Fire Resistant Steel Structure

Abstract

A fire resistant steel structure ( 10 ) comprises a steel beam ( 14 ) for receiving a vertical load and a support structure for supporting the horizontal beam ( 14 ) at two horizontally spaced locations. At least one fire-resistant tension member ( 30 ) has its ends ( 32, 32 ′) anchored outside the steel beam ( 14 ) in the support structure. It is arranged relative to the steel beam ( 14 ) in such a way that when the steel beam ( 14 ) is overheated and yields under the vertical load in case of severe fire conditions, it rests on the at least one fire-resistant tension member ( 30 ) and is vertically supported by the latter.

1 - 20 . (canceled) 
     
     
         21 . A fire resistant steel structure comprising:
 a steel beam for receiving a vertical load;   a support structure for supporting said horizontal beam at two horizontally spaced locations; and   at least one fire-resistant tension member having its ends anchored outside said steel beam in said support structure and being arranged in relation to said steel beam in such a way that when said steel beam is overheated and yields under said vertical load in case of severe fire conditions, said overheated beam rests on said at least one fire-resistant tension member and is vertically supported by the latter, wherein said at least one fire-resistant tension member is designed in such a way as to be able to take essentially all of the load of said steel beam.   
     
     
         22 . The fire resistant steel structure according to  claim 21 , wherein said at least one fire-resistant tension member is dimensioned in such a way as to be able to take at least 70%, preferably at least 80% of the load. 
     
     
         23 . The fire resistant steel structure according to  claim 21 , wherein said at least one fire-resistant tension member does not significantly compress the steel beam. 
     
     
         24 . The fire resistant steel structure according to  claim 21 , wherein the pre-tension in said at least one tension member is not more than 25%, preferably not more than 15% of its tensile strength. 
     
     
         25 . The fire resistant steel structure according to  claim 21 , wherein said steel beam has a lower flange with which said overheated beam rests on said at least one fire-resistant tension member and is vertically supported by the latter. 
     
     
         26 . The fire resistant steel structure according to  claim 21 , wherein said steel beam is a cellular beam with a web having apertures therein; and said at least one fire-resistant tension member is arranged transversally to said steel beam. 
     
     
         27 . The fire resistant steel structure according to  claim 21 , wherein said steel beam is supported by said support structure in such a way that it may axially expand when heating up under severe fire conditions, thereby avoiding excessive compressive axial forces therein. 
     
     
         28 . The fire resistant steel structure according to  claim 21 , wherein said at least one fire-resistant tension member is a fire-protected tension member. 
     
     
         29 . The fire resistant steel structure according to  claim 28 , wherein said at least one fire-resistant tension member comprises a high strength steel strand provided with an envelope filled with a fire insulating mortar or grout. 
     
     
         30 . The fire resistant steel structure according to  claim 28 , wherein said at least one fire-resistant tension member comprises a high strength steel strand provided with an intumescent coating or paint or an intumescent sleeve or a sprayed fire insulating material. 
     
     
         31 . The fire resistant steel structure according to  claim 21 , wherein said at least one fire-resistant tension member comprises one or more strands of material having an appropriate tensile strength under severe fire conditions, without fire-protective coating. 
     
     
         32 . A fire resistant steel structure comprising:
 a steel beam for receiving a vertical load;   a support structure for supporting said horizontal beam at two horizontally spaced locations;   at least one fire-resistant tension member having its ends anchored outside said steel beam in said support structure and extending along said steel beam; and   at least one intermediate support member arranged on said steel beam in such a way that said overheated steel beam rests via said at least one intermediate support member on said at least one fire-resistant tension member and is vertically supported by the latter, when said steel beam is overheated and yields under said vertical load in case of severe fire conditions.   
     
     
         33 . The fire resistant steel structure according to  claim 32 , wherein said at least one intermediate support member arranged on said steel beam is integrated in a transversal web-stiffener. 
     
     
         34 . The fire resistant steel structure according to  claim 32 , wherein said at least one intermediate support member arranged on said steel beam is a stud, hook or eye arranged on said steel beam. 
     
     
         35 . The fire resistant steel structure according to  claim 32 , wherein a series of intermediate support members are arranged on said steel beam so that said at least one fire-resistant tension member has a polygonal shape approximating a parabola. 
     
     
         36 . The fire resistant steel structure according to  claim 32 , wherein said at least one fire-resistant tension member is slightly pre-stressed when said steel beam is not exposed to a fire. 
     
     
         37 . The fire resistant steel structure according to  claim 32 , wherein said at least one fire-resistant tension member is a fire-protected tension member. 
     
     
         38 . The fire resistant steel structure according to  claim 32 , wherein said at least one fire-resistant tension member comprises one or more strands of material having an appropriate tensile strength under severe fire conditions, without fire-protective coating. 
     
     
         39 . A fire resistant steel structure comprising:
 a double-T shaped steel beam for receiving a vertical load, said double-T shaped steel beam having an upper flange, a lower flange and a web connecting said upper flange to said lower flange;   a support structure for supporting said beam at two horizontally spaced locations;   on each side of said web, at least one fire-resistant tension member anchored in said support structure and extending along said web between said upper flange and said lower flange; and   intermediate support members arranged on said steel beam, symmetrically in relation to said web, in such a way that said overheated steel beam rests via said intermediate support members on said fire-resistant tension members and is vertically supported by the latter symmetrically in relation to said web, when said steel beam is overheated and yields under said vertical load in case of severe fire conditions.   
     
     
         40 . The fire resistant steel structure according to  claim 39 , wherein said steel beam is supported by said support structure in such a way that it may axially expand when heating up under severe fire conditions, thereby avoiding excessive compressive axial forces therein. 
     
     
         41 . The fire resistant steel structure according to  claim 39 , wherein said support structure comprises a H-shaped steel column with two flanges and a concrete filling between said flanges, wherein a first end of said steel beam is fixed to a first of said two flanges; and one end of said fire-resistant tension member passes through a through-hole in said first flange and is provided with an anchor that is embedded in the concrete between said column flanges. 
     
     
         42 . The fire resistant steel structure according to  claim 39 , wherein said at least one fire-resistant tension member is a fire-protected tension member. 
     
     
         43 . The fire resistant steel structure according to  claim 39 , wherein said at least one fire-resistant tension member comprises one or more strands of material having an appropriate tensile strength under severe fire conditions, without fire-protective coating. 
     
     
         44 . A fire resistant steel-concrete floor structure comprising:
 a concrete slab;   a support structure for said concrete slab including at least one steel beam; and   at least one fire-resistant tension member having its ends anchored outside said steel beam in said slab and being arranged relative to said steel beam in such a way that when said steel beam is overheated and yields under its load in case of severe fire conditions, said overheated beam rests on said at least one fire-resistant tension member and is vertically supported by the latter, said at least one fire-resistant tension member being designed in such a way as to be able to take essentially all of the load of said beam.   
     
     
         45 . The fire resistant steel-concrete floor structure according to  claim 44 , wherein said support structure for said concrete slab comprises support columns; and said at least one fire-resistant tension member has its ends anchored in said concrete slab in direct vicinity of said support columns.