CN105002816B - Prefabricated and assembled fish-belly I-shaped prestressed steel-concrete composite continuous girder bridge and its construction method - Google Patents

Abstract

The invention discloses a kind of fish belly I shape prestressing force steel reinforced concrete composite continuous bridge of precast assembly, using prefabricated fish belly i-shaped beamses and precast concrete floorings, adopt steel case concrete combined structure in fish belly i-shaped beamses in hogging moment area lower flange, adopt ladle concrete component, stretch-draw prestressing force in the concrete of the ladle concrete component of lower flange in sagging moment area lower flange.Rigidity and the bending resistance of beam body are greatly improved using this structure, and avoid the air exposure of deformed bar, the lower flange concrete filled steel tube of hogging moment region setting is connected WELDING STUDS and reasonably arranges with the top flange prestressing with bond muscle in hogging moment region and the decking in the negative moment region, and durability and the reliability of beam body is greatly improved.Accordingly, inventor has also set up corresponding construction method, using this method construction safety, high-quality, convenient, fast.The present invention is applied to the engineering practice of Long span municipal administration bridge, Long span Box Beam Bridge and the bridge spanning the sea of traffic congestion.

Description

Prefabricated and assembled fish-belly I-shaped prestressed steel-concrete composite continuous girder bridge and its construction method

technical field

The invention belongs to the field of transportation bridge and culvert engineering, in particular to a prefabricated and assembled fish-belly I-shaped prestressed steel-concrete composite continuous beam bridge and a construction method.

Background technique

With the development of three-dimensional transportation infrastructure, in the construction of urban bridges in densely populated areas, expressway cross-lines or sea-crossing bridges, they are faced with the problem of rapid construction of bridges, which require high construction safety and short construction periods. Improve the negative moment zone of continuous girder bridges with steel-concrete composite girders in the unfavorable state where the concrete deck is under tension and the steel girder is under compression, so as to greatly improve the durability of the concrete deck and steel girders of continuous girder bridges.

Contents of the invention

The technical problem to be solved by the present invention is to propose a prefabricated and assembled fish-belly I-shaped prestressed cable with large spanning capacity, rapid prefabricated assembly, avoiding bridge deck cracking in the negative bending moment area, and avoiding the application of external prestressed cables for steel-concrete composite beams. Steel-concrete composite continuous girder bridge.

In order to solve the above technical problems, the present invention adopts the following technical solutions: the prefabricated and assembled fish-belly I-shaped prestressed steel-concrete composite continuous girder bridge adopts prefabricated fish-belly I-shaped beams and prefabricated concrete bridge decks, and the fish-belly I-shaped The lower flange of the beam in the negative bending moment area adopts steel box-concrete composite structure, and the lower flange of the positive bending moment area adopts steel-clad concrete members, and the concrete of the steel-clad concrete members in the lower flange is tensioned and prestressed.

The ratio of the maximum mid-span girder height to the span of the steel-concrete composite continuous girder bridge is controlled between 1/15-1/20, and the fish belly line of the lower flange is a catenary or parabola; the steel-concrete composite continuous girder The ratio of the section height of side supports to the maximum mid-span height of the bridge is controlled between 1/2-2/3, and the ratio of the section height of mid-support to the maximum mid-span section height is controlled between 1.0-1.2.

The construction method of the above-mentioned prefabricated and assembled fish-belly I-shaped prestressed steel-concrete composite continuous girder bridge comprises the following steps:

<1> Prefabricated concrete bridge deck and prefabricated fish-belly I-shaped slab girder

Welding and processing the outsourcing steel pipe plate of steel-clad concrete member of the middle span and lower flange of the prefabricated unit, the prefabricated side-span beam prefabricated unit is made of steel girder platform, and the steel-clad concrete member of the middle and lower flange of the span, the web, and the upper flange plate are prefabricated , transverse stiffeners, longitudinal stiffeners, vertical stiffeners in the middle support, steel boxes on the lower flange of the middle support, steel pipes near the lower flange of the middle support, steel-clad concrete boxes on the upper flange of the middle support, side support members Welded into a single side-span I-shaped prefabricated unit, each prefabricated unit contains two pieces of I-shaped side-span steel beams, and the I-beams are connected with each other by vierendeel diaphragms;

The prefabricated mid-span beam prefabricated unit is prefabricated by the steel girder platform, and the steel-clad concrete member, web plate, upper flange plate, transverse stiffener, middle support vertical stiffener, middle support lower flange The steel pipe and the prestressed box of the upper flange of the support are welded into a single mid-span I-shaped prefabricated unit. Each prefabricated unit contains two pieces of I-shaped mid-span steel beams, and the I-beams are connected with each other by hollow diaphragms; Afterwards, the reinforcement cage is bound in the steel-clad concrete member of the lower flange, and the bellows are installed in the steel-clad concrete member of the lower flange of the mid-span. and the steel-clad concrete member of the middle and lower flange of the middle span is close to the anchorage area of the lower surface of the support; after that, the cladding plate is welded, the concrete inclined formwork is installed, and the inner concrete of the lower flange is poured; the lower flange of the middle support is provided with the lower wing of the middle support The edge steel pipe member, the steel-clad concrete member box is arranged near the upper flange of the middle support, and the bellows are arranged in the steel-clad plate of the steel-clad concrete member box to tension the negative moment prestressed tendon;

<2>On-site hoisting

After the concrete is cured, the fish-belly I-beam prefabricated unit is transported to the construction site and positioned and hoisted; between the two side-span prefabricated units, the hollow diaphragm is used to connect horizontally, and the single-piece I-shaped mid-span steel beam The upper and lower flanges of the upper and lower flanges are provided with cross braces; after the hoisting of adjacent spans is completed, the weld seams of adjacent span supports are welded, and then the steel pipes of the lower flanges in the negative bending moment area and the concrete in the steel box are poured to form concrete filled steel tubes for the supports. For steel box concrete composite components, pour the prestressed anchor concrete in the support area and the concrete in the upper flange steel clad plate in the negative bending moment area. After the concrete curing is completed, lift the mid-span precast concrete bridge deck and pour the bridge deck wet joint concrete;

<3> Tensile prestress

After the concrete is cured, the prestressed beams in the steel-clad concrete members of the middle and lower flanges of the span are stretched, then the prestressed beams of the upper flange in the negative moment area are stretched, and finally the concrete bridge deck in the negative moment area is cast in place to form a prefabricated fish belly I-shaped prestressed steel-concrete composite continuous girder bridge.

The hoisting age of the precast concrete bridge deck is more than 180 days. The concrete bridge deck adopts reserved cast-in-place holes and reserved steel bars in the cast-in-place holes. Rebar connections are reserved; quick-setting micro-expansion concrete is used for the transverse wet joints of the bridge deck, and quick-setting concrete is used for the longitudinal wet joints.

The steel-clad concrete member of the lower flange is welded with the web, and the open diaphragm is welded in the steel-clad concrete member of the lower flange at the lower part of each transverse stiffener of the web, and the web, bottom plate and Shear studs are arranged on clad slabs, and the concrete in the steel-clad concrete components of the lower flange is poured after the entire prefabricated unit is spliced; the concrete in the steel-clad concrete components of the lower flange is made of fine-grained continuous graded crack-resistant concrete; The prestressed tendons in the steel-clad concrete member of the lower flange are partly anchored at the anchorage area of the bridge deck, and partly anchored at the anchorage area of the lower surface of the steel-clad concrete member of the lower flange of the mid-span near the support.

The steel plate box at the support part in the negative bending moment area is composed of the outer plate of the lower flange steel box, the partition plate, the lower flange plate of the support and the web to form an open box without a roof, and the inner surface of the box is uniformly arranged with shear studs; After the steel girders are hoisted and the adjacent beam sections are welded, concrete is poured in the open box; the inclined steel box near the support is composed of an outer plate, a top plate, a lower flange plate near the support, and a web to form a closed box. The pouring holes are reserved in the upper part of the body, and the shear nails are evenly arranged in the closed box; after the steel beams are hoisted and the adjacent beam sections are welded, concrete is poured in the closed box.

The negative moment upper flange steel clad concrete member is composed of the upper flange steel clad plate in the negative bending moment area and the concrete inside the upper flange steel clad plate in the negative bending moment area, and the bellows are reserved inside.

Long and short shear studs are arranged on the upper surface of the upper flange. The short shear studs are uniformly distributed, and the length of the short shear studs is 5-10cm; the long shear studs are clustered, and the length is 20-25cm. ; The shearing stiffness of shear studs per unit length of the upper flange surface in the negative bending moment area along the longitudinal direction is 1/2-1/4 of the mid-span, and the range of the negative bending moment area is taken as 1/8 of the span from the middle fulcrum to the left and right. diameter length.

The hollow-type diaphragm is composed of a transverse upper chord, a diaphragm lower chord, and a transverse diaphragm, and the members are connected by gusset plates.

The diaphragm of the side support and the middle support adopts the hollow diaphragm, and the cross-sectional area of the rod is more than 5 times the area of the corresponding rod of the mid-span hollow diaphragm; the sides of two adjacent I-shaped side span beams Cross braces are arranged between the lower flanges of the support members; the vertical stiffeners of the middle support are butt-welded with the steel plate box partitions at the support.

In order to meet the strict requirements of urban three-dimensional traffic, expressway cross-line construction and sea-crossing bridge construction, the inventor designed a prefabricated and assembled fish-belly I-shaped prestressed steel-concrete composite continuous girder bridge, which adopts prefabricated fish-belly I-shaped Beam and prefabricated concrete bridge deck, steel box-concrete composite structure is used for the lower flange of the fish-belly I-beam in the negative moment area, steel-clad concrete members are used for the lower flange of the positive bending moment area, and steel-clad concrete members are used for the lower flange Tensile prestress in concrete. The use of this structure greatly improves the stiffness and bending resistance of the beam body, and avoids the air exposure of the prestressed steel bars. The rational arrangement of the shear studs connected to the bridge deck in the negative moment zone greatly improves the durability and reliability of the beam. Accordingly, the inventor has also established a corresponding construction method, which is safe, high-quality, convenient and quick to use.

Description of drawings

Fig. 1 is the facade arrangement diagram of the 8-span continuous steel-concrete composite girder bridge applying the present invention.

Fig. 2 is a detailed diagram of the facade layout of one side span and half of the middle span in the continuous steel-concrete composite girder bridge of the present invention.

Fig. 3 is a plane layout diagram of the prefabricated concrete bridge deck in the prefabricated and assembled fish-belly I-shaped prestressed steel-concrete composite continuous girder bridge of the present invention.

Fig. 4 is a schematic diagram of a single prefabricated bridge deck in the prefabricated bridge deck in Fig. 2 .

Fig. 5 is a schematic cross-sectional view of the supporting concrete of the upper flange.

Fig. 6 is a cross-sectional view of a side (middle) span prefabricated unit.

Figure 7 is a detailed diagram of the elevation layout of the middle support.

Fig. 8 is a detailed diagram of cross-sectional layout of main beams in Fig. 2 and Fig. 6 .

Fig. 9 is a detailed diagram of the vertical arrangement of the side support and the arrangement of the diagonal bracing of the lower flange of the side support.

Fig. 10 is a perspective view of the steel-clad concrete member of the lower flange of the 8-span continuous steel-concrete composite girder bridge in Fig. 1 .

Fig. 11 is a perspective view of the prefabricated steel girder section of the main span of the 8-span continuous steel-concrete composite girder bridge in Fig. 1 .

Fig. 12 is a perspective view of the side-span single-piece prefabricated slab girder of the 8-span continuous steel-concrete composite girder bridge in Fig. 1 .

Fig. 13 is a perspective view of the mid-span single-piece prefabricated slab girder of the 8-span continuous steel-concrete composite girder bridge in Fig. 1 .

Fig. 14 is a partial perspective view of the hoisting of the 8-span continuous steel-concrete composite girder bridge in Fig. 1 and the middle support of adjacent spans after welding.

In the figure: 1 prefabricated concrete bridge deck, 1a reserved cast-in-place holes for prefabricated bridge deck, 1b steel bars in reserved holes for prefabricated bridge deck, 1c prefabricated bridge deck wet joint reinforcement, 2 lower flange steel-clad concrete components, 2a lower flange Opening diaphragm of steel-clad concrete member, 2b cladding plate of steel-clad concrete member of lower flange, 2c inner concrete of steel-clad concrete member of lower flange, 2d inner web of steel-clad concrete member of lower flange, 2e bottom plate of steel-clad concrete member of lower flange, 2f Shear nails on the inner surface of the lower flange steel-clad concrete member, 2g top plate of the lower flange steel-clad concrete member, 3 side span beam prefabricated units, 4 steel beam webs, 5 steel beam upper flange plates, 6 transverse stiffeners, 6a longitudinal stiffeners, 7 vertical stiffeners for the support, 8 the lower flange steel box for the middle support, 8a the outer panel of the lower flange steel box, 8b the lower flange steel box partition, 8c the lower flange plate for the support, 8d the inner steel box Cloth shear nails, steel-clad concrete box with flange on middle support in 9, steel-clad steel clad plate in steel-clad concrete box with flange on middle support in 9a, member on side support on 10, longitudinal stiffener on side support on 10a, and steel clad plate on side support on 10b Support stiffener, 10c side support vertical stiffener, 10d side support member lower flange plate, 10e side support member end slant plate, 10f side support member web, 11 single-piece I-shaped side-span steel beam , 12-span hollow diaphragm, 12a mid-span transverse upper chord, 12b mid-span transverse oblique member, 12c mid-span transverse lower chord, 12d mid-span hollow diaphragm gusset plate, 13 mid-span beam prefabricated unit, 14 Single-piece I-shaped mid-span steel girder, 15 full-length bellows in the steel-clad concrete member of the lower flange, 16 anchorage area of the bridge deck, 17 anchorage area of the lower surface of the steel-clad concrete member of the lower flange near the support, 18 on the support The bellows installed in the flange steel-clad concrete box, 19 negative bending moment prestressed tendons, 20 upper and lower flange cross braces, 21 adjacent span support welds, 22 negative bending moment area lower flange steel pipe, steel Concrete in the box, 22a Concrete in the steel pipe, 22b Concrete in the steel box, 23 Concrete in the prestressed anchorage area of the support, 24 Concrete in the steel clad plate of the upper flange of the middle fulcrum, 25 Bridge deck wet joints, 25a Transverse wet joints, 25b Longitudinal wet joints, 26 inner prestressed beams of steel-clad concrete members on the lower flange, 27 bridge decks in the negative moment zone, 28 short shear studs on the upper flange, 29 precast support on the upper flange, and 30 clustered long shear studs , 31 The lower flange inclined steel box near the support, 31a The lower flange inclined steel box outer plate near the support, 31b The lower flange inclined steel box roof near the support, 31c The lower flange near the support Flange plate, 32 negative moment prestressed tendon anchorage area, 33 negative moment prestressed steel bar, 34 support, 35 small longitudinal beam between prefabricated components, 36 support vierendeel diaphragm, 36a support transverse upper chord , 36b support transverse oblique rod, 36c support horizontal lower chord, 36d support vierendeel diaphragm gusset plate, 37 side support lower flange cross bracing, 38 side support anchorage area concrete, 39 side support lower wing Edge brace.

detailed description

1. The basic structure of prefabricated and assembled fish-belly I-shaped prestressed steel-concrete composite continuous girder bridge

Prefabricated fish-belly I-beams and prefabricated concrete bridge decks are used. The lower flange of the fish-belly I-beam in the negative moment area adopts a steel box-concrete composite structure, and the lower flange in the positive bending moment area adopts steel-clad concrete members. Tensile prestressing in the concrete of the ladle concrete member of the lower flange. The ratio of the maximum beam height to the span in the span is controlled between 1/15-1/20, and the fish belly line of the lower flange is a catenary or parabola; if the span-height ratio is too small, the beam will be uneconomical. The structural stress scheme provided by the invention is that the beam, the prestressed beam, and the lower flange steel plate jointly bear the dead load; The length control of the web in the support area along the main girder is determined according to the design shear force of the main girder, and the ratio of the section height of the middle support to the maximum height of the mid-span section is controlled between 1.0 and 1.2. The shear force near the support should satisfy:

V≤t _f h _f f _v +0.75A _g f _g tanθ+A _s f _s tanθ

In the formula, V is the design shear force, tf is the thickness of the web, hf_ is the height of the web, fv is the design value of the shear strength of the web, Ag is the total area of the steel strand, and fg is the design value of the tensile strength of the steel strand , θ is the angle between the steel strand or the concrete flange of the ladle and the horizontal direction, As is the steel area of the ladle flange, and fs is the design value of the tensile strength of the steel of the ladle flange.

2. Construction method of prefabricated and assembled fish-belly I-shaped prestressed steel-concrete composite continuous girder bridge

<1> Prefabricated concrete bridge deck and prefabricated fish-belly I-shaped slab girder

The hoisting age of the precast concrete bridge deck 1 is more than 180 days. The concrete bridge deck 1 adopts the reserved cast-in-place hole 1a and the steel bar 1b in the cast-in-place hole. 30 is connected with the reserved steel bar 1b in the hole; the transverse wet joint 25a of the bridge deck is made of quick-setting micro-expansion concrete to prevent cracking of the wet joint, and the longitudinal wet joint 25b is made of quick-setting concrete.

The outsourcing steel pipe plate of steel-clad concrete member 2 of middle span and lower flange of the prefabricated unit is prefabricated by steel girder girder frame prefabricated side span beam prefabricated unit 3, and steel clad concrete member 2 of middle span and lower flange, web 4, Upper flange plate 5, transverse stiffener 6, longitudinal stiffener 6a, middle support vertical stiffener 7, middle support lower flange steel box 8, middle support lower flange steel pipe 31, middle support upper wing The edge steel-clad concrete box 9 and the side support members 10 are welded into a single side-span I-shaped prefabricated unit 3, each prefabricated unit 3 includes two pieces of I-shaped side-span steel beams 11, and the hollow-type transverse partitions are used between the I-beams the plates 12 are interconnected;

The prefabricated mid-span beam prefabricated unit 13 is prefabricated by a steel girder platform, and the steel-clad concrete member 2 of the mid-span lower flange, the web plate 4, the upper flange plate 5, the transverse stiffener 6, the vertical stiffener 7 of the middle support, The lower flange steel pipe 8 of the middle support and the prestressed box body 9 of the upper flange of the support are welded into a single mid-span I-shaped prefabricated unit 13, each prefabricated unit 13 includes two pieces of I-shaped mid-span steel beams 14, and the I-shaped beam The hollow diaphragms 12 are used to connect with each other; after that, the reinforcement cage is bound in the steel-clad concrete member 2 of the lower flange, and the bellows 15 are set in the steel-clad concrete member 2 of the lower flange of the mid-span, and the bellows 15 pass through all belts Hole diaphragm 2a, and respectively fixed on the anchorage area 16 of the bridge deck at the end of the support and the anchorage area 17 of the lower surface of the steel-clad concrete member 2 of the lower flange of the mid-span near the support; after that, the cladding plate 2b is welded, and the concrete inclined formwork is installed. Concrete 2c is poured in the lower flange; the lower flange near the middle support is provided with the steel pipe member 8 of the lower flange of the middle support, and the steel-clad concrete member box 9 is arranged near the upper flange of the middle support, and the steel-clad plate of the steel-clad concrete member box Bellows 18 are arranged inside to tension the negative bending moment prestressed tendon 19;

Among them, the steel-clad concrete member 2 of the lower flange is welded together with the web 4, and the open diaphragm 2a is welded in the steel-clad concrete member of the lower flange at the lower part of each transverse stiffener 6 of the web, and the steel-clad concrete member of the lower flange Shear nails are arranged on the web 2d, bottom plate 2e and cladding plate 2b of the cladding plate 2b without welding, and the concrete 2c in the steel-clad concrete member of the lower flange is cast in-situ after the splicing of the entire prefabricated unit is completed; the ladle of the lower flange Concrete 2c in the concrete member adopts fine-grained continuous graded crack-resistant concrete, which can well wrap the bellows, prevent cracks, and improve the durability of internal prestressed steel bars; the mid-span and lower wings The prestressed tendons 26 in the edge steel-clad concrete member are partly anchored at the anchorage area 23 of the bridge deck, and partly anchored at the anchorage area 17 of the lower surface of the steel-clad concrete member 2 of the lower flange of the mid-span near the support. Separate anchoring of prestressed steel bars can reduce the stress concentration problem in each anchorage area; part of them can be anchored at 32 anchorages of negative moment steel bars in adjacent beam sections, so that the steel-clad concrete inner prestressed bars 26 of the middle and lower flanges of the span can be simultaneously It can withstand the negative bending moment of some supports.

The steel plate box 8 at the support part in the negative bending moment area is composed of the outer plate 8a of the lower flange steel box, the partition plate 8b, the lower flange plate 8c of the support and the web 4 to form an open box without a roof, and the inner surface of the box is uniform Arrange shear studs 8d; pour concrete 22 in the open box after the steel beams are hoisted and adjacent beam sections are welded. Since the support part is an open box without a roof, the shear nail can play a role in connecting the concrete and the steel plate, improving the stability of the steel plate and transmitting part of the internal force to the concrete body 22 . The inclined steel plate box 31 close to the support is composed of an outer plate 31a, a top plate 31b, a lower flange plate 31c close to the support, and a web 4 to form a closed box. The space of the pouring hole required for the stability is considered and determined, and the shear nails 31e are evenly arranged in the closed box to prevent the buckling of the box plate; after the steel beam is hoisted and the adjacent beam sections are welded, pour concrete 22 .

The negative moment upper flange steel clad concrete member 9 is composed of the upper flange steel clad plate 9a in the negative bending moment area and the inner concrete 24 in the upper flange steel clad plate in the negative bending moment area, and the bellows 9b is reserved inside for tensioning the negative bending moment Area prestressed tendons 33.

The upper surface of the upper flange adopts two arrangements of long and short shear studs. The short shear studs 28 are evenly distributed, and the length of the short shear studs is 5-10 cm, which are used to support the cast-in-place prefabricated upper flange plate 29 The long shear nails are cluster type 30 with a length of 20-25cm, and are used to connect the prefabricated concrete bridge deck 1 according to the position distribution of the reserved cast-in-place holes in the prefabricated bridge deck. Prefabricating the steel-concrete composite flange on the upper flange can prevent possible stability problems of the upper flange during hoisting and construction. The shear studs arranged on the surface of the upper flange in the negative bending moment area along the longitudinal direction per unit length have a shear stiffness of 1/2-1/4 of the mid-span, and the range of the negative bending moment area is taken as 1/8 of the span from the middle fulcrum to the left and right length. The lower rigidity arrangement of the shear studs in the negative moment zone along the longitudinal direction can reduce the participation of the concrete bridge deck in the negative moment zone in the stress of the main girder, and effectively reduce the cracking of the concrete in the negative moment zone.

The diaphragm of the side support and the middle support adopts the hollow diaphragm 36, and the cross-sectional area of the bar is more than 5 times the area of the corresponding bar of the span hollow diaphragm; the hollow diaphragm of the support part needs A large rigidity section is selected to ensure that the lateral torsional deformation of the support is within the allowable range of the specification. Cross braces 37 are arranged between the lower flanges of the side support members 10 of two adjacent I-shaped side span beams 11 to increase the integrity between the steel beams of the side supports; the vertical stiffeners of the middle support 7 It is connected by butt welding with the steel plate box partition plate 8b at the support position.

<2>On-site hoisting

After 28 days of concrete curing, the prefabricated fish-belly I-beam units 3 and 13 were transported to the construction site and positioned and hoisted; between the two side-span prefabricated units 3, the hollow diaphragm 12 was used to connect horizontally, and the single-piece I-beam The upper and lower flanges between the mid-span steel girders 14 are provided with cross braces 20; after the hoisting of adjacent spans is completed, the welds 21 of adjacent span supports are welded, and then the lower flange steel pipes and steel boxes in the negative bending moment area are refilled. Inner concrete 22 is used to form the composite member of steel tube concrete and steel box concrete, and the prestressed anchor concrete 23 in the bearing area and the inner concrete 24 in the upper flange steel clad plate in the negative bending moment area are poured. After the concrete curing is completed, the mid-span precast concrete bridge is hoisted Panel 1, pouring bridge deck wet joint concrete 25;

The hollow diaphragm 12 is composed of a transverse upper chord 12a, a transverse lower chord 12b, and a transverse diaphragm 12c, and each member is connected by a gusset plate 12d.

<3> Tensile prestress

After the concrete is cured, the internal prestressed beam 26 of the steel-clad concrete member at the middle and lower flange of the span is stretched, and then the prestressed beam 19 of the upper flange in the negative moment area is stretched, and finally the concrete bridge deck 27 in the negative moment area is cast in place to form a prefabricated assembly The fish-belly I-shaped prestressed steel-concrete composite continuous girder bridge.

3. Application of prefabricated and assembled fish-belly I-shaped prestressed steel-concrete composite continuous girder bridge

The main span of a bay bridge is designed to have a main span of 120m, 8 consecutive spans, and a bridge deck width of 28m. The owner requires rapid construction and installation of the superstructure, shortening the construction time, reducing construction risks, and not affecting the passage of the waterway. The durability of the bridge, The performance of the bridge deck pavement needs to be very good. However, ordinary steel-concrete composite girder bridges or steel structure bridges are difficult to meet the requirements in terms of force and durability in the bridge-building or hoisting stages. The prefabricated and assembled fish-belly I-shaped prestressed steel-concrete combined continuous girder bridge of the present invention has huge rigidity and light structure, and is easy to prefabricate and hoist. Inner, light in weight and high in durability, so the bridge design proposed by the present invention is adopted.

The designed main span is 120m, adopting 8-span continuous beam structure (Fig. 1, Fig. 2). The mid-span girder height is 6m, the span ratio is set to 1/20, the girder height at the support is 7.8m, the prefabricated bridge deck is 30cm, the supporting height is 15cm, and the plane size of the prefabricated deck is 4m×15m (see Fig. 3 and Figure 4). The supporting width is the same as that of the upper flange (Fig. 5), and the maximum height of the concrete steel box of the lower flange in the negative bending moment area is 3.0m. The distance between the intersection point of the negative bending moment steel pipe and the lower flange of the steel-clad concrete in the positive bending moment area is 24m from the middle fulcrum. Four steel girders are used, which are divided into two prefabricated units (Figure 6), and small longitudinal beams are set between the two prefabricated units. See Figure 7 for the elevation of the middle support, Figure 8 for the important cross-sections of the middle support of the bridge and its vicinity, Figure 9 for the elevation of the side support and the arrangement of the diagonal bracing on the lower flange of the side support, and see Figure 10, see Figure 11 for the prefabricated component segment, see Figure 12-13 for the perspective view of the prefabricated single-piece side and mid-span fishbelly girder, and see Figure 14 for the perspective view of the middle fulcrum.

Engineering Arrangement

(1) Manufacture prefabricated units in the steel structure processing plant, the processing plant should be close to the wharf to facilitate the shipping of beam sections;

(2) After the welding of the steel structure is completed, the lower chord of the steel-clad concrete of the cast-in-place prefabricated unit, the concrete member near the support, and the supporting concrete member, and reserve enough bellows in the member;

(3) Ship the prefabricated components to the construction site and use a large floating crane for one-time hoisting;

(4) The prefabricated units are connected by hollow diaphragms, and diagonal braces are set at the upper and lower flanges between the I-beams;

(5) Hoisting the prefabricated bridge deck, pouring the steel box and concrete inside the steel pipe in the negative moment area;

(6) After the concrete curing is completed, stretch the prestressed tendons in the steel-clad concrete member of the lower flange, and stretch the prestressed tendons in the steel-clad concrete member of the upper flange in the negative bending moment area;

(7) Pouring the bridge deck in the negative moment zone;

Adopting the present invention can complete the transportation and hoisting of a main span steel girder within 5-7 days after the prefabrication of the steel girder is completed, the on-site wet work volume is small, the transportation and hoisting are fast and safe, and the long-term and high-risk operations of offshore bridge construction are greatly reduced quantity.

Claims (10)

1. a kind of precast assembly fish belly I shape prestressing force steel reinforced concrete composite continuous bridge it is characterised in that：Using prefabricated fish belly I-shaped beamses and precast concrete floorings, adopt steel case-Combined concrete in fish belly i-shaped beamses in hogging moment area lower flange Structure, adopts ladle concrete component in sagging moment area lower flange, opens in the concrete of the ladle concrete component of lower flange Draw prestressing force.

2. the fish belly I shape prestressing force steel reinforced concrete composite continuous bridge of precast assembly according to claim 1, its feature exists In：The ratio of the span centre maximum deck-molding of this steel reinforced concrete composite continuous bridge and across footpath controls between 1/15-1/20, lower flange fish belly line Type is catenary or parabola；The side bearing depth of section of this steel reinforced concrete composite continuous bridge and the ratio of span centre maximum height control Between 1/2-2/3, the ratio of middle bearing depth of section and spaning middle section maximum height controls between 1.0-1.2.

3. the construction method of the fish belly I shape prestressing force steel reinforced concrete composite continuous bridge of precast assembly described in claim 1, it is special Levy and be to comprise the following steps：

<1>Precast concrete floorings and prefabricated fish belly I shape plate-girder in advance

The outside steel pipe plate of the span centre lower flange ladle concrete component of welding processing prefabricated unit, using girder steel beam stand The beam prefabricated unit of prefabricated end bay, by span centre lower flange ladle concrete component, web, top flange plate, transverse stiffener, longitudinally plus Strength rib, the vertical ribbed stiffener of middle bearing, middle bearing bottom wing balsh case, close middle bearing lower flange steel pipe, middle bearing top flange ladle Concrete casing, side abutment member are welded into single end bay I shape prefabricated unit, and each prefabricated unit comprises two panels I-shaped side It is connected with each other using open web type diaphragm plate between girder steel, I-shaped end bay girder steel；

Using the prefabricated middle bridge prefabricated unit of girder steel beam stand, by span centre lower flange ladle concrete component, web, top flange Plate, transverse stiffener, the vertical ribbed stiffener of middle bearing, middle bearing lower flange steel pipe, bearing top flange prestressing force casing are welded into list Across I shape prefabricated unit in individual, each prefabricated unit comprises two panels I-shaped mid-span steel girder, using empty between I-shaped mid-span steel girder Abdomen formula diaphragm plate is connected with each other；Banding steel cage in the ladle concrete component of lower flange afterwards, mixes in span centre lower flange ladle Elongated setting corrugated tube in solidifying soil component, corrugated tube passes through all diaphragm plates with holes, and is individually fixed in the floorings at bearing end Anchorage zone and span centre lower flange ladle concrete component are at the lower surface anchorage zone of bearing；Weld wrapper sheet afterwards, install mixed Solidifying soil tiltedly template, pours lower flange inner concrete；Near middle bearing lower flange setting in bearing lower flange steel tube component, in Seat against nearly top flange setting ladle concrete component casing, in the ladle plate of ladle concrete component casing setting corrugated tube in order to Tensioning hogging moment presstressed reinforcing steel；

<2>On-site hoisting

After concrete curing, fish belly i-shaped beamses prefabricated unit is transported to job site and positions lifting；Two end bays are pre- Between unit processed, using open web type diaphragm plate lateral connection, the upper and lower edge of a wing setting cross between monolithic I-shaped mid-span steel girder is handed over Fork diagonal brace；Adjacent weld adjacent across bearing weld seam after the completion of lifting, mixed in Reperfu- sion hogging moment area lower flange steel pipe, steel case Solidifying soil, forms bearing concrete filled steel tube, steel case concrete combined component, pours bearing area prestress anchoraging concrete and hogging moment Area top flange ladle plate inner concrete, after the completion of concrete curing, lifts span centre precast concrete floorings, pours floorings wet Joint concrete；

<3>Stretch-draw prestressing force

After concrete curing, prestressing tendon in the ladle concrete component of tensioning span centre lower flange, post-stretching hogging moment area upper limb Edge prestressing tendon, finally cast-in-place hogging moment area concrete slab, form the fish belly I shape prestressing force steel reinforced concrete group of precast assembly Close continuous bridge.

4. construction method according to claim 3 it is characterised in that：The lifting age of described precast concrete floorings exists More than 180 days, concrete slab, using reserved cast-in-place hole and in cast-in-place in the hole reserved steel bar, was connected by cast-in-place mode during lifting Connect the reserved steel bar of edge of a wing cluster type WELDING STUDS and cast-in-place in the hole；The laterally wet seam of described floorings adopts rapid hardening microdilatancy Concrete, longitudinal wet joint adopts fast hardening concrete.

5. construction method according to claim 3 it is characterised in that：Described lower flange ladle concrete component is welded with web It is connected together, weld, in the lower flange ladle concrete component of each transverse stiffener position bottom of web, the diaphragm plate that punches, Arrange WELDING STUDS on the web of lower flange ladle concrete component, base plate and wrapper sheet, in the ladle concrete component of lower flange Concrete carries out cast-in-place after the completion of whole prefabricated unit splices again；Concrete in the ladle concrete component of described lower flange is adopted With particulate continuous grading anti-crack concrete；Presstressed reinforcing steel part in the ladle concrete component of described span centre lower flange is anchored at bridge At panel anchorage zone, partly it is anchored at span centre lower flange ladle concrete component at the lower surface anchorage zone of bearing.

6. construction method according to claim 3 it is characterised in that：The container body of steel plate at described hogging moment area bearing position by Bottom wing balsh case outer panel, dividing plate, bearing bottom wing listrium and web constitute the open-type box body of no-top plate, and interior is uniform Arrangement WELDING STUDS；After steel beam lifting, adjacent beam section are welded, casting concrete in open casing；Near inclining of bearing position Tiltedly container body of steel plate constitutes closed box by outer panel, top board, close bearing bottom wing listrium, web, and the top of casing is reserved and poured Hole, is evenly arranged WELDING STUDS in closed box；After steel beam lifting, adjacent beam section are welded, concrete perfusion in closed box.

7. construction method according to claim 3 it is characterised in that：Described middle bearing top flange ladle concrete casing by Middle negative moment of backing plate area top flange ladle plate, hogging moment area top flange ladle plate inner concrete composition, interior reserved corrugated tube.

8. construction method according to claim 3 it is characterised in that：Described top flange upper surface is cut using long and short two kinds Power follows closely arrangement, and short WELDING STUDS is even distribution type, and the length of short WELDING STUDS is 5-10cm；Long WELDING STUDS is cluster type, and length is 20-25cm；The 1/2- that shearing rigidity is span centre is arranged, along longitudinal per unit length WELDING STUDS, in described hogging moment area top flange surface 1/4, hogging moment area scope be taken as central bearing point to the left and right each 1/8 across footpath length.

9. construction method according to claim 3 it is characterised in that：Described open web type diaphragm plate is by horizontal top boom, horizontal stroke Every lower boom, tabula brace composition, gusset plate between each rod member, is adopted to connect.

10. construction method according to claim 3 it is characterised in that：Described side bearing, middle bearing diaphragm plate are using on an empty stomach Formula diaphragm plate, its bar cross section area is more than 5 times of the corresponding bar area of span centre open web type diaphragm plate；Adjacent two panels I-shaped side Counterbracing is arranged between the side abutment member lower flange of bridge；The steel plate box at the vertical ribbed stiffener of described middle bearing and bearing position Body dividing plate butt welding connects.