Structural Safety Evaluation
Safety Evaluation for Damaged Structures
1. Development of In-Service Fitness Evaluation Technology for Industrial Infrastructure (2005-)
- This long-term project deals with fitness-for-service which is defined by API as the ability to demonstrate the structural integrity of an in-service component containing a flaw or damage.
- I am taking charge of crack like flaws in steel bridges.
2. Quantification of Structural Response Variations by Damage for Safety Evaluation of Steel Box Girder Bridges (2003-)
- The objective of this project is to obtain quantified relationships between crack like damages and structural response variations. The relationships represented as relation curves might be utilized for detecting damage or evaluating structural performances. To obtain these relationships, 1/5 scaled models simulating steel box girder with cracks of various locations and shapes were produced and finite element analyses and structural experiments were carried out with the models.
- I am playing a leading role in this project. I have operated the experiments, analyzed the measured and calculated data, and designed the model specimens, virtual steel box girder bridges, and strong frames for sustaining applied load.
3. Development of Crack Detection Technique and Failure Criterion for Fatigue Damaged Steel Bridges (2002-2004)
- As a preceding study of the project described above, the object of this study was I-sectioned steel beam with cracks. The variations of structural responses were investigated with crack growth. Fracture toughness and tension tests were also performed to obtain material properties of ductile structural steels. It was found out that general fracture toughness tests could not be applied to the structural steels because of ductility, and therefore, the critical stress intensity factors for various thicknesses could be more available.
- I have played a leading role in this project. It was a particularly good opportunity for me to experience various kinds of standardized material tests including JIC, KIC, and tension tests.
4. Fatigue Damage Evaluation for Steel Structural Members (1999-2001)
- The estimation of stress intensity factor in structural members of complicated boundary conditions was the main subject on this project. To estimate stress intensity factor by measuring strain around the crack, the location of measurement, type of strain gage, and the process of data analysis were investigated.
- I have played a leading role in this project.
5. Structural Safety Evaluation for Various Structures (1995-1997)
- In graduate school days, I participated in structural safety evaluations in order to determine load carrying capacity for about 10 bridges.
- This long-term project deals with fitness-for-service which is defined by API as the ability to demonstrate the structural integrity of an in-service component containing a flaw or damage.
- I am taking charge of crack like flaws in steel bridges.
2. Quantification of Structural Response Variations by Damage for Safety Evaluation of Steel Box Girder Bridges (2003-)
- The objective of this project is to obtain quantified relationships between crack like damages and structural response variations. The relationships represented as relation curves might be utilized for detecting damage or evaluating structural performances. To obtain these relationships, 1/5 scaled models simulating steel box girder with cracks of various locations and shapes were produced and finite element analyses and structural experiments were carried out with the models.
- I am playing a leading role in this project. I have operated the experiments, analyzed the measured and calculated data, and designed the model specimens, virtual steel box girder bridges, and strong frames for sustaining applied load.
3. Development of Crack Detection Technique and Failure Criterion for Fatigue Damaged Steel Bridges (2002-2004)
- As a preceding study of the project described above, the object of this study was I-sectioned steel beam with cracks. The variations of structural responses were investigated with crack growth. Fracture toughness and tension tests were also performed to obtain material properties of ductile structural steels. It was found out that general fracture toughness tests could not be applied to the structural steels because of ductility, and therefore, the critical stress intensity factors for various thicknesses could be more available.
- I have played a leading role in this project. It was a particularly good opportunity for me to experience various kinds of standardized material tests including JIC, KIC, and tension tests.
4. Fatigue Damage Evaluation for Steel Structural Members (1999-2001)
- The estimation of stress intensity factor in structural members of complicated boundary conditions was the main subject on this project. To estimate stress intensity factor by measuring strain around the crack, the location of measurement, type of strain gage, and the process of data analysis were investigated.
- I have played a leading role in this project.
5. Structural Safety Evaluation for Various Structures (1995-1997)
- In graduate school days, I participated in structural safety evaluations in order to determine load carrying capacity for about 10 bridges.
Application of Acoustic Emission Technique
1. Development of Acoustic Emission Monitoring Technique for Reinforced Concrete Flexural Members (2001-2003)
- The subject of this project is to identify the differences of acoustic emission signal patterns between normal and abnormal conditions. Since the concrete under loads has so many signal sources even in normal conditions, the approach of analyzing acquired signals should be different with the case of steel. The signal patterns of normal conditions under various loading amplitudes and of abnormal conditions when the failure was in process, were acquired by experiments, and those signal patterns were classified. A prototype acoustic emission system suited for concrete structures was also developed.
- I have played a leading role in this project.
2. Application of Acoustic Emission Technique for Detecting Fatigue Crack in Steel Bridge (1998-2000)
- Several field tests in real bridges and some fatigue tests in laboratory were carried out to develop a process for applying acoustic emission technique to steel bridge. Characteristics of acoustic emission signals from fatigue crack were obtained, and field application process of the technique was proposed.
- This is a posterior study of the project described below. I have continually played a leading role to develop practical techniques at KRISS.
3. Development of Acoustic Emission Technique for Detecting Fatigue Crack in Steel Bridge (1995-1997)
- This was a ground work for applying acoustic emission techniques to detect fatigue crack in steel bridges, basic properties of elastic waves in structural steels and methods to acquire acoustic emission signals were examined. The kinds, speed, and attenuation of the waves, the sensor arrangement to locate fatigue crack, and the methods to eliminate noises were obtained from this project.
- This was my first research project. With my entrance to graduate school, I joined this project from the beginning and completed it just before my graduation. The subject of my master’s thesis was the application of acoustic emission and I formed a connection with KRISS as a cooperating institute through this project.
- The subject of this project is to identify the differences of acoustic emission signal patterns between normal and abnormal conditions. Since the concrete under loads has so many signal sources even in normal conditions, the approach of analyzing acquired signals should be different with the case of steel. The signal patterns of normal conditions under various loading amplitudes and of abnormal conditions when the failure was in process, were acquired by experiments, and those signal patterns were classified. A prototype acoustic emission system suited for concrete structures was also developed.
- I have played a leading role in this project.
2. Application of Acoustic Emission Technique for Detecting Fatigue Crack in Steel Bridge (1998-2000)
- Several field tests in real bridges and some fatigue tests in laboratory were carried out to develop a process for applying acoustic emission technique to steel bridge. Characteristics of acoustic emission signals from fatigue crack were obtained, and field application process of the technique was proposed.
- This is a posterior study of the project described below. I have continually played a leading role to develop practical techniques at KRISS.
3. Development of Acoustic Emission Technique for Detecting Fatigue Crack in Steel Bridge (1995-1997)
- This was a ground work for applying acoustic emission techniques to detect fatigue crack in steel bridges, basic properties of elastic waves in structural steels and methods to acquire acoustic emission signals were examined. The kinds, speed, and attenuation of the waves, the sensor arrangement to locate fatigue crack, and the methods to eliminate noises were obtained from this project.
- This was my first research project. With my entrance to graduate school, I joined this project from the beginning and completed it just before my graduation. The subject of my master’s thesis was the application of acoustic emission and I formed a connection with KRISS as a cooperating institute through this project.
Large Scale Structural Test
1. Establishment of Calibration System of Safety Measurements for Blade of Wind Power Generator (2004-)
- I am taking charge of designing structural experiment systems including reaction wall, loading frames, and grips.
2. Fatigue Life Evaluation Test for Corroded Checkered H-Beam (2004)
3. Durability Test of Hydraulic Top Bracing in Huge Cargo Ship (2004)
4. Fatigue Strength Evaluation Test for Steel-Concrete Composite Slab in Bridge (2002-2003)
5. Damage Evaluation Test of Bolted Joints for Steel Structures (2002-2003)
6. Simulation Test of Offshore Structures for Evaluating Seismic Effect (2002)
7. Friction Coefficient Test for Spherical Bearing of Bridge Shoe (2002)
8. Construction of Large Scale Structural Test Laboratory (1999-2001)
- To extend the structural test facility, another structural laboratory with a strong floor of 40×30 (m) was built in our research center. I joined as a vice-supervisor from design to construction of the laboratory.
9. Design and Development Test of Korean Trainer and Light Attack Plane (1999-2001)
- This test was part of a national project to develop a Korean trainer and light attack plane. The mission of our team was to evaluate damage tolerances by simulated random loading fatigue tests for the components of the rear fuselage.
- Since the manager of our structural laboratory left for a year just after setting the test, I had to play roles not only of an operator but also as a manager. During the next two years, I worked eighteen hours a day to submit test results on time and wrote 2,700 pages of technical reports. From this opportunity, I learned so much about structural experiments.
- I am taking charge of designing structural experiment systems including reaction wall, loading frames, and grips.
2. Fatigue Life Evaluation Test for Corroded Checkered H-Beam (2004)
3. Durability Test of Hydraulic Top Bracing in Huge Cargo Ship (2004)
4. Fatigue Strength Evaluation Test for Steel-Concrete Composite Slab in Bridge (2002-2003)
5. Damage Evaluation Test of Bolted Joints for Steel Structures (2002-2003)
6. Simulation Test of Offshore Structures for Evaluating Seismic Effect (2002)
7. Friction Coefficient Test for Spherical Bearing of Bridge Shoe (2002)
8. Construction of Large Scale Structural Test Laboratory (1999-2001)
- To extend the structural test facility, another structural laboratory with a strong floor of 40×30 (m) was built in our research center. I joined as a vice-supervisor from design to construction of the laboratory.
9. Design and Development Test of Korean Trainer and Light Attack Plane (1999-2001)
- This test was part of a national project to develop a Korean trainer and light attack plane. The mission of our team was to evaluate damage tolerances by simulated random loading fatigue tests for the components of the rear fuselage.
- Since the manager of our structural laboratory left for a year just after setting the test, I had to play roles not only of an operator but also as a manager. During the next two years, I worked eighteen hours a day to submit test results on time and wrote 2,700 pages of technical reports. From this opportunity, I learned so much about structural experiments.