“Design Guidelines for Lateral Load-carrying Capacity Calculation of Prestressed Concrete Buildings（Draft）” has been published by Architectural Institute of Japan in 2020. Many PC buildings were designed using the revised seismic design method in 1981. However, there is no guideline from AIJ about its design method of PC structures. The characteristic of this guideline that a damage control design for the 1^st level and a safety design for the 2^nd level, are clearly shown. The members have to be designed serviceability limit at the 1^st level. And the lateral load-carrying capacity calculation for the assumed hinge mechanism of a building, are carried out at the 2^nd level.

Applying buckling restrained braces (BRBs) is effective in ensuring the earthquake resistance of reinforced concrete (RC) frames. However, to fully achieve the intrinsic performance of BRB, it is necessary to ensure sufficient rigidity and strength against the combined stresses acting on the connections between the RC frame and BRBs. In this study, we propose a new connecting method and clarify its mechanical behavior. First, component tests and analysis of the proposed BRB connection were performed, and a strength evaluation formula was proposed. Next, experiments and analyzes of RC frame subassemblies incorporating BRBs were performed, and their mechanical behavior was ascertained. Further, seismic response analysis of RC frames incorporating BRBs was performed to ascertain their dynamic behavior. A construction experiment was also conducted to determine workability. Lastly, the design method of the proposed BRB connection is described.

Round robin test for repair methods at Hashima was performed by technical committee of Japan Concrete Institute. Reinforced concrete structures in Hashima would be the most extreme deteriorated ones in the world. Hence, round robin test for repair methods would be a good opportunity to consider their conservation of the concrete structures. The round robin test will contribute improvement of repair method for reinforced concrete structures. This paper reports on results of 2-year exposure test at Hashima Island.

Established by the Japan Concrete Institute, the “Technical Committee on Clarification of Mechanism and Countermeasure for Combined Deterioration of RC Structures” operated from April 2017 to September 2019. This committee sorted out the research findings and investigation results regarding combined deterioration of RC structures and examined the progression mechanism and actual conditions of combined deterioration, and the achievements made with regard to repair and reinforcement for combined deterioration. Focusing on chloride attack and carbonation, chloride attack and frost attack, chloride attack and ASR, and frost attack and ASR, this paper clarifies the progression mechanism of deterioration from the perspective of materials science, and reports the results of the investigation of the actual conditions of the progression of deterioration both in the lab and in actual structures. Further, based on comparison of the above factors, it sorts out the respective effects of the various deterioration factors on combined deterioration.