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TOKYO METROPOLITAN UNIVERSITY

Research Issuescompany

In this research, we focused on the following five categories:
‘Concrete Engineering’ and ‘Steel & Composite Structural Engineering’ as the structural materials, ‘Underground Structure’ as the structural form, ‘Soil Mechanics’ which significantly influences on structures, and ‘Traffic Engineering & Infrastructure Planning’ plays an important role in the infrastructure systems.
We worked on the 5 tasks as follows to seek the measures for ensuring the long-term safety of urban infrastructures.

1 Defining the Deterioration Mechanisms and Establishing the Methods of Degradation Prediction and Durability Evaluation

Concrete Engineering Field
We examine the methods of degradation prediction and durability evaluation with defining the cracking behavior which affects the durability of concrete structures and the relationships between degrading factors and pore structures of cement hydrate, and clarifying the impacts of the quality of constructions and materials on the structures’ durability.
Steel and Hybrid Structural Engineering Field
Considering fatigue crack and steel corrosion, we explore how to evaluate the load-bearing capacity of the aging structures and try to establish the residual life prediction, the degradation control method, and the permanent repairing and reinforcing measures.
Underground Structure Field
Underground structures in big cities have many destabilizing factors like tunnels in close proximity or in the soft ground. We examine the evaluation methods of the subsidence and deformation behaviors based on the characteristics of the unstable ground such as soft foundation, liquefaction, landslide and cutting.

2 The Examinations and the Diagnoses by Non-destructive Tests, Monitoring Inspections, and Maintenance Methodologies

Concrete Engineering Field
From the point of the view of the economic efficiency and the damages to structures, it is important to figure out the structures’ performances or the conditions by aging degradation without destroying, though, it seems the truth about the reliability of data by the non-destructive tests is poor at the current level of the measurement accuracy. However, it is expected that the aging structure will be increased more and more in the future, we try to improve its accuracy by evaluating the applicability of the non-destructive diagnostic techniques that can be used with relative ease such as the ‘Acoustic Emission’ method to concrete structures.
Steel and Hybrid Structural Field
Monitoring the progress of fatigue crack and corrosion degradation is useful to ensuring the structural safety. We conduct our research on monitoring techniques for steel and hybrid structures.
Underground Structure Field
In order to ensure the safety of underground structures considering the ground characteristics, ground characterization technology by the non-destructive diagnosis is indispensable. We work on the evaluation techniques for the micro-tremor measurement results of the ground, the adaptability to the geophysical exploration technology for the subsurface geology and improving its accuracy.

3 The Repair and Strengthening Techniques for Ensuring Structural Safety

Concrete Engineering Field
Recovering the required performance of the aging structures is crucial for ensuring the structural safety. We aim to establish the strengthening technique for the existing concrete structures with the results of the examinations for the load-bearing capacity of the repaired or strengthened structures and the measures to prevent peeling by bonding the repaired surface.
Steel and Hybrid Structural Engineering Field
It is known that fatigue cracks due to cyclic loading has been becoming seriously in steel and hybrid structures. With the aim of ensuring the structural safety by inhibiting cracks, we develop the fatigue life prediction methods and the repair and strengthening techniques by using CPFR plates for steel and composite structures.

4 The Ground Characteristics Affecting Underground Structures and the Stabilization Technologies of Unstable Ground

Underground Structure Field
The ground characteristic in the urban area is not always in good conditions for construction. Underground structures are built in severe conditions, such as some structures have been constructed close to each other, and it is difficult to be repaired or strengthened compared to other subsurface infrastructures. So, maintaining their original quality when building is crucial for making underground infrastructures to last for ages. We pursue the high-accuracy technologies for underground construction and the high-quality techniques for building underground structures, like the way of driving tunnels by controlling deformation due to excavation.
Soil Mechanics Field
In order to inhibit the deterioration of underground structures due to ground deformation, we should recognize the deformation around the structures and improve or reinforce its characteristics appropriately. In our research, we examine the evaluation methods for ground deformation because of soft foundation, liquefaction, landslide or cutting and the stabilization technologies of unstable ground.

5 The Estimation Methods of Traffic Conditions Applied to the Asset Management　

Traffic Engineering and Infrastructure Planning Field
Due to changes in economic activity and society in future, utilization and priority of existing urban infrastructures are expected to be changed. From the standpoint of the asset management and securing the emergency road networks in the disaster circumstances as earthquake at the metropolitan area, we consider about the ideal form of the road transportation network in big cities and study the estimation methods of traffic conditions.