Bridge Structures

Abstract

A bridge structure, comprising: a deck ( 1 ) for supporting a load thereon; first and second abutments ( 13 a, b ) which support respective ends of the deck and bear a compressive load from backfill (5) at the respective outer sides thereof; and at least one displacement compensation unit ( 21 ) which is configured such as to accommodate longitudinal displacement of the deck and maintain a predeterminable longitudinal force between the abutments, wherein the at least one displacement compensation unit has a load-displacement characteristic which provides for a reduced rate of change in the longitudinal force with longitudinal displacement of the deck as compared to a conventional bridge structure which incorporates no displacement compensation unit.

1 - 46 . (canceled) 
   
   
       47 . A bridge structure, comprising:
 a deck for supporting a load thereon;   first and second abutments which bear a compressive load from backfill at the respective outer sides thereof; and   at least one displacement compensation unit which is disposed between the abutments to receive the compressive load and has a load-displacement characteristic which maintains a longitudinal force between the abutments and on the backfill, against the compressive load, such as to accommodate longitudinal displacement of the deck.   
   
   
       48 . The bridge structure of  claim 47 , wherein the deck comprises a plurality of deck parts. 
   
   
       49 . The bridge structure of  claim 48 , wherein the deck comprises first and second deck parts which are monolithically formed with respective ones of the abutments, and the at least one displacement compensation unit is disposed between opposed ends of the first and second deck parts. 
   
   
       50 . The bridge structure of  claim 49 , wherein the opposed ends of the first and second deck parts include a respective one of a projection and a recess which receives the projection, such that the projection and the recess allow for relative movement of the deck parts and define a shear transfer joint. 
   
   
       51 . The bridge structure of  claim 48 , wherein the deck comprises first and second deck parts which are monolithically formed with respective ones of the abutments, and a third, suspended deck part which defines a central span between the opposed ends of the first and second deck parts, and comprising:
 first and second displacement compensation units which are disposed between opposed ends of the first and second deck parts and the third, suspended deck part.   
   
   
       52 . The bridge structure of  claim 48 , comprising:
 a plurality of displacement compensation units.   
   
   
       53 . The bridge structure of  claim 48 , further comprising:
 one or a plurality of supporting piers for supporting the deck.   
   
   
       54 . The bridge structure of  claim 47 , wherein the abutments support respective ends of the deck. 
   
   
       55 . The bridge structure of  claim 47 , wherein the deck comprises a single deck part. 
   
   
       56 . The bridge structure of  claim 55 , comprising:
 a plurality of displacement compensation units, with the displacement compensation units being disposed between opposite ends of the deck and the respective abutments.   
   
   
       57 . The bridge structure of  claim 55 , wherein the abutments support respective ends of the deck. 
   
   
       58 . The bridge structure of  claim 57 , wherein the abutments each comprise a supporting member on which the respective ends of the deck are slideably disposed. 
   
   
       59 . The bridge structure of  claim 59 , further comprising:
 one or a plurality of supporting piers for supporting the deck.   
   
   
       60 . The bridge structure of  claim 59 , wherein the deck and the one or more supporting piers are monolithically formed. 
   
   
       61 . The bridge structure of  claim 47 , wherein at least one of the at least one displacement compensation unit comprises at least one resilient unit which expands or is compressed in response to longitudinal displacement of the deck. 
   
   
       62 . The bridge structure of  claim 61 , wherein the at least one displacement compensation unit has a non-linear load-displacement characteristic. 
   
   
       63 . The bridge structure of  claim 62 , wherein the at least one displacement compensation unit maintains the longitudinal force within a predeterminable range. 
   
   
       64 . The bridge structure of  claim 61 , wherein the at least one displacement compensation unit provides for a substantially uniform longitudinal force with expansion or compression of the at least one resilient unit. 
   
   
       65 . The bridge structure of  claim 61 , wherein the resilient unit comprises a resilient element which expands or is compressed in response to longitudinal displacement of the deck. 
   
   
       66 . The bridge structure of  claim 65 , wherein the resilient element comprises one of an elastomeric component, a compression spring or a plurality of conical spring washers. 
   
   
       67 . The bridge structure of  claim 65 , wherein the resilient unit comprises a casing which encloses the resilient element. 
   
   
       68 . The bridge structure of  claim 47 , wherein at least one of the at least one displacement compensation unit comprises at least one hydraulic unit which expands or is compressed in response to longitudinal displacement of the deck. 
   
   
       69 . The bridge structure of  claim 68 , wherein the at least one displacement compensation unit provides for a substantially uniform longitudinal force with expansion or compression of the at least one hydraulic unit. 
   
   
       70 . The bridge structure of  claim 68 , wherein the hydraulic unit comprises a hydraulic actuator which is actuatable, under control of a controller, to maintain a predeterminable longitudinal force between the abutments with longitudinal displacement of the deck. 
   
   
       71 . The bridge structure of  claim 70 , wherein the controller is one of an active pneumatic or hydraulic pressure control system or a passive dead-weight control system. 
   
   
       72 . The bridge structure of  claim 47 , wherein at least one of the at least one displacement compensation unit comprises a single displacement compensation element which extends across substantially a full width of the deck or a plurality of displacement compensation elements which extend across substantially a full width of the deck. 
   
   
       73 . The bridge structure of  claim 47 , wherein the at least one displacement compensation unit has a load-displacement characteristic which provides for a reduced rate of change in the longitudinal force with longitudinal displacement of the deck as compared to a load-displacement characteristic of a material of the deck. 
   
   
       74 . The bridge structure of  claim 47 , wherein the at least one displacement compensation unit accommodates a displacement of at least about 25 mm per 100 m length of the deck. 
   
   
       75 . The bridge structure of  claim 74 , wherein the at least one displacement compensation unit accommodates a displacement of at least about 50 mm per 100 m length of the deck. 
   
   
       76 . The bridge structure of  claim 47 , where having a length of at least about 100 m. 
   
   
       77 . The bridge structure of  claim 76 , where having a length of at least about 200 m. 
   
   
       78 . The bridge structure of  claim 47 , where formed of one of concrete, steel or concrete and steel. 
   
   
       79 . The bridge structure of  claim 47 , where supporting a road surface. 
   
   
       80 . A bridge structure, comprising:
 a deck for supporting a load thereon;   first and second abutments which bear a compressive load from backfill at the respective outer sides thereof; and   at least one displacement compensation unit which is disposed between the abutments to receive the compressive load and maintains a longitudinal force between the abutments and on the backfill, against the compressive load, such as to accommodate longitudinal thermal displacement of the deck.   
   
   
       81 . The bridge structure of  claim 80 , wherein the abutments support respective ends of the deck. 
   
   
       82 . A method of constructing the bridge structure of  claim 47 , comprising the steps of:
 installing the deck and the first and second abutments;   compressing the at least one displacement compensation unit with a predeterminable longitudinal force;   backfilling the opposite outer sides of the abutments with backfill; and releasing the at least one displacement compensation unit, such that the backfill is compressed with the predeterminable longitudinal force.   
   
   
       83 . The method of  claim 82 , wherein the backfill is backfilled to a predeterminable compressive state. 
   
   
       84 . The method of  claim 83 , wherein the backfill is backfilled to a compressive state which is less than an isotropic stress state of the backfill. 
   
   
       85 . The method of  claim 83 , wherein the backfill is backfilled to a compressive state which exceeds an isotropic stress state of the backfill. 
   
   
       86 . The method of  claim 83 , wherein the backfill is backfilled to a compressive state which is substantially an isotropic stress state of the backfill. 
   
   
       87 . The method of  claim 82 , wherein the predeterminable longitudinal force corresponds to a force required to maintain the backfill substantially in an isotropic stress state, such that, on releasing the at least one displacement compensation unit, the backfill attains substantially the isotropic stress state.