Study on 2-D Fibers for Force-based Finite Fiber Element Model

• Main Authors: Chih-Ming Chang, 張志明
• Other Authors: Chyuan-Hwan Jeng
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/76667801039872113167

碩士 === 國立暨南國際大學 === 地震與防災工程研究所 === 95 === The force-based finite fiber element model with an iterative element state determination procedure has been regarded as one of the most promising simulation methods for reinforced concrete (RC) frames subjected to cyclic-static or dynamic excitations. Compared to the conventional displacement-based approach, the force-based method can accurately simulate the flexural behavior of RC frames with robust computational stability. The OpenSees software framework developed at UC Berkeley has built-in the force-based finite fiber element model. This force-based method, however, does not incorporate the trickier shear effect due to the use of uniaxial fibers and thus is unable to reflect the shear behavior of RC frames. To reflect the shear effect, the fibers sub-dividing the cross sections need to take into account at least the bi-axial or 2-D stress state. Hence, the objective of this thesis is developing a 2-D fiber suitable for the force-based finite fiber element model. In this thesis, the general formulation of 2-D fibers for both RC sections and elasto-plastic sections is presented. The sectional tangent stiffnesses of these two types of sections are derived. The elasto-plastic fiber using the von Mises yielding criteria and the Prandtl-Reuss flow rule is implemented in OpenSees and analyses using the 2-D elasto-plastic fibers are conducted to verify the newly proposed formulation. The analytical results of the static-monotonic, static-cyclic, and dynamic analyses of a cantilever beam basically verify the feasibility of the formulation of 2-D elasto-plastic fibers proposed in this thesis.