Civil Engineering
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Development of radiation technology to clarify the microstructure of concrete, which is becoming more diverse in a decarbonized society
Concrete, the main construction material, is the second most widely used substance after water. As concrete has a large environmental impact on a global scale, we are conducting research at the ultrafine level of its internal structure of concrete using advanced radiation technology to develop a new type of concrete that reduces the emissions of carbon dioxide and other gases that accompany its manufacture, without compromising its strength or durability. In this way, we can achieve a decarbonized society.
Takafumi Sugiyama, Katsufumi Hashimoto, and Michael Angelo B. Promentilla,
Grant-in-Aid for Scientific Research(B) 2025.4.1～2028.3.31
Transport of radioactive elements in concrete due to utilization of recycled aggregate contaminated with nuclides
In the future, a huge amount of concrete waste will be generated in preparation for the demolition of nuclear power plants. From the perspective of rational processing and disposal, it is possible to reuse this waste, particularly waste with low levels of radioactivity, as recycled aggregate. Clarifying how radioactive materials migrate inside concrete is extremely important in building a safe and secure society.
Yingyao Tan, Takafumi Sugiyama, Katsufumi Hashimoto, and Junxiao Liu
Construction and Bulding Materials, Volume 471, 11 April 2025, 140689
Seismic performance of a bridge pier integrated by multiple steel pipes with directly-connected piles using soil-water coupled with three-dimensional elasto-plastic finite element analysis
A new type of bridge support using connected steel pipes was tested to see if it performs as well as traditional designs during earthquakes. Small-scale shaking tests showed that it works just as well or even better. However, since only one type of shaking was tested, we are now using computer simulations to see how it reacts to different kinds of earthquake motions. This will help us better understand how safe and reliable this new bridge design is for the future.
Muhammad Mahmood Ul Hassan, Koichi Isobe, Yasumasa Soga, Yasuo Sawamura, Hiroki Sugiyama, and Masatsugu Shinohara
Study on long-term subsidence of soft clay due to Niigata-ken Chuetsu-oki earthquake of 2007
In the 2007 Niigata-ken Chuetsu-oki Earthquake, ground liquefaction was severe in sandy areas, but long-term settlement occurred in soft clay in Kashiwazaki’s Shinbashi district. Even without visible damage, the ground sank 71 mm over 14 years. We studied this by boring and testing soil samples, finding the clay to be soft and highly compressible. Using a specialized computer model (TS-CM), we successfully simulated the ground’s behavior, showing that this type of clay is prone to long-term sinking after earthquakes due to water pressure buildup and delayed consolidation. These findings help predict future ground behavior in similar soils.
Yazhou Jiang, Koichi Isobe, Satoru Ohtsuka, and Toshiyuki Takahara