Application Of Real-Time Hybrid Model Test In Wind-Induced Vibration Analysis Of Sager Building

With the development of construction technology,the number and size of super high-rise buildings in our country are in the forefront of the world.But at the same time,they also have the characteristics of large volume,more kinds,long service cycle,complex service environment and so on.Their safe operation and maintenance face many challenges and difficulties.In particular,the wind induced vibration event of Sager Building in Shenzhen in2021 had aroused wide attention to the safety operation and maintenance of super high-rise buildings.Therefore,it is necessary to simulate and test the vibration problems occurring in the long-term service of super high-rise buildings,so as to predict the potential problems of buildings and evaluate their safety.The current test methods of super high-rise buildings vibration generally include field in-situ test,wind tunnel test,shaking table test and so on.The field in-situ test is affected by the field environment greatly,the test cost is high,and the reliability and accuracy of the test results are limited.Due to the limitation of cost and model size,its some components in wind tunnel test cannot be effectively simulated due to the too small scale ratio.Because of the limitation of bearing capacity,shaking table test can only carry out small scale model test for super high-rise buildings,and only qualitative study can be made on vibration of super high-rise buildings.Therefore,an economical and reliable test method is needed to study the wind-induced vibration in the safety operation and maintenance of super high-rise buildings.In this paper,the wind induced abnormal vibration of Sager Building is studied by using real-time hybrid model test method.Firstly,field in-situ test was carried out to obtain the building’s modal shape and other data,then the vortex-induced vibration frequency and wind load on the mast were determined by the wind tunnel test of the rigid mast model.Secondly,the off-line hybrid simulation was carried out by using the wind tunnel test data.Finally,the phenomenon of abnormal vibration of Sager Building was reproduced by real-time hybrid model test.The main research contents of this paper are as follows:(1)In situ test was carried out to obtain the modal shapes of the mast and the tower.Field tests of fixed-frequency excitation were carried out with the actuator on the mast,the69 th floor and the 70 th floor respectively.The dynamic characteristics of the Sag Tower were identified,and the modal information such as the frequencies,mode shapes and damping ratios were obtained to the following paper.(2)The frequency of vortex-induced vibration was determined and the wind load was calculated through the wind tunnel test with the rigid mast model.Wind tunnel tests of rigid mast model were designed and carried out.the wind pressure distribution and aerodynamic characteristics of single and double masts under various working conditions was analyzed.the cylindrical flow around and Reynolds number effect was discussed.The vortex shedding frequency of masts was deduced.Based on the wind pressure data obtained from the wind tunnel test,the actual shear time history of the mast bottom is calculated for off-line hybrid simulation.(3)Wind tunnel test data was used for offline hybrid simulation of the multi-degree-of-freedom(MDOF)model of the Sager Tower.The MDOF model,which includes the tower and mast,was used as the numerical substructure,while the mast test model(the outer part of the mast)in the wind tunnel test was used as the experimental substructure.The shear forces obtained from the mast test model in the wind tunnel test was input into the MDOF model to calculate the wind vibration response through offline hybrid simulation.The response was qualitatively compared with the on-site measured data to prove the validity of the MDOF model Sager Tower offline hybrid simulation.(4)A real-time hybrid model testing system was set up to preliminarily reproduce the abnormal vibration phenomenon of the Sager Tower.The tower was taken as the numerical substructure,while a scaled model of the mast was used as the experimental substructure for real-time hybrid model testing.The numerical substructure solves the boundary velocity command between the top of the tower and the bottom of the mast.The command was loaded by a shaking table to drive the mast model vibrating.While a fan was used to input wind load to the experimental substructure.The base shear of the experimental substructure was fed back to the numerical substructure.A real-time hybrid model testing system was built.Real-time hybrid model testing was conducted to reproduce the abnormal wind-induced vibration phenomenon of the Sager Tower and verify its effectiveness.