r - The Hong Kong Polytechnic University

3.3.1 Software System for Instrumentation System Control and Display
The software system for instrumentation system control and display is deployed in the DPCS for carrying out
the operation control and operation display of the instrumentation system. It is devised to carry out two major
functions; (i) to control the operation of all fixed data acquisition systems regarding data acquisition, signal
conditioning, data pre-processing, data temporary storage and data transmissions (from individual data
acquisition system to DPCS and from DPCS to SHDMS) and (ii) to display the operation status of all sensors,
the key components in the fixed DAS-Static & Dynamic or the eight data acquisition units (such as the
PCI-controller, the signal conditioner, the A/D converter, the serial interfacing device, the hard disk storage
status, the network interfacing device, the air conditioner, etc.), the key components in other fixed data
acquisition systems which are not connected to the DAS-Static & Dynamic (such as DAS-DWIMS, DAS-GPS,
DAS-TMU-5 and DAS-Video – as shown in Figures 3 and 4) and all the key components in cabling network
systems such as the media access unit and the input/output fiber optic repeater, etc. The required items for
control and display of instrumentation system are shown in Figure 8. Figure 9 illustrates a typical display form
of the software system for instrumentation system.
3.3.2 Software System for Bridge Monitoring and Display
The software system for bridge monitoring and display is deployed in the DPCS for carrying out the operation
monitoring and operation display of the bridge structural system and its environment. It is devised to have the
capabilities in processing and analysis of the afore-mentioned fifteen types of measurands and to generate the
corresponding monitoring reports, i.e., (i) the wind and weather monitoring report, (ii) the temperature
monitoring report, (iii) the seismic monitoring report, (iv) the corrosion status monitoring report, (v) the
highway traffic monitoring report, (vi) ship impacting monitoring report, (vii) the permanent load monitoring
report, (viii) the static bridge features monitoring report, (ix) the dynamic bridge features monitoring report, (x)
the stay cables monitoring report, (xi) the tendons monitoring report, (xii) the displacements monitoring report,
(xiii) the stress/force distribution monitoring report, (xiv) the fatigue damage monitoring report, and (xv) the
articulation monitoring report. All software tools for processing, analysis and reports generation are customized
in accordance with the six aspects of programming consideration, i.e. type of input data, type of data processing,
type of data classification, type of data analysis, type of derived parameters, and type of plots and/or outputs. As
the deployment of sensory systems has a strong influence on the methods or strategies of data processing and
analysis, the functional description of the customized software tools are therefore incorporated with the
deployment strategies of sensory systems. The following paragraphs (A to O) therefore outline the strategies
and/or methods of sensors arrangement and software tools customization.
A. Customized Software Tools for Wind and Weather Monitoring [Ref. 2, 3, 5, 11, 12, 13, 14, 15, 17, 20,
and 31]
Stonecutters Bridge is identified as a wind-sensitive structure because over twenty numbers of its natural
frequencies are falling within the normal wind frequency range of 0-1 Hz (approximately), as shown in Figure
10. Wind loads and load-effects monitoring is therefore an essential part of the SHMS. The wind responses of
the bridge are composed of two parts, namely the along-wind responses and the across-wind responses. The
former is predominated by steady wind components; whereas the latter is predominated by the fluctuating wind
components. The steady wind is normally monitored by measuring the mean wind characteristics of wind speeds
and directions. The fluctuating wind is monitoring by measuring/deriving the turbulent wind characteristics of
wind turbulence intensities, wind turbulence length scales, wind turbulence auto spectra, wind turbulence
co-spectra and wind turbulence coherence spectra. The wind load-effects are monitoring by correlation analysis
of wind speeds and responses. As various types of aeroelastic instabilities such as vortex shedding, galloping
and fluttering have been designed not to occur or suppressed to be occurred at higher wind speeds exceeding the
performance requirements at ultimate limit state, the wind load-effects monitoring are therefore referring to the
monitoring of the steady wind responses and the buffeting responses at the serviceability limit state.
For wind speeds and wind directions measurements, three types of anemometers are used, i.e. 3D ultrasonic type
anemometers (12 nos. which are digital sensors – Ultrasonic Grill R3-50, each with a sampling rate of 50 Hz),
2D ultrasonic type anemometers (10 nos. which are digital sensors – Ultrasonic Enercorp 2D, each with a
sampling rate of 10 Hz) and 2D propeller type anemometers (2 nos. which are analogue sensors – RM Young
05106, and each of them is configured with a sampling rate of 50 Hz). The first type is deployed for the
monitoring of incidence and horizontal winds speeds below 45 m/s (which is the maximum wind speed to be
measured by the current 3D ultrasonic anemometers) at deck-levels and at tower-tops and for the direct
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