Parametric study on effects of load position on the stress distribution in network arch timber bridges with light timber decks on transverse crossbeams

Hanger arrangements suitable for timber network arch bridges with light timber decks on transverse crossbeams have been studied. The focus was on radial hanger patterns for glulam arches with circular shapes. The premise for the patterns are that the hangers always are attached in pairs to the transverse crossbeams, which are evenly distributed along the deck. The arrangement of hangers in network arch bridges is crucial for the structural performance of the bridges, as well as the stress distribution among the hangers. In the paper the performance of network bridges with classical radial patterns as well as introduced modified patterns under various load positions are compared. The underlying research is based on two-dimensional parametric numerical models of the network outlines. The parameters which have been varied are arch rise, hanger spread angle and location of a focal point for hanger creation. A comparison of stress ranges in hangers as well as bending moments in the arch for the considered patterns have been emphasized. The paper shows how the introduced pattern modifications influence the network arch performance. The intention is to provide a rational basis for better material utilization and design. In general it is recommended to apply a design modification leading to separate centres for the arch and the focal point for the hanger creation.