CN111636286A - Pretensioned broken line prestressed I-beam bridge and construction method - Google Patents

Abstract

The invention relates to a pretensioned broken line prestressed I-beam bridge and a construction method thereof, wherein the pretensioned broken line prestressed I-beam bridge comprises a plurality of bridge piers and a beam body arranged between adjacent bridge piers, the beam body comprises a plurality of I-beams which are arranged in parallel and the two ends of which are arranged at the tops of the bridge piers, bridge decks are cast on the upper surfaces of the I-beams, prestressed pieces are arranged in the I-beams, and the prestressed pieces comprise linear prestressed pieces and broken line prestressed pieces.

Description

Pretensioned broken line prestressed I-beam bridge and construction method

Technical Field

The invention relates to the technical field of municipal and highway bridge construction, in particular to a pretensioned broken line prestressed I-beam bridge and a construction method thereof.

Background

The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.

In the current bridge engineering, the linear pretensioning method prestressed concrete is mainly applied to a linear bundled prestressed hollow slab bridge, the structural span is generally below 20m, transverse force transmission is mainly carried out between precast slabs through hinge joints and the pavement effect of a concrete bridge deck, and the inventor finds that in the later operation process, vehicle load is repeatedly acted, the hinge joints are easy to generate fatigue failure, after the hinge joints are damaged to a certain degree, the longitudinal cracks are caused to occur on a bridge deck pavement layer at the corresponding position, and the safety and the durability have problems.

For the prefabricated bridge with the structural span of more than 20m, the structure types of a post-tensioning prestressed concrete T beam or a small box beam and the like are basically adopted, and transverse force transmission is carried out between the two beams through flange wet joints, diaphragm plates and the pavement effect of a concrete bridge deck. The inventor finds that for the T-beam and small box girder structures, the wet joints are mutually connected with the transverse partition plates, so that the site reinforcement connection is more, the binding amount is larger, the construction difficulty is larger, meanwhile, the concrete loss of the transverse partition plates is easily caused, the reinforcement is exposed, the broken line arrangement of the transverse partition plates, the water leakage of the wet joints, the support of the small box girder is emptied and the like.

According to the data, the linear pretensioning method is not suitable for bridge structures with the length of more than 20m, and the post-tensioning method can arrange prestressed steel bundles into various forms such as linear shapes, curved shapes or fold shapes according to stress requirements and is suitable for stress characteristics of members, so that the prestressed steel bundles are applied to large-span structures, but the process is complicated, problems are easy to occur in the grouting process, a plurality of fatal diseases such as cracks, concrete cracking and continuous downward deflection are often caused, and the safety and the service life of the bridge are seriously influenced.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, and provides a pretensioned broken line prestressed I-beam bridge which is simple to construct, good in quality and suitable for bridges with the span of more than 20.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, an embodiment of the present invention provides a pretensioned broken line prestressed i-beam bridge, including a plurality of bridge piers and a beam body disposed between adjacent bridge piers, where the beam body includes a plurality of i-beams arranged in parallel and having two ends disposed at the tops of the bridge piers, a bridge deck is cast on the upper surfaces of the i-beams, and a linear prestressed member and a broken line prestressed member are disposed in the i-beams.

With reference to the first aspect, an embodiment of the present invention provides a possible implementation manner of the first aspect, where cast-in-place end beams are cast between end surfaces of two rows of i-beams on a same bridge pier.

In a second aspect, an embodiment of the present invention provides a construction method of a pretensioned broken line prestressed i-beam bridge: the prefabricating method of the I-beam comprises the following steps: hoisting a steel reinforcement framework of the bound I-shaped beam to a tensioning pedestal, installing a linear type prestress piece and a broken line type prestress piece on the tensioning pedestal, bending the broken line type prestress piece at a set position, tensioning the prestress piece until a set tension force is reached, performing concrete pouring and curing on the I-shaped beam, releasing the prestress piece after the concrete strength of the I-shaped beam reaches a set value, and cutting off the prestress piece parts at two ends of the I-shaped beam.

With reference to the second aspect, an embodiment of the present invention provides a possible implementation manner of the second aspect, where the method for prefabricating the i-beam includes: hoisting a steel reinforcement framework of the bound I-shaped beam to a tensioning pedestal, installing a linear type prestress piece and a broken line type prestress piece on the tensioning pedestal, bending the broken line type prestress piece at a set position, tensioning the prestress piece until a set tension force is reached, performing concrete pouring and curing on the I-shaped beam, releasing the prestress piece after the concrete strength of the I-shaped beam reaches a set value, and cutting off the prestress piece parts at two ends of the I-shaped beam.

The invention has the beneficial effects that:

1. according to the I-beam bridge, the I-beams are connected into a whole through the bridge deck slab, the cast-in-place end cross beam is arranged between the two rows of I-beam end faces of the same bridge pier, the construction of the cross diaphragm and the wet joint in the span is saved, the problem in the flow construction process is reduced, and the construction quality is guaranteed.

2. According to the I-beam bridge, the I-beam is constructed by adopting a pre-tensioning method, so that the phenomenon that a post-tensioning prestressed concrete beam pore is not filled firmly is avoided, and the effective bonding of concrete and a prestressed part is improved; the corrosion of a prestressed part caused by concrete cracking is avoided, and the durability of the structure is obviously improved; the corrugated pipe and the anchorage device do not need to be pre-embedded, so that the cost is reduced, and the construction process is simpler.

3. According to the I-beam bridge, the I-beam is constructed by adopting a pretensioning method, and the I-beam bridge is provided with the broken line prestressed piece, so that the defects that the linearity of the prestressed tendon of a traditional concrete member adopting a linear prestressed tendon pretensioning method cannot be changed, the prestressed tendon is not suitable for large span and unreasonable stress is overcome, the prestressed effect is better, the prestressed tendon is saved, the stress is more reasonable, and the shearing resistance and the durability of the member are improved.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application.

FIG. 1 is a schematic end view of a beam body according to example 1 of the present invention;

FIG. 2 is a schematic view of the arrangement of an I-beam and a bridge deck according to embodiment 1 of the present invention;

FIG. 3 is a schematic view of a beam body according to embodiment 1 of the present invention along a longitudinal direction;

FIG. 4 is a schematic view of binding a first reinforcing bar and a second reinforcing bar according to embodiment 1 of the present invention;

fig. 5 is a schematic view illustrating distribution of first reinforcing bars on a lower flange of an i-beam in embodiment 1 of the present invention;

fig. 6 is a schematic view of the distribution of third reinforcing bars and fourth reinforcing bars on a boundary beam in embodiment 1 of the present invention;

fig. 7 is a schematic view of the distribution of third reinforcing steel bars and fourth reinforcing steel bars in a center sill according to embodiment 1 of the present invention;

fig. 8 is a schematic view of a structure of a first steel bar in a cast-in-place end beam according to embodiment 1 of the present invention;

FIG. 9 is a schematic view of a portion of a bridge body at a pier in accordance with embodiment 1 of the present invention;

FIG. 10 is a schematic view showing the distribution of the prestressing force members in the I-beam according to embodiment 1 of the present invention;

FIG. 11 is a schematic view showing the distribution of horizontal segments and linear prestressing members in a broken line type according to embodiment 1 of the present invention;

FIG. 12 is a schematic diagram of distribution of bending sections and linear prestressed members of a broken line type prestressed member according to embodiment 1 of the present invention;

FIG. 13 is a front view of a tension table base structure according to embodiment 2 of the present invention;

FIG. 14 is a top view of a tension table structure according to example 2 of the present invention;

FIG. 15 is a side view showing the structure of a diverter in accordance with embodiment 2 of the present invention;

FIG. 16 is a front view showing the construction of a steering gear in accordance with embodiment 2 of the present invention;

wherein, 1, an edge beam, 2, a middle beam, 3, a bridge deck, 4, a cast-in-place end beam, 5, an upper flange, 6, a lower flange, 7, a web, 8, a chamfer, 9, a third reinforcing steel bar, 10, a fourth reinforcing steel bar, 11, a first rib part, 12, a second rib part, 13, a third rib part, 14, a second reinforcing steel bar, 15, a first reinforcing steel bar structure, 16, a second reinforcing steel bar structure, 17, an asphalt pavement layer, 18, a linear prestressed member, 19, a broken-line prestressed member, 20, a force transfer column, 21, a gravity base, 22, a bottom membrane, 23, a steel box reaction column, 24, a tensioning beam, 25, a limiting member, 26, a jack, 27, a movable beam, 28, a first cutting seam, 29, a second cutting seam, 30, a connector, 31, a tensioning screw, 32, a steering gear, 32-1, an anchoring screw, 32-2, a sleeve, 32-3, a fixed support and 32-4, 32-5, pulley, 33, mounting groove.

Detailed Description

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

For convenience of description, the words "up", "down", "left" and "right" in the present invention, if any, merely indicate correspondence with up, down, left and right directions of the drawings themselves, and do not limit the structure, but merely facilitate the description of the invention and simplify the description, rather than indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the invention.

Just as the introduction of background art, the bridge of present span more than 20 meters adopts structural style such as post-tensioned prestressed concrete T roof beam or little case roof beam, is provided with wet seam and cross slab, and the construction degree of difficulty is big, and post-tensioned construction process is loaded down with trivial details, easily goes wrong in the grout in-process, to above-mentioned problem, this application has provided a pre-tensioned broken line prestressing force I-beam bridge.

In this embodiment, "longitudinal" is defined as the bridge length direction, i.e., the traveling direction of the vehicles on the bridge, and "transverse" is defined as the bridge width direction.

In a typical embodiment example 1 of this application, a pretensioning broken line prestressing force i-beam bridge, includes a plurality of piers, is provided with the roof beam body between two adjacent piers, and the roof beam body both ends utilize the pier to support.

As shown in fig. 1-3, the beam body includes a plurality of prefabricated i-beams, the i-beams are pre-cast with concrete, the axis of the multi-i-beam is arranged along the longitudinal direction of the bridge, the i-beams in the same beam body are arranged in parallel and distributed along the transverse direction of the bridge, the i-beams at both ends are edge beams 1, the rest i-beams are middle beams 2, the upper surfaces of the i-beams are cast with bridge decks 3, the bridge decks are made of reinforced concrete structures, the bridge decks are arranged in an inclined manner, the inclination angles are transverse slopes, both ends of the i-beams of the beam body are erected on bridge piers, two rows of i-beams are erected on the bridge piers, cast-in-place end beams 4 are cast between the end surfaces of the two rows of i-beams, the bridge decks and the cast-in-place end beams connect the edge beams and the middle beams into a whole to transmit transverse acting force to the i-beams, and asphalt pavement layers, and other ancillary facilities are installed.

The I-beam comprises an upper flange 5 and a lower flange 6 which are arranged in parallel, a web 7 which is perpendicular to the upper flange and the lower flange is arranged between the upper flange and the lower flange, a chamfer 8 is arranged at the connecting position of the upper flange and the web, and a chamfer 8 is arranged at the connecting position of the lower flange and the web.

As shown in fig. 4-5, the end portion of the lower flange of the i-beam is provided with a first reinforcing steel bar, the first reinforcing steel bar comprises a first rib portion 11 and a second rib portion 12 which are arranged at the end portion of the lower flange of the i-beam, the first rib portion and the second rib portion are arranged in parallel and are parallel to the axis direction of the i-beam, the first rib portion and the second rib portion extend out of the outer side of the i-beam, a part extending out of the outer side of the i-beam is connected with a third rib portion 13 in an arc shape, the first reinforcing steel bar is bound and fixed with a second reinforcing steel bar 14 arranged inside the cast-in-place end beam through the third rib portion, the second reinforcing steel bar passes through the center of the third rib portion, the second reinforcing steel bar is arranged along the transverse through length of the bridge, the relation between the cast-in-place end beam and the i-beam is enhanced, the relation between two beam bodies on.

As shown in fig. 6-7, a plurality of vertically arranged third reinforcing steel bars 9 are arranged in the web plate of the i-beam, the bottom ends of the third reinforcing steel bars extend into the lower flange, the top ends of the third reinforcing steel bars penetrate out of the upper flange and extend into the bridge deck, and the connection between each i-beam and the bridge deck is strengthened by arranging the third reinforcing steel bars, so that the i-beam and the bridge deck are connected into a whole.

As shown in fig. 6-7, a plurality of fourth reinforcing steel bars 10 are vertically distributed between the end portions of the i-beams in the same beam body, the fourth reinforcing steel bars are perpendicular to the webs of the i-beams, the fourth reinforcing steel bars penetrate through the webs of the middle beam and extend into the webs of the two side beams, the end portions of the fourth reinforcing steel bars are about 6cm away from the exposed surfaces of the webs of the side beams, and the transverse connection between the beam at the cast-in-place end and the i-beams is strengthened by arranging the fourth reinforcing steel bars.

In this embodiment, as shown in fig. 8, the bridge deck and the cast-in-place end beam are both made of reinforced concrete structures, and the reinforced concrete structures are arranged inside the bridge deck and the cast-in-place end beam, the reinforced concrete structures in the cast-in-place end beam are first reinforced concrete structures, the reinforced concrete structures in the bridge deck are second reinforced concrete structures 16, and the first reinforced concrete structures 15 of the cast-in-place end beam extend into the bridge deck, so that the relationship between the cast-in-place end beam and the bridge deck is enhanced.

Through setting up first reinforcing bar, second reinforcing bar, third reinforcing bar and fourth reinforcing bar and cast-in-place end crossbeam and the steel bar structure in the decking, connect each I-beam, cast-in-place end crossbeam and decking as a whole for the structural strength of the whole roof beam body is high, and stability is good.

As shown in fig. 9, the bridge deck directly above the bridge pier and the asphalt pavement layer 17 are provided with a kerf, the kerf is perpendicular to the axis of the i-beam and is arranged along the transverse through length of the bridge, preferably, the kerf is arranged directly above the center point of the bridge pier, in this embodiment, the first kerf 28 in the bridge deck is 0.3cm wide and 3cm high, the kerf of the bridge deck is stuffed with high aluminum sheets, and the second kerf 29 in the asphalt pavement layer is 0.3cm wide and 6cm high.

At least two-layer reinforcing bar net of upper and lower distribution has been buried underground in the decking directly over the pier, and in this embodiment, the reinforcing bar net sets up two-layerly, and the reinforcing bar net has K1 horizontal reinforcing bar and the vertical reinforcing bar of K2 to be twisted and weaved, and two-layer reinforcing bar net is along horizontal and vertically edge all staggers 10cm, and vertical reinforcing bar and the setting of staggering of horizontal reinforcing bar in K1 vertical reinforcing bar and the K2 horizontal reinforcing bar of two-layer reinforcing bar net and the decking.

Through setting up reinforcing bar net, joint-cutting and high aluminum sheet, can strengthen the structural strength on decking and the pitch layer of mating formation between two adjacent girders of pier department, prevent the fissured production in decking and pitch layer of mating formation.

As shown in fig. 10-12, the i-beam has therein prestressed members, which are prestressed reinforcements or prestressed strands, the prestressed members include 4-6 linear prestressed members and 4-6 broken prestressed members,

the linear type prestress member 18 is arranged inside a lower flange of the I-beam and arranged along the axis direction of the I-beam.

The broken line type prestressed part 19 comprises a horizontal section arranged in a lower flange and a bending section extending into a web plate, the bending section is arranged at two ends of the horizontal section, the bending section comprises a plurality of prestressed portions, and two adjacent prestressed portions are set to form an included angle at the bending point.

In this embodiment, the pitch of the bending points is processed in a modulus manner, the pitch is an integral multiple of 2m, and the bending slope is not greater than 1: 8.

The arrangement positions and the number of the linear prestressed pieces and the broken-line prestressed pieces can be adjusted according to actual conditions to adapt to span without bridges

In the embodiment, the span of the beam body is within the range of 25m-40m, the beam body is prefabricated in a standardized span of 25m, 30m, 35m and 40m in the actual factory prefabrication, the height of the I-beam is within the range of 1.5m-2.3m, the width of an upper flange is 91cm, the width of a lower flange is 66cm, the thickness of a web plate is 18cm, the chamfering length of the lower flange and the web plate is 24cm and the width of the lower flange and the web plate is 15cm, the chamfering length of the upper flange and the web plate is 29cm, the width of the upper flange and the web plate is 7.5cm, the length of a secondary chamfering is 7.5cm and the width of the upper flange and the web plate is 7.5cm, the width of a.

In the embodiment, the bridge pier supports the beam body through the cross beam, the width of the cross beam is adjusted according to the change of the span of the bridge, when the span of the bridge is 25-40 m, the width of the cross beam is 0.8-1.4 m, the arrangement width of the reinforcing mesh is adjusted according to the span of the bridge, and the value range is 2.5-4 m.

Example 2:

the embodiment discloses a construction method of a pretensioned broken line prestressed i-beam bridge, which comprises the following steps: the method comprises the following steps:

step 1: the construction method of the pier is a conventional construction method of the pier, which is not described in detail herein,

the prefabricated I-beam is transported to a construction site, and when the I-beam is transported, a temporary action measure for generating positive bending moment is applied outside the I-beam, so that the negative bending moment generated by the prestressed part on the I-beam can damage the I-beam.

Step 2: and hoisting and erecting the I-shaped beam on a pier, supporting two ends of the I-shaped beam by using the pier, and erecting a beam body.

And step 3: and after the I-shaped beam is erected, roughening treatment is carried out on the contact surfaces of the edge beam, the middle beam and the cast-in-place end cross beam, and roughening treatment is carried out on the contact surfaces of the edge beam, the middle beam and the bridge deck. The steel bar structure of the bridge deck at the middle position of the adjacent pier span is bound, a template is erected, concrete pouring is carried out on the bridge deck at the middle part of the adjacent pier span, after the concrete strength reaches 90%, the next procedure is carried out, in the embodiment, pouring is carried out on the bridge deck at the middle part of the adjacent pier span, and the I-shaped beam can be connected into a whole and reasonably stressed.

And 4, step 4: and binding a steel bar structure of the cast-in-place end beam and a steel bar structure of the bridge deck right above the bridge pier on the bridge pier, erecting a steel bar mesh, then pouring the cast-in-place end beam and the bridge deck part right above the bridge pier by utilizing concrete, constructing a first slit 28 on the bridge deck after pouring, filling a high aluminum sheet in the slit, and enabling the steel bar structure of the cast-in-place end beam to extend into the bridge deck.

And 5: and after the bridge deck and the cast-in-place end beam reach the set strength, paving an asphalt pavement layer on the upper surface of the bridge deck, constructing a second joint-cutting 29 on the asphalt pavement layer, installing an accessory facility, and finishing the installation of the whole I-beam bridge.

According to the construction method of the I-beam bridge, the cast-in-place end cross beam is poured between the end faces of the two rows of I-beams on the bridge pier, a wet joint and a cross diaphragm plate do not need to be constructed, the problems that on-site steel bars are connected more, the binding amount is larger, the construction difficulty is larger, meanwhile, the concrete of the cross diaphragm plate is easy to lose, the steel bars are exposed, the broken line of the cross diaphragm plate is arranged, the water leakage of the wet joint is caused and the like are solved, and.

The embodiment also discloses a manufacturing method of the I-beam, which comprises the following steps: the method comprises the following steps:

step a: and manufacturing a tensioning pedestal, wherein the tensioning pedestal is required to be arranged in a flat and compacted field, the field is firstly flattened and compacted, 25cm of lime soil is paved, the ground is flattened, compacted and compacted, and then C15 concrete with the thickness of 15cm is poured on the ground.

As shown in fig. 13-14, the tensioning pedestal adopts a groove type four-line tensioning pedestal, can foresee two i-beams, including the dowel post 20, the both ends of the dowel post are provided with gravity base 21, and the surface of the dowel post sets up one H shaped steel every 2 meters, and 3cm thick steel plate is laid on the shaped steel top surface as the basement membrane 22 that the i-beam was pour, be provided with steel box reaction column 23 on the gravity base, inside steel box reaction column bottom stretched into the gravity base, steel box reaction column adopts the shaped steel structure, and the little expansive concrete of inside pouring, the lateral surface welding of steel box reaction column has tensioning crossbeam 24, and steel box reaction column and tensioning crossbeam all reserve the pore that the prestressing force piece passed, the outside of tensioning crossbeam can set up movable beam 27, and can set up jack 26 between tensioning crossbeam and the movable beam, and steel box reaction column, crossbeam, movable crossbeam and dowel perpendicular setting, and the reserved pore channels on the steel box reaction column, the tensioning cross beam and the movable cross beam are aligned. One side of the inner side of the steel box reaction column is further provided with a limiting part 25, and the limiting part is provided with a limiting hole. The tensioning table seat can be repeatedly used, is simple to operate, effectively reduces the cost, and has remarkable economic benefit.

Step b: the steel bar framework of the I-beam is bound on the special jig frame, namely the first steel bar, the third steel bar and the fourth steel bar of the I-beam are bound, the steel bar framework is formed by arranging modular and standardized common steel bars, construction is convenient, an isolating agent is brushed on the bottom die of the tensioning pedestal, and the steel bar framework of the I-beam is hoisted to the bottom die.

Step c: install steering gear 32 on the stretch-draw pedestal to prestressed piece unloading, as shown in fig. 15-16, the steering gear includes the mounting, the mounting adopts anchor screw 32-1, anchor screw bottom can pass the basement membrane, fixes in the mounting groove 33 that the dowel post was reserved, the mounting groove mainly bears the tensile force of prestressed piece, anchor screw top and sleeve 32-2 fixed connection, sleeve and fixed bolster 32-3 fixed connection, the fixed bolster adopts L type frame, and sets up on the sleeve relatively, forms U type structure, has passed two dabber 32-4 that set up from top to bottom between two L type frames, the dabber passes the sleeve setting, is provided with two pulleys 32-5 respectively between the L type frame of sleeve and both sides, and the pulley is connected with the dabber rotation respectively.

And (3) installing a steering gear at a set bending point of the tensioning pedestal, and enabling pulleys of different steering gears to be at different heights according to a set bending line form.

In this embodiment, broken line type prestressing force spare and the partial contact of the outer peripheral face bottom of pulley pass each steering gear in proper order, utilize the steering gear to buckle broken line type prestressing force spare, and broken line type prestressing force spare continues to pass behind the spacing hole on the locating part, is connected with stretch-draw screw 31 through connector 30, the finish rolling screw connector is used to the connector, and stretch-draw screw passes the spacing hole of reserving on steel case reaction column and the stretch-draw crossbeam in proper order to utilize the bolt anchor on movable beam and stretch-draw crossbeam, and set up a plurality of jacks that the symmetry set up between movable beam and stretch-draw crossbeam, the jack adopts the punching type to advance the jack.

The steering gear with the pulleys is adopted, so that the plurality of prestressed pieces can be bent at multiple points to steer, the steering frictional resistance is reduced, the slippage in the tensioning process is avoided, and the stress effect of the structure is more matched. The steering gear is simple in structure, economical and reliable.

The linear type prestressed part does not need to be bent, and is directly connected with the tensioning screw rod through the connector after penetrating through the limiting hole.

Step d: the jack is adopted to stretch the prestressed part integrally, before stretching, the jack is calibrated, and the prestressed part can be used after the anchorage device is qualified. In the tensioning process, a plurality of jacks synchronously supply oil and have consistent stroke, drive the prestressed part to perform tensioning, adopt the integral tensioning by stages in the tensioning process, and divide into: 0 → initial tension control force 15% → 30% tension control force → 100% tension control force (hold load 5min) → anchoring. The tension control force is 1339.2 MPa.

During tensioning of the prestressed part, a double control method is adopted, namely the design tension and the elongation value of the prestressed part are controlled, the prestress is accurately applied mainly by controlling the design tension, and tensioning records are carefully made.

Step e: and after the prestressed member is tensioned to a set tension force, installing a template for pouring the I-beam, wherein the template consists of a plurality of template units, the length of each template unit is 5m, the template adopts a steel template, and before installation, an isolating agent is coated on the inner side surface of the template.

Step f: after the formwork for pouring the I-beam is installed, concrete is poured, whether embedded parts of auxiliary facilities such as expansion joints and supports are complete or not is checked before pouring, and a concrete cushion block is designed between the reinforcing steel bars and the formwork to guarantee the thickness requirement of a reinforcing steel bar protective layer.

And (3) vibrating by using a vibrator when concrete is poured, and immediately starting curing after the concrete is poured and initially set by adopting a steam curing method. Steam curing comprises four processes of firstly, standing for 4-6 hours after concrete pouring, and heating; secondly, heating, wherein the beam body is uniformly heated during heating; ③ keeping the temperature constant, wherein the constant temperature lasts for 24 hours, and the temperature is preferably not more than 60 ℃; cooling, the cooling speed is not more than 6 ℃/h.

Step g: the method comprises the steps of removing a template and a steering gear after poured I-beam concrete reaches set strength, removing the template when the difference between the surface temperature of the I-beam and the ambient temperature is not more than 10 ℃, and covering the surface of the I-beam after the template is removed to prevent the temperature from being too fast and enable the concrete to shrink cracks, loosening the joint of an anchoring screw and a sleeve when the steering gear is removed, and enabling partial structures such as the sleeve, a fixed support and a pulley of the steering gear to be left in the I-beam, wherein the anchoring screw can be recycled.

Step h: after the template and the steering gear are dismantled, the jack is used for integrally releasing the prestressed part, specifically, the concrete strength reaches 85% of the designed concrete strength grade, and after the age is not less than 7d, the jack is used for integrally releasing the prestressed part, and when the prestressed part is released, two ends are simultaneously released in a time division manner. And after the prestressed part is loosened, cutting off the prestressed part parts at the two ends of the member by using a cutting machine to finish the manufacturing of the I-beam.

The pre-tensioning construction method is adopted, so that the problem that the hole of the post-tensioning prestressed concrete beam is not filled firmly is avoided, and the effective bonding of concrete and a prestressed part is improved; the corrosion of a prestressed part caused by concrete cracking is avoided, and the durability of the structure is obviously improved; the corrugated pipe and the anchorage device do not need to be pre-embedded, so that the cost is reduced, and the construction process is simpler.

After the I-beam is manufactured, the I-beam is moved away for storage and beam storage, and in order to prevent overlarge camber on the I-beam and overlarge shrinkage difference between the I-beam and the bridge deck caused by age difference, the beam storage period is preferably controlled according to 90 d.

The manufacturing method of the I-beam adopts the pretensioning method for construction, is provided with the broken line prestressed piece, overcomes the defects that the traditional concrete member adopting the linear prestressed tendon pretensioning method has the prestressed tendon linearity which cannot be changed, is not suitable for large span and is unreasonable in stress, has better prestressed effect, saves the prestressed tendon, is more reasonable in stress, improves the shearing resistance and the durability of the member, and is suitable for bridges with the span diameter of 25-40 meters.

Although the embodiments of the present invention have been described with reference to the accompanying drawings, it is not intended to limit the scope of the present invention, and it should be understood by those skilled in the art that various modifications and variations can be made without inventive efforts by those skilled in the art based on the technical solution of the present invention.

Claims (10)

1. A pretensioned broken line prestressed I-beam bridge comprises a plurality of bridge piers and a beam body arranged between the adjacent bridge piers, and is characterized in that the beam body comprises a plurality of I-beams which are arranged in parallel and two ends of each I-beam are arranged at the tops of the bridge piers, bridge decks are poured on the upper surfaces of the I-beams, prestressed pieces are arranged in the I-beams, and each prestressed piece comprises a linear prestressed piece and a broken line type prestressed piece.

2. The pretensioned fold line prestressed i-beam bridge of claim 1 wherein cast-in-place end beams are cast between the end faces of two rows of i-beams on the same pier.

3. The pretensioned polyline prestressed i-beam bridge of claim 2, wherein said i-beam ends are provided with first reinforcing steel bars which extend outside the paper i-beam and are bound and fixed with second reinforcing steel bars provided in the cast-in-place end beam.

4. The pretensioned polyline prestressed i-beam bridge of claim 1, wherein a vertically disposed third reinforcement is provided within said i-beam, the top end of said third reinforcement extending into the interior of the deck slab.

5. The pretensioned polyline prestressed i-beam bridge of claim 1, wherein a fourth reinforcing bar is inserted between the ends of the i-beams of the same beam body.

6. The pre-tensioned polyline prestressed i-beam bridge according to claim 1, wherein the portion of the deck slab above the pier is provided with at least two layers of reinforcing meshes arranged one above the other, the edges of the plurality of layers of reinforcing meshes are staggered, and the reinforcing meshes are staggered with the reinforcing structure in the deck slab.

7. The pre-tensioned polyline prestressed i-beam bridge as claimed in claim 1, wherein said deck slab has an asphalt pavement layer laid on the upper surface thereof, said asphalt pavement layer and deck slab have slits formed at positions above the bridge piers, the slits are arranged perpendicular to the axis of the i-beam and directly above the center point of the bridge piers, and the slits of the deck slab are filled with high aluminum sheets.

8. A construction method of a pretensioned broken line prestressed I-beam bridge according to any of claims 1 to 7, characterized in that a prefabricated I-beam is hoisted to a pier, both ends of the I-beam are supported by the pier, a bridge deck is cast at a midspan position between two adjacent piers on the upper surface of the I-beam, a plurality of I-beams are connected into a whole by the bridge deck, and after the casting of the bridge deck at the midspan position is completed, a cast-in-place end beam between two rows of I-beam end surfaces at the top of the pier and the bridge deck above the pier are cast.

9. The construction method according to claim 8, wherein the prefabrication method of the I-beam comprises the following steps: hoisting a steel reinforcement framework of the bound I-shaped beam to a tensioning pedestal, installing a linear type prestress piece and a broken line type prestress piece on the tensioning pedestal, bending the broken line type prestress piece at a set position, tensioning the prestress piece until a set tension force is reached, performing concrete pouring and curing on the I-shaped beam, releasing the prestress piece after the concrete strength of the I-shaped beam reaches a set value, and cutting off the prestress piece parts at two ends of the I-shaped beam.

10. The construction method according to claim 9, wherein the bending of the pre-stress member of the broken line type is performed by a deflector, the deflector includes a fixing member which is fixedly connected to the tension pedestal, the fixing member is provided with a bracket which is rotatably connected to a pulley by a mandrel, and the pre-stress member of the broken line type is capable of contacting with a lower outer circumferential surface of the pulley.

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