Ultimate strength of eccentrically loaded steel plates and steel box-sections | |
| Author | Narong Rerkshanandana |
| Call Number | AIT Diss. no.D39 |
| Subject(s) | Plates (Engineering) Strength of materials |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | A finite element method is applied to compute the elastic-plastic post-buckling behavior of initially deflected and eccentrically loaded steel plates and box-sections. In addition, an approximate method has been proposed to evaluate the interaction between the flexural buckling of steel box columns and local buckling of their component plates. A rectangular element with a linear function and the Eogner's compatible function for the in plane and out of plane displacements, respectively, are used in the analysis. A modified Ilyushin's yield criterion, which is ex- pressed in terms of the stress resultants, is utilized. Linearly varying edge displacements along the loading edges of plates and box-sections are imposed as eccentric loadings. Comparisons with available results reveals that the present finite element analysis gives extremely accurate results even with small numbers of elements. And the present numerical solutions are generally in good agreement with the existing test results. According to the study of eccentrically loaded plates with various unloaded edge conditions, it is found that the post yielding strength of a plate is larger in pure compression than that under eccentric loading; and under the former loading condition, the post yielding strength increases as the width-thickness ratio of plates becomes larger. The eccentricity of the edge compressive force resulting from an imposed edge displacement varies with the progress of post buckling and the rate of the change increases with the width thickness ratio. However, the magnitude of the change is acceptably small for the plates considered. Ultimate strengths of plates plotted against the modified width thickness ratios are presented graphically. The parameters considered are associated with the linearly—varying edge diaplacement condition, the unloaded edge supporting condition, and the magnitude of the maximum initial deflection. It is also found that the ultimate strength curves are nearly independent of the difference of the aspect ratio of plates. Moreover, the ultimate strength curves of plates with various unloaded edge conditions under various loading conditions are remarkably similar except for clamped free plates. Since Winter's ultimate strength formula, which was originally proposed for simply supported plates in pure compression, is found to be a good lower bound curve for all the curves Considered; it is proposed for the prediction of the ultimate strengths of eccentrically loaded plates whose unloaded edges are either simply supported simply supported, clamped-clamped, or simply supported clamped. The study of eccentrically loaded box-sections shows that the post-yielding strength of a box-section increases with the width-thickness ratio of its com ponent plates. Ultimate strengths of various box sections are presented graphically. The Winter's formula is again found to be a good prediction for the ultimate strength of this type of columns. Finally, the interaction strength between the local and the overall flexural buckling of steel square box-columns is estimated under the con dition that their centroidal axis is initially straight. For relatively short columns, it is found that this strength is Controlled solely by the strengths of their component plates. The interactiOn range, where the ulti mate cross section strength is reduced by the effect of the overall buckling, widens as the width thickness ratio of component plates becomes larger. |
| Year | 1978 |
| Type | Dissertation |
| School | AIT Publication (Year <=1978) |
| Department | Other Field of Studies (No Department) |
| Academic Program/FoS | Dissertation (D) (Year <=1978) |
| Chairperson(s) | Usami, Tsutomu;Pisidhi Karasudhi |
| Examination Committee(s) | Pama, Ricardo P.;Chiev, Khus;Lee, Seng-Lip |
| Scholarship Donor(s) | King's Scholarship, Thailand Government |
| Degree | Thesis (Ph.D.) - Asian Institute of Technology, 1978 |