Toshiaki Mizobuchi

Prediction of Complex Deterioration and Evaluation of RC Structural Performance

RC structural performances (load-bearing performance) degrade by deterioration of reinforcement bar. We should maintenance to structural performance degradation.

Study on Effect of Heat Elimination by Pipe Cooling System in Beam Using High Strength Engineered Cementitious Composites

In the field of construction, the innovative technique using the coupling beam making use of characteristics of the Engineered Cementitious Composites (ECC) has been proposed, for instance the energy absorption by concentrating the seismic force in the core wall is implemented in high-rise R/C structures (Kanda 2006). Moreover, study with the aim of high strengthening of the coupling beam has been carried out. However, in the high strengthening coupling beam, possible temperature increase in a relatively massive element section exceeding 100 °C due to the heat of cement hydration has been concerned. When temperature in the member exceeds 100 °C due to the heat of cement hydration, the performance of organic fibers (the high-strength polyethylene fibers) is significantly reduced. Hence, in order to control the excessive temperature rise due to the heat of cement hydration, the analytical study was carried out for a pipe cooling system adopted as a countermeasure. On the basis of results of temperature measurement for the ECC coupling beam, design of the pipe layout to control the maximum temperature in the member lower than 90 °C was carried out and thermal properties were also identified. In this report, the experiments for evaluating the effectiveness of pipe cooling were described and the results were discussed.

Theoretical and experimental study on estimation of chloride content in concrete using electromagnetic wave

It is very difficult to detect chloride-induced corrosion early, because it is not possible to confirm the degradation of concrete until cracks induced by corrosion expansion of re-bars appear on the concrete surface. Thus, development of truly non-destructive tests to estimate the chloride content in concrete could make it possible to study the changes in chloride concentration over time, without having to physically approach the structure, or cause any damage to it. Such methods would greatly improve our ability to foresee the possibility of reinforcement corrosion at early stages, and enable us to take the required corrective action at an appropriate time. In this report, in order to evaluate the applicability of non-destructive method which is possible to estimate the chloride content included in cover concrete, the results of theoretical and experimental attempts to estimate the chloride content in cover concrete of the RC structure using the electromagnetic waves are reported.

Development of FEM Thermal Analysis for Concrete Structures with Pipe Cooling System

In this study, a new numerical method of pipe-cooling thermal analysis is presented in order to achieve arbitrary layout of the cooling pipe independent of FEM mesh arrangement. Then, some thermal analyses for concrete structural model with pipe cooling system are executed and validity of the proposed numerical method is discussed. As a result, it is confirmed that the proposed analytical procedure can simulate quite rational temperature histories despite of the cooling pipe layout independent of FEM mesh arrangement.