CN107916625B - Widening structure and method of wide cantilever box girder - Google Patents

Abstract

The invention is specifically a widening structure of a wide cantilever box girder and a method thereof, which solves the problems of complicated process, high cost, large damage to the original structure and inconvenience of later maintenance caused by widening of the existing wide cantilever box girder. The upper end of the beam bottom steel plate is provided with longitudinal stiffening steel plates and connecting steel bars, the left and right sides of the longitudinal stiffening steel plates are provided with vertical anchor bolts, and the inner sides of the adjacent webs of the original box girder and the widened box girder are provided with transverse anchor bolts. On the adjacent side of the box girder and the widened box girder, there are bottom plate implanted steel bars and bottom plate reserved steel bars, and a concrete bottom plate cast-in-place layer is set on the beam bottom steel plate; Steel bars and reserved steel bars at the bottom of the top slab, and cast-in-place steel bars and reserved steel bars for the cast-in-place layer of the original box girder and widened box girder. The invention improves the safety performance of the structure, ensures the durability of the original structure at the same time, and has the advantages of low construction cost and short construction period.

Description

Widening structure and method of wide cantilever box girder

technical field

The invention relates to a widening technology for highway bridge and culvert engineering, in particular to a widening structure of a wide cantilever box girder and a method thereof.

Background technique

At present, the construction of new highways in my country has reached an unprecedented scale, and the reconstruction and expansion projects in operation in the future will gradually become a major focus of highway construction. In highway reconstruction and expansion projects, one of the key technical issues is the widening and reconstruction of existing bridges. Different from general bridge design, the design of bridge widening and reconstruction must consider the interaction between the old and new beam-slab structures during the construction phase and the use phase. It is necessary to adopt reasonable structural measures and appropriate construction methods to minimize the damage to the original structure, so as to ensure Safety, durability and serviceability of wide rear bridges.

For wide cantilever box girder structures, the problem of widening and reconstruction is more prominent. In conventional design methods, only the flange plates of the main girder are generally connected laterally. The lateral connection stiffness of the old and new structures is poor, and the structure cannot overcome the deflection difference between the old and new box girders. In the long-term operation, it is inevitable that pavement cracks will appear at the joints, which will bring safety hazards to later maintenance. However, in other horizontal connection designs using steel reinforcement technology, the construction technology is complicated, there are many steps, the project cost is high, and the original structure is greatly damaged.

Contents of the invention

The invention provides a widening structure and method of a wide cantilever box girder to solve the problems of complex process, high cost, large damage to the original structure, and poor connection rigidity resulting in inconvenient maintenance in the widening of the existing wide cantilever box girder.

The present invention is realized by adopting the following technical scheme: a widening structure of a wide cantilever box girder, including a beam bottom steel plate arranged between the original box girder and the widened box girder and close to the lower end surfaces of the bottom plates of the two, and the beam bottom steel plate The end face is provided with a number of longitudinally stiffened steel plates distributed left and right. The longitudinally stiffened steel plates are pierced with a number of connecting steel bars distributed front and rear. The left and right sides of the longitudinally stiffened steel plates are provided with vertical anchor bolts fixed to the original box girder and the widened box girder floor. , the inner sides of the adjacent webs of the original box girder and the widened box girder are provided with transverse anchor bolts fixed to the longitudinal stiffening steel plates at the left and right ends, and the right side of the bottom plate of the original box girder is provided with a bottom plate implanted steel bar fixed with the connecting steel bars, The left side of the bottom slab of the widened box girder is provided with the reserved reinforcement for the bottom slab fixed to the connecting steel bars, and the cast-in-place concrete layer for the bottom slab is set on the steel plate at the bottom of the beam; The left side of the top plate of the box girder is provided with the reserved steel bar of the roof connected to the steel bar of the roof and the reserved steel bar of the bottom of the roof connected with the bottom steel bar of the roof. The left side of the cast-in-place layer is provided with the reserved steel bar of the cast-in-place layer connected with the steel bars of the cast-in-place layer.

The structural design utilizes the characteristics of concrete compression resistance and steel plate bending resistance, and good deformation adaptability. The steel plate at the bottom of the beam is used to form a new steel-concrete composite box girder between the old and new box girders, which improves the overall rigidity and stability between the old and new box girders. The torsion resistance greatly reduces the damage at the joints of the old and new bridges during the operation stage, and increases the bending resistance of the widened structure. At the same time, because the large-area reinforcement process is not used, the damage to the original structure is minimized. It overcomes the problems of complex process, high cost, large damage to the original structure and poor connection rigidity that cause inconvenience in later maintenance when the existing wide cantilever box girder is widened.

A kind of widening method of wide cantilever box girder adopts the following steps: a. Implant horizontal anchor bolts, vertical anchor bolts and bottom slabs into steel bars on the bottom slab of the original box girder and the widened side web, and then place the girder bottom steel plate and the connecting steel bars passed on it are hoisted in place and then anchored and connected with the original box girder, then the beam bottom steel plate and the connecting steel bars passed on it are anchored and connected with the widened box girder, and then poured concrete to form a whole; b. When the flange part of the original box girder roof is the same thickness as the end of the flange of the cast-in-place box girder roof, the roof steel bars and roof reserved steel bars in the original box girder and the widened box girder roof, as well as the roof bottom steel bars and the roof bottom pre-prepared Retain steel bars for welding and connection, and then pour concrete on the roof; c. Cut off the cast-in-place layer at the cantilever of the original box girder, and use the cast-in-place layer steel bars and the reserved steel bars in the cast-in-place layer for welding, then pour the original box girder bridge deck into cast-in-place layer to complete the widening of the wide cantilever box girder.

The steel plate at the bottom of the beam is used as a template for concrete pouring, which is more convenient for construction and shortens the construction period.

The widening technology of the wide cantilever box girder of the present invention greatly improves the overall rigidity and torsional performance between the old and new box girders, greatly reduces the defects in the operation stage, increases the driving comfort, and increases the structural stability. The bending bearing capacity improves the safety performance of the structure, reduces the damage to the original structure at the same time, ensures the durability of the original structure, and has the advantages of low construction cost and short construction period.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

In the figure: 1-original box girder, 2-widened box girder, 3-beam bottom steel plate, 4-longitudinal stiffening steel plate, 5-connecting steel bar, 6-vertical anchor bolt, 7-horizontal anchor bolt, 8-bottom plate planting Reinforcement, 9- cast-in-place layer of concrete floor, 10- roof reinforcement, 11- roof bottom reinforcement, 12- cast-in-place layer reinforcement, 13- reserved reinforcement for bottom floor, 14- reserved reinforcement for roof, 15- reserved reinforcement for roof bottom , 16-Reserved reinforcement for the cast-in-place layer.

Detailed ways

A widening structure of a wide cantilever box girder, comprising a beam bottom steel plate 3 arranged between the original box girder 1 and the widened box girder 2 and close to the lower end surfaces of the bottom plates of the two. The longitudinally stiffened steel plate 4 is pierced with a number of connecting steel bars 5 distributed front and rear, and the left and right sides of the longitudinally stiffened steel plate 4 are provided with vertical anchor bolts fixed to the bottom plates of the original box girder 1 and the widened box girder 2 6. The inner sides of the adjacent webs of the original box girder 1 and the widened box girder 2 are provided with transverse anchor bolts 7 fixed to the longitudinal stiffening steel plates 4 at the left and right ends, and the right side of the bottom plate of the original box girder 1 is provided with connecting steel bars 5 The fixed bottom plate is implanted with steel bars 8, and the left side of the bottom plate of the widened box girder 2 is provided with a reserved steel bar 13 fixed to the connecting steel bar 5, and a concrete bottom plate cast-in-place layer 9 is set on the beam bottom steel plate 3; the original box girder 1 top plate The right side of the roof is provided with a roof reinforcement 10 and a roof bottom reinforcement 11, and the left side of the widened box girder 2 roof is provided with a roof reserved reinforcement 14 connected with the roof reinforcement 10 and a roof bottom reinforcement 15 connected with the roof bottom reinforcement 11. , the left side of the cast-in-place layer of the original box girder 1 is provided with a cast-in-place layer reinforcement 12, and the left side of the widened box girder 2 cast-in-place layer is provided with a cast-in-place layer reserved reinforcement 16 connected with the cast-in-place layer reinforcement 12.

A kind of widening method of wide cantilever box girder, adopt following steps: a, implant horizontal anchor bolt 7, vertical anchor bolt 6 and bottom plate implant reinforcement bar 8 on the bottom plate of original box girder 1 and widened side web, then Hoist the beam bottom steel plate 3 and the connecting steel bar 5 pierced thereon to the original box girder 1 for anchor connection, then anchor the beam bottom steel plate 3 and the connecting steel bar 5 pierced thereon to the widened box girder 2 After pouring concrete to form a whole; b. When the flange part of the top plate of the original box girder 1 is chiseled to the same thickness as the flange end of the top plate of the cast-in-place box girder 2, the top plate in the top plate of the original box girder 1 and the widened box girder 2 The steel bar 10 and the reserved steel bar 14 of the roof and the steel bar at the bottom of the roof and the reserved steel bar 15 at the bottom of the roof are welded and connected, and then the roof concrete is poured; After welding with the reserved steel bar 16 of the cast-in-place layer, the cast-in-place layer of the original box girder 1 bridge deck is poured to complete the widening operation of the wide cantilever box girder.

Claims (1)

1. A widening method of a wide cantilever box girder is characterized by comprising the following steps: the method is realized based on a widening structure of a wide cantilever box girder, the structure comprises a girder bottom steel plate (3) which is arranged between an original box girder (1) and a widening box girder (2) and is tightly attached to the lower end surfaces of bottom plates of the original box girder and the widening box girder, a plurality of left and right distributed longitudinal stiffening steel plates (4) are arranged on the upper end surfaces of the girder bottom steel plate (3), a plurality of connecting steel bars (5) which are distributed front and back are penetrated in the longitudinal stiffening steel plates (4), vertical anchor bolts (6) which are fixed with the bottom plates of the original box girder (1) and the widening box girder (2) are arranged on the left and right sides of the longitudinal stiffening steel plates (4), transverse anchor bolts (7) which are fixed with the longitudinal stiffening steel plates (4) at the left and the right ends are arranged on the inner sides of adjacent webs of the original box girder (1) and the widening box girder (2), bottom plate implantation steel bars (8) which are fixed with the connecting steel bars (5) are arranged on the left side of the bottom plate of the original box girder (1), bottom plate reservation steel bars (13) which are fixed with the connecting steel bars (5), and a concrete bottom plate layer (9) is arranged on the girder bottom steel plate (3) in a cast-in place; the right side of the top plate of the original box girder (1) is provided with a top plate reinforcing bar (10) and a top plate bottom reinforcing bar (11), the left side of the top plate of the widened box girder (2) is provided with a top plate reserved reinforcing bar (14) connected with the top plate reinforcing bar (10) and a top plate bottom reserved reinforcing bar (15) connected with the top plate bottom reinforcing bar (11), the left side of the cast-in-situ layer of the original box girder (1) is provided with a cast-in-situ layer reinforcing bar (12), and the left side of the cast-in-situ layer of the widened box girder (2) is provided with a cast-in-situ layer reserved reinforcing bar (16) connected with the cast-in-situ layer reinforcing bar (12); the method comprises the following steps: a. a transverse anchor bolt (7), a vertical anchor bolt (6) and a bottom plate implantation reinforcing steel bar (8) are implanted on a bottom plate and a widened side web plate of an original box girder (1), then a girder bottom steel plate (3) and a connecting reinforcing steel bar (5) penetrating through the girder bottom steel plate are hoisted in place and then are connected with the original box girder (1) in an anchoring manner, and then the girder bottom steel plate (3) and the connecting reinforcing steel bar (5) penetrating through the girder bottom steel plate are connected with the widened box girder (2) in an anchoring manner and then concrete is poured into a whole; b. chiseling out the flange part of the top plate of the original box girder (1) until the thickness is the same as that of the flange end part of the top plate of the widened box girder (2), welding and connecting the original box girder (1) with the top plate reinforcing steel bars (10) and the top plate reserved reinforcing steel bars (14) in the top plate of the widened box girder (2) and the top plate bottom reinforcing steel bars and the top plate bottom reserved reinforcing steel bars (15), and pouring top plate concrete; c. and chiseling a cast-in-situ layer at the cantilever of the original box girder (1), and pouring a bridge deck cast-in-situ layer of the original box girder (1) after welding by utilizing cast-in-situ layer steel bars (12) and cast-in-situ layer reserved steel bars (16), so as to complete the widening operation of the wide cantilever box girder.

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