拘束材に集成材を用いた座屈拘束ブレース(木鋼BRB)の繰り返し載荷実験を行いました。本研究は木鋼ハイブリッド構造に関する研究シリーズの1つです。近年の木質構造需要を受けて、拘束材を木質化した座屈拘束ブレースの開発が国際的にもホットな話題になりつつありますが、脆性的な破壊が想定される木質拘束材の変形性能はいまだ不明な点が多いです。そこで本研究は実大を含む13体の木鋼BRBの繰り返し載荷実験を行い、その破壊性状と変形性能の関係を調べました。今度はそう壊れたか、というように毎回異なる破壊モードが確認され、今後の設計式の完成に必要な基礎的知見が溢れんばかりに得られた感動的な実験でした。論文はこちら
Buckling-restrained braces with mass timber restrainers (MT-BRBs) have recently been investigated by several researchers. However, timber restrainers exhibit brittle failure modes and have lower stiffness and strength than their composite and steel counterparts. Previous experiments have demonstrated that timber restrainers are particularly susceptible to local bulging and that this is a brittle failure resulting in a near total loss of strength. Nevertheless, local bulging and global stability design methods have not yet been established for BRBs with timber restrainers. This paper presents cyclic loading tests of MT-BRBs featuring different bolted restrainer compositions, core plate clearances, reinforcing plate arrangements, connections and boundary conditions. These tests produced a variety of weak- and strong-axis bulging and global buckling failure modes. Design methods were developed to prevent each failure mode and then used to design full-scale MT-BRBs that were successfully tested and exhibited excellent performance.