Structural failure of transmission line systems is often attributed to dynamic effects such as a broken conductor, a broken insulator, or conductor galloping. The focus of this research was to develop a computer program, DYNTRN, that can analyze the structural response of a transmission line system due to dynamic effects, and present the response in a graphical form. The program uses the stiffness method to analyze a system consisting of conductors, insulators, and support structures. Four types of elements can be used to model the transmission line components: beam elements, cable elements, truss elements, and spring elements. A dynamic condensation method was introduced to efficiently model cable elements. Geometric nonlinearities were accounted for using the Newton-Raphson method. State-of-the-art software tools and object oriented design were used to develop a program that is modular and interactive. An object oriented method was developed to efficiently store and solve the stiffness matrix of the structure. Results obtained from the program were verified using commercial finite element software. The program was also validated using published experimental work. The final product of this research is a computer program that can graphically simulate dynamic behavior of transmission lines.