Segmental precast composite-material composite-slab composite beam and construction method thereof

Abstract

A segmental precast composite-material composite-slab composite beam and a construction method thereof are provided, relating to the technical field of bridge design and construction. The segmental precast composite-material composite-slab composite beam mainly includes a segmental precast orthotropic composite top slab, a web, a bottom slab, and a wet joint between segments. The orthotropic composite top slab is composed of an orthotropic slab and an ultra-high-performance concrete layer (UHPC), and the interface connection of the orthotropic slab and the UHPC structural layer is achieved by a shear key. The UHPC structural layer is superposed with the orthotropic slab in segments in a precast plant to form a composite-slab composite beam segment to be entirely transported, hoisted and assembled, and the connection of the UHPC structural layers between the segments is achieved by casting a transverse wet joint in place.

What is claimed is: 
     
         1 . A segmental precast composite-material composite-slab composite beam structure, comprising a segmental precast orthotropic composite top slab, a web, a bottom slab, and a wet joint between segments, wherein an orthotropic composite-material composite top slab is composed of an orthotropic slab and an ultra-high-performance concrete layer (UHPC), and forms a segmental precast composite-material composite-slab composite beam structure with the web and the bottom slab; the composite beam structure sequentially comprises the bottom slab, the web, the orthotropic top slab, a shear key, a reinforced UHPC structural layer from bottom to top; the bottom slab, the web, the orthotropic top slab and subsidiary members thereof are manufactured in elements in a plant and pre-assembled into a main beam segment, then the shear key is installed on and a reinforcing mesh is laid on the orthotropic top slab, and a UHPC layer is cast and cured to form a precast composite-material composite-slab composite beam segment, which is then transported, hoisted and assembled as a whole, and the connection of the UHPC structural layers between the segments is completed by casting a transverse wet joints in place. 
     
     
         2 . The segmental precast composite-material composite-slab composite beam structure according to  claim 1 , wherein a single segment in the main beam segment has a length of 14 m to 20 m, and the composite top slab is a composite structure formed by superposing the orthotropic top slab and the UHPC structural layer. 
     
     
         3 . The segmental precast composite-material composite-slab composite beam structure according to  claim 2 , wherein the orthotropic slab is made of high-strength steel or fiber reinforced polymer (FRP), and the UHPC layer employs a UHPC structure reinforced by high-strength steel bars or the FRP. 
     
     
         4 . The segmental precast composite-material composite-slab composite beam structure according to  claim 2 , wherein the strength grade of the high-strength steel used in the orthotropic slab is not less than 345 MPa, the strength grade of the fiber reinforced polymer (FRP) is not less than 500 MPa, and the strength grade of the UHPC is not less than 120 MPa. 
     
     
         5 . The segmental precast composite-material composite-slab composite beam structure according to  claim 2 , wherein the orthotropic slab is formed by a deck slab, longitudinal stiffeners and diaphragms, and the longitudinal stiffener is closed U-shaped, inverted T-shaped, or inverted L-shape. 
     
     
         6 . The segmental precast composite-material composite-slab composite beam structure according to  claim 2 , wherein the UHPC structural layer has a thickness of 40 mm to 100 mm, comprising in-plant segmental precast parts and an inter-segment post-cast wet joint part in site. 
     
     
         7 . The segmental precast composite-material composite-slab composite beam structure according to  claim 2 , wherein the UHPC structural layer and the orthotropic slab are connected by a shear key group arranged in an array, and the shear key is made of a material homogenous to the orthotropic slab. 
     
     
         8 . The segmental precast composite-material composite-slab composite beam structure according to  claim 7 , wherein the shear key is constructed with ribbed slabs which are longitudinally arranged along a main beam and has steel bars embedded in notches, and is pre-installed on an element of the orthotropic slab; the shear key is also configured to provide a reinforcement positioning function, and the reinforcement of the UHPC structural layer is precast according to a mesh and positioned and installed at one time; and the thickness of a protective layer, embedded in the UHPC structural layer, of the shear key is not less than 10 mm. 
     
     
         9 . The segmental precast composite-material composite-slab composite beam structure according to  claim 6 , wherein a transverse wet joint of the UHPC structure layers between the segments is arranged at a middle region of adjacent diaphragms of the orthotropic slab, and an area ratio of a single inter-segment wet joint to the UHPC structural layer in a single element is not more than 10%, and the casting is conducted after the adjacent segments are assembled. 
     
     
         10 . The segmental precast composite-material composite-slab composite beam structure according to  claim 7 , wherein the ribbed slabs of the shear key are continuous at a transverse wet joint interface of the UHPC structural layers between the segments. 
     
     
         11 . A construction method of the segmental precast composite-material composite-slab composite beam structure according to  claim 1 , wherein
 the premanufacturing is as follows: a web, a bottom slab, and an orthotropic slab of a top slab, comprising a shear key on the top thereof, of a main beam, are manufactured in a precast site according to the elements and are transported to an assembly site to be assembled into a segment, and then a UHPC structural layer is casted on the orthotropic slab and then is cured to form a segmental precast composite-material composite-slab composite beam segment;   site installation is as follows: the segment is transported to a bridge site to be hoisted and assembled, and after the connection of the members such as the web, the bottom slab and the orthotropic slab of the top slab of the main beam is completed, a transverse wet joint between segments is cast in place;   construction steps are as follows: manufacturing of a main beam element, assembling of a beam segment, installation of a reinforcement mesh and an end formwork, in-plant pouring and curing of a UHPC layer, transportation and hoisting of a composite-slab composite beam segment, assembling of a beam, cast-in-place and curing of a transverse wet joint between the segments.