GeoSIG — through a strategic alliance with Dr. Farzad Naeim, an internationally renowned expert in structural health monitoring — can offer consultancy and turnkey solutions for structural health monitoring of all types of structures including high-rise buildings, public buildings, bridges, tunnels and other special structures.
Using the expertise of the highly respected Dr. Farzad Naeim, who boasts over 35 years' experience and publications ranging from textbooks to journal papers, you can have peace of mind that your structure is safely surveyed and the most reliable solution is specified.
GeoSIG, with more than 25 years' expertise in structural monitoring solutions, can fulfil the requirements of the most challenging structure. Click here to visit his Website, or look over the solutions leaflet to see what we can offer.
Our Solutions for Structural Health and Response Monitoring
GMS Series Recorders for distributed and hybrid systems
- CR-6 Series Modular Multichannel Recording System for central and hybrid systems
- A wide variety of high quality sensors to measure acceleration, velocity, displacement, strain, tilt and environmental phenomena.
- Software solutions with highly customisable options
What is Structural Health and Response Monitoring?
Structural Health and Response Monitoring is an innovative method of monitoring structural status and performance without otherwise affecting the structure itself. Structural Health and Response Monitoring utilises several types of sensors embedded in, or attached to a structure to detect exceedance of allowed performance criteria as well as identify and verify structural behaviour.
Why Structural Health and Response Monitoring?
- The strength and serviceability of a structure can be considerably reduced by natural or human-made events, and increased levels of use
- Utilising Structural Health and Response Monitoring systems, timely notifications about any potential problems can be generated and behaviour of the structure can be monitored.
- The emerging use of Structural Health and Response Monitoring especially in the last decade, is a result of the increasing need for the monitoring of innovative designs and materials as well as a better management of existing structures.
What are the advantages of Structural Health and Response Monitoring?
- GeoSIG Structural Health and Response Monitoring systems not only help reducing risks and costs, but also help avoiding disaster by its notifications which allows to initiate early damage detection and therefore helps saving lives as well as assets.
- In case of any evacuation of the structure due to a transient event (such as an earthquake), the system allows to rapidly evaluate the structural response thus provides a highly useful measure for decision making whether to allow the occupants back in or to initiate a more comprehensive inspection before doing so.
- The ideal GeoSIG Structural Health and Response Monitoring system provides you with on-demand information about your structure's measured features, as well as warnings concerning any exceedance detected. Therefore Structural Health and Response Monitoring also significantly reduces repair costs through early damage detection, making the monitored structure safer and increasing the cost efficiency of its maintenance.
- Structural Health and Response Monitoring can significantly reduce insurance premiums for those operating - or in charge of - the safety of infrastructure such as bridges, railways or tunnels.
- increased understanding of in-situ structural behaviour and decreased down-time for inspection and repair.
Case Study:Tainan Railway, Taiwan
Railways move goods and people safely from place to place including across continents at far higher speeds than any national or international road network will ever allow. This enhanced speed is achieved through building in safety factors that remove almost every barrier that otherwise would exist.
The first railway focus in the early 19th Century was on building bridges and tunnels and it was only found out later that some could have benefited from solutions that monitored possible damage by motorists (known some countries as bridge bashing) or flooding during severe storms. Railways have moved into the 21st century with both bridges and tunnels being progressively electrified around the world and as a result overhead wires can sway in high winds and the impact of ever increasing train speeds and heavy loads potentially has new implications for both track foundations and bridge constructions.
As a general rule of thumb, the higher the railway line speed the more likely that monitoring interventions in some form will be needed for such high profile projects.
The railway industry is one where the terminology used can at times require some clarification, even translation. Induced vibration means vibration caused by trains passing next to infrastructures, buildings, residential areas at great speeds where the movement of this rolling stock causes vibrations.
The Taiwan HSR line runs approximately 345 km from Taipei to Kaohsiung (Tsoying), passing 14 major cities and counties and 77 townships and regions. The line is a high capacity and high speed railway. It is capable of carrying over 300’000 passengers in a single day of operation. After commissioning, it is expected to reach a normal speed of up to 300 km/h, and ultimately 350 km/h, shortening the north-south journey time to within 90 minutes.
The Tainan Science Park, located in the Tainan County in southern Taiwan, will be a new location for many vibration sensitive high-tech factories. Realizing that the high-speed rail alignment passes through the Tainan Science Park, the Taiwan High-Speed Rail Corporation (THSRC) has set up design requirements such that during operation, the vertical vibration within 200 meters on either side of the rail centerline do not exceed 46 dB (10-6 inch/sec) in the high frequency range ( 12.5 Hz ) and do not exceed 68 dB in the low frequency range ( < 12.5 Hz ). Besides these measures to be taken, to satisfy the highly sensitive high-tech factories in the park, TSIP initiated the Vibration Mitigation Project, and the Vibration Measurement for Verification of Vibration Mitigation Effectiveness Project linked to that.
GeoTech Engineering Consultant Co., Ltd., a company who focuses on automated, remote and integrated geotechnical instrumentation monitoring systems as well as the development of corresponding database management software, is assigned by TSIP to accomplish the mitigation project.
The purpose of this project is to obtain instrument-recorded in-situ ground vibration data for verification of effectiveness of vibration-mitigation measures implemented in Tainan Science-Based Industrial Park (TSIP) for reducing ground vibrations induced by the Taiwan High Speed Rail (THSR) train operations. The THSR track passes through the eastern edge of TSIP.
The vibration mitigation measures constructed in TSIP for reducing high-speed-running-train-induced ground vibrations consist of the following two specific measures:Stiffening the elevated guideway structure foundations in TSIP with foundation-stiffening blocks (FSB) that structurally link the pilecaps of the pile-foundations together in the longitudinal direction of the THSR alignment.
Constructing underground wave-barrier-wall (Diaphragm Wall) at approximately 30 m away to the west of and parallel to the THSR alignment.The elevated guideway structure segment in TSIP implemented with the vibration mitigation measures is approximately 4.85 km long from the THSR Chainage TK290+700.000 to TK295+548.716.
Instrument Recording Stations
Since the THSR trains are not yet operational before vibration mitigation measures are constructed, no measurements of train-induced free-field ground vibrations can be made before implementation of vibration mitigation measures to provide reference ground vibration data to be used for comparison with the corresponding data obtained after mitigation. Therefore, two sites are required for ground vibration measurement.
One site, referred to herein as “Site A”, is located in the mitigated structure section in TSIP; the other site, referred to herein as “Site B”, is located in the unmitigated structure section outside TSIP but close to Site A.
Site A: Located in Mitigated Section
Site A is located approximately at the middle of a selected approximately 10 consecutive 30-m-long girder-spans section of the mitigated elevated structures in TSIP.
A total of 14 instrumented recording stations, all from VE-13 Triaxial Velocity Sensors, are deployed for Site A. These recording stations are arranged in two parallel-lines perpendicular to and on the west side of the THSR alignment. The two recording lines are selected at approximately the mid-section within the 4.85-km long mitigated section of elevated structures in TSIP. Each recording line is aligned with the transverse centerline of each selected pier, which is pier 287 & pier 289. The two parallel, transverse recording lines are spaced with a distance in the longitudinal direction of the THSR alignment of approximately 90 meters or three 30-m-long-spans apart.
On each transverse recording line, seven (7) VE-13 instrumented recording stations are deployed. One station is located on the pilecap of the selected pile-foundation and the other six are located on the free-field ground surface at distances 70, 100, 200, 300, 400, and 600 meters away from the THSR alignment centerline.
There are 3 VE-13 measuring sensors at the station on the pilecap; two out of the three measuring sensors measure y-axis, y-axis & z-axis respectively, where y-axis is the direction of the train path, which is believed to be producing the most vibration.
Site B: Located in Unmitigated Section
Site B is located outside, to the south of the 4.85-km long mitigated structure section in TSIP in subsurface ground condition that is similar to that of the selected recording Site A.
In a one-to-one correspondence to the instrumented recording stations in Site A, a total of 14 VE-13 recording stations are also deployed for this recording site in the same pattern as that for Site A. The selected recording Site B is approximately 4.53-km distance away from the south end of the 4.85-km-long mitigated structure section.
The locations of the 14 VE-13 instrumented recording stations for each of Site A and Site B is shown schematically in Figure 4 and Figure 5. In this figure, the solid line represents the mitigated structure section in TSIP having vibration mitigation measures implemented; the dashed line represents a selected unmitigated structure section outside TSIP without any vibration mitigation measures implemented.
2 x 21 Sensors
2 x Central Recorder
Integrated Into LAN
data Center 1000SPS Permanent Data Recording
Case Study:Preveza Tunnel, Greece
Tunnels feature within transportation solutions throughout the world. They can be under water, underground or built through otherwise awkward to navigate geographical terrain. Tunnels may feature as a man made solution within both rail and road transportation solutions where safety factors between different modes of travel must be separated normally owing to the natural high volume of people movement activity.
Tunnels may feature in geographical areas that alone warrant the monitoring the seismic effects caused by both natural earth activity and temperature, and will feature elsewhere throughout the world when transportation movements of people, goods and services has to maintain the right speed of movement to maintain a viable economic solution for any country to stay competitive within global markets. This sector is one in which GeoSIG has to rely on different forms of intelligence to know what is happening when and where at least from its own representatives and elsewhere as possible. GeoSIG receives leads through various partnership activities and demonstrates through its website that it has the necessary understanding of the technological solutions sought for tunnel monitoring equipment to be a serious competitor offering a Swiss made quality solution no matter how complex the tunnel challenge first appears.
This scope of the Preveza-Aktio Immersed tunnel project was to provide a seismic tunnel monitoring system where the tunnel equipment provided monitored the seismic effects of earth activity alongside the dynamic loads of natural transportation movements whether planned or by any unforeseen event. The scope included expansion or contraction surveillance due to the intensity of temperature changes impacting on the tunnel monitoring environment through whatever reason. The data is then assessed and compared to tunnel data recorded against seismic design criteria applicable to tunnel structural design and construction. Improvements to tunnel emergency and safety measuring solutions as well as awareness also featured alongside the needs to appropriately maintain tunnel data management systems given the wider scope of measuring solutions possible within this segment owing to geographical location.
4 x Accelerometers
Triaxial Force Balance Accelerometer
44 x Displacement Sensors
Linear Variable Displacement Transluder (LVDT)
2 x Metereological Sensors
Humidity / Temperature Sensor
1 x Data Aquisition And Processing Centre
Electronic Cabinet Computer Software
RACK-1 Computer GeoDAS, CMS
Case Study:Øresund Bridge, Danemark/Sweden
Bridges feature within lifelines where the sheer volume of traffic without any monitoring solution would cause severe safety problems and significant interference to the free movement of goods, services and people between trading nations. Bridges can feature within road to road traffic solutions within traffic management systems designed to minimise lengthy road transport delays, and longer bridges can feature as essential links between any mainland and its nearby island otherwise separated by sea. Bridges may feature in geographical areas that alone warrant the monitoring of seismic effects caused by natural earth activity, and may feature at localities exposed to higher than average wind speeds. As with tunnels GeoSIG demonstrate the necessary understanding of the technologies required to become a genuine competitor offering a Swiss made solution no matter how daunting the bridge challenge first appears.
The scope of the Oresund project was to deliver a Cable Stayed Bridge Structural Monitoring System. Oresund is an Impressive highway and railway link consisting of an immersed tunnel, artificial island and a combination bridge requiring observation of the oscillations of cables of the stayed bridge under heavy wind conditions. The bridge system solution monitors the deflections of the bridge under loads generated by the highway and railway traffic. An on-site traffic control centre of the bridge is where excesses of any threshold values are recorded and managed from.
The system comprises 105 channels and a data acquisition and processing centre, digital RS-485 cable communication with provision for 15 hours autonomy in case of power failure. Temperature/environmental data correlation are made alongside strain gauge measurements. A single CR-4 PC based recording system running programs, SEISLOG data acquisition, CENTRAL remote access, CMS, and static data processing. A telephone line connection to the traffic control centre is provided for data, event and alarm transmission.
22 x Accelerometers
Triaxial Force Balance Accelerometer
19 x Strain Sensors
Uniaxial Strain Gage
14 x Metereological Sensors
Temperature Sensor, Weather Station
1 x Data Acquisition And Processing Centre
Electronic Cabinet computer Software
RACK-1 Computer GeoDAS, CMS
Case Study:Metsovo Bridge, Greece
Metsovo Bridge is a highway bridge in the course of the east-west connection “Egnatia Odos” in the north of Greece.
The 4-span, totally 540 m long prestressed concrete bridge traverses an approximately 120 m deep ravine and lies between two tunnel portals. The main span is given with 235 m. The deck is constructed to the balanced cantilever method. Both main piers are founded on shafts with diameters of 12 m and length up to 25 m. The design is governed mainly by the high seismic loads in this region.
The scope of the project was monitoring the structure with respect to ground motions and other ambient dynamic activity such as dynamic loads imposed by the traffic, environmental effects, etc.
The system is composed of two main sensor groups and the central acquisition computer. The first group measures the acceleration of the ground and vibrations of the bridge.
The accelerometers are placed on the basement of two main pylons and in the maintenance tunnel below the deck. The second group consists of strain gage sensor and displacement transducers. The displacement transducers are located at the end of the bridge at the conjunction point between the bridge and the ground, whereas the strain gauge sensors are positioned in different points along the bridge (see figure).
All measured data are acquired at the Central Recording Unit (CR-5P). The CR-5P integrates the digitiser board and an industrial PC in oneplatform, simply controlled through the Windows XP operating system. The measured data are managed by GeoSIG developed seismic software GeoDAS.
4 x Accelerometers
Triaxial Force Balance Accelerometer
14 x Strain Sensors
Uniaxial Strain Gage
4 x Displacement Sensors
1 x Meteorological Sensor
Wind Speed and Direction
1 x Central Recorder
Multichannel Recording systemAll the data are stored locally and accessible via the Remote Desktop available on all operating system (Windows, MacOS X and Linux). The Recording Unit sends SMS and e-mails alarms to selected user groups.
Case Study:Humber Bridge, United Kingdom
When opened in 1981 the Humber Bridge in the UK was the largest single span bridge in the world with a total length of 2220 metres. The road distance in the UKbetween Hull and Grimsby was reduced by nearly 80km (50 miles) as a result of this transportation achievement. Where the UK leads the rest of the world eventually follows and the Humber Bridge in the UK is now statistically placed 5th place, the 4 ahead (in alphabetical order) now being Akashi-Kaikyo, Great Belt, Runyang and Xihoumen. The Humber Bridge, however, still remains the largest bridge with a lower level foot and cycle path on both sides. Bridge monitoring has since moved into the 21st century with technology changes that have moved away from analogue to digital bridge monitoring solutions.
Such new technologies bring with them the need re-evaluate the most suitable monitoring solutions and in this instance re-evaluations were necessary on the modal properties of the Humber Bridge alongside the viability of using stand alone recorders with provision timing (via GPS) to provide histories of response within the analysis of such an extended open space structure. The Humber Bridge as designed can tolerate constant motion and bends more than 3 metres in winds of 129 km/hr (80 mph) at which point safety factors emerge but the towers, although both vertical, are not parallel, these being under 50mm further apart at the top than at the bottom.
An international team comprising:
- Prof. JMW Brownjohn, University of Sheffield, UK
- Dr. Paul Reynolds, University of Sheffield, UK
- Mr. Chris Middleton, University of Sheffield, UK
- Mr. Filipe Magalhaes, FEUP Porto, Portugal
- Prof. Elsa Caetano, FEUP Porto, Portugal
- Prof. Ivan Au, City University Hong Kong
- Prof. Paul Lam, City University Hong Kong
with support from Dr. Ivan Munoz Diaz, Prof. Aleksandar Pavic, Dr. Stana Zivanovic, Mrs. Eunice Lawton, Mrs. Tuan Norhayati Tuan Chik and Mr. Mohammad Muaz Aldimashki from Sheffield, Prof. Alvaro Cunha from FEUP and Mr John Cooper, Mr Peter Hill and Mr Ian Allenby from Humber Bridge Board tested the bridge during the week 14th-18th July 2008 as part of EPSRC funded research project:
EP/F035403/1, Novel Data Mining and Performance Diagnosis Systems for Structural Health Monitoring of Suspension Bridges.
The exercise had several purposes:
- To re-evaluate the modal properties of the bridge and provide a modal model in digital form, that would be used as a baseline for calibration of a finite element model of the bridge
- To evaluate the viability of using standalone recorders with precision timing (via GPS) to provide time histories of response that could be used for operational modal analysis of such an extended open-space structure
- To evaluate the difficulties of operational modal analysis procedures in estimating modal parameters for super-low frequency structures with short data lengths and to evaluate the effect of non-stationary structural (hence modal) parameters on the procedure of gluing mode shape pieces.
The 1985 test used only three Schaevitz LSOC accelero-meters, about 2 km of cable, a two channel spectrum analyzer and a four-channel analog tape recorder. The testing lasted two weeks, and data processing to identify the modes, replaying data tapes through the spectrum analyzer and using the procedure known as ‘peak picking’ lasted about 6 months. The analog tapes can no longer be read and the digital modal description did not survive migration between storage formats in the last 23 years. Hence while the mode frequencies and general form of most of the mode shapes are useful these are not available digitally.
Also the resolution was poorer, the damping ratio estimates are known to be heavily biased due to the crude technology, the signal to noise ratios of the sensors are poor and, made worse by the poor dynamic range of the tape recorder, the torsional mode shapes could not be resolved using only three sensors and it was not possible to measure simultaneously points on towers, main span and side spans. So there are several reasons to need an up to date study.
The new study involved new instruments consisting of ten GSR-24’s utilising internal or external accelerometers, all brought together from FEUP and Sheffield.
The testing was divided into 28 measurements spanning five days: For example on day 2, measurements concentrated on the southern part of the bridge, in the direction of the town of Barton. Each of the box sections of the bridge, are identified by an odd number with prefix b (for Barton, south) or h (for Hessle, north). Recordings were made mainly at alternate hanger locations, in each case maintaining at least one fixed (reference) location on the main span. The set of seven measurements on day 2 listed below used a reference pair (21h) on the Hessle side and one (49b) on the Barton side, with the remaining three pairs of recorders roving on the Barton side with 10-minutes to relocate between one-hour recordings.
Measurements included one at the Barton tower (78b) with including locations 77b/79b across the bearings, then moved into the Barton side span. Measurement setup 14a was a short recording to cross-check calibrations (as shown in Figure 3). The configuration for measurement setup 9 is shown in Figure 4 the red dots indicate the 10 recorder locations.