Time-Variation Reliability Research Of Steel-Concrete Composite Beam Bridges

The structural performance of existing steel-concrete composite beam bridges graduallydeteriorates during active time due to material aging, overload or other factors, and structuralreliability decreases. The reliability of existing steel-concrete composite bridge is time-variant.Time-variation reliability research of steel-concrete composite beam bridges has importanttheoretical significance and engineering application value.This paper referenced the statistical analysis method of existing structural resistance,built the time-variation resistance model of steel-concrete composite bridges. UsingMATLAB to compile reliability calculation program MPFS based on Monte carlo method andJCPFS based on JC method. Researching the influence of shear connectors’ reliability ofdifferent diameter and number of shear connectors, concrete and shear connectors strengthlevel under different ratio of live load and dead load. And compared characteristic of differentshear connectors’ bearing capacity calculation formulas based on reliability.To consider time-variation fatigue strength of concrete, shear connectors and steel,building fatigue time-variation reliability analysis model of steel-concrete composite bridgesbased on AASHTO fatigue design standard method.For a steel-concrete composite beam bridge do capacity time-variation reliability ofsystem and fatigue time-variation reliability analysis through the time-variant reliabilitytheory and time-variant resistance model which has been built. Analysis found that steelstrength attenuation is an important influence factor of time-variation reliability ofsteel-concrete composite structures; the variability of concrete time-variation strength has alarger influence on capacity reliability index, reliability index decreases with the increase ofvariation; the variability of steel time-variation strength has almost no influence on capacityreliability index; the variability of dead load and live load influence on capacity reliabilityindex is getting smaller and smaller as time goes on; equivalent stress variation coefficient ofthe smaller, fatigue reliability index of the more severe attenuation.