CN211689854U - Large-span steel truss combined continuous beam structure - Google Patents

Abstract

The utility model provides a large-span steel truss composite continuous beam structure, which comprises a concrete bridge deck, two sets of steel trusses, a side span fulcrum and a middle fulcrum; the steel truss includes an upper chord and a lower chord, and the upper chord and the lower chord are connected There are multiple web rods; the upper chord is a horizontal straight rod structure, an upper parallel connection is set between the two upper chords, the concrete bridge deck is connected with the upper chord of the steel truss, the lower chord is in a parabolic shape, and the full length of the side span and the middle span are negative. A concrete bottom plate is arranged between the two lower chords in the bending moment area, and a lower parallel is arranged between the two lower chords in the remaining area of the mid-span. The utility model adopts a steel truss girder as the main force-bearing structure, the concrete bridge deck is combined with the upper chord, and the side span and the main span are provided with a concrete bottom plate and combined with the lower chord, so as to give full play to the characteristics of light weight and high strength of the steel structure, and can It is suitable for larger bridge spans, and the residual creep deflection value of the composite beam is very small, and the total structure height is smaller than other concrete composite structure bridges.

Description

A long-span steel truss composite continuous beam structure

technical field

The utility model belongs to the technical field of bridge design and construction, in particular to a large-span steel truss combined continuous beam structure.

Background technique

High-speed railways have very strict requirements on the deformation and settlement of bridges and subgrades, which is one of the key control factors in the selection of high-speed railway bridges. Prestressed concrete beams have the advantages of high rigidity, good dynamic performance and easy maintenance, and are the preferred beam type for railway bridges. However, the concrete structure has the characteristics of shrinkage and creep, and the mid-span deflection will gradually increase with the passage of time. At present, the maximum span of prestressed concrete continuous beams for high-speed rail is about 135m. In theory, when it exceeds 150m, it is difficult to control the residual creep deflection value after track laying within the range of 20mm (L/5000) allowed by the specification. At the same time, the impact of nonlinear problems brought about by large spans is more prominent, and structural risks are increased.

In order to avoid the above problems, the concrete girder bridges with the main span of 150~300m in domestic high-speed railways generally adopt the composite structure system, such as beam-arch composite structure, beam-truss composite structure, low tower cable-stayed bridge and so on. These systems are based on concrete beams as the main force-bearing structure, and arches, trusses, and tower-stay cables are used as stiffening structures to control the deflection of the main span and reduce the stress level of the concrete main beams.

However, there are also some problems in the high-speed railway composite structural system bridge: (1) The suspension rods and stay cables are multiple statically indeterminate structures, and the tension force affects the alignment of the bridge deck, and the construction accuracy is required to be high; Cable-stayed cables have a great impact on railway operations; (3) The height above the bridge deck is large, which may break the aviation height limit; (4) When steel trusses are used to stiffen the concrete bridge deck, the aesthetic effect is poor, and the part above the bridge deck The maintenance and coating operation of the steel structure can only be carried out in the skylight point.

Within the above span range, steel truss girder is a very competitive bridge type, with high stiffness, small deformation in the later stage, and convenient and fast construction. The traditional railway steel truss girder is generally of the bottom bearing type, that is, the railway bridge deck is attached to the lower chord, and is surrounded by the truss web on the inside, which hinders the view of passengers when riding the train; and the long-span variable-height steel truss is generally the lower chord is kept horizontal, The beam height change is realized by the change of the upper chord, and the shape is not as simple and bright as the concrete continuous beam.

Utility model content

The purpose of this utility model is to overcome the existing large-span bridges with concrete beams as the main force-bearing structure and steel structures as the stiffening structure, which have higher construction precision requirements, larger overall height, and are restricted by aviation height restrictions, and It is inconvenient to maintain the steel structure.

To this end, the utility model provides a large-span steel truss composite continuous beam structure, which includes a concrete bridge deck, two sets of steel trusses that are relatively arranged to support the concrete bridge deck together, and two span fulcrums used to support the steel trusses and Two middle fulcrums; the steel truss includes an upper chord and a lower chord arranged along the length of the bridge, and a plurality of web rods are connected between the upper chord and the lower chord; the upper chord is a horizontal straight rod structure, two The upper chords of the steel trusses are connected to the upper parallel, and the transverse bridges of the concrete bridge deck are respectively connected to the upper chords of the two groups of steel trusses. The ends are respectively supported on the fulcrums of both sides of the span, and the lowest point of the lower chord is supported on the middle fulcrum. A concrete bottom plate is arranged between the lower chords of the two sets of steel trusses in the negative bending moment area of the mid-span and the full-length area of the side span. The lower parallel is set between the two lower chords in the remaining area.

Further, the plurality of web bars between the upper chord and the lower chord are connected end to end in sequence to form a zigzag structure, and two adjacent web bars are connected by a gusset plate.

Further, the steel truss adopts a fully welded structure, and the gusset plate adopts a full arc transition structure.

Further, the upper parallel connection includes a plurality of upper beams arranged at intervals along the bridge direction between two upper chords, and upper diagonal braces arranged between two adjacent upper beams; both ends of the upper beams They are respectively fixed on two upper chords, and the upper beams extend along the horizontal transverse bridge direction, and the bottom of the concrete bridge deck is connected with the upper beams.

Further, longitudinal and transverse wet joints of the concrete bridge deck are respectively provided with longitudinal wet joints and transverse wet joints, the longitudinal wet joints are arranged on the top surface of the upper chord, and shear force is passed between the longitudinal wet joint and the upper chord. Nail connection, the transverse wet seam is arranged on the top surface of the upper beam of the upper parallel connection, and the transverse wet seam and the upper beam are connected by shear nails.

Further, the lower parallel connection includes a plurality of lower beams arranged at intervals along the bridge direction between two lower chords, and lower diagonal braces arranged between two adjacent lower beams; two ends of the lower beams They are respectively fixed on the two lower chords, and the lower beams are arranged along the horizontal transverse bridge direction.

Further, the thickness of the concrete floor is the same as the height of the lower chord, and the concrete floor and the lower chord are connected by shear nails.

Further, several longitudinal prestressed steel bars are arranged in the concrete bridge deck.

Compared with the prior art, the beneficial effects of the present utility model:

(1) This large-span steel truss composite continuous beam structure provided by the present utility model adopts steel truss girder as the main force-bearing structure to give full play to the characteristics of light weight and high strength of the steel structure, which can adapt to larger bridge spans and avoid large spans. The residual creep deflection of the span concrete beam after laying the track is too large, which cannot meet the relevant technical requirements of the high-speed railway. At the same time, the concrete bridge deck is adopted, which avoids the disadvantages of large vibration and noise of the steel bridge deck, and is more convenient for maintenance.

(2) The large-span steel truss composite continuous beam structure provided by the utility model forms a double combination through the concrete bridge deck, the concrete bottom plate and the steel truss girder, which increases the stiffness of the bridge structure, and the side-span concrete bottom plate plays the role of weight , to avoid tension at the fulcrum of the side span, without the use of complex tension bearings, and at the same time, the concrete bottom plate and the lower chord in the negative bending moment area of the mid-span participate in the compression together, reducing the amount of steel used for the lower chord; while in the concrete bridge deck Longitudinal prestressed steel bars are arranged inside, which participate in the stress together with the upper chord, which reduces the amount of steel used for the upper chord at the middle fulcrum.

(3) The large-span steel truss composite continuous beam structure provided by the utility model adopts the upper bearing type variable-height steel truss composite beam, the upper chord is kept horizontal, the lower chord changes in a curve, and the total height of the building is significantly smaller than other combinations of the same span At the same time, the full arc type gusset plate structure is used between the web bars, and the shape is transparent and beautiful.

(4) In this large-span steel truss composite continuous beam structure provided by the utility model, the steel truss girder is arranged below the bridge deck, and above the bridge deck is the same as the ordinary concrete girder, and the painting and maintenance operation of the steel structure is below the bridge deck, No impact on railway operations.

The present utility model will be described in further detail below with reference to the accompanying drawings.

Description of drawings

Fig. 1 is the vertical structure schematic diagram of the large-span steel truss composite continuous beam structure of the present utility model;

Fig. 2 is the cross-sectional schematic diagram of the bridge at the place where the concrete bottom plate is connected to the lower chord in the present utility model;

FIG. 3 is a schematic cross-sectional view of the bridge where the lower chord is connected by the middle and lower parallel joints of the present invention.

Description of reference numerals: 1. Concrete bridge deck; 2. Upper chord; 3. Web rod; 4. Lower chord; 5. Node plate; 6. Side span fulcrum; 7. Middle fulcrum; Parallel joint; 10. Shear nails; 11. Longitudinal wet seam; 12. Lower parallel joint.

Detailed ways

The technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the implementations. example. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

In the description of the present invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal" , "top", "bottom", "inside", "outside" and other indicated orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, only for the convenience of describing the present utility model and simplifying the description, rather than indicating Or imply that the referred device or element must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be construed as a limitation of the present invention. In the description of the present invention, unless otherwise specified, the meanings of "plurality" and "several" are two or more.

As shown in Figure 1, Figure 2 and Figure 3, the present embodiment provides a large-span steel truss composite continuous beam structure, including a concrete bridge deck 1, and two sets of steel trusses are arranged opposite to jointly support the concrete bridge deck 1, And the two-side span fulcrums 6 and the two middle fulcrums 7 for supporting the steel truss; the steel truss includes an upper chord 2 and a lower chord 3 extending along the bridge direction, and the upper chord 2 and the lower chord 3 are connected with A plurality of web rods 4; the upper chord rod 2 is a horizontal straight rod structure, the upper chord rods 2 of the two groups of steel trusses are connected to the upper parallel connection 9, and the transverse bridge sides of the concrete bridge deck 1 are respectively connected with the two groups of steel trusses. The upper chord 2 is connected, and the lower chord 3 is a number of parabolic shapes that are continuously connected. The two ends of the lower chord 3 are respectively supported on the fulcrums 6 on both sides. A concrete bottom plate 8 is arranged between the lower chords 3 of the two groups of steel trusses in the negative bending moment area and the full-length area of the side span. The structure is complex tension bearing; the concrete bottom plate 8 in the negative bending moment area of the mid-span can participate in the compression together with the lower chord 3, thereby reducing the steel consumption of the lower chord 3, and the two lower chords 3 in the remaining area of the mid-span are A lower parallel 12 is set between the two to maintain the lateral stability of the steel truss girder. In this embodiment, the steel truss girder of the upper bearing type with variable height is used as the main force-bearing structure to give full play to the characteristics of light weight and high strength of the steel structure, which can adapt to a larger bridge span, and the concrete bridge deck 1 and the steel truss girder are connected. The upper chord 2 is combined, and the concrete bottom plate 8 is set in the side span and the middle span and is combined with the lower chord 3 of the steel truss girder. The residual creep and deflection value of this steel truss composite girder is very small, and the total structure height is smaller than other concrete The composite structure bridge avoids the problem that the residual creep deflection of the existing large-span concrete beams after laying rails is too large, which cannot meet the relevant technical requirements of high-speed railways; at the same time, the steel truss beams are set under the concrete bridge deck 1, and the painting and maintenance work of the steel structure is carried out. Below the bridge deck, there is little impact on railway operations.

In a refined embodiment, the upper chord 2 and the lower chord 3 are mutually consolidated through the web 4, and the plurality of webs between the upper chord 2 and the lower chord 3 are connected end-to-end in sequence to form a zigzag structure, In addition, the two adjacent web bars 4 are connected by the node plate 5, and the plurality of web bars 4 are connected into a whole through the node plate 5, which increases the vertical rigidity of the steel truss structure. Optimized, the steel truss adopts a fully welded structure, and the node plate 5 adopts a full arc transition structure, which reduces the amount of steel used and the weight of the structure, improves the stress concentration at the nodes, and the steel truss segments can be transported as a whole. and hoisting, reducing the number of on-site welding joints, and at the same time, the lower chord 3 adopts a curve (continuous quadratic parabola) change, with the full arc type gusset plate 5 structural design, making the steel truss beam transparent and beautiful.

Specifically, the upper parallel connection 9 includes a plurality of upper beams arranged between two upper chords 2 at intervals along the bridge direction, and upper diagonal braces arranged between two adjacent upper beams; Both ends are fixed on two upper chords 2 respectively, and the upper beams are arranged extending along the horizontal transverse bridge direction, and the bottom of the concrete bridge deck 1 is connected with the upper beams. The lower flat joint 12 includes a plurality of lower beams arranged at intervals along the bridge direction between the two lower chords 3, and lower diagonal braces arranged between the two adjacent lower beams; the two ends of the lower beam are respectively It is fixed on two lower chords 3, and the lower beams are arranged along the horizontal transverse bridge direction. In this embodiment, the transverse stability of the upper and lower parts of the steel truss girder structure is effectively ensured through the design of the beams and diagonal braces of the upper parallel link 9 and the lower parallel link 12 .

In addition, in this embodiment, the concrete bridge deck 1 is prefabricated in blocks. When the concrete bridge deck 1 is spliced and installed, the longitudinal and lateral sides of the concrete bridge deck 1 are respectively provided with longitudinal wet joints 11 and transverse wet joints (Fig. (not shown), the longitudinal wet seam 11 is arranged on the top surface of the upper chord 2, and the longitudinal wet seam 11 and the upper chord 2 are connected by shearing nails 10, and the transverse wet seam is arranged on the upper parallel 9 The top surface of the upper beam, and the transverse wet joint and the upper beam are also connected by shear nails, and the steel-concrete composite system is formed through the upper chord 2 and the shear nails on the top surface of the upper beam and the concrete bridge deck 1. The thickness of the concrete bottom plate 8 is the same as the height of the lower chord 3 , and the concrete bottom plate 8 and the lower chord 3 are connected to form a whole through shear nails. Optimized, the concrete bridge deck 1 is not only provided with ordinary steel bars, but also with a number of longitudinal prestressed steel bars to avoid tensile cracking of the concrete bridge deck 1; while the concrete bottom plate 8 is mainly subjected to compression or minor tensile stress, The concrete base plate 8 is not provided with prestressed steel bars, but only with ordinary steel bars.

The following is an example of a top-supported variable-height steel truss composite continuous beam with a span of (86+172+86) m on a high-speed railway. The beam height is 7.5m, and the specific construction process is as follows:

First, the pier construction is completed, while the concrete deck 1 and the steel truss girder segments are prefabricated at the factory. The concrete bridge deck 1 is prefabricated in blocks, with a maximum block size of 6.8×2.8m and a thickness of 40cm. It is stored for more than 6 months and then shipped to the site for installation. The steel truss girder is manufactured in sections in the factory, using all-welding technology, and is transported and hoisted by river shipping. The maximum size of the steel truss girder section is 17.2 × 15 × 8.7m, and the maximum lifting weight is 180 tons.

Then, install the steel truss girder segments symmetrically and synchronously to both sides from the two middle fulcrums 7 until the steel truss girder is closed. Relying on the steel truss girder, the concrete base plate 8 between the negative bending moment area of the cast-in-place middle span of the hanging basket and the two lower chords 3 in the full-length area of the side span is used. Weld shear nails 10 at corresponding positions on the top surface. Specifically, each side span 86m and the mid-span 7 are provided with a concrete base plate 8 within a range of 52m to the mid-span, and L10 temporary angle steel transverse braces are set between the lower chords 3 within this range, and the rest of the mid-span are not provided with two lower chords within the range of the concrete base plate 8 The lower parallel 12 is arranged between the rods 3; the thickness of the concrete bottom plate 8 and the height of the lower chord 3 are the same as 120cm, only ordinary steel bars are arranged, and no prestressed bars are arranged.

Finally, the prefabricated concrete bridge decks 1 are installed one by one above the steel truss. The longitudinal wet joints 11 are 60cm wide and the transverse wet joints are 40cm wide. The longitudinal wet joints 11 are arranged on the top surface of the upper chord 2, and the transverse wet joints On the top surface of the upper beam, a steel-concrete composite system is formed through the upper chord 2 and the shear nails on the top surface of the upper beam, so as to complete the connection between the concrete bridge deck and the steel truss girder.

The concrete bridge deck 1 is installed after the steel truss girder is erected and the concrete bottom plate 8 is poured. This fixing process makes the concrete bridge deck 1 only bear the effects of the second-stage dead load and live load instead of the steel truss and the concrete bottom plate 8 The effect of self-weight can give full play to the high-strength advantage of the steel structure and reduce the tensile force on the concrete bridge deck 1 in the negative bending moment area near the mid-fulcrum.

Optimized, a row of longitudinal prestressed steel bars are arranged in the concrete bridge deck 1, the prestressing adopts 15- ^Φs 15.24 steel strands, the horizontal spacing is 25cm, and there are a total of 40 prestressed steel tendons in the middle fulcrum section. Eight prestressed steel bars are anchored symmetrically at intervals of 17.2m. The anchorage points of the prestressed tendons are located under the concrete bridge deck where there are no steel beams.

It has been verified by calculation that after the track laying is completed in this embodiment, the residual creep deflection of the middle span and side span is 3mm, and the deflection under static and live load is 104mm, all of which meet the technical requirements of the high-speed railway with a speed of 350km/h.

The above examples are only examples of the present utility model, and do not constitute a limitation on the protection scope of the present utility model. All the same or similar designs as the present utility model belong to the protection scope of the present utility model.

Claims (8)

1. a long-span steel truss composite continuous beam structure, is characterized in that: comprise concrete bridge deck, two groups of relative arrangement are used to support the steel truss of concrete bridge deck together, and the two sides span fulcrum for supporting steel truss and two middle the fulcrum; the steel truss includes an upper chord and a lower chord that are arranged along the length of the bridge, and a plurality of webs are connected between the upper chord and the lower chord; the upper chord is a horizontal straight rod structure, and two sets of steel The upper chords of the trusses are connected to the upper parallel, and the transverse bridges of the concrete bridge deck are respectively connected to the upper chords of the two groups of steel trusses on both sides. It is supported on the fulcrums of both sides of the span, and the lowest point of the lower chord is supported on the middle fulcrum. The negative bending moment area of the middle span and the lower chords of the two groups of steel trusses in the full-length area of the side span are provided with concrete bottom plates. A lower parallel is set between the two lower chords in the area. 2. The large-span steel truss composite continuous beam structure according to claim 1, wherein the plurality of web rods between the upper chord and the lower chord are connected end to end in sequence to form a zigzag structure, and adjacent ones The two webs are connected by gusset plates. 3 . The large-span steel truss composite continuous beam structure according to claim 2 , wherein the steel truss adopts a fully welded structure, and the gusset plate adopts a full arc transition structure. 4 . 4. The long-span steel truss composite continuous beam structure according to claim 1, wherein the upper parallel connection comprises a plurality of upper beams arranged at intervals along the bridge direction between two upper chords, and a plurality of upper beams arranged at intervals along the bridge direction. The upper diagonal brace between two adjacent upper beams; the two ends of the upper beam are respectively fixed on the two upper chords, and the upper beam extends along the horizontal transverse bridge direction, and the bottom of the concrete bridge deck is connected with the upper beam. 5 . The large-span steel truss composite continuous beam structure according to claim 4 , wherein the longitudinal and transverse directions of the concrete bridge deck are respectively provided with longitudinal wet joints and transverse wet joints, and the longitudinal wet joints are provided with On the top surface of the upper chord, and the longitudinal wet seam and the upper chord are connected by shear nails, the transverse wet seam is arranged on the top surface of the upper beam of the upper flat connection, and the transverse wet seam and the upper beam pass through Shear nail connection. 6 . The long-span steel truss composite continuous beam structure according to claim 1 , wherein the lower parallel connection comprises a plurality of lower beams arranged at intervals along the bridge direction between two lower chords, and a plurality of lower beams arranged in the opposite The lower diagonal braces are adjacent to the two lower beams; both ends of the lower beams are respectively fixed on the two lower chords, and the lower beams are arranged extending along the horizontal transverse bridge direction. 7 . The large-span steel truss composite continuous beam structure according to claim 1 , wherein the thickness of the concrete floor is the same as the height of the lower chord, and the concrete floor and the lower chord are connected by shear nails. 8 . 8 . The large-span steel truss composite continuous beam structure according to claim 1 , wherein a plurality of longitudinal prestressed steel bars are arranged in the concrete bridge deck. 9 .

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