Elastic-Plastic Analysis of Suspension Bridge Towers Subjected to Earthquake Ground Motions

This paper deals theoretically with the elastic-plastic analysis of suspension bridge towers subjected to ground motions. In a previous theoretical study it was concluded that the response of the towers of a long span suspension bridge was more significant than that of suspended structures. For convenience of analysis a simplified structural system for a suspension bridge tower with finite degrees of freedom of motion was adopted, and ground disturbances of a simple shape and of an actual earthquake were used. The numerical computation were done on the Kyoto University High Speed Digital Computer, KDC-I. In this investigation some remarkable conclusions on the elastic-plastic response of the system were obtained

Bridging the Mississippi: A History of the Rivalry between Suspension and Arch Modes of Engineering

In this work I examined the evolution of bridge-building technology, specifically suspension bridge-building technology, researched the decision making process Eads employed in selecting an arch bridge design, and presented conclusions that Eads reached that resulted in his belief that an arch bridge, built with the new technology of steel, was superior to a suspension bridge

Fundamental Studies on Earthquake Response of a Long Span Suspension Bridge

This paper deals theoretically with the earthquake response of a long span suspension bridge. An exact solution of this problem is seldom possible because of the complexity of the structure and the earthquake motions. For the convenience of the analysis a simplified structural system of the suspension bridge with finite degrees of freedom of motion is adopted, and the ground disturbances are assumed to be a simple shape. To simplify the problem, linearized deflection theory of suspension bridges is employed. Some parts of numerical calculation, natural frequencies and modes of the system, had been done on a high speed digital computer. On this investigation some response spectra are given, and the fundamental earthquake response characteristics of the suspension bridge are made clear

Dynamic Analysis of Suspension Bridge

Any pedestrian who has crossed a suspension bridge will agree to the fact that it will move. The motion of the bridge represents the dynamic response. Typically, researchers use a combination of both analytical and experimental methods, coupled with system identification technique. However, only analytical method was implemented in this project. The suspension bridge was modeled as a fixed-fixed beam, while ignoring the effects of the hangers, bridge pylons and cable backstays. A single walking person is modeled as a single point load moving across the beam with constant speed. The critical speeds of the beam were also determined. Four different moving speeds were used. Maximum deflection of the beam occurs when the location of the load coincides with that particular node. But at speeds near critical speeds, the maximum beam deflections do not occur at location of the load. Also, the maximum deflection undergone by a node does not occur when the load coincides with that particular node. In future, some of the simplifications done such as ignoring should be omitted in order to produce more accurate results. A wider range of speeds should be used to further explore the effects and to determine if there is any predictable pattern of deflections in the beam model. In addition to that, the forces generated from walking should be offset to left and right of the middle of the beam or deck to imitate the alternating footsteps of a walking person. A 3D model can be created in order to study the torsional and lateral vibrations of the bridge. It can even be used to study combined vibration modes

Dynamic Anaiysis of Suspension Bridge

Any pedestrian who has crossed a suspension bridge will agree to the fact that it will move. The motion of the bridge represents the dynamic response. Typically, researchers use a combination of both analytical and experimental methods, coupled with system identification technique. However, only analytical method was implemented in this project. The suspension bridge was modeled as a fixed-fixed beam, while ignoring the effects of the hangers, bridge pylons and cable backstays. A single walking person is modeled as a single point load moving across the beam with constant speed. The critical speeds of the beam were also determined. Four different moving speeds were used. Maximum deflection of the beam occurs when the location of the load coincides with that particular node. But at speeds near critical speeds, the maximum beam deflections do not occur at location of the load. Also, the maximum deflection undergone by a node does not occur when the load coincides with that particular node. In future, some of the simplifications done such as ignoring should be omitted in order to produce more accurate results. A wider range of speeds should be used to further explore the effects and to determine if there is any predictable pattern of deflections in the beam model. In addition to that, the forces generated from walking should be offset to left and right of the middle of the beam or deck to imitate the alternating footsteps of a walking person. A 3D model can be created in order to study the torsional and lateral vibrations of the bridge. It can even be used to study combined vibration modes

On a nonlinear nonlocal hyperbolic system modeling suspension bridges

We suggest a new model for the dynamics of a suspension bridge through a system of nonlinear nonlocal hyperbolic differential equations. The equations are of second and fourth order in space and describe the behavior of the main components of the bridge: the deck, the sustaining cables and the connecting hangers. We perform a careful energy balance and we derive the equations from a variational principle. We then prove existence and uniqueness for the resulting problem

Ohio River Suspension Bridges: An Inspection Report

For many years, suspension bridges have been employed to economic advantage where long uninterrupted spans were required. While they have been supplanted for most common applications by cantilever and arch bridges in the United States, suspension bridges are a valid design type. Two American suspension bridges have been in service for over 100 years. A new form of suspension bridge, the cable-stayed bridge, is widely used in Europe and is expected to be as popular in the United States. The key to the success of suspension bridges lies in the use of high-strength wires that are consolidated into the main cables. These cables support very heavy loads, compared to common structural-steel members. This allows designers of suspension bridges to employ lower dead loads than necessary for other types of bridges for equivalent live loads and spans. Unfortunately, to achieve economy of construction, load-bearing redundancy is usually sacrificed in most suspension-bridge designs. If a main cable of a suspension bridge should beak, the bridge would collapse in a catast rophic manner. Therefore, defects in the main cable wires of a suspension bridge may be significantly more critical than defects in structural members of other bridge types