چكيده لاتين :
A reliability analysis offan type cable stayed bridges
against first passage failure under earthquake forces is performed
using the method ofcrossing analysis and the basic theory ofreliability.
Failure of the bridge deck being the point of interest, the bridge is
modeled as a beam supported on springs at different points. The
stiffnesses of the springs are determined by a separate 2D static
analysis ofcable-tower-deck system. The analysis provides a coupled
stiffness matrix for the spring system. Using a frequency domain
spectral analysis, the power spectral density functions of bending
moments at different points of the deck are obtained. Using the first
few moments of the power spectral density function, the crossing
analysis is carried out to obtain the conditional probability offirst
passage failure of the bridge deck for a given earthquake ground
motion intensity (expressed as r.m.s. ground motion and related to the
magnitude ofearthquake by an empirical relationship). Probability of
occurrence ofdifferent magnitudes ofearthquake is then combined with
the conditional probability offailure to ·obtain the reliability of the
bridge deck against first passage failure. A three span double plane
symmetricalfan type cable stayed bridge oftotal span 689.0 m, is used
as an illustrative example. The reliability against first passage failure
of the bridge deck is obtained under a number of parametric
variations.
