M.Sc Thesis

M.Sc StudentDachkovsky Yakov
SubjectGeometrically Non-linear Behavior of Plane Frames
DepartmentDepartment of Civil and Environmental Engineering
Supervisors MR Dimitry Val
ASSOCIATE PROF. Konstantin Volokh
Full Thesis textFull thesis text - English Version


Most modern standards for steel structures provide approximate approaches in accounting for the influence of P-Δ effect for plane frames behavior, without carrying out a numerical non-linear analysis, because of their simplicity and convenience. Some of these methods underestimate the internal forces and structural displacements, and the others overestimate them. There are also no recommendations in the standards for approximate accounting for  P-Δ effect for portal frames with peach roofs slopes higher than 1:2 (vertical: horizontal) (260 slope). This study mainly focuses on accuracy estimating of the approximate approaches in accounting for P-Δ effect for rectangular plane frames. It also demonstrates that the design of roof portal frames, with peach roofs slopes higher than 1:2 (vertical: horizontal), can be performed by implementing less conservative approximate approach.

Another issue which is addressed in the thesis is the influence of geometrical non-linearity on structural stability (or the evaluation of buckling load). In structural stability analysis it is often assumed that structural deflections are small so that their influence on the structural stiffness is neglected. The influence of geometrical changes on the buckling load will be checked for different plane frames which material behavior is linear or non-linear as well.

Another questions discussed in this study is the influence of geometrical and material non-linearities on the estimate of the robustness of a structure (i.e., its resistance against progressive collapse). The comparison of linear and non-linear computations is done for a steel plane frame structure which is damaged at different locations.                           

In the present work the numerical non-linear calculations were implemented by non-linear computer program “ANSYS”. In addition, some of non-linear calculations, including those estimating elastic buckling load, were calculated by a program developed by the author. The computing algorithm and the program on the compact disc attached to the thesis are also presented.