โปรแกรมการวิเคราะห์ไม่เชิงเส้นทางเรขาคณิต สำหรับอาคารชนิดโครงข้อแข็งร่วมกับผนังต้านแรงเฉือน / วิกรม พนิชการ = A program for geometric nonlinear analysis of frame-shear wall building / Vicrom Panichacarn
A geometric nonlinear analysis accounts for the interaction between out-of-plane deformations and axial forces in the deformed configuration. Such an analysis is essential in high-rise buildings with large axial forces in columns. The axial forces produce additional bending moments due to P-∆ effect when the building sways. The effect is more important in the case of a slender building which may deflect a large amount because of its flexibility. A micro computer program was developed for geometric nonlinear analyses of 2-D frame-shear wall buildings by modifying the structural analysis program SUPER-ETABS to have the iteration capability for geometric nonlinear problems using the direct substitution method. The geometric stiffness matrix of a column was derived by including in the strain-displacement relation the second order nonlinear axial strain term arising from bending deformation. The Lagrangian-fixed coordinate system was used in the formulation using the Principle of a Stationary Value of the Total Potential Energy. The shear wall geometric stiffness matrix was derived from that of the column by transforming from the column displacement coordinate system to the shear wall element coordinate system. The modified program developed could predict the Euler buckling load of a cantilever column accurately to within 0.64%. Analyses of a portal frame a 4-story frame and a 25-story, 3-bay frame-shear wall building yielded results in good agreement with those of previous researchers with only approximately 4% difference in lateral displacement at an externally applied load of 67% of the critical value.
