Method for pre-stressing a steel structure, and steel structure pre-stressed using said method

Abstract

According to the method, at least one carbon fibre-reinforced polymer band is joined to the steel structure at the end regions thereof, capable of transferring tensile forces. Subsequently, at least one lifting element ( 7 ) disposed between the carbon fibre-reinforced polymer band ( 4 ) and the steel girder ( 3 ) to be reinforced in a region between these end anchorages ( 5 ), is extended substantially perpendicular to the carbon fibre-reinforced polymer band ( 4 ). So, a tensile force stress is generated between the end regions of the carbon fibre-reinforced polymer band ( 4 ). Then, a steel girder treated in such a manner includes at least one carbon fibre-reinforced polymer band, which is each joined to the steel structure ( 1 ) at the end regions thereof, capable of transferring tensile forces. In the region between these end regions, a lifting element ( 7 ) is disposed between the carbon fibre-reinforced polymer band ( 4 ) and the steel girder ( 3 ) to be reinforced, by means of which the carbon fibre-reinforced polymer band ( 4 ) is subjected to tensile stress by lifting away from the steel girder ( 3 ). The tensile force is transferred to the steel girder ( 3 ) via the anchoring elements ( 5 ).

1 . Method for pre-stressing a steel structure, in which at least one carbon fiber-reinforced polymer band ( 4 ) each is loosely joined to a steel girder of the steel structure ( 1 ) to be reinforced at the end regions thereof with end anchorages ( 5 ) in the form of clamping shoes purely based on friction forces and without gluing, capable of transferring tensile forces, and subsequently, in a region between these end anchorages ( 5 ), at least one hydraulically, pneumatically, electrically or mechanically operated lifting element ( 7 ) disposed between the respectively carbon fibre-reinforced polymer band ( 4 ) and the steel girder to be reinforced ( 3 , 8 ), is extended substantially perpendicular to the carbon fibre-reinforced polymer band ( 4 ) above the tensile stress to be finally achieved for generating several 10 kN lifting force and the lifting of the polymer band ( 4 ) by means of a mechanical latch is secured, then supports are placed between the polymer band ( 4 ) and the steel structure and subsequently the lifting element ( 7 ) is relieved again, so that the target stress is achieved and the supporting force is absorbed by the supports for providing a permanent tensile force stress between the end regions of the respective carbon fibre-reinforced polymer band ( 4 ). 
     
     
         2 . Method for pre-stressing a steel structure according to  claim 1 , characterized in that several carbon fibre-reinforced polymer bands ( 4 ) are laid on the same over the length of the steel girders ( 3 , 8 ) to be reinforced. 
     
     
         3 . Method for pre-stressing a steel structure according to  claim 1 , characterized in that several carbon fibre-reinforced polymer bands ( 4 ) are aligned parallel to each other over the length of the steel girder ( 3 , 8 ) to be reinforced and each is laid on the same over the entire length of the steel beam ( 3 , 8 ). 
     
     
         4 . Method for pre-stressing a steel structure according to  claim 1 , characterized in that several carbon fibre-reinforced polymer bands ( 4 ) are laid over partial sections of the lengths of the steel girders ( 3 , 8 ) aligned parallel to each other, over the length of the steel girders ( 3 , 8 ) to be reinforced. 
     
     
         5 . Method for pre-stressing a steel structure according to  claim 1 , characterized in that several carbon fibre-reinforced polymer bands ( 4 ) are laid over partial sections of the lengths of the steel girder ( 3 , 8 ) aligned parallel to each other, over the length of the steel girder ( 3 , 8 ) to be reinforced, so that these are adjacent to each other and overlap in partial sections with reference to the lengths thereof. 
     
     
         6 . Method for pre-stressing a steel structure according to  claim 1 , characterized in that several carbon fibre-reinforced polymer bands ( 4 ) are mislaid over the lengths of the steel beam ( 3 , 8 ) to be reinforced, which are disposed extending in a direction deviating from the longitudinal direction of the steel girder ( 3 , 8 ) and are intersected. 
     
     
         7 . Steel structure, characterized in that at least one carbon fibre-reinforced polymer strip ( 4 ) each is joined to a steel girder of the steel structure ( 1 ) to be reinforced at the end regions thereof, capable of transferring tensile forces, wherein at least one lifting element ( 7 ) disposed between the respective carbon fibre-reinforced polymer band ( 4 ) and the steel girder ( 3 , 8 ) to be reinforced in the region between these end regions, by means of which the respective carbon fibre-reinforced polymer band ( 4 ) is subjected to tensile stress from the steel girder ( 3 , 8 ) by substantially perpendicular lifting of the carbon fibre-reinforced polymer band ( 4 ) and supports are inserted between the polymer band ( 4 ) and the steel structure on both the sides of the lifting element ( 7 ). 
     
     
         8 . Steel structure according to  claim 7 , characterized in that the lifting elements ( 7 ) are the hydraulically, pneumatically, electrically or mechanically operated lifting elements ( 7 ) with such a translation that only fractions thereof are generated by their paths as the reaction paths of the lifting element. 
     
     
         9 . Steel structure according to  claim 7 , characterized in that in addition to the lifting elements ( 7 ), mechanical supports are installed between the band ( 4 ) and the steel girder ( 3 , 8 ) to be reinforced, for relieving the lifting elements ( 7 ) after completion of the working stroke of the same. 
     
     
         10 . Steel structure according to  claim 8 , characterized in that in addition to the lifting elements ( 7 ), mechanical supports are installed between the band ( 4 ) and the steel girder ( 3 , 8 ) to be reinforced, for relieving the lifting elements ( 7 ) after completion of the working stroke of the same.