Conducting on a Sturdy Building
Professor Yoo Doo-yeol (Department of Architectural Engineering)
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The current society is suffering from various natural and man-made disasters starting from terrors to earthquakes, such as the recent earthquake that panicked the citizens in Pohang. When a strong impact is made upon the ground, buildings require enough solidity to endure damage in order to protect the people. For a stronger, safer building, professor Yoo Doo-yeol (Department of Architectural Engineering) introduced an improvised concrete in his paper, ‘Effect of fiber geometric property on rate dependent flexural behavior of ultra-high-performance cementitious composite’.
Most buildings are made of concrete, and it takes a huge part on the safety of a building. Concrete is initially vulnerable in tension, so there are already improvised versions of concrete commonly used in North America. The new model contains Micro steel fibers within the concrete to prevent the concrete from breaking into two big pieces. Through the steel fiber, the concrete only results in having micro-cracks even when a sudden weight is stressed upon the concrete. In this already improvised concrete, Yoo made a further research to strengthen this concrete in both quasi-static (a state in which something is almost still, but not completely) and impacted states.
A ‘quasi-static’ state refers to an ordinary state with only mere impacts such as the vibration of footsteps everyday. These two states require a different sturdiness for different purposes, and the researchers concentrate on improving both of these conditions. Yoo focused on the aspect ratio of the micro steel fibers installed in the current improvised concrete. Aspect ratio is a numerical figure of the division of the diameter from the length of the fiber. Once this aspect ratio was changed in a quasi-static state, Yoo found out that the solidity was maintained and the energy absorption force was strengthened even when the amount of micro steel fibers were reduced. With the same amount of micro steel fibers with the changed ratio, Yoo was able to discover that the energy absorption force almost doubled within a shocked state.
Yoo emphasized the importance of this improvised matter. “Protecting the citizens within the buildings is becoming an urgent matter as countless accidents are occurring more frequently. The current structures lack enough safety to minimize the loss of lives.” The breaking of cement is distinctly more critical than the cracks in cement. Therefore, thorough research is required to make a sturdy building. “We had difficulties in capturing the process when the cement was impacted,” reminisced Yoo. The test cement is fully demolished within 0.001 second (a millisecond), and he had to capture all of the procedures within that millisecond. No kinetic equipment is available in Korea. As a result, he had to proceed with his research research by using the equipment from the University of British Columbia. Despite their mechanical hardships, Yoo made an innovative result in the field of architecture.
2017 is only his second year as a professor in Hanyang University. As the field of architecture is conservative, his final goal is to make practical application with his research. “Various factors such as durability and energy absorption force need to be considered when building a structure as it is directly related to the people living inside the building. This is only the beginning. I still have a lot more factors to work on, but I will continue my research enthusiastically until my studies can be applied to daily structures,” commented Yoo.
On Jung-yun firstname.lastname@example.org
Photos by Choi Min-ju
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