2d Truss Analysis in ANSYS

2d TRUSS ANALYSIS in ansys and 3d Truss Analysis in ANSYS

Structural Analysis of a Simple Warren Truss Using Direct Generation

Abstract:
In this exercise, you will create a finite element model of a simple Warren truss using direct generation of the nodes and elements. ansys academic teaching mechanical and CFD with the truss will be modeled using spar (truss) elements. This allows uniaxial tension and compression within the members, but no bending of the members. All joints are pinned and can rotate freely. The pin in the lower left corner of the truss is fixed in space. The lower right corner of the truss is supported by rollers. A downward force of is applied to the bottom center joint of the truss. Because there are no out-of-plane boundary conditions, the truss will be modeled in 2D. The goal of the analysis is to determine the displacements of the various joints in the truss and the component forces for the members of the truss. Given these assumptions and boundary conditions, the truss is statically determinate. All displacements and forces can be calculated by hand. Selected results are calculated at the end of the exercise for verification.

Concrete Gravity Dams are important lifeline structures and represent the fragrance of people’s standard of living.Dam structures with ANSYS ACADEMIC MECHANICAL that span navigable waterways are inherently at a risk for seismic vibrations and as such they must be designed to resist these vibrations. These are very complex structures and subjected to various types of forces both static and dynamic in nature. Conventional 2 dimensional methods are used for the preliminary analysis and to check the stability criteria for dam structures. Provided the results obtained from such analysis are over-estimated, it is still useful for the preliminary analysis. In this work a 2 dimensional stability analysis of a non-overflow section of the Koyna dam having maximum height of 103 m and base width of 70 m is done first using the Gravity method of analysis which is a rational analysis method. Various forces acting on the dam body including vertical and horizontal earthquake forces are worked out and the stresses are manually calculated at different points, i.e. at heel and toe. Considering the same cross sectional dimensions and material properties a 2D finite element model of the dam is simulated using ANSYS APDL R.18.2. The stress results found through both approaches are tabulated and are compared for the accuracy of manual calculations. Dam-foundation-reservoir interaction is neglected and the dam is assumed to be fixed at the base. Earthquake force is the inertia force induced due to acceleration caused by earthquake, and this acceleration is considered as a fraction of Peak Ground Acceleration (PGA) applied to the dam. The dam material is assumed to be elastic and isotropic. The worst conditions for earthquake forces are considered and two cases i.e. reservoir empty and reservoir full conditions are considered.

Horizontal Inertia Force:In addition to exerting the hydrodynamic pressure, the horizontal acceleration produces an inertia force into the body of the dam. This force is generated in order to keep the body and the foundation of the dam together as one piece. The direction of the produced force will be opposite to the acceleration imparted by the earthquake. Since an earthquake may impart either upstream or downstream acceleration, we have to choose the direction of this force in our stability analysis of dam structure in such a way that it produces most unfavorable effects under the considered condition. Under reservoir empty condition, earthquake forces produce effects which may cause slight tension near the toe; and hence stability analysis for reservoir empty case may be carried out only on the basis of weight of the dam by ignoring earthquake forces and keeping the section free from tension. However, for all precise designs, these forces must be fully considered.