Investigation and Development of a Three-Dimensional Transmission Tower-Line System Model Using Nonlinear Truss and Elastic Catenary Elements for Wind Loading Dynamic Simulation

The accuracy of transmission tower-line system simulation is highly impacted by the transmission line model and its coupling with the tower. Owing to the high geometry nonlinearity of the transmission line and the complexity of the wind loading, such analysis is often conducted in the commercial software. In most commercial software packages, nonlinear truss element is used for cable modeling, whereas the initial strain condition of the nonlinear truss under gravity loading is not directly available. Elastic catenary element establishes an analytical formulation for cable structure under distributed loading; however, the nonlinear iteration to reach convergence can be computational expensive. To derive an optimal transmission tower-line model solution with high fidelity and computational efficiency, an open-source three-dimensional model is developed. Nonlinear truss element and elastic catenary element are considered in the model development. The results of the study imply that both elements are suitable for the transmission line model; nevertheless, the initial strain in nonlinear truss element largely impacts the model accuracy and should be calibrated from the elastic catenary model. To cross-validate the developed models on the coupled transmission tower and line, a one-span eight-line system is modeled with different elements and compared with several state-of-the-art commercial packages. The results indicate that the displacement time-history root-mean-square error (RMSE) of the open-source transmission tower-line model is less than 1 % and with a 66 % computational time reduction compared with the ANSYS model. The application of the open-source package transmission tower-line model on extreme wind speed considering the aerodynamic damping is further implemented.

EXPERIENCE OF INSPECTION OF DAMAGES OF METAL BEARING STRUCTURES

The article deals with the damaged metal structural elements of the out-center compressed I-pillar, corner of a single corner and others. The work of the metal element in the elastic region was experimentally studied and compared with the results of FEM calculation using ANSYS software. Good convergence of results (less than 5%) is received at calculation of stresses in a place of death of the damaged basic brace of a truss of an industrial building. The reliability of the truss element with a defect (0.892) and without it (1.0) and the category of technical condition before and after damage are determined. Despite the fact that the voltage at the site of the defect does not exceed the maximum permissible, the category of technical condition changes from serviceable to serviceable category, and the design itself must be repaired with the elimination of damage on the support strip.

Developing Excel-VBA Spreadsheet for Truss Element Analysis and Design

In this paper EXCEL Visual Basic application spreadsheet has used in analyzing and designing truss elements. EXCEL spreadsheet was developed to draw and analyzes different type of truss elements for tension and compression forces. The truss members were tested under dead, imposed, and wind load. Members capacity was provided according to BS 5950. Different type of joints connection was designed and recommended for support and internal joints.

Efficient Visualization Method of Buckling Region in Dynamic Transient Analysis of Cable Network Structures

Deployable structure system using flexible members is necessary to construct a large structure in the space. The flexible members easily buckle as seen in wrinkles and slack. Therefore, it is available at designing of spacecraft to grasp when, where and how large the buckling occurs in the entire structure during the deployment. When dynamic analysis of large flexible structures which can ignore bending is conducted, the truss element and the membrane element, which do not consider the bending of an element, are often used from the viewpoint of calculation cost. Therefore, this paper proposes a comprehensive and efficient visualization method of buckling occurrence region and buckling magnitude during dynamic response analysis using the truss element to progress convenience in design. The method proposed in this paper is based on two previous studies. The proposed method is verified by a simple truss model, and an application example is shown.