Sensitivity of concrete network arch bridges to time-dependent and thermal effects

Network arches are efficient tied arch bridges with inclined hangers, in which some hangers cross each other twice or more. This paper is focused on one of the concerns regarding the use of concrete network arches, which is their sensitivity to environmental and time-dependent effects. A validated 3D finite element model of a real-world concrete network arch bridge that was instrumented during construction and over time was developed, in which shrinkage and creep of concrete, as well as solar radiation, daily and seasonal temperature changes, and heat transfer phenomena were simulated. Fifty-four variants of this reference bridge, each with a different hanger arrangement, were developed and subjected to environmental and time-dependent effects for 1 year, during which fluctuations in strains, stresses, axial forces, bending moments, and hanger forces were evaluated. Results showed that thermal changes affect network arches much more significantly than concrete creep and shrinkage. Network arches with the arrangement in which the distance between nodes on the tie varies according to the geometry of an ellipse, exhibited the least sensitivity to environmental and time-dependent effects, whereas the radial and vertical arrangements showed smaller tendency for hanger relaxation due to such effects.