In this study, the possibility of carbonation prediction using the surface water absorption test was compared and reviewed with the air permeability test for concrete with various water cement ratios, mixed with fly ash with various replacement rates, and concrete placed in normal and hot environments. As a result, the relationship between carbonation coefficient, water absorption coefficient, and effective cement amount was very correlated by proposed equation (4) regardless of the type of mixture, water cement ratio, and hot or normal environment. Therefore, the surface water absorption test method is useful in predicting carbonation for a range of concrete.

Using of phenolphthalein solutions in fire-damaged concrete was investigated, leading to the following conclusions.

1. Traditionally, colorless areas appeared after spraying waterless phenolphthalein solution on fire-affected concrete, thought to be above 500°C. However, these areas were actually dry regions exposed to temperatures over 150°C.

2. Even in aged concrete structure undergoing carbonation and drying over time, it was determined that the use of a waterless PP solution enables the identification of areas experiencing temperatures above 150°C.

3. By using water-containing PP solution, the thermal decomposition range of CaCO₃ where was heated above 600°C can be identified.

Each time a new problem has arisen in the concrete field, solutions have been sought. Although the process of dealing with such problems has been documented in the historical timelines of academic societies, the efforts of companies have not been covered. Therefore, we will use patent information to examine technological transitions, including the efforts of companies.

This study investigates one of the technologies for solving chloride attack of concrete from a microscopic point of view, using the citation relationship of patents. This will provide basic data to clarify one specific transition in surface impregnation method and inspire the new developments.

This paper proposes a methodology that can accurately predict the overall response of base-isolated structures by leveraging eigenvalues (natural period, viscous damping constant), participation vectors, and bilinear hysteresis parameters (hysteresis damping constant, bilinear coefficient, ductility factor) derived from complex eigenvalue analysis. This analysis introduces estimating formulas for complex eigenvalues, which can be calculated using data obtained from elastic eigenvalue analysis.

As a result, it was found that complex eigenvalues could be estimated with high precision using the proposed estimating equation. Moreover, it was confirmed that the method provides high accuracy in predicting both response displacement and response acceleration.

An analytical model for evaluation and its validity were verified by walking experiments regarding the structural design for floor vibration caused by walking in over-track buildings composed of passageways and concourses.

(1) In the area of the passageway, the frequency that excels as the frame and the frequency that excels as a slab is different. Therefore, it is necessary to evaluate it with an analytical model for the frame that can evaluate the frequency of both.

(2) In the concourse area, it is possible to evaluate the floor vibration even with an analysis model of the floor slab range.

In passive control systems in wooden houses, the members and joints around the damper (: support member) tend to be deformed locally, which reduce the energy absorption of the damper. The authors have proposed the passive control system with post-tensioned and reinforced support members. In this paper, the effectiveness of the system is verified from the mechanical and dynamic characteristics and seismic behavior obtained through static and dynamic tests and shaking table tests. Also, the maximum response prediction method of the passively controlled wooden frame with oil dampers is proposed and predict the results of the shaking table tests.

When the ductile behavior is ensured by yielding at moment resistant joints in semi-rigid timber frame structures, the elastic stiffness decreases. When the yield strength of the moment resistant joints increases, the load carrying capacity of frames is determined by the shear failure at the panel zone in through columns. Furthermore, plastic deformation at the compression side in the moment resistant joints causes slip behavior, which reduces the amount of absorbed energy. In order to solve these problems, the structural system with the yielding mechanism which is made from the yielding at the panel zone joint metal is devised.

In recent earthquakes, it has been reported that members supporting air-conditioners (suspension support members) have been cyclically deformed and fractures at the suspension source or equipment support. The fall of the equipment due to the fracture of suspension support members is a serious damage that directly leads to the loss of building functions. In this study, cyclic loading tests were conducted to investigate the stiffness, strength, and low cycle fatigue characteristics of the suspension support members. Based on these findings, the results of the study on the necessary strength of the suspension support members were presented.