Komputasi analisis non linear geometrik struktur Space Truss dengan metode elemen hingga

BUDIYONO, Tri Fajar, Ir. Bambang Suhendro, MSc.,PhD

2001 | Tesis | S2 Teknik Sipil

Analisis linier struktur belum dapat menggambarkan perilaku struktur yang sesungguhnya, karena hampir semua struktur menunjukan perilaku nonlinier pada saat pembebanan menjelang mencapai kondisi batas dengan tejadinya deformasi yang relatif besar. Tujuan yang diharapkan melalui penelitian ini adalah untuk dapat menganalisis nonlinier geometrik secara optimal struktur space truss dan untuk memahami perilaku nonlinier geometrik dari struktur space truss. Cara analisis yang dilakukan meliputi formulasi elemen hingga nonlinier dan teknikteknik numeris sebagai berikut : (I) matrik kekakuan struktur diturunkan dari prinsip virtual displacement dari formulasi inkrimental Lugrangan, (2) penyelesaian persamaan matrik menggunakan metoda modzjied Cholesky dengan faktorisasi Skyline, (3) penyelesaian persamaan keseimbangan nonlinier struktur menggunakan prinsip inkrimental dan iterasi dikembangkan dari metoda generalized displacement control. Hasil penelitian berupa program komputer yang merupakan implementasi dari algoritma-algoritma yang dikembangkan dari prinsip-prinsip metoda elemen hingga, teknikteknik numeris, dan metoda generalized displacement control. Contoh-contoh numerik dengan validasinya digunakan untuk mengetahui ketelitian dan kebenaran prosedur implementasi yang telah diterapkan

One drawback of linear elastic analysis is its inability to reflect the real behaviour of structures approaching ultimate loading conditions, since almost all structures behave in some nonlinear nlifnner prior reaching their limit of resistance. The basic consideration here or the factor of safety, can be achieved only by analysis that take into account various nonlinear effwts. The objectives of this study are to find an effective and efficient method for analysing space truss structures and to observe the nonlinear behaviour of space truss due to geometric nonlinew it y . A method is developed to analyze space truss structure by combining finite element theory and nunierid tediriiques. The procedure of analysis and fumiulations of the nonlinear finite element technique as follows: (I) element stiffness is developed by using the pkixcipal of virtual displacement in the incremental Lagangian fomtulation, (2) siittultaneous equation solved by using modified Cholesky method with skyline factorization matrix, and (3) solution of nonlinear incremental and iterative equation were performed using generalized displacement control method. A cottiputtx progrin implementing the analysis procedures discussed herein has been developed, and numbers of numerical examples are considered to demonstrate effectiveness and accuracy of the proposed analysis method. Numerical results of various types of 2- and 3-dimensionaf truss have been considered. The curve of load factor-displacement shows such itodinear behaviour of truss structure attd it could be used for predicting the limit load of the structure being analyzed and their associated factor of safety. is tla-t a ix-lor e realistic evaluation of the strength of structures ag&iut the failure conditiatrs,

Kata Kunci : Struktur, Analisis Perhitungan, Program Komputer, analysis, nonlinear, geometry, stiflness, truss, and load factor.