Simplified formulas for evaluation of across-wind dynamic responses of rectangular tall buildings

Lianghao Zou,Shuguo Liang,Q. S. Li,J. R. Wu 한국풍공학회 2005 Wind and Structures, An International Journal (WAS Vol.8 No.3

Investigation of 3-D dynamic wind loads on lattice towers

Lianghao Zou,Shuguo Liang,Q. S. Li,Lin Zhao,Yaojun Ge 한국풍공학회 2008 Wind and Structures, An International Journal (WAS Vol.11 No.4

In this paper, the along-wind, across-wind as well as torsional dynamic wind loads on three kinds of lattice tower models are investigated using the base balance technique in a boundary layer wind tunnel. The models were specially designed, and their fundamental frequencies in the directions of the three principal axes are still in the frequency range of the spectra of wind loads on lattice towers. In order to clear contaminations to the spectra of wind loads induced by model resonance, the generalized force spectra of the first mode of the models in along-wind, across-wind and torsional directions were derived based on measured base moments of the models. The RMS generalized force coefficients are also obtained by removing the contributions of model resonance. Finally, the characteristics of the 3-D dynamic wind loads, especially those of the across-wind dynamic loads, on the three kinds of lattice towers are presented and discussed.

Investigation of 3-D dynamic wind loads on lattice towers

Zou, Lianghao,Liang, Shuguo,Li, Q.S.,Zhao, Lin,Ge, Yaojun Techno-Press 2008 Wind and Structures, An International Journal (WAS Vol.11 No.4

In this paper, the along-wind, across-wind as well as torsional dynamic wind loads on three kinds of lattice tower models are investigated using the base balance technique in a boundary layer wind tunnel. The models were specially designed, and their fundamental frequencies in the directions of the three principal axes are still in the frequency range of the spectra of wind loads on lattice towers. In order to clear contaminations to the spectra of wind loads induced by model resonance, the generalized force spectra of the first mode of the models in along-wind, across-wind and torsional directions were derived based on measured base moments of the models. The RMS generalized force coefficients are also obtained by removing the contributions of model resonance. Finally, the characteristics of the 3-D dynamic wind loads, especially those of the across-wind dynamic loads, on the three kinds of lattice towers are presented and discussed.

Wind tunnel tests of 3D wind loads on tall buildings based on torsional motion-induced vibrations

Lianghao Zou,Guoji Xu,C. S. Cai,Shuguo Liang 한국풍공학회 2016 Wind and Structures, An International Journal (WAS Vol.23 No.3

This paper presents the experimental results of the wind tunnel tests for three symmetric, rectangular, tall building models on a typical open terrain considering the torsional motion-induced vibrations. The time histories of the wind pressure on these models under different reduced wind speeds and torsional amplitudes are obtained through the multiple point synchronous scanning pressure technique. Thereafter, the characteristics of both the Root Mean Square (RMS) coefficients and the spectra of the base shear/torque in the along-wind, across-wind, and torsional directions, respectively, are discussed. The results show that the RMS coefficients of the base shear/torque vary in the three directions with both the reduced wind speeds and the torsional vibration amplitudes. The variation of the RMS coefficients in the along-wind direction results mainly from the change of the aerodynamic forces, but sometimes from aeroelastic effects induced by torsional vibration. However, the variations of the RMS coefficients in the across-wind and torsional directions are caused by more equal weights of both the aerodynamic forces and the aeroelastic effects. As such, for the typical tall buildings, the modification of the aerodynamic forces in the along-wind, across-wind, and torsional directions, respectively, and the aeroelastic effects in the across-wind and torsional directions should be considered. It is identified that the torsional vibration amplitudes and the reduced wind speeds are two significant parameters for the aerodynamic forces on the structures in the three directions

Wind tunnel tests of 3D wind loads on tall buildings based on torsional motion-induced vibrations

Zou, Lianghao,Xu, Guoji,Cai, C.S.,Liang, Shuguo Techno-Press 2016 Wind and Structures, An International Journal (WAS Vol.23 No.3

This paper presents the experimental results of the wind tunnel tests for three symmetric, rectangular, tall building models on a typical open terrain considering the torsional motion-induced vibrations. The time histories of the wind pressure on these models under different reduced wind speeds and torsional amplitudes are obtained through the multiple point synchronous scanning pressure technique. Thereafter, the characteristics of both the Root Mean Square (RMS) coefficients and the spectra of the base shear/torque in the along-wind, across-wind, and torsional directions, respectively, are discussed. The results show that the RMS coefficients of the base shear/torque vary in the three directions with both the reduced wind speeds and the torsional vibration amplitudes. The variation of the RMS coefficients in the along-wind direction results mainly from the change of the aerodynamic forces, but sometimes from aeroelastic effects induced by torsional vibration. However, the variations of the RMS coefficients in the across-wind and torsional directions are caused by more equal weights of both the aerodynamic forces and the aeroelastic effects. As such, for the typical tall buildings, the modification of the aerodynamic forces in the along-wind, across-wind, and torsional directions, respectively, and the aeroelastic effects in the across-wind and torsional directions should be considered. It is identified that the torsional vibration amplitudes and the reduced wind speeds are two significant parameters for the aerodynamic forces on the structures in the three directions.

Analysis of three dimensional equivalent static wind loads of symmetric high-rise buildings based on wind tunnel tests

Shuguo Liang,Lianghao Zou,Dahai Wang,Guoqing Huang 한국풍공학회 2014 Wind and Structures, An International Journal (WAS Vol.19 No.5

Using synchronous surface pressures from the wind tunnel test, the three dimensional wind load models of high-rise buildings are established. Furthermore, the internal force responses of symmetric high-rise buildings in along-wind, across-wind and torsional directions are evaluated based on mode acceleration method, which expresses the restoring force as the summation of quasi-static force and inertia force components. Accordingly the calculation methods of equivalent static wind loads, in which the contributions of the higher modes can be considered, of symmetric high-rise buildings in along-wind, across-wind and torsional directions are deduced based on internal forces equivalence. Finally the equivalent static wind loads of an actual symmetric high-rise building are obtained by this method, and compared with the along-wind equivalent static wind loads obtained by China National Standard.

Analysis of three dimensional equivalent static wind loads of symmetric high-rise buildings based on wind tunnel tests

Liang, Shuguo,Zou, Lianghao,Wang, Dahai,Huang, Guoqing Techno-Press 2014 Wind and Structures, An International Journal (WAS Vol.19 No.5

Using synchronous surface pressures from the wind tunnel test, the three dimensional wind load models of high-rise buildings are established. Furthermore, the internal force responses of symmetric high-rise buildings in along-wind, across-wind and torsional directions are evaluated based on mode acceleration method, which expresses the restoring force as the summation of quasi-static force and inertia force components. Accordingly the calculation methods of equivalent static wind loads, in which the contributions of the higher modes can be considered, of symmetric high-rise buildings in along-wind, across-wind and torsional directions are deduced based on internal forces equivalence. Finally the equivalent static wind loads of an actual symmetric high-rise building are obtained by this method, and compared with the along-wind equivalent static wind loads obtained by China National Standard.

Performance of wind-excited 1000 kV substation gantry by aeroelastic model wind tunnel test

Feng Li,Yin Chen,Lianghao Zou,Jie Song,Shu-Guo Liang 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.33 No.4

This study aims to investigate the performance of wind-excited 1000 kV substation gantry via the aero-elastic model wind tunnel test. An aero-elastic model that can simulate the first four frequencies was designed and manufactured by the method of combining semi-rigid segments by V-shape springs. Making use of the aero-elastic model wind tunnel test, the structural displacement and acceleration responses of the model were investigated for different wind speed and wind direction cases. Results show that the method of combining semi-rigid segments by V-shape springs can simulate the key parameters such as geometric shape, mass, frequency and damping ratio well. Wind direction plays an important role in the mean displacement responses, and the worst wind direction is 15° deviating from the corresponding axis. The root mean square of acceleration responses is remarkable in both the along-wind and cross-wind directions. In the direction perpendicular to the span, the windinduced vibration of the middle tower mainly depends on the resonance component of the first mode. By contrast, the contributions of the first and higher modes are all important for the side towers’ wind-induced responses. Gust response factors (GRFs) were estimated by the inertial wind loading method and the gust loading factor method, respectively. The range of the GRFs determined by the two methods is close to each other, which can provide guidance for assessing the performance of similar substation gantries subjected to wind.

Simplified formulas for evaluation of across-wind dynamic responses of rectangular tall buildings

Liang, Shuguo,Li, Q.S.,Zou, Lianghao,Wu, J.R. Techno-Press 2005 Wind and Structures, An International Journal (WAS Vol.8 No.3

Tall buildings under wind action usually oscillate simultaneously in the along-wind and across-wind directions as well as in torsional modes. While several procedures have been developed for predicting wind-induced loads and responses in along-wind direction, accurate analytical methods for estimating across-wind and torsional response have not been possible yet. Simplified empirical formulas for estimation of the across-wind dynamic responses of rectangular tall buildings are presented in this paper. Unlike established empirical formulas in codifications, the formulas proposed in this paper are developed based on simultaneous pressure measurements from a series of tall building models with various side and aspect ratios in a boundary layer wind tunnel. Comparisons of the across-wind responses determined by the proposed formulas and the results obtained from the wind tunnel tests as well as those estimated by two well-known wind loading codes are made to examine the applicability and accuracy of the proposed simplified formulas. It is shown through the comparisons that the proposed simplified formulas can be served as an alternative and useful tool for the design and analysis of wind effects on rectangular tall buildings.