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.

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

테일홴 성능시험장치의 운용과 진동특성

송근웅(Song, Keun-Woong),김준호(Kim, Jun-Ho),강희정(Kang, Hee-Jung),이욱(Rhee, Wook),심정욱(Sim, Joung-Wook) 한국소음진동공학회 2005 한국소음진동공학회 논문집 Vol.15 No.4

This paper described operation and vibration characteristics of a 'tail-fan' anti-torque performance test system. KARI (Korea Aerospace Research Institute) developed a 'tail-fan' anti-torque system of a helicopter and a performance test-rig to test the performance of the tail-fan. The performance test-rig consists of driving, supporting and rotating parts. In the process of the performance test, firstly, operation test of the test-rig were carried out to verify design specifications. Secondly, natural frequencies of fan blade and test-rig were measured respectively. Lastly, to find the operation rotating speed for the performance test, vibration test were carried out using accelerometers on tail gear box. The performance test conditions of the tail-fan to avoid a resonance were found from the fan-plot and vibration test results. The tail-fan performance tests were well done safely.

횡-비틀림 연성진동하는 L형 단면 보의 크랙 검출에 대한 실험적 연구

손인수(Son, In-Soo),이두호(Lee, Doo-Ho),노태우(No, Tae-Woo) 한국소음진동공학회 2011 한국소음진동공학회 논문집 Vol.21 No.2

In this paper, the natural frequency of a cracked cantilever L-beams with a coupled bending and torsional vibrations is investigate by theory and experiment. In addition, a method for detection of crack in a cantilever L-beams is presented based on natural frequency measurements. The governing differential equations of a cracked L-beam are derived via Hamilton's principle. The two coupled governing differential equations are reduced to one sixth order ordinary differential equation in terms of the flexural displacement. Futher, the dynamic transfer matrix method is used for calculation of a exact natural frequencies of L-beams. The crack is assumed to be in the first mode of fracture and to be always opened during vibrations. In this study, the differences between the actual and predicted positions and sizes of crack are less than about 10 % and 39.5 % respectively.

Shaking table test and horizontal torsional vibration response analysis of column-supported vertical silo group silo structure

Li, Xuesen,Ding, Yonggang,Xu, Qikeng Techno-Press 2021 Advances in concrete construction Vol.12 No.5

Reinforced concrete vertical silos are universal structures that store large amounts of granular materials. Due to the asymmetric structure, heavy load, uneven storage material distribution, and the difference between the storage volume and the storage material bulk density, the corresponding earthquake is very complicated. Some scholars have proposed the calculation method of horizontal forces on reinforced concrete vertical silos under the action of earthquakes. Without considering the effect of torsional effect, this article aims to reveal the expansion factor of the silo group considering the torsional effect through experiments. Through two-way seismic simulation shaking table tests on reinforced concrete column-supported group silo structures, the basic dynamic characteristics of the structure under earthquake are obtained. Taking into account the torsional response, the structure has three types of storage: empty, half and full. A comprehensive analysis of the internal force conditions under the material conditions shows that: the different positions of the group bin model are different, the side bin displacement produces a displacement difference, and a torsional effect occurs; as the mass of the material increases, the structure's natural vibration frequency decreases and the damping ratio Increase; it shows that the storage material plays a role in reducing energy consumption of the model structure, and the contribution value is related to the stiffness difference in different directions of the model itself, providing data reference for other researchers; analyzing and calculating the model stiffness and calculating the internal force of the earthquake. As the horizontal side shift increases in the later period, the torsional effect of the group silo increases, and the shear force at the bottom of the column increases. It is recommended to consider the effect of the torsional effect, and the increase factor of the torsional effect is about 1.15. It can provide a reference for the structural safety design of column-supported silos.

점성 비틀림진동 댐퍼의 공장 성능 테스트와 계측 기술에 관한 연구

권성훈(Sunghun Kwon),박주민(Jumin Park),한국현(Kukhyun Han),트렁 헝남(Hoangnam Truong),이돈출(Donchool Lee) 한국소음진동공학회 2016 한국소음진동공학회 학술대회논문집 Vol.2016 No.4

Before the development of high performance tuned dampers, viscous torsional vibration damper (VTVD) are being produced and applied on marine diesel engines from the 1950s for its simple and excellent damping performance. Further, the 1970s oil shock led to higher performance of diesel engines - increased combustion pressure and mean effective pressure with lower fuel consumption – and the demand to solve the torsional vibration problems likewise increased. In addition, torsional vibration dampers are also widely applied on recently developed two-stroke low-speed ultra long-stroke engine having lower operating speed in order to increase the propeller efficiency. The torsional vibration resonance for these engines are relatively higher compared to the 5 – or 6 – cylinders engine. A VTVD model being developed by Samyoung Machinery Co., Ltd was employed on a domestic vessel powered by about 900kW class engine. It is an utmost importance, particularly on dampers, to guarantee a satisfactory reliability before being installed on engines for the safety of vessels. In this paper, the manufacturer constructed a suitable device to verify the performance and applied different measurement methods to ensure the verification method.

Dynamic analysis of a megawatt wind turbine drive train

Caichao Zhu,Shuang Chen,Chaosheng Song,Hua iju Liu,Houyi Bai,Fei Ma 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.5

The dynamic performance of a wind turbine drive train significantly influences the operation of an entire machine. In this work, amegawatt wind turbine drive train is subject to theoretical and experimental dynamic analysis. The method of rigid-flexible couplingmultibody dynamics was applied to develop a dynamic model of the entire drive train. This model was then used to study the naturalcharacteristics of the system. The blades, hub, main shaft, and speed-up gearbox in the dynamic model were modeled as flexible bodies. The potential resonances of the system were detected through Campbell and modal energy distribution analyses. Theoretical results showthat the first-order natural frequency of the system is approximately 1.72 Hz. This frequency represents a torsional vibration mode,Moreover, resonances are not observed within the normal operating speed range of the drive train. An experimental remote real-timesystem was developed to monitor the torsional vibration of the drive train. This vibration was used to measure the torsional vibration ofthe system overall. The experimental results are consistent with the theoretical results.

축계 모의 시험 장치를 이용한 비선형 축계 진동 분석

한형석(HyungSuk Han),박성호(SungHo Park),전수홍(SooHong Jeon) 한국소음진동공학회 2018 한국소음진동공학회 학술대회논문집 Vol.2018 No.10

Experimental analysis of an asymmetric reinforced concrete bridge under vehicular loads

Thambiratnam, D.P.,Brameld, G.H.,Memory, T.J. Techno-Press 2000 Structural Engineering and Mechanics, An Int'l Jou Vol.9 No.1

Dynamic response of a three span continuous bridge has been determined by full scale experiments on the bridge. In the experiments, a heavy vehicle was driven across the bridge at different speeds and along different lanes of travel and the strains were recorded at different locations. The bridge was made of reinforced concrete and was asymmetric in plan and in elevation. Frequencies and modes of vibration excited by the vehicle were determined. The dependence of the dynamic amplification on bridge location and vehicle speed was investigated and dynamic amplifications up to 1.5 were recorded, which was higher than values predicted by bridge design codes. It was evident that when this asymmetric bridge was loaded by an asymmetric forcing function, higher modes, which are lateral and/or torsional in nature, were excited. Dynamic modulus of elasticity and the support stiffness influenced the natural frequencies of the bridge, which in turn influenced the dynamic amplifications. Larger than anticipated dynamic amplification factors and the excitation of lateral and/or torsional modes should be of interest and concern to bridge engineers.

P1-P2 하이브리드 시스템의 내장형 댐핑 시스템 검증에 대한 연구

신택현(Taek-hyun Shin),박찬석(Chan-seok Park),백성환(Seong-hwan Bark),강효은(Hyo-eun Kang) 한국자동차공학회 2021 한국자동차공학회 부문종합 학술대회 Vol.2021 No.6

P1-P2 TMED system is a hybrid powertrain to improve performance and fuel economy through the application of a P1 motor. Since the overall length is lengthened due to the addition of the P1 motor, we reduced the length of transmission by applying a torsion damper in the inner space between P1 and P2. In this study, the verification method for the torsion damper system applied inside the P1-P2 system was reviewed. Through the analysis of the damper system, verification targets and methods were discussed, and we divided the verification of the torsion damper into the damper only system, the drivetrain of the P1 rotor, and the total verification of the entire powertrain system.