Passive control of along-wind response of tall building

Most of modern tall buildings using lighter construction materials with high strength and less stiffness are more flexible, which occurs excessive wind-induced vibration, resulting in occupant discomfort and structural unsafety. It is necessary to predict wind-induced vibration response and find out a method to mitigate such an excessive wind-induced vibration at the preliminary design stage. Recently, many studies have been conducted in using actuator control force based on the linear quadratic optimum control algorithm. It was accepted as a common knowledge that the performance of passive tuned mass damper(TMD) could increase by incorporating a feedback active control force in the design of TMD, which is called active tuned mass damper(ATMD). However, the fact that ATMD is superior to TMD to reduce wind-induced vibration of a tall building is still a question. The effectiveness of TMD for mitigating the along-wind vibration of a tall building was investigated. Optimum parameters of tuning frequency and damping ratio for TMD under a random load which has a white noise spectra were used. Fluctuating along-wind load acting on a tall building treated as a stationary Gaussian random process was simulated numerically using the along-wind load spectra. And using this simulated along-wind load, along-wind responses of a tall building with and without TMD were calculated and the effectiveness of TMD in mitigating the along-wind response of a tall building was found out.

Across and along-wind responses of tall building

Most modern tall buildings using lighter construction materials are more flexible, which can lead to excessive wind-induced vibrations resulting in occupant discomfort and structural unsafety. It is necessary to predict and mitigate such wind-induced vibration at the preliminary design stage. Fluctuating across and along-wind loads acting on a tall building that could not be formulated theoretically were simulated numerically in the time domain using known across and along-wind load spectra. These simulated wind loads were used to estimate the across and along-wind responses of a tall building, which are less narrow-banded processes, based on the state space variable approach. The simulated across-wind response of root-mean-square value(0.0047) and that of KAREEM's(0.0040) and the simulated along-wind response of root-mean-square value(0.021) and that of SOLARI's(0.027) were compared. It is found that these are good approximations of closed form responses. Therefore, these numerically simulated across and along-wind loads can be used for across and along-wind responses estimation for the wind-resistant design of a tall building at the preliminary design stage.

Wind response of high-rise building in diversified inlets to construct wind turbine system on roof

Many skyscrapers have installed wind turbine systems to use new renewable energy. In particular, building an integrated wind power generation system by installing a wind power generator inside a building is an attractive method to secure safe energy. However, most studies have dealt with the efficiency of wind turbines and the response effects of wind induced vibration; space preparation for wind turbine installations has not been sufficiently considered. This work reviewed the shapes of openings where wind turbines can be installed in skyscrapers, and the characteristics of wind induced vibration responses occurring in the building with changes in cross sectional area. Nine wind power models were constructed to carry out the experiment. According to the experimental results, wind speed varies with shape of opening in the order of C-type>S-type>R-type. Moreover, wind speed increases as the area is reduced.