FUNDAMENTALS OF ASEISMIC TECHNIQUES IN BRIDGES

ABSTRACT: The design of bridges, the majority of which are long, has to compromise both functional and earthquake resistant requirements, which are conflicting components of the same problem and they impose opposite design requirements. The functional problem, which is mainly critical for the longitudinal direction of the bridge, requires the free contraction and expansion of the deck, due to annual thermal cycle, shrinkage and creep. On the other hand, the earthquake resistance of the bridge is enhanced by implementing monolithical systems as being possible. To improve structural safety and integrity against severe earthquakes, more effective and reliable techniques for aseismic design of structures based on structural control concepts are desired. The differences of bridge damages due to earthquakes in USA, Japan and Taiwan are introduced first in this paper, then an over view on seismic isolation technology as well as other seismic protection technologies adopted and applied to protect the bridges against earthquakes are presented in which a brief review of the earlier and current base isolation devices and aseismic techniques, proposed or implemented, are given, and aspects for future research in the area of isolation of bridges are discussed

Computational Investigation of Electronic and Optical Properties of Si, Ge and Si 1-x Ge x Alloys Using the FP-LMTO Method Augmented by a Plane-Wave Basis

Abstract An investigation into the structural, electronic and optical properties of Si, Ge, and Si 1-x Ge x for different compositions was conducted using first-principles calculations based on density functional theory (DFT). The total energies were calculated within the full -potential linear muffin-tin orbital (FP-LMTO) method augmented by a plane-wave basis (PLW), implemented in Lmtar code. The effects of the approximations to the exchange-correlation energy were treated by the local density approximation (LDA). From our simulation results, it is found that the theoretical ground-state parameters, the band structure, the density of states (DOS), the chemical bonding and the optical properties agree well with the experiment and other theoretical calculations. The accuracies found from the present calculations allow us to describe the properties of the electronic as well as the optoelectronic devices based on the Si 1-x Ge x alloy