THEORY AND PROGRAM IMPLEMENTATION OF MFBFE ELEMENT FOR NONLINEAR ANALYSIS OF R/C SHEAR WALL

A modified force-based fibre element (MFBFE) is popular for the nonlinear analysis of beams and columns in a reinforced concrete structure. However, for a shear wall, a fibre element can take inaccuracy for the reason that one of its basic plane-section assumption. In order to use a fibre element to analyze a shear wall, a force-based fibre element is modified. The key technique of the implement process is discussed, especially the formulation of a modified force-based fibre element and the uniaxial constitution of the material. The whole implement process in OpenSees contains nonlinear solution algorithm in the interactive process and the realizing way of elements and material constitution relations is presented. The numerical analysis for a low-cyclic loading test of two groups of six shear wall specimens based on an MFBFE element is done to test the new process. The analysis results show that the MFBFE element can perform well with kinds of aseismic behavior indexes, including the initial stiffness, yield strength, ultimate strength, unloading stiffness, residual displacement, ductility and energy dissipation. It is concluded that the analysis precision of MFBFE can be accurate enough for shear wall analysis.