Earthquake Resistant Engineering
To ensure the structural safety under large earthquakes, our research is aimed at establishing comprehensive seismic design methodologies as well as characterizing earthquake response characteristics and failure mechanisms of structures through analytical and experimental investigations.
The emphasis is placed on the collapse mechanisms and associated behaviors of structures and their members under large cyclic loading. Experimental techniques integrated with stable control algorithm is being developed in order to simulate the seismic behavior of structures under large deformations. The outcomes of our research would motivate advances in seismic design practices.
Associate Professor (Disaster Prevention Research Institute)
- Autonomous Structural Integrity Assessment System for Steel Structures
- Heuristic Damage Detection of Structures Using Model Updating Approach
- Cyber-enabled Wireless Monitoring System for Large Scale Structures
- Structural Members Capable of Self Damage-Prognosis.
Uji Campus, Main Building S-308D
Experiments and Analyses on Behavior of Structures to Complete Collapse
In modern seismic design, the performance-based design philosophy has been adopted. According to this design philosophy, structures are designed to satisfy a set of performance objectives so as to maintain functionalities, limit structural damage, and ensure the life safety during earthquakes.
To ensure the life safety, it is important to quantify the collapse mechanism as well as strength and deformation capacity of structures. Here, collapse is defined at the stage in which the structure is no longer capable of sustaining gravity loads. The collapse limit is quantified experimentally.
Figure 1 Loading Test of Full-Scale Moment Frame
Simulation of Responses of High-rise Buildings under Earthquakes
To establish comprehensive seismic design method, experimental information on the collapse behavior of structures is of necessity. Experimental techniques commonly employed are quasi-static test, in which a structural model is loaded slowly in accordance with a specified load history, and shake table test, in which a structural model is vibrated on a shaking table. In addition, a testing procedure called the on-line test is a promising alternative. According to this technique, experimental testing on a structural model is conducted in conjunction with numerical analyses wherein experimental and numerical information is exchanged continuously.
The on-line test is now extensively developed. It is used along with the substructure technique, in which a part of a structure is tested under real-time loading while the behavior of the other parts of the structure is simulated through dynamic analysis. An earthquake response simulation system, which can deal with structures whose behavior depends strongly on the velocity, is also developed.
Figure 2 Real-time On-line Test of Base-Isolated Structure
(Application of Substructure Method)
Connection Quality and Seismic Performance of Existing Steel Buildings
Welding inspection and loading tests are conducted to beam-to-column connections cut out from existing steel buildings constructed in several decades to verify the true connection quality and seismic perfoemance.
Beam-to-column connections are cut out from the demolish work site of existing buildings and brought into the laboratory. First, coupon tests and ultrasonic inspection of welds are conducted. Then dynamically loaded with increasing amplitude to verify plastic deformation capacity and the fracture process of connections. After that, welded joints are cut off and the fracture surfaces are observed circumstantially and weld defects are inspected by macro-structure tests.
Figure 3 Dynamic loading test of subassemlage obtained from existing building