NETWORK  
ARCH  
HANGERS  
CONNECTIONS  
TIE  
WIND-BRACING  

Network

The hanger arrangement is the heart of a network arch and constitutes the main difference to tied arches with vertical hangers. The fact that longitudinal bending moments and shear forces are relatively large and decisive in tied arches with vertical hangers is not true for network arches, because the hanger net acts more like a truss. In network arches, axial forces are predominant in arch and tie, for all load cases.

There exist at least two theories of how the hangers should be arranged in order to achieve an efficient structure. Both suggest placing the upper hanger nodes equidistantly along the arch, which is, amongst other, to create a uniformly in-plane buckling resistance of the arch.

The first theory provides a fixed pattern (by Per Tveit) of a hanger web, which can be adjusted for each bridge project. For more concentrated loads the slope of the hangers has to be decreased and vice versa.

The second theory suggests a radial hanger arrangement (by Brunn & Schanack). All hangers cross the arch with the same angle. This hanger arrangement can very easily be used for different bridge projects.

The arch springing point constitutes a disturbance range in the structural behaviour of a network arch, due to the rigidity of the connection between arch and tie. Therefore every specific bridge project requires an empiric adjustment of the first few hangers. Help can be found here.