Reliability-based analysis, sensitivity and design of partially prestressed concrete systems

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" Reliability-based analysis, sensitivity and design of partially prestressed concrete systems "
M. A. Khaleel R. Y. Itani

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1112441
Doc. No	:	TLpq303997492
Main Entry	:	M. A. Khaleel
	:	R. Y. Itani
Title & Author	:	Reliability-based analysis, sensitivity and design of partially prestressed concrete systems\ M. A. KhaleelR. Y. Itani
College	:	Washington State University
Date	:	1992
student score	:	1992
Degree	:	Ph.D.
Page No	:	314
Abstract	:	Structural reliability and sensitivity procedures for serviceability and ultimate limit states of partially prestressed concrete girders are developed. The reliability of the bridge girders designed according to the AASHTO (1989) is evaluated for different girder types, partially prestressing ratios (PPR), correlation between the basic variables, human errors and span length. Sensitivity functions for each limit states are developed. Most limit states are sensitive to changes in the depth and cross-sectional area of prestressing steel. The fatigue of non-prestressing steel seems to be the binding limit state for partially prestressed girders with PPR usd\leusd 0.80. Efficient methods for evaluating the safety of existing girder bridges as a function of the load and resistance parameters is presented. The bridge capacity is determined using a nonlinear finite element program in terms of the maximum truck load before failure. The truck load is increased until collapse of the structure occurs. The reliability of fully prestressed bridges is higher than that of partially prestressed bridges. The bridge system reliability is one and one half to two times the girder reliability index. The system reliability is more sensitive to accidental or local damage of the exterior girders than the interior ones. The applicability of the Birnbaum-Saunders distribution for modelling the fatigue-life of bridge components is argued. The maximum likelihood estimates of the parameters of the fatigue-lives of partially prestressed concrete girders are found from randomly censored samples and for several censored data-sets under various stress regimes. An estimated distribution of the fatigue-lives with their parameter functions of the stress regime which are applicable under virtually any realistic conditions is obtained. The service life of bridges subjected to stochastically varying loads is investigated. The probability distribution of the cumulative damage sustained by a structure at any time is calculated presuming several categories of vehicles, with multiple Poisson arrivals. The median fatigue life of ordinary reinforcing bars, which results from the spectrum of loads induced by vehicular traffic mix, is the lowest among the girder components. Partially prestressed concrete girder bridges designed with low partial prestressing ratio (PPR) have a much shorter median fatigue-life than those designed with high PPR.
Subject	:	Applied sciences
	:	bridge girders
	:	Civil engineering
	:	concrete
	:	Pure sciences
	:	Statistics