مقاله انگلیسی پاسخ قاب ها و دیوارهای بتن مسلح بحرانی برشی تحت بارگذاری یکنواخت
Abstract
Keywords
Introduction
Proposed formulation
Constitutive model
Experimental database
Results and discussion
Summary of the experimental validation
Conclusions
CRediT authorship contribution statement
Declaration of Competing Interest
Appendix A.
References
Abstract
This paper focuses on a novel finite element formulation which can predict the bending moment-shear force-axial force interaction of reinforced concrete frames and walls, and validate it against 170 experiments available in literature. This distributed plasticity element is established on force-based finite element method, where the relationship between element nodal forces and section forces are exactly known. Hence, element discretization is nonessential when modelling frames using this formulation, reducing the number of degrees of freedom in the numerical model compared to displacement-based formulations. The computations are carried out at four hierarchical levels, namely structure, element, section and fibre. There are two nested iterative procedures at the structure level and the section level. In the existing formulation, these iterative procedures are computationally demanding due to use of initial stiffness matrices. Furthermore, it uses Modified Compression Field Theory at the fibre level, which has inherent drawbacks compared to its more evolved version, the Disturbed stress Field Model. The current study refines the iterative procedures at structure and section levels to fully operate with tangent stiffness matrices to improve the speed of convergence. In addition, the Modified Compression Field Theory is replaced with the Disturbed stress Field Model at the fibre level to compute fibre resisting force for a given fibre deformation, accounting for both averaged behaviour and local crack slip. The novel element is validated by comparing the predicted results with experimental results of 170 tests found in the literature. It is shown that the novel element predicts the load carrying capacity well with an average experimental-to-predicted load carrying capacity ratio of 0.99 and a coefficient of variation of 12.8%. Furthermore, the element can be used to discuss the different failure mechanisms of reinforced concrete frame elements.
Introduction
Developing a robust, rational and computationally efficient numerical tool to perform nonlinear analyses of reinforced concrete (RC) frames accounting for bending moment-shear force-axial force (M-V-N) interaction is a challenging problem. Modelling RC frames with fibre beam-column elements have become popular over the years owing to its balanced accuracy of prediction and computational efficiency. The relationship between nodal forces and nodal deformations of such elements can be derived using displacement-based [1–4], force-based or mixed finite element methods [5–7]. Among these methods, force-based finite element method is preferred to be used with fibre beam-column elements as it waives the need for element discretization owing to the exactly known force interpolation functions [8–18].