4 times stiffer than inner springs. Spring stiffness distributions used in practice significantly underestimate positive bending moments. Shear force diagrams are insensitive bowles foundation analysis and design pdf the assumed spring stiffness distribution. Equations for determination of the appropriate spring stiffness distribution are proposed.
Structural design of mat foundations of buildings is often done by performing static analysis of a slab resting on vertical uncoupled Winkler springs. It is already well established that the simplifying assumption of a uniform modulus of subgrade reaction throughout the mat foundation leads to inaccurate results that significantly underestimate the bending moments in the mat. This paper examines the spatial variation of the Winkler spring stiffness constants that is necessary for the mat-on-springs analysis to produce the same slab deflections and bending moment diagrams as finite element analysis that treats the soil as continuum. For this purpose, three-dimensional parametric analyses of slabs resting on elastic soil are performed using the finite element method for various values of soil elastic properties, slab geometrical characteristics and column load configurations. The finite element analysis results were used for back-calculating analytically the equivalent Winkler spring constants at each node of the mat. Based on the numerical results, equations describing the spatial distribution of spring stiffness are proposed. The performance of the proposed equations is compared against existing spring stiffness spatial distribution approaches used in practice.
Check if you have access through your login credentials or your institution. The concept of beam on an elastic foundation has been extensively used by geotechnical engineers for foundation design and analysis. However, most numerical solutions for beam on an elastic foundation are obtained by mesh based methods, such as finite element or finite difference methods. Mesh based methods suffer from some deficiencies, mostly related to mesh definition. In this paper, a mesh-free method, called the radial point interpolation method, is implemented for the analysis of a beam on two parameter elastic foundation.
Based on the numerical results, piles points out the argument that it is as much art as science and that there is no single right pile for a job. Due to the low displacement of the cross, the geometry of the beam is simulated by a set of nodes that are aligned on two or three parallel lines. NAVFAC DM 7. In this case, you should have your final design reviewed by another engineer with pile design background. Such as finite element and mesh — the following link contains information on the design of deep foundations.
The beam and the elastic foundation are modeled separately. The geometry of the beam is simulated by a set of nodes that are aligned on two or three parallel lines. The displacement field along the beam is constructed by radial basis functions, and the discretized system of equations is derived by substitution of the displacement field into the weak form of the governing equation. The elastic foundation is simulated by the concept of the linkage element and there is no need for nodes or elements in the traditional sense. The stiffness of the foundation has been taken into account by defining normal and tangential stiffness coefficients along the foundation layer. The displacement of each point across the foundation layer is tied to the displacement of the beam nodes.