Effects of thermal cycles and time-dependent behavior of the deck on steel network arch bridges

Abstract

Network arches are a type of arch bridges with inclined hangers, in which some hangers cross each other at least twice. This paper aims to evaluate the effects of thermal fluctuations and volumetric changes of the concrete deck on steel network arches. Fifty-nine variants of a reference network arch bridge were developed, assuming identical arch geometries but varying hanger arrangements. Each bridge was modeled using the finite element method and subjected to heat flux due to solar radiation and changes in ambient temperature in addition to heat transfer via conduction, convection, and radiation. The time-dependent deformations of the concrete deck were implemented using a rate-type formulation. Results obtained during a one-year period after the assumed end of construction showed that stress changes in the arch bridge due to ambient and time-dependent effects were not very sensitive to the hanger layout. Neglecting concrete creep and shrinkage was found to cause a 15-20% underestimation of maximum stresses in the concrete deck, whereas a 40-60% error was observed in both the deck and rib when thermal effects were ignored. The radial arrangement of hangers, already known to perform favorably under live loads, was also found to provide the smallest bending moments and the fewest number of relaxed hangers due to thermal and time-dependent effects.