A method for constructing reinforced concrete foundations using earth retaining walls exists, but prolonged work periods in the case of specifications that call for a large amount of reinforcement are a concern. To address this issue, the authors devised a method utilizing H-shaped steel with protrusions, which is typically used for bridge pier structures. However, in foundation structures, the main reinforcement ratio is sometimes higher than that of bridge piers, and the structural performance of foundations using H-shaped steel was unclear. In this study, the reversed cyclic load test was carried out using test specimens with a main steel ratio of 4%. The results confirmed that the proposed foundation exhibits structural performance equivalent to or exceeding that of a conventional reinforced concrete foundation.

Cracking and spalling in cover concrete caused by steel corrosion are known to result from the combined effects of carbonation and water ingress. Therefore, in order to reasonably predict future durability during the maintenance phase, it is essential to develop an anomaly prediction method that appropriately accounts for both factors. The present study proposes such an anomaly prediction method for practical application in maintenance planning. The proposed method incorporates a model in which the corrosion rate of steel varies depending on the degree of carbonation progress when water ingress occurs, enabling simple prediction of the onset of corrosion-induced cracking and spalling. Furthermore, by applying the method to actual inspection data of existing structures, it was confirmed that the proposed method can reasonably predict the timing of the appearance of anomalies.

In this study, we developed and validated a monitoring system for RC residential buildings that enables damage assessment using only two accelerometers, without requiring prior structural analysis or design documentation. The system utilizes two indicators estimated from acceleration records: the maximum overall drift angle and the overall plasticity ratio, as metrics for damage evaluation. The overall plasticity ratio is defined as the ratio of the maximum relative displacement to the displacement at which the global stiffness of the building decreases due to yielding of structural members (hereafter referred to as the "damage displacement"). The accuracy of estimating relative and damage displacements was verified primarily through time-history response analysis results. The results demonstrated that damage assessment is feasible using the maximum overall drift angle and overall plasticity ratio, and confirmed the potential applicability of the system for quick inspection.

In this study, the properties of recycled concrete powder (RCP), assumed to be generated as a by-product during the production of recycled aggregates, were first characterized. Then, the compressive strength and chloride permeability of mortars incorporating a small amount of silica fume and RCP activated by the ball mill mixing method were evaluated. The results showed that combining the two materials enhanced the compressive strength of mortars made with ordinary Portland cement and blast furnace cement type B. Notably, in the case of blast furnace slag cement, adding RCP and silica fume greatly enhanced the silica fume’s pozzolanic reaction. Furthermore, the addition of RCP was found to suppress chloride permeability regardless of the type of cement used.

A damage classification method for unbonded precast prestressed concrete columns was proposed, based on the assumption that the maximum experienced bending moment is known. When classifying the damage of a member based on the limit state, assuming the reuse of the precast columns, only the concrete compressive strain and the residual crack width need to be determined to obtain the final damage judgement result. By converting the criteria of the limit states expressed in terms of compressive strain of concrete into bending moments, the experimental results could be evaluated conservatively.