No abstract

Cable-stayed bridges are important infrastructure facilities serving the world today. Therefore, their safety against earthquake ground motions is crucial. However, due to their long spans, the affecting seismic excitations might be spatially non-synchronous. This paper presents a study of the effect of non-synchronous seismic excitations on Aswan cable-stayed bridge located at southern Egypt. Nonlinear time history analysis was conducted on a three-dimensional finite element model of the bridge. The spatial variability was represented in terms of the wave passage effect which was simulated via different delay times between the arrivals of the ground motion to bridge supports. Results indicated that spatial variability of earthquake ground motion has, in general, a favorable effect on most bridge response parameters. This is attributed to the flexibility of the overall bridge provided by the flexibility of the bridge structural system and/or by existence of seismic isolation.

Liquid storage structures represent an important component of modern infrastructure. They can take variety of shapes of which the conical shape is one of the most common configurations. Both architects and structural engineers because of their appealing look and structural efficiency in addition to their large capacities with relatively small footprint area prefer conical tanks. The state of stresses in these tanks is rather complicated and needs powerful computational tools. However, in the preliminary design phase, it is important to have a simplified analysis method for selection of economic design parameters including tank height, inclination angle, and footprint radius needed to achieve the desired tank capacity. It is also of importance that the structural engineer has an insight and understanding of the effect of these various parameters on the resulting internal forces acting on the tank. This paper presents a simplified analysis of conical tanks under hydrostatic loading based on the application of the membrane theory. The equations governing the behavior of these structures are first derived. Then, they are applied on several vessels of practical dimensions and the resulting of stresses are presented to give a deeper understanding of the resulting internal actions. Moreover, a simple guide to achieve efficient structural preliminary design parameters for a wide range of tank capacities is introduced.