Structural Health Monitoring and Damage Detection

Summary of Activities

Structural health monitoring and damage detection refers to the use of in-situ, non-destructive sensing and analysis of structural characteristics for the purpose of detecting changes that may indicate damage or degradation. With the advance in sensor systems, data acquisition, data communication and computational methodologies, instrumentation-based monitoring has been a widely accepted technology to monitor and diagnose structural health and conditions for civil infrastructure systems. The Centre has undertaken a lot of research and consultancy projects related to vibration measurements of tall buildings and long-span bridges, bridge dynamic loading and moving force identification, vibration-based damage detection of large-scale bridges, fatigue assessment from health monitoring data, post-earthquake damage evaluation of high-rise buildings, and finite element modelling and dynamic analysis of complex structures. Technological Services provided include the following:

• Ambient and forced vibration testing of buildings and bridges
• Design of structural health monitoring systems
• Moving force identification and condition evaluation of bridges
• Finite element modelling and dynamic analysis of cable-supported bridges
• Model updating and validation based on field vibration measurement.

Representative Projects

•  Vibration monitoring of Lautau Fixed Crossing
• Commissioned by Highways Department of HKSAR Government
• To carry out 7 ambient vibration measurements for the erected suspension Tsing Ma Bridge and cable-stayed Kap Shu Mun Bridge at different construction stages to identify the modal properties and their change with construction progress. Finite element model for each construction stage has been developed and validated by the measured modal parameters.
• Lantau Fixed Crossing and Ting Kau Bridge wind and structural health monitoring masterplan task 7.12
• Commissioned by Flint and Neill Partnership/Highways Department of HKSAR Government
• To study the feasibility of using measured dynamic characteristics to detect structural damage in the cable-supported Tsing Ma, Kap Shu Mun and Ting Kau Bridges which have been permanently instrumented with a long-term monitoring system consisting of about 800 sensors.
• Field tests under agreement No. CE76/97: Investigation for rehabilitation of Tsing Yi South Bridge
• Commissioned by Taywood Engineering Limited/Hyder Consulting Limited/Hong Kong Highways Department
• To carry out residual stress tests, static load test and dynamic test for the investigation for Rehabilitation of Tsing Yi South Bridge.
• Structural damage detection of cable-supported bridges by vibration measurement
• Supported by the Hong Kong Research Grants Council
• To develop a hierarchical identification strategy in terms of neural network novelty detector, probabilistic neural network and multi-layer perceptron for successive detection of the occurrence, location and extent of structural damage in three cable-supported bridges instrumented with an on-line monitoring system.
• Experimental study on seismic damage detection of tall building structures
• Supported by the Hong Kong Polytechnic University
• To conduct an experimental study on post-earthquake damage assessment of a 38-storey building model on a shaking table to verify the applicability of a near real-time method to evaluate building damage and appraise building performance immediately after major hazardous events.
• Innovative optical fibre sensors for structural health monitoring of Tsing Ma Bridge
• Supported by the Hong Kong Polytechnic University
• To explore innovative optical fibre sensor and signal interrogation technique for continuous monitoring of civil structures and to implement this technique in the Tsing Ma Bridge for developing experimental procedures to determine the capabilities of optical fibre sensors in detecting structural health and conditions of bridges.

Sensor Map of Ting Kau Bridge

Gain Information of the selected sensors

Data Display

Major Facilities

• B&K vibration testing package (BK4802&4817 exciters; BK1049 sine/noise signal generator; BK2708 power amplifier; BK3550 16-channel spectrum analyzer including data acquisition unit BK2816 and signal analyzer unit BK2035).
• 32 Channel INV303E Data Acquisition and Signal Processing System (with INV-DASP632 software);
• Computer system with DAT Tape Drive and SPiDAR software specific for on-line health monitoring and compatible with WASHMS;
• A set of field measurement instrument including exciters, accelerometers, displacement transducers, anemometers, tape recorders, etc.
• 3m x 3m shaking table (Type: MTS; Degree of freedom: one direction; Frequency range: 1 to 50 Hz; Displacement limit: 100 mm; Acceleration limit: 1 g; Load limit: 10 ton);
• dSPACE DS1005 real-time control system (DS1005DSP board; DS2003 32ch A/D; DS2102 6ch parallel D/A; PX10N expansion box; CDP1005 total development package);

Select Publications

• Lam, H.F., Ko, J.M. and Wong, C.W. (1998), "Localization of damaged structural connections based on experimental modal and sensitivity analysis", Journal of Sound and Vibration, Vol. 210, No. 1, 91-115.
• Law, S.S., Shi, Z.Y. and Zhang, L.M. (1998), "Structural damage detection from incomplete and noisy modal test data", Journal of Engineering Mechanics, ASCE, Vol. 124, No. 11, 1280-1288.
• Chan, T.H.T., Law, S.S. and Yung, T.H. (2000), "Moving force identification using an existing prestressed concrete bridge", Engineering Structures, Vol. 22, No. 10, 1261-1270.
• Ni, Y.Q., Lou, W.J. and Ko, J.M. (2000), "A hybrid pseudo-force/Laplace transform method for non-linear transient response of a suspended cable", Journal of Sound and Vibration, Vol. 238, No. 2, 189-214.
• Xu, Y.L., Zhu, L.D., Wong, K.Y. and Chan, K.W.Y. (2000), "Field measurement results of Tsing Ma suspension Bridge during Typhoon Vector", Structural Engineering and Mechanics, Vol. 10, No. 6, 545-559.
• Chan, T.H.T., Li, Z.X. and Ko, J.M. (2001), "Fatigue analysis and life prediction of bridge with health monitoring data - Part II: application", International Journal of Fatigue, Vol. 23, No. 1, 55-64.
• Law, S.S., Chan, T.H.T., Zhu, X.Q. and Zeng, Q.H. (2001), "Regularization in moving force identification”, Journal of Engineering Mechanic"s, ASCE, Vol. 127, No. 2, 136-148.
• Xu, Y.L. and Zhan, S. (2001) "Field measurements of Di Wang Tower during Typhoon York", Journal of Wind Engineering and Industrial Aerodynamics, Vol. 89, No. 1, 73-93.
• Ko, J.M., Sun, Z.G. and Ni, Y.Q. (2002), "Multi-stage identification scheme for detecting damage in cable-stayed Kap Shui Mun Bridge", Engineering Structures, Vol. 24, No. 7, 857-868.

Contact Information of the contact person

Fax:     + 852 - 2362 2574
Phone:   + 852 - 2766 5036
E-mail:  cejmko@polyu.edu.hk