Wednesday, 9 May 2018

Experimental validation of bridge damage detection method using rotation measurements

Hello Everybody,

I carried out experimental studies in collaboration with a research group at Kyoto University, in an attempt to validate a newly developed bridge condition assessment methodology. The test is performed at the Structures Laboratory on a 5.6 metre long simply supported bridge structure at Kyoto University. Figure 1 shows the test structure.

Figure 1. Test Structure

The test structure is stiffened at various locations by attaching steel plates on the girder flanges and response of the structure to a moving 4-axle vehicle is measured using QA-750 uniaxial accelerometers. Subsequently, developed bridge condition assessment algorithm is applied to validate the robustness of the methodology.

Figure 2. Four-axle vehicle model

Figure 3. Inclinometer attached at the support location

Figure 4. Stiffening plate attached at midspan location

The results obtained from the study prove that the developed methodology successfully identifies stiffening locations and it is a promising tool for real bridge condition assessment applications. As a future work, it is planned to validate the procedure on a full-scale railway bridge structure.

Whilst in Kyoto I also had a chance to go for sightseeing and take some nice pictures

View from Nijo Castle

Thursday, 8 February 2018

Structural Testing of a Heritage Railway Bridge with the Flying Scotsman Locomotive

On Tuesday 5th September 2017 a team of researchers from Full Scale Dynamics Ltd and the Vibration Engineering Section at the University of Exeter conducted field testing on the Mineral Line Bridge in Somerset. The bridge forms part of the West Somerset Railway (WSR), a heritage railway line with 20 miles of track in South West England. The purpose of the field testing was to monitor the deflections of the bridge while Flying Scotsman engine was running on the line. The team consisted of Farhad Huseynov, Yan Xu and Karen Faulkner.
The Flying Scotsman, one of the most well-known steam engines, was constructed in 1923 and was the first steam engine to officially record a speed of over 100 mph. To achieve this speed, the engine itself measures 21.3 m in length and weighs 97.8 tonnes. This is significantly larger than the Raveningham Hall engine, with a length of 19.2 m and a weight of 76.4 tonnes, is the largest train belonging to the WSR. The aim of the testing was to measure deformations of the bridge under loading from the passing trains and to determine the effect of the larger Flying Scotsman locomotive on the bridge.

Flying Scotsman Locomotive passes over the Mineral Line Bridge

The Mineral Line Bridge is located on the outskirts of Watchet and was originally constructed to carry the Minehead route over the West Somerset Mineral Railway. The Mineral Railway now operates as a footpath and cycle path open to the public. The bridge opened in 1862, has a single span of 14.8 m and is constructed skewed an angle of 60° to the pathway beneath.

A series of accelerometers were installed on the bridge deck at five test points, measuring at each abutment and at quarter-span, mid-span and three-quarter-span. The angle of rotation of the bridge deck at each test point was inferred from the accelerometer data. This rotation data was then used to determine the deflection of the bridge.

Accelerometers installed on the bridge

The Imetrum camera was used to measure deflections of the bridge under loading from the passing trains. Three Imetrum cameras were set up on tripods and targets were installed, one at mid-span on the bridge deck and two on the western abutment. The abutment deflection was monitored to gather info as part of a previous study, but the main focus of the testing on the day was to measure the deflection at mid-span of the bridge.

Imetrum cameras and targets installed on the bridge

By comparing the results of the deflection calculated from the rotation data and measurements from the Imetrum camera, the team were able to verify the deflection measurements obtained from the accelerometers. There was a good correlation between the two measurements, verifying the procedure used by the research team.

The results indicated increased deflections and rotations under loading from the Flying Scotsman but were safely within the tolerances of the bridge.

Raveningham Hall Locomotive passes over the Mineral Line Bridge

The weather conditions were not ideal on the day, with periods of rainfall intermixed with sunny periods throughout the day. This required the equipment to be covered with plastic bags for parts of the day, though this was found to have a negligible effect on the data.

Stay tuned!

Monday, 7 August 2017

Technical Trip to Shinjuku Mitsui Building in Tokyo, Japan

Hello Everybody,

In this post, I would like to share some of the interesting photos taken during the technical visit to Shinjuku Mitsui Building which is located in Nishi-Shinjuku area in Tokyo, Japan.

The Shinjuku Mitsui Building is a high-rise building in Nishi-Shinjuku area in Tokyo and it is owned by Mitsui Fudosan. It is one of the 10 tallest buildings in Tokyo and was the tallest building in Japan from September 1974 until March 1978. The photo of the skyscraper is shown in the figure below.

Figure 1. Shinjuku Mitsui Building

The building was subject to substantial long-period ground motion during Great East Japan Earthquake on March 11, 2011, and was observed to sway approximately 2 meters. Although the building was a structurally rated, Ministerial-approved building that provided a high level of safety, and its seismic performance was proved to be fully adequate during the earthquake, there were increased concerns among tenants about the safety and security of the building since the earthquake. Therefore, the building owner decided to upgrade the structure by installing Tuned Mass Dampers (TMDS) to further strengthen the structure against even stronger earthquakes and to provide peace of mind for the occupants.

Figure 2. Sketch of Shinjuku Mitsui Building with TMDs

TMDs are simply gigantic pendulum-like counterweights that are placed on the top of the structure and tuned to pull a building’s mass in the opposite direction of the prevailing vibrations. So when the ground beneath a foundation moves laterally—either because of the wind or seismic activity—the counterweight moves in the opposite direction, taking the structure with it. 

Figure 3. Photo of a Tuned Mass Damper on the top of Shinjuku Mitsui Building.

The video below simulates the building behavior during the earthquake with and without TMDs.

Video 1. Earthquake simulation of Shinjuku Mitsui Building with and without TMDs

Installing TMDs to the Shinjuku Mitsui Building cost approximately $50 million.

In the below photo me and three other ESRs are on the roof of the Shinjuku Mitsui Building.

Figure 4. ESRs on the top of the Shinjuku Mitsui Building. From left to right - Me (ESR 7), Matteo Vagnoli (ESR 9), John James Moughty (ESR 10), Antonio Barrias (ESR 11)

Stay Tuned!

Bridge Visual Inspection Using Robotic Camera

Hello Everybody,

During my trip in Japan, I had a chance to attend a bridge visual inspection demonstration using a robotic camera devise which is designed by Hitachi Industry & Control Solutions, Ltd for use at locations where close visual inspection is difficult, such as inspection of bridge soffits, or around bearings. Using pole units, it facilitates the process of positioning a camera at a height within visual range, conducting inspections, measurements, and acquiring video recordings. The photo provided below shows the devise mounted on an elevating type pole.

Figure 1. Bridge inspection robotic camera mounted on an elevating type pole unit.

Two pole units are available, the Suspending Type and the Elevating Type. By installing the base of the pole unit on a parapet, the suspending type can extend downwards to a maximum of 6.0m. In contrast, using a stand placed on the ground, the elevating type pole unit can extend a camera upwards to a maximum of 10.5m. The camera can be operated remotely from a tablet computer using wireless communications. On the video provided below, a site personnel explains how the system works.

Priorly, the company began development of robotic pole cameras for inspection of house roofs and similar applications in 1995, and they are now in wide spread use for bridge visual inspection activities.

The distance from the camera to the object is measured using a laser range finder mounted on the camera. Sizes on the surface of the object are assessed according to the distance measured, and an appropriately-scaled crack scale/ruler or L-square can be displayed on the operation tablet. When the engineer performing the inspection is unable to approach closer to the object, this function enables measurement of crack widths, lengths, and other damage. By adjusting the crack scale on the tablet, you can measure the actual width of the crack. In the below video technician measures the crack width using the system which is about 0.5mm thick.

I also attended some other technical visits during my trip in Japan which I will share in the following posts.

Stay tuned!

Monday, 26 September 2016

Detecting Damage on Bridge Structures Using Inclinometers

Hello Everybody,

I have been developing a new bridge Condition Assessment (CA) concept recently that I would like to share with you through this post. The idea is about detecting any possible anomalies involved in bridge structural condition using rotation as a main parameter. To achieve so, I conducted the below mentioned studies.

I developed an algorithm, which employs the Influence Line and the Moment Area theorems, to study the sensitivity of rotation to detect change in structural stiffness of a bridge structure under moving load. The algorithm calculates the rotation recorded along the length of a simply supported beam structure while load is moving. It also simulates damage at any point across the structure in terms of reduction in stiffness. The figures provided below depicts the results obtained from the aforementioned study.

Figure 1. Rotation recorded at the left end of a beam structure under moving load

Figure 2. Difference in rotation between healthy and damaged cases

Figure 1 shows the rotation recorded at left end (x=0) of a beam structure while load is moving from one end to another. 15% damage was also simulated in the study at midspan of the beam and blue plot shows the healthy and red plot the damaged cases. Figure 2 shows the difference between two plots where peak of the graph matches with the damage location and its magnitude represents the severity of the damage. From this study the required resolution of a sensor (inclinometer) was determined as 10^-3 radians to detect 15% stiffness loss on a beam structure. Following this, I made an extensive research about inclinometer sensors available in the market. It was a challenging task to find a high resolution sensor which is also cost efficient. Eventually, I came up with an idea of using accelerometers to record rotation. The idea was tested on a bridge structure available in the Structures Laboratory at the University of Exeter. The inclinometers were placed horizontally on the structure and recorded accelerations while loaded trolley were manually pulled (8 runs) from one end to another. Because the output of the accelerometer obeys a sinusoidal relationship as it is rotated through gravity, the inverse sine function of it converted recorded acceleration to rotation (angle). The idea worked well and 10-6 radians resolution was obtained.

Figure 3. 15m long bridge structure available in the Structures Lab at The University of Exeter

Figure 4. Rotation time history obtained using accelerometers under loaded trolley

The findings obtained from the above mention numerical analysis are promising to detect any possible damage involved in structural condition of a bridge structure. The idea is still being developed. I built up a 3m long simply supported beam structure in the lab and will test the concept experimentally. I look forward to sharing the results through upcoming posts.

Figure 5. 3m long, simply supported beam structure built in the lab.
Stay tuned!

Monday, 8 August 2016

Case Study: Analysis of Transverse Load Distribution Characteristics of Exe North Bridge

Hello Everybody,

     It has been quite a while I haven't been updating my blog!!! I was busy organizing a field test on one of the bridges in Exeter, UK which I would like to share with you over this blog post. 

     The test was performed on the Exe North Bridge (Figure 1) which is one of the two almost identical adjacent bridges crossing River Exe and forming a big roundabout in Exeter, UK. It is 60m long and consists of three spans, resting on two wall type pier structures in the river and abutments at the ends. It was constructed in 1969, so it is very close to its 50 years of designed service life.

Figure 1
Figure 1. Exe North Bridge spanning the River Exe

     The north span of the test structure was instrumented with 12 strain transducers (Figure 2 & 3), which made it possible to study the load shedding characteristics of the deck structure under moving load. As a test vehicle, a four-axle, 32 tonne lorry was used to obtain a quasi-static strain response (Figure 4). The load test was performed overnight to avoid disturbing traffic. The truck made several passes in each lane, stopping every time for 30-45 seconds to record static strain (Video 1).

Figure 2. Strain sensors installed on the soffit of the deck structure.

Figure 3. Me installing strain transducers on the deck soffit.

Figure 4. 32 tonne, 4-axle lorry remaining stationary over the bridge to record static strains.

Video 1. 

The test was supported by Full Scale Dynamics Limited where I am employed and The Vibration Engineering Section from The University of Exeter within the scope of undergraduate engineering student project "Analysis of transverse load distribution of Exe North Bridge superstructure". The purpose of the test was to study the load shedding characteristics of the structure as well as to showcase the importance of field testing in efforts to deal with the deteriorating infrastructure. The load test revealed that, although the structure is nearing its 50 years of designed life, it still retains significant strength reserves. Further findings about the test was presented on a conference paper in 6th Civil Structural Health Monitoring (CSHM-6) workshop in Belfast, UK [1].

Figure 5. Phd student Zandy Muhammed (left) from The University of Exeter and Me (right) supervising the undergraduate student Nick Trump (middle).

Stay tuned!

Saturday, 2 April 2016

Introduction to my blog

Hello Everyone and welcome to my blog! 

My name is Farhad Huseynov and I am a Structural Engineer mainly specialized in Bridge Engineering. Currently I am working as an Early Stage Researcher (ESR 7) for Full Scale Dynamics LTD in Exeter, UK and have been involved in research project named "Railway Weigh-in-Motion for Bridge Safety" which is part of the Marie Sklodowska - Curie ITN Project "TRUSS" funded by the European Union under the Horizon 2020. At the same time I am a PhD student in Civil Engineering Department at the University College Dublin (UCD). Throughout this social media platform I will regularly share my social and professional activities that I hope you will enjoy while reading.

As a first blog entry, a brief description about myself and my research topic would be a good idea to start with...

So, I am 29 years old and was born in Baku, capital city of the Republic of Azerbaijan. It is a small yet culturally rich country in the Caucasus region, situated at the crossroads of Eastern Europe and Western Asia and also known as a Land of Fire (Odlar Yurdu) that some of you might have already noticed the phrase on Atletico Madrid's shirts as of 2012 :)

Lovely view of Baku taken from the Mountain Park

I obtained my BSc degree in Civil Engineering from the Middle East Technical University (METU) in Ankara, Turkey and MSc degree in Structural Engineering from The University of Sheffield in Sheffield, UK and graduated with distinction in 2009 and 2012, respectively. During my MSc degree I worked on a dissertation topic named "Finite Element Modelling of Bosporus Suspension Bridge", the bridge that crosses the Bosporus strait in Istanbul and connects two continents, Europe and Asia. Since then I am fascinated with design and analysis of bridge structures. Hence, after graduation I started working as a Bridge Design Engineer for an industry leading company in Turkey, particularly in Istanbul, and had a chance to design around 30 bridges all over that region before I joined TRUSS. 
Illuminated view of Bosporus Suspension Bridge. Istanbul, Turkey

After gaining extensive bridge design experience now I have been involved in a research project that aims to develop a Structural Performance Monitoring technique for bridges that is cost efficient, practically applicable, and provide higher confidence in estimating the performance condition of the applied bridge structure. The main task behind the proposed research study is to reduce the uncertainties (e.g traffic/railway loading) involved in bridge assessment and to 'measure' quantitatively the performance of a bridge structure using Virtual Instrumentation (VI) concept. VI is a simple concept that integrates the field monitoring tests with a physics based model. It uses deformations (in terms of displacement) obtained from a few installed instruments as a load on a calibrated/updated 3-D FE model to accurately predict the pertinent response of a bridge structure.

The proposed research idea is to first develop an appropriately detailed 3-D FE model of a bridge and calibrate/update it using deformations obtained from intense field tests. Later the final model will be integrated with continuous monitoring system to calculate the stresses and deformations across the whole structure i.e. non-instrumented locations. This concept will also be used to estimate the traffic/railway loading which is the main source of uncertainties involved in bridge assessment. Directly measured or recorded  train/vehicle load and bridge responses will be used to characterise the bridge structure. Later so called Moving Force Identification (MFI) techniques will be applied to estimate the load of a passing train/vehicle.

Currently I am running a test at one of the bridges in Exeter and will update you soon with the results. Hope to see you all again next time!

Stay tuned!