| Summary: | 博士 === 國立成功大學 === 土木工程學系碩博士班 === 91 === This study presents the convected material frame approach to study the nonlinear behavior of inelastic frame structures. The convected material frame approach is a modification of the co-rotational approximation by incorporating an adaptive convected material frame in the basic definition of the displacement vector and strain tensor. In the formulation, each discrete element is associated with a local coordinate system that rotates and translates with the element. For each load increment, the corresponding strain-displacement and nodal force-stress relationships are defined in the updated local coordinates, and based on the updated element geometry. The rigid body motion and deformation displacements are decoupled for each increment. This modified approach incorporates the geometrical nonlinearities through the continuous updating of the material frame geometry. A generalized nonlinear function is used to derive the inelastic constitutive relation and the kinematic hardening is considered. The equation of motion is integrated by an explicit procedure and it involves only vector assemblage and vector storage in the analysis by assuming a lumped mass matrix of diagonal form.
Many features of the adopted approach are presented in this research. For the purpose of considering the gradual plastification through the cross section and along the member length, the Bauschinger effect, strain hardening and residual stresses produced during hysteretic plastic deformation, the convected material frame approach adopted the Dafalis-Popov two-surface model analyze the nonlinear cyclic plasticity behavior of the steel frames in this research. The structures subjected to horizontal triangular wave load, sine wave load, earthquake load, and horizontal harmonic wave load are studied. The numerical results show that the present approach is capable of simulating the nonlinear transient responses of frame structures.
The convected material frame approach is presented for analysis of nonlinear behavior of steel frames subjected to fire in the present study. The material and geometrical non-linearity as well as the uniform profile of temperature across section of frame members are taken into account. In recent years the rapid development of computer hardware environments with parallel processing capabilities has created new opportunities for revolutionizing engineering computing. The constant improvement of price/performance ratio of commodity computing hardware, coupled with the innovation of networking technology, has made cluster computing one of the most attractive computing architectures for both academic institutes and industrial organizations in the last several years. Therefore, this study investigates a parallel processing strategy for simulations of nonlinear behavior of inelastic structures. A parallel explicit finite element approach is employed to facilitate inelastic structural analysis more efficient. All the computation is carried out on the PC clusters in Linux and conventional parallel machine IBM SP2 at the National Center for High-Performance Computing (NCHC), Hsinchu, Taiwan. The message passing software package, MPI, is utilized as a parallel construct for data communication and message passing among processors.
Several numerical examples are demonstrated in close agreement with the solutions obtained by the ANSYS code. Numerical studies show that the proposed approach is capable of investigating large deflection of inelastic planar structures and providing an excellent numerical performance. The performance parallel computation studies indicate that this explicit algorithm is highly adaptive for parallel processing.
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