Summary of Activities

There are many natural and man-made hazards, such as windstorms, earthquakes and fires that threaten infrastructures and human lives in dense urban cities. The area of natures and effects of severe hazards in the Center thus focuses on wind, earthquake, fire effects on buildings and structures to lead to a safe and economical design of buildings and structures and provide a friendly and safe environment to their occupants. Systematic investigations have been carried out by the Center on typhoon-induced wind characteristics, wind pressures and forces, wind-induced vibration, and wind and structural health monitoring of tall buildings and long span bridges, seismic hazard assessment, seismic design, seismic vulnerability, soil-pile-structure interaction, structural retrofitting using FRP composites, and simulation-based structural design method for fire loads. Technological services provided include:

Interpretation of wind loading codes and standards

Wind monitoring and terrain study

Numerical computation of wind pressures and forces on special buildings

Wind response measurement and data analysis of buildings and structures during typhoons

Serviceability performance assessment of tall buildings under strong winds

Wind-induced fatigue damage assessment of building and structure components

Risk evaluation and post-disaster investigation

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Representative Projects

• Fully-coupled aerodynamic response of long span cable-supported bridges: analysis, control and validation
  Supported by the Hong Kong Research Grants Council
  To propose a systematic approach for predicting fully-coupled buffeting response of long span cable-supported bridges under skew winds, to investigate aerodynamic interaction between the bridge deck, towers and cables, and to facilitate the comparison and verification of the current wind-resistant design practice.
  
• The influence of high cross winds on the safety of high-speed vehicles running over long span cable supported bridges
  Supported by the Hong Kong research Grants Council
  To establish a rational analytical procedure for predicting the response of coupled bridge-vehicle systems under high winds, to evaluate the running safety of high speed vehicles, and to propose the wind speed threshold to guide the decision on whether the railway/highway should be closed or not.
  
• Wind and structural response monitoring of tall buildings
  Supported by the Hong Kong Polytechnic University and collaborated with China Academy of Building Research
  To monitor and measure the mean wind speed and gust wind speed at the top of Di Wang Building and its alongwind, crosswind and torsional vibrations during strong typhoons, to develop system identification techniques for characterizing typhoon-induced winds and estimating building dynamic properties, and to provide information on wind-resistant design of tall buildings in Hong Kong and Shenzhen.
  
• Numerical simulation of wind loading on buildings
  Supported by the Hong Kong Research Grants Council Direct Allocation Grant
  To modify a self-developed fully 3D numerical water flow model for efficient application in the simulation of wind flow around buildings, with particular attention on the effects of special shapes of buildings, complex terrain and wind environment on the wind pressures and forces on buildings.

An improved approach for predicting buffeting response of long span cable supported bridges: Tsing Ma suspension bridge
	Wind environmental and structural response monitoring of Di Wang building during Typhoons Sam and York in August and September 1999.
	Wind tunnel tests for aerodynamic coefficients of bridge deck under skew wind
Wind tunnel tests for flutter derivatives of bridge deck under skew wind
Numerical simulation of wind flow around buildings

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Major Facilities

• Ultrasonic and mechanical wind anemometers 
• A set of field measurement instrument including accelerometers, displacement transducers, pressure transducers, amplifiers, signal conditioners, and recorders 
• Computer facilities and software for data processing and analysis   
• GPS receivers and data processing software

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Selected Publications

• Xu, Y.L. and Kwok, K.C.S. (1993) 'Mode shape corrections for wind tunnel tests of tall buildings', Engineering Structures, Vol. 15, No.5, 387-391.
  
• Xu, Y.L. and Reardon, G.F. (1993)  'Test of screw fastened profiled roofing sheets subject to simulated wind uplift', Engineering Structures, Vol. 15, No. 6, 423-430.
  
• Zhang, W.J., Xu, Y.L. and Kwok, K.C.S (1993) 'Torsional vibration and stability of wind-excited tall buildings with eccentricity', Journal of Wind Engineering and Industrial Aerodynamics, Vol. 50, 299-308.
  
• Zhang, W.J., Kwok, K.C.S. and Xu, Y.L. (1994)  'Aeroelastic torsional behavior of tall buildings in wakes', Journal of Wind Engineering and Industrial Aerodynamics, Vol. 52, No. 2, Feb., 229-248.
  
• Xu, Y.L. (1995) 'Determination of wind-induced fatigue loading on roof cladding', Journal of Engineering Mechanics, ASCE, Vol. 121. No.9, 956-963.
  
• Xu, Y.L. (1995) 'Model- and full-scale comparison of fatigue-related characteristics of wind pressures on the Texas Tech Building', Journal of Wind Engineering and industrial Aerodynamics, Vol.58, 147-173.
  
• Zhang, W.J., Xu, Y.L. and Kwok, K.C.S. (1995) 'Interference effects on aeroelastic torsional response of structurally asymmetric tall buildings, Journal of Wind Engineering and Industrial aerodynamics, Vol.57, 41-61.
  
• Xu, Y.L. (1996) 'Wind-induced fatigue loading and damage to hip and gable roof claddings", Journal of Structural Engineering, ASCE, Vol.122, No.12,1475-1483.
  
• Xu, Y.L. and G.F. Reardon (1998) "Variations of wind pressure on hip roof with roof pitch", Journal of Wind Engineering and Industrial Aerodynamics, No.73, 267-284.
  
• Sze, K.P.K. and Xu, Y.L.(1998) "Feasibility study of codification for wind-induced dynamic response of tall buildings in Hong Kong", Transactions of Hong Kong Institution of Engineers, Vol. 5, No.3. 125-130.
  
• Xu, Y.L., Sun, D.K., Ko, J.M., and Lin, J.H. (1998) "Buffeting analysis of long span bridges: a new algorithm", Journal of  Computers & Structures, Vol.68, No.4 pp.303-313.
  
• Gu, M., Xu, Y.L., Chen, L.Z., and Xiang, H.F.(1999) "Fatigue life estimation of steel girder of Yangpu cable-stayed bridge due to buffeting", Journal of Wind Engineering and Industry Aerodynamics, Vol.80, No.3, 383-400.
  
• Sun, D.K., Xu, Y.L., Ko, J.M. and Lin, J.H. (1999) "Fully-coupled buffeting analysis of long span cable-supported bridges: formulation", Journal of Sound and Vibration, Vol.228 (3), 569-588.
  
• Xu, Y.L., Zhang, W..S., Ko, J.M., and Lin, J.H. (1999) "Pseudo-excitation method for vibration analysis of wind-excited structures", Journal of Wind Engineering and Industrial Aerodynamics, Vol. 83, 443-454.
  
• Xu, Y.L., Sun, D.K., Ko, J.M. and Lin, J.H. (2000) 'Fully-coupled buffeting analysis of Tsing Ma suspension bridge", Journal of Wind Engineering and Industrial Aerodynamics, Vol.85, No.1, 97-117.
  
• Xu, Y.L., Zhan, S. and Ko, J.M. (2000)"Effects of Typhoon Sam on Di Wang Tower: Field Measurement', Transactions of Hong Kong Institution of Engineers, Vol. 7, No.2, 41-48.
  
• Xu, Y.L., Zhu, L.D., K.Y. Wang, and K.W.Y. Chan (2000) "Field measurement results of Tsing Ma suspension Bridge during typhoon Victor, ' Journal of Structural Engineering and Mechanics, Vol. 10, No.6, 545-559.
  
• Xu,Y.L. and Zhan, S. (2001) "Field measurement of Di Wang Tower during Typhoon York," Journal of Wind Engineering and Industrial Aerodynamics, Vol. 89, 73-93.
  
• Lin, P. and Li, C.W.(2002) "A  -coordinate three-dimensional numerical model for surface wave propagation", International Journal of Numerical Methods in Fluid, 38, 1045-1068.

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Contact Information

Contact Person

Prof. Y.L. Xu
Department of Civil & Structural Engineering
The Hong Kong Polytechnic University
Kowloon, Hong Kong Fax:     + 852 - 2334 6389
Phone:   + 852 - 2766 6050
E-mail:  ceylxu@polyu.edu.hk

Other Investigators

Prof.  S.L. Chan (ceslchan@polyu.edu.hk)
Prof. K.T. Chau (cektchau@polyu.edu.hk)
Prof. C.W. Li (cecwli@polyu.edu.hk)
Dr. K.F. Chung (cekchung@polyu.edu.hk)
Dr. Y. L. Wong (ceylwong@polyu.edu.hk)