Device for damping movements of structural elements and a bracing system

Abstract

The invention relates to the protection of structural systems such as apartment houses against dynamic loading caused by earthquakes, wind, traffic etc. When a frame structure is excited by a horizontal external force, the girders starts to displace horizontally. If such displacements are large or if they occur periodically they may have serious impact on the conditions of the structure and may cause severe damages or even result in a collapse. The present invention relates to a very simply designed and easily produced damper with two members being interconnected in a rotational joint. By means of the arrangement of the damper in the structural system, displacement occurring in the system is transferred to the members being forced to rotate in relation to each other. Frictional resistance between the two members is dampening the rotational movement and thus the displacement in the system. The invention further relates to a device wherein the frictional resistance may be varied dynamically based on the displacements occurring in the system.

1 - 33 . (canceled)  
   
   
       34 . A device for damping movements of structural and non structural elements in civil engineering structures, the device comprising: 
 at least two members being interconnected in a rotational joint for frictional damping of relative rotational movement between the at least two members, the two members rotationally moving in opposite directions,    clamping means for clamping the at least two members together, so as to maintain a clamping force and friction between the at least two members in the rotational joint,    means for connecting each of the at least two members to respective ones of the structural elements.    
   
   
       35 . A device according to  claim 34 , further comprising a frictional pad arranged between the two members so as to establish contact between the members and the frictional pad so that the relative rotational movement of the members is dampened by friction.  
   
   
       36 . A device according to  claim 34 , wherein the clamping means are adapted to vary the clamping force.  
   
   
       37 . A device according to  claim 34 , wherein the joint comprises a pin extending through each of the at least two members.  
   
   
       38 . A device according to  claim 37 , comprising a bolt, at least a portion of the bolt constituting the pin, the bolt having: 
 a bolt member with a bolt head,    a nut with a nut head,    the clamping force being determined by the pretension of the bolt.    
   
   
       39 . A device according to  claim 38 , further comprising means for maintaining a substantially constant clamping force with time.  
   
   
       40 . A device according to  claim 39 , wherein the means for maintaining a substantially constant clamping force comprises at least one spring arranged between the bolt head and a surface of one of the members and/or between the nut head and a surface of one of the members.  
   
   
       41 . A device according to  claim 40 , wherein the spring comprises a disc spring.  
   
   
       42 . A device according to  claim 41 , comprising at least two disc springs.  
   
   
       43 . A device according to  claim 42 , wherein at least one disc spring is arranged between the bolt head and a surface of one of the members, and wherein at least one disc spring is arranged between the nut head and a surface of another one of the members.  
   
   
       44 . A device according to  claim 39 , wherein the means for maintaining a substantially constant clamping force comprise hydraulic, pneumatic and/or electric means for maintaining the clamping force.  
   
   
       45 . A device according to  claim 34 , wherein the at least two members comprise: a side plate and a central plate extending in substantially parallel planes.  
   
   
       46 . A device according to  claim 45 , wherein the frictional pad is arranged between the side plate and the central plate.  
   
   
       47 . A device according to  claim 45 , and comprising two side plates arranged symmetrically around the central plate.  
   
   
       48 . A device according to  claim 47 , comprising two frictional pads, each frictional pad being arranged between a respective one of the side plates and the central plate.  
   
   
       49 . A device according to  claim 45 , wherein the central plate is adapted to be connected to one of the structural elements in a pivotal manner, so as to allow relative rotational movement between the central plate and the structural element.  
   
   
       50 . A device according to  claim 45 , wherein the central plate is adapted to be connected to one of the structural elements in a fixed manner, so as to prevent relative movement between the central plate and the structural element.  
   
   
       51 . A device according to  claim 47 , wherein the side plates are adapted to be connected to one of the structural elements in a pivotal manner, so as to allow relative rotational movement between the side plates and the structural element.  
   
   
       52 . A device according to  claim 47 , wherein the side plates are adapted to be connected to one of the structural elements in a fixed manner, so as to prevent relative movement between the side plates and the structural element.  
   
   
       53 . A device according to  claim 34 , wherein the friction pad material comprises a MK101 asbestos free friction material by Eurodeal A/S.  
   
   
       54 . A device according to  claim 34 , wherein the at least two members are made of steel, anti-corrosive steel, brass, aluminium or any alloys comprising aluminium or any other steel material or composite of steel and plastics or composites of plastics and fibres of glass, carbon, Kevlar or similar or composites of any ceramics materials and fibres of glass, carbon, Kevlar or similar.  
   
   
       55 . A device according to  claim 34 , wherein the clamping force shows a variation of less than 5% in a 400 cycle test with 0,5 Hz±0,1 Hz forcing excitement frequency and an displacement amplitude of one of the at least two members of up to 10 mm at an applied excitement force of ±2.5 kN and an initial clamping force of 4 kN±0,5 kN.  
   
   
       56 . A device according to  claim 34  wherein the frictional moment in the frictional joint of the device shows a forcing frequency dependent variation of less than 5% in the range 2-7 Hz at a nominal frictional moment of 200 Nm±20 Nm in 30-cycle tests at each frequency.  
   
   
       57 . A device according to  claim 34 , having a substantially linear relationship between displacement amplitude of one of the at least two members and energy dissipation in the frictional joint.  
   
   
       58 . A device for damping movements of panel walls in building structures, the device comprising: 
 at least one member interconnected to at least one panel in a first rotational joint,    the at least one member being further connected to another panel or similar part of the building structure in a second rotational joint,    one or both of the first or the second rotational joints providing a frictional damping of relative movement between the at least one member and the panel or similar building structure,    one or both of the first or the second rotational joints further providing a sliding movement of the at least one member in relation to the panel or similar building structure to which it is attached, 
 clamping means for clamping the at least one member together with the panel or similar building structure, so as to maintain a clamping force and friction between the at least one member and the panel or similar building structure in the rotational joint.