本研究は，スラブ状RC構造物の押抜きせん断破壊性状に対して我々が提案する非線形三次元有限要素法の適用性を検討したものである． これまで，RC構造物の押抜きせん断破壊耐力算定に関する解析的な研究は少なく，主として経験的なアプローチが数多くなされてきたが，本研究では，載荷位置を変化させた薄いRCスラブおよび，フーチングのようなやや厚みのあるスラブや曲げモーメントを受ける柱付きフーチングの押抜きせん断実験結果とFEM解析結果の比較検討を行った．その結果，著者らが開発した解析方法によって，耐荷力，斜めひび割れ性状および，荷重－変位関係において実験結果を概ね捉えられる事が示された．
3次元剛体バネモデルによりコンクリートの圧縮破壊挙動を定量的に再現することを目的とし,同手法の構成モデルの検討と材料パラメータの同定を行った.その結果,垂直バネの引張側に引張軟化挙動を,圧縮側に逆S字形の非線形挙動を,せん断バネにモール・クーロン型の降伏基準と軟化をモデル化することにより,1軸圧縮下におけるコンクリートの軟化・局所化挙動および高拘束圧領域に至るまでの多軸効果による強度増加,体積変化挙動を妥当な精度で再現できることが分かった.
In order to enhancement accuracy of shear design of reinforced concrete (RC) beams, detail understanding of the shear resistance mechanism is required. This study evaluated the shear resistance mechanism of RC beams based on arch and beam actions by using three dimensional Rigid-Body-Spring-Method (3-D RBSM). Firstly, RC deep and slender beams with and without shear reinforcement failed in shear were tested to measure local behavior. Then, the validity of local behaviors obtained from 3-D RBSM was confirmed by comparing with the test results and the applicability of decoupling of shear resistance mechanism using simulated stress distribution was presented. Moreover, the contributions of arch and beam actions in RC beams until failure stage were investigated numerically by changing the shear reinforcement ratio and shear span to depth ratio and was compared with the current shear design recommendations in JSCE Standard Specification. As a significant finding, the numerical results upon the quantitatively evaluation of shear resistance mechanisms that the shear strength of RC beam could be evaluated without classification of deep beams and slender beams was presented.
In order to accumulate data on tritium transferred to cooling water of a fusion reactor, a series of experiments of tritium permeation into water jacket pressurized to 0.8MPa by He gas was performed through pure iron piping, which contained about 1 kPa of pure tritium gas at 423 K. Chemical forms of tritium permeated into water were monitored periodically under continuous purging water jacket by He. Observation of metal surface was also carried out periodically by SEM and XRD analysis.The actual tritium permeation rate was about 1/5 level of the calculated value. Even if surface oxide layer (magnetite, porous & fine layers) grew in the water boundary, tritium permeation rate to water was not changed drastically. On the other hand, hydrogen gas (HT) fraction of tritium permeated in water jacket decreased drastically with oxide layer growth. Furthermore, permeated species and amounts were not affected clearly by the dissolved hydrogen in water by purging 1% H2 in He.
