Buckling of Columns on Elastic Foundation with different Boundary Conditions

Abstract

In This research, the subject of buckling of columns on elastic foundation with different boundary conditions by energy approach has been presented. Columns modeled by two-end rigid bars where interconnected to each other by rotational springs, and elastic foundation modeled by translational springs. By preparing computer programs for five column types with different boundary conditions, the critical loads of these columns have been obtained. This five types of columns include two hinge end column, one fix end-one hinge end column, two fix end column, one fix end-one free end column and one hinge end-one free end column which are located on elastic foundation. At first, the stiffness of translational springs is set equal zero, and by knowing the analytical solutions, the stiffness coefficients of rotational springs have been gathered. Then, by defining a dimensionless parameter which showing the relative stiffness of elastic foundation, the critical load for a wide range of foundation stiffness has been obtained and results are presented in form of some graphs. There is analytical solution for two hinge end column on elastic foundation, therefore, at this stage, verification has been done for this kind of column and a very good consistency is observed between analytical buckling load and finite element buckling load for different relative stiffness of foundation. In fact, there is a linear relation between buckling load of two hinge end column and relative stiffness coefficient of foundation. But, for other four type columns, this relation may not be linear. Therefore, by means of fitting curve method, for other four type columns, some mathematical relations are proposed, which by these mathematical relations, the buckling load of above mentioned columns are computed in according to relative stiffness of foundation by acceptable errors.

Keywords

• buckling
• elastic foundation
• boundary conditions
• finite element model
• analytical solution