness of both the numerical procedure and the presented methodologies. Finally, a procedure is proposed to detect aerodynamic instability due to galloping phenomena.