| 種別 | paper |
| 主題 | Nonlinear Response of RC In-Plane Structures Surround-ed by Soil Continuum under Shear |
| 副題 | |
| 筆頭著者 | Ashraf SHAWKY（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 | 1303 |
| 末尾ページ | 1308 |
| 年度 | 1993 |
| 要旨 | INTRODUCTION In the design of underground RC structures, soil and RC structures are basically treated as independent systems. This is due to the insufficient knowledge about the interaction between the soil and RC structures especially in the elasto-plastic stages. Several researches were undergone on underground structures subjected to seismic loading. These researches considered low stress levels which are close to the elastic range. As a result,underground structures have high structural stiffness and high factor of safety which would bring uneconomical decision and lower ductility of structures in some cases.This paper treats underground RC structures subjected to high shear deformation through surrounding soil medium.In present design practice,the earth pressure is generally specified independent on the structural deformations and types.But,it was clearly proved through experiments that the induced force from surrounding soil varies according to the structural nonlinearity of RC.For rationale design of underground structures,the possible mode of failure of RC underground should be known.In this paper,numerical parametric FEM analysis is carried out to investigate the change in the response due to the nonlineariry of RC shell type structures (tanks,ducts,cason…) surrounded by soil medium under high shear transferred through the surrounding soil.Due to these loads,the nonlinearity of the RC structure is induced by cracking of concrete and yield of reinforcement.From this analysis,failure mode, residual deformation and nonlinearity of underground structures are investigated to obtain rationalized guidelines for the future improvement of underground structural design. CONCLUSIONS In case of safety of underground structures under high shear deformation of whole soil-structure system, the rigidity of the structure and surrounding soil are closely interlinked in deciding the thickness of RC.However, in present design practice, the minimum thickness of structure is computed based on an earth pressure,which is taken constant and independent of structural stiffness and the soil rigidity.The applied load to underground RC depends on the feature of Structure itself and especially on the mechanical stiffness of soil.The intensity of expansive deformation and crack condition is controlled mainly by reinforcement ratio and also dependent on the stiffness of the surrounding soil.As a matter of fact,changing reinforcement ratio is not very effective as for safety of the structure.The structural strength and induced force from surrounding soil increase proportionally.But the reinforcement ratio has great effect on the soundness of the structure.Deciding the reinforcement ratio should be done in terms of the function and serviceability of the underground structure.The concept of designing underground structures may be further improved in terms of the safety,dynamic load estimation and the design function of structure. |
| PDFファイル名 | 015-01-2220.pdf |