AbstractThis paper presents the numerical simulations of the reinforced concrete (RC) panels and the RC shear walls under monotonic and cyclic loading in order to validate the ability of the proposed model which is based on the Rigid-Body-Spring Model (RBSM) to predict the crack propagation behaviours. The authors have already developed constitutive models for the three-dimensional RBSM with random geometry in order to quantitatively evaluate the mechanical responses including softening and localization fractures, and have shown that the model can well simulate the cracking and failure behaviours of RC members. In this study, the constitutive models were extended to include cyclic effects and the model was validated through the simulations of the RC panel tests under cyclic loadings, which were reported in the literatures. Furthermore, the simulations of the RC shear wall tests, which were tested in the context of the international benchmark ConCrack (http://www.concrack.org/) were carried out, and the capability of the model to predict the detailed cracking information, such as crack width, spacing and direction of propagation is discussed.Keywords: rigid-body-spring modelcrack propagationshear wallcyclic loading AcknowledgementsThis study was financially supported by JSPS, Grant-in-Aid for Young Scientists (B), No. 24760373.
This study investigated applicability of the developed numerical simulation analysis that comprised of corrosion-induced crack, bond deterioration and the change of mechanical properties with beam element for rebar introduced in 3D-RBSM. The developed analysis was first applied to pull out bond test of corroded rebar. Then, the analysis was applied to PC member failed in flexure to validate the accuracy and the influence of rebar corrosion on mechanical behaviors of members. As a results, it was confirmed that the manifestation and propagation of crack due to rebar corrosion, reduction of bond strength due to corrosion induced crack and the reduction of bending cracking load, stiffness and ultimate displacement with PC tendon breaking can be calculated reasonably. The proposed numerical analysis has capability simulate the corrosion-induced crack distribution and ultimate state of deteriorated PC structures due to rebar corrosion.
本研究は,帯鉄筋により補強された横拘束コンクリートの内部抵抗機構を解明することを目的として,著者らが提案している,コンクリートの準微視的な力学挙動をモデル化した3次元RBSMの適用性を検証するとともに,供試体形状・寸法,帯鉄筋形状,帯鉄筋比および帯鉄筋間隔を変化させた横拘束コンクリートの1軸圧縮破壊解析を行ったものである.既往の実験結果および提案式との比較により,提案手法は,1軸圧縮下における横拘束コンクリートの耐力および軟化・局所化挙動に加え,応力分布性状や帯鉄筋の変形性状などの詳細な力学応答までを妥当な精度で再現できることが分かった.さらに,実験では観察が困難な内部の3次元的な損傷進展過程および応力分布性状を可視化することにより,横拘束コンクリートの内部抵抗・破壊機構を解析的に評価した.
Abstract The titled compounds (3) were synthesized by the reaction of nitrile oxides with 1-azirines and also the reaction of aliphatic nitro compounds with dibenzoylmethane derivatives in the presence of acetyl chloride and sodium methoxide. The structure of 3 was established by single crystal X-ray analysis. A mechanism of the formation for 3 is proposed.
A nondestructive and noncontact method for observation of microdefects in GaAs wafers has been developed with a new photo-thermal-radiation (PTR) microscope. We measured the PTR signal as a function of excitation energy (PTR spectrum) and the spatial distribution of PTR intensity (PTR image) of n-GaAs wafers at room temperature. We found that the PTR spectra have a peak due to a nonradiative state of microdefects at wavelengths ranging from 895 to 903 nm. The present PTR image shows inhomogeneities of microdefect density in GaAs wafers which cannot be observed by X-ray topography.
