CN103015304B - Prestressed concrete variable-cross-section box girder bridge with internal tilted-leg rigid frame and construction method of prestressed concrete variable-cross-section box girder bridge - Google Patents

Abstract

The invention discloses a prestressed concrete variable-section box girder bridge with built-in slanted-leg rigid frame, which comprises a bottom plate and a web plate constituting the box girder. The frame structure includes built-in longitudinal girders and built-in oblique legs. The built-in longitudinal girders are set upwards from the mid-span to the bridge pier along the longitudinal direction of the box girder. In the section from the mid-span to 3L/8, the built-in longitudinal girders and the bottom plate are integrated One piece, the rest of the parts are separated, the mid-span positive moment floor cables are bent upward along the built-in longitudinal girder, the anchorage position of the floor cables on the built-in longitudinal beam is provided with sawtooth blocks, and the anchorage ends of the floor cables are at the sawtooth blocks After being bent into the box, the floor cable is tensioned symmetrically at the two tension anchor ends and anchored on the sawtooth block. The upward radial force of the floor cable eliminates or reduces the effect of the second-stage dead load on the downward deflection of the main girder, and the box girder structure bears a reasonable force. The invention also provides a construction method of a prestressed concrete variable-section box girder bridge with built-in oblique-leg rigid frame.

Description

Prestressed concrete variable section box girder bridge with built-in slanted leg rigid frame and its construction method

technical field

The invention relates to the technical field of civil engineering bridges, more specifically, to a prestressed concrete variable-section box girder bridge with built-in oblique-leg rigid frame and a construction method thereof.

Background technique

Long-span prestressed concrete variable-section box-girder bridges are widely used bridge types at present, and continuous beams and continuous rigid-frame bridges are the most common, and they are often constructed by hanging basket cantilever casting method. Figure 1 is a facade layout diagram of a long-span prestressed concrete variable-section box girder bridge in the prior art, which is a continuous rigid frame bridge, the mid-span girder height is less than the fulcrum girder height at pier 06, and the bottom is the box girder floor 01. The facade of the lower edge of the main girder is in the shape of a flat arch, and the bridge is constructed using the cantilever cast-in-place technique of segmented hanging baskets. It includes the mid-span closing section 08, the side-span closing section 09, the pier top segment box girder 011, the side-span cast-in-place section 010 and the cantilever cast-in-place part of the hanging basket, among which the adjacent mid-span closing section 08 is the pier top Segmental box girder 011 and hanging basket cantilever cast-in-place part, and both ends of the bridge are side-span cast-in-place section 010. The box girder 011 of the pier top section is cast-in-situ by the pier top bracket, and then it is cast-in-situ by hanging basket cantilever to the side of the mid-span closing section 08 and side-span closing section 09, and the side-span cast-in-place section 010 is completed on the support. Then carry out the construction of side-span closing section 09, and finally carry out the construction of mid-span closing section 08.

As shown in Figures 3 to 5, the commonly used cross-section form of this kind of variable-section box girder bridge in the prior art is a single-box single-chamber cross-section. Increase, resulting in the lower edge of the bottom plate 01 arched, from the mid-span to the direction of the cantilever root fulcrum at the pier 06, the clearance of the box room is increased, the beam height is increased, the bottom plate 01 is gradually thickened, and the web 02 is close to the fulcrum section It is also partially thickened. The longitudinal elevation of the base plate 01 is arched, and the arched rise-span ratio of the base plate 01 (sag height/main span diameter) is generally about 1/20. The sawtooth block 03 for anchoring the bottom plate cable 05 is arranged at the combined corner of the web 02 and the bottom plate 01 to shorten the force transmission route. As shown in Figures 13 to 16, the longitudinal arrangement of the steel cables in the prior art is: the negative moment cables on the roof are arranged horizontally, anchored near the web 02, and the downward bending arrangement of the web cables 07 provides a certain upward resistance. Shear component force, mid-span positive bending moment bottom plate cable 05 is bent down inside the bottom plate 01, bottom plate cable 05 is anchored on the sawtooth block 03, bottom plate cable 05 is bent down, the elevation of the bottom plate cable 05 is in the same arch shape as the bottom plate 01, The rise-to-span ratio (sagittal height/cable span of the bottom plate) is generally about 1/20. Therefore, the arched bottom cable 05 will generate a downward radial force when it is under tension, and the downward radial force of the bottom cable 05 whose anchoring end is far away from the mid-span is large.

When the bridge span increases, the existing technology adopts measures such as increasing the beam height, thickening the bottom plate 01, thickening the web plate 02, and increasing the configuration of the bottom plate cable 05, and increasing the beam height, increasing the distribution cable, and bending the bottom plate cable 05 The radial resultant force of the bridge is further increased, and this unreasonable structure leads to the problem of unfavorable force bearing. The larger the span of the bridge, the more serious this problem is, which restricts the development of this type of bridge.

As shown in Figure 6 to Figure 12, in order to solve the above problems, a bridge is designed, that is, a prestressed concrete variable-section box girder bridge with built-in oblique leg rigid frame (patent number: ZL 200610167317.X), and Figure 2 is its elevation layout. Including the bottom plate 01 and web 02 constituting the box girder, a rigid frame structure with oblique legs is set in the box girder of variable cross-section box girder bridge. Set at the corresponding beam height of the mid-span mid-slab 01 of the box girder, the mid-span L/2 section to the section near the 3L/8 section bottom plate 01 and the built-in longitudinal beam 041 are integrated, and the height of the built-in longitudinal beam 041 is equal to the thickness of the mid-span bottom plate 01 Consistent; one end of the built-in slanted leg 042 is integrated with the built-in longitudinal beam 041, and its two sides are connected with the web 02 as a whole. The built-in slanted leg 042 is arranged in parallel with the bottom plate 01 of the box girder. The radial distance between the built-in slanted leg 042 and the bottom plate 01 is 1/4~1/5 of the total girder height H of the fulcrum, the built-in slanted legs 042, box girder bottom plate 01 and web plate 02 are all of equal cross-section, and the thickness is 40-60cm; the lower edge of box girder bottom plate 01 adopts suspension lines , the net rise-span ratio is 1/7~1/9; the mid-span positive moment floor cable 05 is arranged horizontally along the built-in stringer 041, and the sawtooth block 03 is set on the built-in stringer 041 where the floor cable 05 is tensioned and anchored, and the floor cable 05 The tensioned anchor end is bent into the box at the sawtooth block 03, and the two anchor ends of the floor cable 05 are symmetrically tensioned and anchored on the sawtooth block 03.

The main defects or deficiencies of the existing patented technology "Prestressed Concrete Variable Section Box Girder Bridge with Built-in Diagonal Leg Frame and Its Construction Method" (patent number: ZL 200610167317.X) are as follows:

(1) The layout of floor cable 05 and the bending moment envelope diagram (generally parabolic) of the long-span prestressed concrete variable-section box girder bridge using the cantilever construction method cannot be completely consistent, and there is a certain deviation.

(2) In order to reduce the pier height of the side spans and save costs, improve the clearance under the main span bridge or overcome the deflection in the middle of the span, the main span is generally set with a longitudinal slope of about 2% in both directions. On bridges with longitudinal slopes, for the convenience of design and construction, generally The built-in longitudinal girder 041 is arranged parallel to the bridge deck, and the bottom cable 05 is arranged on a longitudinal slope of about 2% in both directions, and there is part of the downward radial force on the bottom cable 05.

(3) It cannot provide an upward component force, and cannot balance the second phase dead load and the downward force of the lane load.

(4) There is no control method to eliminate or reduce the deflection deformation of the main girder caused by the second-stage dead load, and the deformation of the main span is not easy to control after the main span is closed.

(5) On a bridge with a two-way longitudinal slope in the main span, the downward radial force of the floor cable 05, the first-phase and second-phase dead load, and the driveway load are all downward, which intensifies the shrinkage and creep effect of the concrete, resulting in Must continue to scratch.

(6) The built-in slanted leg 042 and the box girder floor 01 are arranged in parallel, the radial distance between the built-in slanted leg 042 and the bottom plate 01 is 1/4 to 1/5 of the height H of the fulcrum, and the built-in longitudinal beam 041 and built-in The distance between the inclined legs 042 is too large, exceeding 5 to 6 meters, and the stability of the web 02 and the torsional capacity of the box girder are not good.

In addition, the follow-up construction work after the main girder of the large-span prestressed concrete variable-section box girder bridge using the cantilever construction method in the prior art has the following characteristics:

In the prior art, after the box girders of the long-span prestressed concrete variable-section box girder bridge are closed, the construction of cast-in-place leveling concrete with a thickness of about 10 cm, the construction of asphalt concrete pavement with a thickness of about 10 cm, and the construction of sidewalks, railings or anti-collision guardrails are carried out.

The weight of cast-in-place leveling concrete with a thickness of about 10 cm, asphalt concrete pavement, sidewalks, railings or crash barriers with a thickness of about 10 cm is generally called the second-phase dead load. In the phase II dead load construction stage, the floor cable 05 is generally stretched and completed. The second-phase dead load generally adopts concrete materials, and some bridge railings adopt steel structures, and the dead weight is relatively large.

The following table lists the proportional relationship between the phase II dead load and the design lane load of the highway. The second-stage dead load is generally about twice the design lane load of the highway. Eliminating or reducing the impact of the second-stage dead load on the deflection of the main girder is of great significance for improving traffic capacity and reducing the difficulty of construction control.

Contents of the invention

Aiming at the defects and deficiencies of the prior art, the first object of the present invention is to provide an upward radial force generated by the mid-span positive moment floor cable to eliminate or reduce the influence of the downward deflection of the main girder caused by the second phase dead load. Prestressed concrete variable-section box with oblique-leg rigid frame built-in oblique-leg rigid frame with built-in slanted-leg rigid frame, which has high overall rigidity, small deflection, strong shear resistance, reasonable cable routing, good web stability and box girder torsion resistance, reasonable box girder structure stress and convenient construction. girder bridge. The second object of the present invention is also to provide a construction method for a prestressed concrete variable-section box girder bridge with built-in oblique-leg rigid frame.

In order to achieve the above-mentioned first object, the present invention provides the following technical solutions:

A prestressed concrete variable-section box girder bridge with built-in oblique-leg rigid frame, including a bottom plate and a web plate constituting the box girder, and a diagonal-leg rigid frame structure is arranged inside the variable-section box-girder bridge box, and the oblique-leg rigid frame structure includes a built-in Longitudinal girders and built-in oblique legs, the built-in longitudinal girders are set upwardly inclined or bent along the longitudinal direction of the box girder from the mid-span to the pier direction, and in the mid-span L/2 section to 3L/8 section section, the built-in longitudinal girders It is integrated with the bottom plate, and the rest of the built-in longitudinal beams are separated from the bottom plate;

One end of the built-in slanted leg is connected to the built-in longitudinal girder, and the other end is connected to the pier, the end connected to the built-in girder is higher than the end connected to the pier, and the end of the built-in slanted leg connected to the pier The section is located in the middle of the beam height between the built-in longitudinal beam and the bottom plate and is connected to the diaphragm of the bridge pier, and the built-in inclined leg is connected to the built-in longitudinal beam at the middle part of the box girder height at the L/4 section;

The mid-span positive bending moment floor cables are bent upward along the built-in longitudinal beams, and sawtooth blocks are arranged on the anchorage positions of the floor cables on the built-in longitudinal beams, and the anchorage ends of the floor cables are bent into the box at the sawtooth blocks. The floor cable is tensioned symmetrically at the two tensioned anchor ends and anchored on the sawtooth block.

Preferably, the construction section of the built-in longitudinal beam in the mid-span closing section is a horizontally arranged section, and the separation section separated from the bottom plate is arranged obliquely upward to form a straight line or a curve. When the separation section is curved and upwardly inclined, its The anchor points are located on the same oblique straight line, and the upward component force provided by the floor cables can offset the in-situ leveling concrete thickness of 10 cm and the asphalt concrete pavement thickness of 10 cm through the upward component force provided by the floor cables. 10 cm, the weight of sidewalks, railings or anti-collision guardrails and 50% of the design lane load of the highway are calculated and determined, and a curved transition section is set between the horizontal arrangement section of the built-in longitudinal beam and the upwardly curved separation section.

Preferably, the built-in longitudinal girder is arranged horizontally near the last sawtooth block on the side of the pier and extends to the pier, the built-in slanted leg is provided with a horizontal section of the pier top at the pier, and both the built-in longitudinal girder and the built-in slanted leg pass through The diaphragm at the top of the pier is respectively connected with the built-in longitudinal beam and built-in slanted leg of the adjacent span, and a curved transition section is set between the horizontal section of the pier top of the built-in longitudinal beam and the inclined or upwardly curved section of the bridge span.

Preferably, the surface of the main span part of the built-in stringer is depressed downwards to form a concave parabolic surface, and the upper surface of the built-in stringer is raised upwards to form a convex parabolic surface and is connected to the pier top of the bridge pier. The horizontal sections are connected, and the lower part of the built-in longitudinal beam is integrated with the bottom plate of the horizontal section of the construction section of the mid-span closing section.

Preferably, the transverse structural steel bars of the built-in longitudinal girder and built-in slanted legs are bent at the web and welded firmly or overlapped with the vertical steel bar of the web. When lap joint is adopted, the built-in longitudinal beam and The transverse structural reinforcement with built-in oblique legs is bent at the web, and the anchorage length in the web is guaranteed to be more than 40 times the diameter of the reinforcement.

Preferably, a transverse reinforcing rib is provided on each construction section of the built-in stringer of the floor cable arrangement section.

Preferably, the transverse prestressing rib is applied with transverse prestress, and the transverse prestress can be stretched at both ends outside the box, or one end is anchored in the concrete at the web, and the other end is bent into the box for tension, and the transverse prestress The transverse prestressing construction applied to the stiffeners precedes the tensioning construction of the longitudinal floor cables.

A construction method for a prestressed concrete variable-section box girder bridge with a built-in slanted leg rigid frame. The bridge is constructed using the hanging basket cantilever pouring method. Delay a construction stage with built-in diagonal legs, cast-in-situ on box supports or hangers.

Preferably, the tensioning of the floor cables is carried out in multiple batches and stages according to the change of the mid-span elevation; the box girder is closed and stretched by 40%, and the cast-in-place leveling concrete in the later stage is 10 cm thick and then stretched by 20%. Railings or anti-collision guardrails are stretched by 20% after completion, asphalt concrete pavement is 10 cm thick and then stretched by 20%; 30% tension after completion, and 30% tension after completion of asphalt concrete pavement with a thickness of 10 cm; during construction, the dynamic adjustment of the tensioning process of the upper curved floor cable is carried out according to the elevation measured at the mid-span section.

It is the same as the existing patent "Prestressed Concrete Variable Section Box Girder Bridge with Built-in Diagonal Leg Rigid Frame and Its Construction Method" (Patent No.: ZL 200610167317.X) and the existing floor cable downward bending arrangement of large-span prestressed concrete single-box single-chamber substation Compared with cross-section box girder bridge structure, the main beneficial effects of the present invention are:

(1) Since the up-curved built-in longitudinal beams are provided, and the floor cables are arranged in the up-curved built-in longitudinal beams, the mid-span positive moment floor cables of the present invention are arranged in an upcurve. On roads with various longitudinal slopes, by setting The different upward bending slope ratios completely eliminate the downward radial force of the positive bending moment cables in the mid-span of the single-box single-chamber variable-section box girder bridge with the downward bending arrangement of the floor cables, and completely eliminate the existing two-way longitudinal slope of the main span. Patent "Prestressed Concrete Variable Section Box Girder Bridge with Built-in Diagonal Leg Frame and Its Construction Method" (Patent No.: ZL200610167317.X) The downward radial force of the bottom plate cable solves the problem of the mid-span positive bending of the large span variable section box girder bridge The problem that the downward radial force of the moment cable increases with the span can effectively solve the cracks along the bridge direction that are prone to occur in the mid-span of variable-section box girder bridges caused by radial force, and the common downward deflection and deflection in the mid-span. The main tensile stress crack problem that is easy to appear in the web.

(2) and the existing patent "Prestressed Concrete Variable Section Box Girder Bridge with Built-in Diagonal Leg Rigid Frame and Its Construction Method" (Patent No.: ZL 200610167317.X) and the existing technology of single box and single chamber variable cross section arranged with downward bending of floor cables Compared with the box girder bridge, the invention provides a method for eliminating or reducing the deflection deformation of the main girder caused by the secondary dead load and the lane load. The upward radial force can balance the second-stage dead load and the lane load, which is of great significance for improving the carrying capacity and reducing the difficulty of construction control.

(3) The floor cables of the present invention are arranged in the built-in longitudinal girder of the upward bend, and the elevation of the floor cables forms a concave parabola, which is basically consistent with the bending moment envelope diagram of the long-span prestressed concrete variable-section box girder bridge adopting the cantilever construction method, It can overcome the large positive bending moment of the mid-span section L/2 to 3L/8, and can resist part of the negative bending moment near the L/8 section. Compared with the prior art, the single-box single-chamber variable-section box girder bridge with a single-box single-chamber variable-section box girder bridge with downward bending of the floor cable and the existing patent "Prestressed concrete variable-section box girder bridge with built-in oblique leg rigid frame and its construction method" (patent number: ZL200610167317.X) published Cables and forces are more reasonable, saving materials, thus bringing economy.

(4) The root section of the lower pier with built-in oblique legs is located in the middle of the girder height between the built-in longitudinal girder and the bottom plate, which improves the stability of the web compared with the parallel arrangement of built-in oblique legs and the bottom plate.

(5) On bridges with various longitudinal slopes, the upward radial force of the floor cables is opposite to the first-phase and second-phase dead loads and lane loads, which can improve the shrinkage and creep effect of concrete and overcome the continuous downward deflection during the mid-span operation period .

(6) The bridge of the present invention can adopt prior art cantilever pouring method construction, built-in longitudinal beam and built-in slanted leg can cantilever cast-in-situ together with box girder section during construction, in order to reduce hanging basket cantilever pouring weight, built-in longitudinal beam and built-in slanted leg The legs can also be cast in-situ on the brackets or hangers in the box after a construction stage is postponed, and the construction is easy to control.

(7) The tensioning of the floor cables is carried out in multiple batches and in multiple stages according to the reasonable range of mid-span elevation changes. After the main span is closed in the first stage, the bridge elevation is basically unchanged, and the construction is easy to control.

(8) The transverse prestressing construction applied to the transverse rib of the built-in longitudinal beam is earlier than the tensioning construction of the longitudinal floor cables to ensure that the floor does not produce longitudinal cracks.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is the structural representation of long-span prestressed concrete variable section box girder bridge in the prior art;

Fig. 2 is the structural schematic diagram of the prestressed concrete variable section box girder bridge with built-in slanted leg rigid frame of the existing patent;

Fig. 3 is the structural diagram of the prior art long-span prestressed concrete variable section box girder bridge;

Fig. 4 is the B-B sectional view of Fig. 3;

Fig. 5 is A-A sectional view of Fig. 3;

Fig. 6 is the structural diagram of the prestressed concrete variable section box girder bridge with built-in slanted leg rigid frame of the existing patent;

Fig. 7 is A-A sectional view of Fig. 6;

Fig. 8 is the B-B sectional view of Fig. 6;

Fig. 9 is a C-C sectional view of Fig. 6;

Fig. 10 is a D-D sectional view of Fig. 6;

Fig. 11 is the E-E sectional view of Fig. 6;

Fig. 12 is the F-F sectional view of Fig. 6;

Fig. 13 is the longitudinal arrangement diagram of the steel cables of the long-span prestressed concrete variable-section box girder bridge in the prior art;

Fig. 14 is A-A sectional view of Fig. 13;

Fig. 15 is a B-B sectional view of Fig. 13;

Fig. 16 is a C-C sectional view of Fig. 13;

Fig. 17 is a longitudinal layout diagram of steel cables of a prestressed concrete variable-section box girder bridge with built-in slanted-leg rigid frame of the existing patent;

Fig. 18 is the A-A sectional view of Fig. 17;

Fig. 19 is a B-B sectional view of Fig. 17;

Figure 20 is a C-C sectional view of Figure 17;

Fig. 21 is the structural diagram of the prestressed concrete variable section box girder bridge with built-in slanted leg rigid frame of the present invention;

Figure 22 is a D-D sectional view of Figure 21;

Fig. 23 is the E-E sectional view of Fig. 21;

Fig. 24 is the F-F sectional view of Fig. 21;

Fig. 25 is the A-A sectional view of Fig. 21;

Figure 26 is a B-B sectional view of Figure 21;

Fig. 27 is the sectional view of C-C of Fig. 21;

Fig. 28 is a longitudinal arrangement diagram of steel cables of a prestressed concrete variable-section box girder bridge with built-in slanted-leg rigid frame in the present invention;

Fig. 29 is the A-A sectional view of Fig. 28;

Figure 30 is a B-B sectional view of Figure 28;

FIG. 31 is a C-C sectional view of FIG. 28 .

Accompanying drawing 1-Fig. 20 mark as follows:

01-bottom plate, 02-web plate, 03-sawtooth block, 041-built-in stringer, 042-built-in slanted leg, 05-bottom plate cable, 06-pier, 07-web cable, 08-span closing section, 09- Side span closing section, 010-side span cast-in-place section, 011-pier top section box girder;

Accompanying drawing 21-Fig. 31 mark as follows:

1-bottom plate, 2-web plate, 3-sawtooth block, 41-built-in stringer, 42-built-in oblique leg, 5-bottom plate cable, 6-pier.

Detailed ways

The first object of the present invention is to provide an upward radial force generated by the positive moment floor cable at mid-span, which can eliminate or reduce the influence of the downward deflection of the main girder caused by the second-stage dead load. The overall structure has high rigidity, small deflection, and A prestressed concrete variable-section box girder bridge with built-in slanted-leg rigid frame with strong shear capacity, reasonable cabling, good web 2 stability and box girder torsion resistance, reasonable box girder structural stress, and convenient construction. The second object of the present invention is also to provide a construction method for a prestressed concrete variable-section box girder bridge with built-in oblique-leg rigid frame.

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Please refer to Figures 21-31, the built-in slanted leg rigid frame prestressed concrete variable section box girder bridge provided by the embodiment of the present invention includes pier 6 and the bottom plate 1 and web 2 constituting the box girder, and the variable section box girder bridge box is arranged There is a rigid frame structure with diagonal legs, and the rigid frame structure with diagonal legs includes built-in longitudinal beams 41 and built-in diagonal legs 42 .

Among them, the built-in longitudinal beam 41 is set upwardly inclined or bent from the mid-span to the pier 6 along the longitudinal direction of the box girder. In the mid-span L/2 section to the 3L/8 section section, the built-in longitudinal beam 41 and the bottom plate 1 are integrated One body, that is, a solid section, and the rest of the built-in stringer 41 is separated from the bottom plate 1; one end of the built-in slanted leg 42 is connected to the built-in stringer 41, and the other end is connected to the pier 6, and the end connected to the built-in stringer 41 is higher than the pier 6, and the section of the end of the built-in slanted leg 42 connected to the pier 6 is located in the middle of the beam height between the built-in longitudinal beam 41 and the bottom plate 1 section and connected to the diaphragm of the pier 6, the built-in slanted leg 42 is at L The middle part of the height of the box girder at the /4 section is connected to the built-in slanted beam, preferably the built-in slanted leg 42, the bottom plate 1 and the web 2 of the box girder are all of equal cross-section, and the thickness is about 60 cm. The lower edge of the box girder floor 1 adopts a semi-cubic parabola, and the net rise-span ratio (height difference/span) is about 1/20.

The mid-span positive bending moment floor cable 5 is bent upward along the built-in longitudinal beam 41, and the anchorage position of the 5-tensioned floor cable on the built-in longitudinal beam 41 is provided with a sawtooth block 3, and the anchorage end of the 5-tensioned floor cable is bent at the sawtooth block 3. In the box, the floor cable 5 is symmetrically tensioned at the two tension anchor ends and anchored on the sawtooth block 3 . The top of the built-in inclined leg 42 is integrated with the built-in longitudinal beam 41, and the two sides of the built-in inclined leg 42 and the built-in longitudinal beam 41 are respectively connected with the web 2 to form a space box structure.

Since the built-in longitudinal girder 41 is provided, and the floor cable 5 is arranged in the built-in longitudinal beam 41, the positive bending moment floor cable 5 in the mid-span of the present invention is arranged in an upward bend. On various longitudinal slope roads, through Different upward bending slope ratios are set to eliminate the downward radial force of the positive bending moment cables in the mid-span of the single-box single-chamber variable-section box girder bridge with the downward bending arrangement of the floor cables, and eliminate the existing patent for setting the two-way longitudinal slope of the main span "Prestressed concrete variable section box girder bridge with built-in oblique leg rigid frame and its construction method" (Patent No.: ZL 200610167317.X) The downward radial force of the floor cable solves the problem of the mid-span positive bending of the large span variable section box girder bridge The problem that the downward radial force of the moment cable increases with the span can effectively solve the cracks along the bridge direction that are prone to occur in the mid-span of variable-section box girder bridges caused by radial force, and the common downward deflection and deflection in the mid-span. The main tensile stress crack problem that is easy to appear in the web.

Preferably, in this specific embodiment, the built-in longitudinal girder is arranged to be inclined or bent upward along the longitudinal direction of the box girder at a slope rate of 5% from the mid-span to the bridge pier. Of course, it is also possible to adopt different slope gradients according to different bridges.

Preferably, the construction section of the built-in longitudinal beam 41 in the mid-span closing section is a horizontally arranged section, and the separation section separated from the bottom plate 1 is arranged obliquely straight or curved upward. When the separation section is curved upward, its anchor points are located at the same On the oblique straight line, the upward component force provided by the floor cable 5 can offset the 10 cm thick cast-in-place leveling concrete, 10 cm thick asphalt concrete pavement, and The weight of sidewalks, railings or anti-collision guardrails and 50% of the design lane load of the highway are calculated and determined, and a curved transition section is provided between the horizontally arranged section of the built-in stringer 41 and the upwardly curved separation section.

Preferably, the surface of the main span part of the built-in stringer 41 is depressed downwards to form a concave parabolic surface, and the upper surface of the built-in stringer 41 is convexly arranged to form a convex parabolic surface and is connected to the horizontal section of the pier top of the pier, The lower part of the built-in longitudinal beam 41 is integrated with the bottom plate of the horizontal section of the construction section of the mid-span closing section. That is, the separation section where the built-in longitudinal girder 41 is separated from the bottom plate 1 can be a concave parabola, the part connected to the top of the pier is the horizontal section of the pier top, and the horizontal section of the pier top at the part connected to the top of the pier passes through the convex parabola section and the concave parabola. section connection.

The horizontal structural steel bars of the built-in longitudinal beam 41 and the built-in slanted leg 42 are bent at the web 2 and welded or overlapped with the vertical steel bar of the web 2 firmly. The 42 transverse structural steel bar is bent at the web 2, and the anchorage length in the web 2 is guaranteed to be more than 40 times the diameter of the steel bar. If necessary, a transverse reinforcing rib can be set at each construction section on the built-in longitudinal beam 41 of the layout section of the floor cable 5 . If necessary, transverse prestress can be applied to the transverse reinforcing ribs, and the transverse prestress can be stretched at both ends outside the box, or one end is anchored in the concrete at 2 places on the web, and the other end is bent into the box for tension, and the transverse reinforcement The transverse prestressing construction applied to the ribs is earlier than the tensioning construction of the longitudinal floor cables 5 .

The present invention also provides a construction method for a prestressed concrete variable-section box girder bridge with a rigid frame with built-in slanted legs. The bridge is constructed by the hanging basket cantilever pouring method. Cast-in-situ, or the built-in longitudinal beam 41 and built-in slanted leg 42 postpone a construction stage, and cast-in-situ on the bracket or hanger in the box.

Among them, the tensioning of the floor cable 5 is carried out in multiple batches and stages according to the change of the mid-span elevation; the box girder is closed and stretched by 40%, and the cast-in-place leveling concrete is 10 cm thick and stretched by 20% after completion. Railings or anti-collision guardrails are stretched by 20% after completion, asphalt concrete pavement is 10 cm thick and then stretched by 20%; 30% tension after completion, and 30% tension after completion of asphalt concrete pavement with a thickness of 10 cm; during construction, the dynamic adjustment of the 5-tension process of the upper-bend floor cable is carried out according to the elevation measured at the mid-span section.

Each embodiment in this specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts of each embodiment can be referred to each other.

It should be noted that the built-in slanted-leg rigid frame prestressed concrete variable-section box girder bridge and its construction method provided in this specific embodiment are applicable to bridges with a main span of 150 to 200 meters on a longitudinal slope (4 to 200 m wide bridges). 6 lanes), certainly, do not rule out adopting the girder bridge and the construction method in this specific embodiment when carrying out the girder bridge design of other forms.

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (8)

1. a built-in oblique leg rigid-frame prestress concrete variable cross-section box girder bridge, comprise the base plate (1) and web (2) that form case beam, it is characterized in that, an oblique leg rigid-frame structure is provided with in variable cross-section box girder bridge case, described oblique leg rigid-frame structure comprises built-in longeron (41) and built-in oblique leg (42), described built-in longeron (41) to bridge pier (6) direction along case beam by span centre is longitudinally inclined upwardly or bends up setting, at span centre L/2 cross section to 3L/8 cross section section, described built-in longeron (41) and base plate (1) combine together, the built-in longeron of remainder (41) is separated with base plate (1),

Described built-in oblique leg (42) one end is connected with described built-in longeron (41), the other end is connected with described bridge pier (6), its one end be connected with built-in longeron (41) is higher than the one end be connected with bridge pier (6), and the cross section of one end that described built-in oblique leg (42) is connected with bridge pier (6) is positioned at the centre of described built-in longeron (41) and base plate (1) interval deck-molding and is connected with the diaphragm of bridge pier (6), described built-in oblique leg (42) is connected with described built-in longeron (41) in the middle part of L/4 section case depth of beam,

Positive moment of span central point base plate rope (5) is along the upper curved layout of built-in longeron (41), upper described base plate rope (5) stretch-draw anchor position is provided with sawtooth block (3) to described built-in longeron (41), base plate rope (5) stretch-draw anchor end bends up in case at sawtooth block (3) place, and base plate rope (5) is in the symmetrical stretch-draw of two stretch-draw anchor ends and be anchored on sawtooth block (3).

2. built-in oblique leg rigid-frame prestress concrete variable cross-section box girder bridge according to claim 1, it is characterized in that, described built-in longeron (41) is in the span centre closure segment construction sections section of being arranged horizontally, the segregation section be separated with described base plate (1) is inclined upwardly and is arranged to skew lines or curve, when described segregation section is curved be inclined upwardly time, its anchor point is positioned on same skew lines, the inclination ratio of slope of the upper curved inclination of described base plate rope (5) can be offset case beam by the upwards component that described base plate rope (5) provides and be closed up later stage cast-in-place leveling Concrete Thick 10 centimetres, thick 10 centimetres of asphalt concrete pavement, sidewalk, railing or anticollision barrier weight and 50% Road Design lane load add up to calculating to determine, and be provided with curve transition between the horizontal arrangement section of described built-in longeron (41) and upper curved segregation section.

3. built-in oblique leg rigid-frame prestress concrete variable cross-section box girder bridge according to claim 1, it is characterized in that, described built-in longeron (41) is near last sawtooth block (3) place horizontal arrangement of bridge pier (6) side, and extend to bridge pier (6) place, built-in oblique leg (42) is provided with pier top horizontal segment at bridge pier place, built-in longeron (41) and built-in oblique leg (42) all through pier top diaphragm respectively with adjacent across built-in longeron (41) and built-in oblique leg (42) be connected as a single entity, the pier top horizontal segment of built-in longeron (41) and spanning tilt or arrange curve transition between upper bend section.

4. built-in oblique leg rigid-frame prestress concrete variable cross-section box girder bridge according to claim 1, it is characterized in that, the surface of the main span part of described built-in longeron (41) is concave parabola shape surface to lower recess, the upper face of described built-in longeron (41) raises up and arranges the surface in convex parabola shape and be connected with the pier top horizontal segment of described bridge pier, and the construct base plate (1) of horizontal segment of sections of described built-in longeron (41) bottom and span centre closure segment combines together.

5. the built-in oblique leg rigid-frame prestress concrete variable cross-section box girder bridge according to claim 1-4 any one, it is characterized in that, the transverse structure reinforcing bar of described built-in longeron (41) and built-in oblique leg (42) bends up at web (2) place also and the vertical reinforced-bar-welding of described web (2) is firm or overlap joint, when adopting overlap joint, the transverse structure reinforcing bar of described built-in longeron (41) and built-in oblique leg (42) bends up at web (2) place, and the anchorage length ensureing in web (2) is more than 40 times of bar diameter.

6. built-in oblique leg rigid-frame prestress concrete variable cross-section box girder bridge according to claim 5, is characterized in that, arranges that each construction section on the built-in longeron (41) of section arranges horizontal ribs together at base plate rope (5).

7. built-in oblique leg rigid-frame prestress concrete variable cross-section box girder bridge according to claim 6, it is characterized in that, described horizontal ribs is applied with transverse prestress, transverse prestress can adopt in the outer two ends stretch-draw of case, or adopt one end to be anchored in web (2) place concrete, the other end bends up stretch-draw in case, and the transverse prestress construction that horizontal ribs applies will early than the stretching construction of longitudinal base plate rope (5).

8. a built-in oblique leg rigid-frame prestress concrete variable cross-section box girder bridge construction method, it is characterized in that, bridge adopts Hanging Basket case-in-place cantilever method, during construction, cantilever is cast-in-place together for built-in longeron (41), built-in oblique leg (42) and box girder segment, or built-in longeron (41) and built-in oblique leg (42) postpone a construction stage, cast-in-place on case inner support or suspension bracket;

The stretch-draw of base plate rope (5) divides many batches to construct stage by stage according to the change of span centre absolute altitude; Case beam closes up post tensioning 40%, and later stage cast-in-place leveling Concrete Thick 10 centimetres completes post tensioning 20%, and sidewalk, railing or anticollision barrier complete post tensioning 20%, and thick 10 centimetres of asphalt concrete pavement completes post tensioning 20%; When not arranging leveling concrete, case beam closes up post tensioning 40%, and sidewalk, railing or anticollision barrier complete post tensioning 30%, and thick 10 centimetres of asphalt concrete pavement completes post tensioning 30%; Measure according to spaning middle section the dynamic conditioning that absolute altitude carries out upper bent bottom plate rope (5) stretching process during construction.