| 種別 | paper |
| 主題 | Computational Model for Steel Bar Embedded in Concrete under Combined Axial Pullout and Transverse Shear Displacement |
| 副題 | |
| 筆頭著者 | J.QURESHI（Graduate Student, The University of Tokyo） |
| 連名者1 | Koichi MAEKAWA（Associate Professor, The University of Tokyo） |
| 連名者2 | |
| 連名者3 | |
| 連名者4 | |
| 連名者5 | |
| キーワード | |
| 巻 | 15 |
| 号 | 2 |
| 先頭ページ | 1249 |
| 末尾ページ | 1254 |
| 年度 | 1993 |
| 要旨 | INTRODUCTION For rational and accurate prediction of the behavior of reinforced concrete structures the understanding and formulation of predictive models for both strength and deformational behavior are needed.At present several constitutive laws exist at the material level,which can be combined to formulate plate and joint models for smeared and discrete crack elements for FEM application,which is one of the powerful tools to predict strength and deformational structural concrete behavior.However these constitutive laws have been verified under simplified and idealized loading conditions,and their applicability under generic conditions need to be checked.The relation between bond stress-slip-strain has been formulated in the past by treating the reinforcement in concrete as a one dimensional cord element.This consideration is valid for a single mode deformational path in which the reinforcement is subjected to axial deformation only.However in reality when deformational paths are of a mixed mode nature,i.e. axial pull-out coupled with transverse shear displacement,as shown in Fig.the applicability of the existing model is invalidated due to the reduction in the axial stiffness and the mean yield strength of the reinforcement,due to a zone of localized curvature in the reinforcement close to the crack plane.This paper attempts to formulate a relationship between the localized shear displacement and the maximum curvature in the reinforcement,thereby proposing an enhanced computational model for the prediction of bar behavior under the generic condition of axial pullout and transverse shear. CONCLUSIONS 1) By utilizing two basic proposals,based on experimental results,of a 'Bond Deterioration Zone' and a 'Curvature Influencing Zone',coupled with a compatibility relation to predict curvature from shear slip,the internal stresses and strains (both along the bar axis and across its section) along with the entire system of forces acting on a bar embedded in concrete,subjected to coupled pullout and transverse shear slip,can be computed.2) The compatibility relation between bar curvature and the normal displacement of the bar can be established using the Euler-Kirchoff hypothesis of plane sections,and is verified with experimental results,by predicting transverse shear displacement of the bar from its curvature distribution.3) The reduced axial stiffness of the bar can be computed from the initiation of localized plasticity in the reinforcement inside concrete,even as the section at the interface is in purely elastic state.The progressive reduction of axial stiffness,due to gradually increasing plasticity both along the bar axis and across the bar section,with increasing shear displacement,can be predicted for test data.4) The maximum axial confining stress attained in the reinforcement at the interface can be predicted by considering the ultimate interactive stress possible at the maximum curvature location,due to combined axial and bending stresses.5) The proposed model has been independently verified when coupled displacement paths is used as an input parameter.For versatile applicability the prediction of stress transfer behavior of a RC interface,by combining with an aggregate interlock model,needs to be established.A supplementary feature of the proposed model is the evaluation of shear force acting on the bar at the crack,i.e.dowel shear,which can be added to the aggregate interlock model to obtain the total shear transferred at the interface,without any additional superpositional considerations. |
| PDFファイル名 | 015-01-2211.pdf |