INVESTIGATION OF FLEXURAL – TORSION INSTABILITY OF PILES BY MODIFIED NEWMARK METHOD

The aim of this dissertation is to introduce a new approximate procedure on the basis of the Newmark method, which can treat the structural stability problem without the aforementioned shortcomings. The emphasis of the methodology is that it has sufficient power to generalise different types of stability problems, and is well suited to the use of computers. The major objectives of this thesis are categorised in two parts. The first part, which constitutes the mainhypothesis and idea, is devoted to developing a procedure here in called the Modified Newmark Method. the response of these kind of structures under the loading, namely the relationship between the displacement field and the loading field, can be predicted by the solution of thesedifferential equations and on satisfying the given boundary conditions. When the effect of change of geometry under loading is taken into account in modeling of equilibrium state, then these differential equations are partially integrable in quartered. They also exhibit instabilitycharacteristics when the structures are loaded compressively. The purpose of this Paper is to represent the ability of the Modified Newmark Method toanalyses the flexural-tensional instability of strut for both bifurcation and non-bifurcation structural systems , and the results are shown to be very accurate with only a small number of iterations. The method is easily programmed, and has the advantages of simplicity and speeds of convergence and easily is extended to treat material and geometric nonlinearity including no prismatic members and linear and nonlinear spring restraints that would be encountered in frames. In this Paper these abilities of the method will be extended to the system of linear differential equations that govern strut flexural torsional stability

کلیدواژه ها:

Instability ، Torsion ، flexural ، Buckling ، Modified Newmark Method Stability