A nonlinear dynamic analysis of the traffic signal cable system.

摘要

Finite element analysis of linear structures is an increasingly popular tool of choice for analysis by engineers. Only recently has this tool been applied to the case of nonlinear cable structures with a sufficient degree of veritable accuracy. Work in this dissertation provides a finite element approach to the analysis of cable structures with verification of the approach done for a traffic signal cable structure. There has been a preponderance of work done on the dynamic analysis of single cables and cable networks but very little is known about dynamic analysis of non-grid-like cable elements in conjunction with other elements such as beams and trusses. The approach of analysis presented in this dissertation provides a valuable bridge in available theories by creating a program that dynamically analyzes a cable in context of other types of elements also present within the structure. Using the principle of virtual work, the cable element developed in this dissertation is based upon a total Lagrangian formulation. The cable element models geometric nonlinear capability. Also modeled in the program developed is a nonlinear loading capability. A realistic wind load generation was accomplished by the use of auto-regressive numerical filters. With a complete finite element model sufficiently exhibiting the elastic and kinematic properties of the true structure, dynamic analysis was accomplished by numerical integration of the equation of motion. An incremental form of the general equation of motion is used because of a piecewise linear assumption. The numerical integration scheme presented in this dissertation is the Newmark's Beta method. The Newmark's Beta method reduces the equation of motion to a set of nonlinear algebraic equations. These equations are then solved using a modified Newton-Raphson. The finite element approach presented in this dissertation is programmed into a software, DYNASS. Verification of the program DYNASS and subsequently the solution approach is done by comparing predictions from DYNASS to test results obtained from recent traffic signal experiments performed at the Civil Engineering Department, University of Florida.