A pre-stressing device, and a method for reinforcing a structural member

Abstract

A pre-stressing device for reinforcing and/or repair a structural member by means of a pre-stressed cover plate is provided. The device comprises a stress member being connected to an attachment structure or at least temporarily securing said device to the cover plate, wherein the stress member is configured such that when a force is applied to the stress member, different portions of the stress member will immediately be subjected to different magnitudes of force.

1 . A pre-stressing device for reinforcing or repairing a structural member using a pre-stressed cover plate, comprising
 a stress member being connected to an attachment structure for at least temporarily securing said device to the cover plate,   wherein the stress member is configured such that when a force is applied to the stress member, different portions of the stress member will immediately be subjected to different magnitudes of force.   
     
     
         2 . The device according to  claim 1 , further comprising a pressure source for generating a pre-stressing force to the device by applying stress to the stress member. 
     
     
         3 . The device according to  claim 2 , wherein said pressure source comprises at least one of a hydraulically or mechanically operated piston-cylinder unit, a screw link actuator, and a screw. 
     
     
         4 . The device according to  claim 1 , wherein the stress member comprises a body having a tapered shape. 
     
     
         5 . The device according to  claims 1 , wherein the stress member comprises a series of tabs. 
     
     
         6 . The device according to  claim 5 , wherein each tab is connected to an adjacent tab by at least one spring, and wherein an axial stiffness of said at least one spring is decreasing along the length of the device. 
     
     
         7 . The device according to  claim 5 , wherein each tab is connected to a pressure source for applying a pre-stressing force to the device using a spring. 
     
     
         8 . The device according to  claim 5 , wherein each one of said tabs is connected to an associated pressure source. 
     
     
         9 . The device according to  claim 1 , wherein the device is attached to the cover plate via an intermediate medium including at least one of a strip of fiber reinforced polymer, a wooden strip, and a plastic strip. 
     
     
         10 . A method for reinforcing a structural member by applying a pre-stress to a cover plate being attached to the structural member, comprising:
 at least temporarily securing a stress member to the cover plate using an attachment structure, and   applying force to the stress member such that when the force is generated, different portions of the stress member will immediately be subjected to different magnitudes of force.   
     
     
         11 . A pre-stressing device for reinforcing or repairing a structural member by a pre-stressed cover plate, comprising:
 a stress member being connected to an attachment structure for at least temporarily securing said device to the cover plate,   wherein the stress member has a varying axial stiffness along a longitudinal direction such that when a force is applied to the stress member, different portions of the cover plate will immediately be subjected to different magnitudes of stress.   
     
     
         13 . The device of claim  12 ,
 wherein the stress member further comprises a body having a tapered shape.   
     
     
         14 . The device of claim  12 ,
 wherein the stress member further comprises a series of tabs, each one of said tabs being connected to an associated pressure source such that when different forces are applied to the individual tabs, the different portions of the cover plate will immediately be subjected to different magnitudes of stress.