Zur Querkrafttragfähigkeit von dünnwandigen Hohlkästen mit unbewehrten Fugen in den Stegen

Abstract

On the shear load-bearing capacity of thin-walled box girders with unreinforced joints in the webs. As part of the LT bridge construction method (L: Longitudinal, T: Transversal), which is being developed at TU Wien, thin-walled hollow concrete box girders are used longitudinally and are combined with deck slab elements and in-situ concrete. Due to the construction process, unreinforced joints remain in the webs of these box girders, while the bottom and deck slabs can be continuously reinforced due to the in-situ concrete layers. The question arose as to how this joint configuration affects the shear load-bearing capacity of the box girders. In order to gain a fundamental understanding, two large-format test specimens, one with joints in the webs and one without, were investigated experimentally. The shear force capacity of the girder with joints corresponded approximately to the one of the girder without joints, showing that it was possible to transfer significant shear forces despite the joints. The joint opening proved to be characteristic for the shear load-bearing behaviour, as the stirrups adjacent to the joint act like a suspension reinforcement. A local increase in the stirrup reinforcement in this area is therefore recommended. Non-linear finite element analyses were carried out to analyze the effects of post-tensioning, as used in the LT method, on the load-bearing behavior. It was shown that the load-bearing behavior of the post-tensioned girder with joints largely corresponds to the one without joints.