1. A railway continuous beam prestress construction method comprises an A-section box beam at a front construction section and a B-section box beam at a rear construction section, and is characterized by comprising the following steps:

s100: the prestress tensioning and grouting of the A-section box girder are completed, a connector 20 is pre-buried at the end part of the A-section box girder, a second steel strand 14 penetrates through the A-section box girder, one end of the second steel strand is fixed in the connector 20, and the second steel strand 14 is used for prestress tensioning and grouting of the A-section box girder and concrete;

s200: mounting a B-section box girder prestressed pipeline;

s300: finishing blanking of the B-section box girder steel strand, blanking the first steel strand bundle 10, and binding iron wires to prevent loosening and winding;

s400: completing the penetration of the steel strand of the B-section box girder, and penetrating the first steel strand bundle 10 through the B-section box girder prestressed pipeline by using a winch or a steel strand penetrating machine;

s500: completing the installation of the connector 20 of the B-section box girder, manufacturing a B-section box girder steel strand extrusion head at the end of the first steel strand bundle 10, and connecting the B-section box girder steel strand extrusion head with the second steel strand bundle 14 through the connector 20;

s600: the prestressed tensioning and grouting of the B-section box girder are completed;

s700: completing concrete pouring and maintenance of the B-section box girder;

s800: and (5) completing the tensioning and grouting of the B-section box girder concrete.

2. The prestress construction method for the continuous railway beam as claimed in claim 1, wherein the step S500 comprises the following steps:

s501: manufacturing a B-section box girder steel strand extrusion head, wherein the extrusion head comprises an extrusion sleeve 6 and an extrusion spring 19, the extrusion spring 19 is tightly sleeved on the surface of the end part of the first steel strand bundle 10 in a screwing mode, the extrusion sleeve 6 is sleeved outside the extrusion spring 19 and assembled into a combined body, the reserved part of the first steel strand bundle 10 exceeds the extending section of the extrusion sleeve 6, the combined body is installed in the extrusion sleeve of the extrusion machine to be extruded, the extrusion sleeve 6 is deformed inwards, and the combined body is fastened to the end part of the first steel strand bundle 10;

s502: connect B festival section case roof beam steel strand wires and connector 20, connector 20 is including anchor backing plate 3, connector 4 and pterygoid lamina 13 of fixed connection in proper order, anchor backing plate 3 with the through-hole that runs through is established to connector 4, second steel strand 14 passes the through-hole is fixed in connector 4 tip, pterygoid lamina 13 centers on the connector 4 outside is fixed, is equipped with the U-shaped of a plurality of equipartitions on it and separates the groove, the first carry of extrusion is fixed in on the pterygoid lamina 13.

3. The prestress construction method for the railway continuous beam according to claim 2, wherein the step S501 comprises:

after assembly, the combination is placed in the sleeve from which the pressing spring 19 projects, and the pressing sleeve 6 is brushed with clean oil before pressing.

4. The prestress construction method for a railway continuous beam according to claim 2, wherein the connector 20 comprises a spiral bar 2, a protection cover 7, a fastening bolt 8, a first binding band 16, a second binding band 17, and a third binding band 18;

the spiral ribs 2 are pre-embedded in the A-section box girder and are arranged around the periphery of the anchor backing plate 3;

the first strapping band 16 secures the extrusion head outside the connecting body 4 around the extension, the second strapping band 17 secures the extrusion head outside the connecting body 4 around the extrusion sleeve 6, and the third strapping band 18 secures around the first steel strand bundle 10 at the bottom end of the wing plate 13;

the protective cover 7 is formed by combining two halves of the casing through the fastening bolt 8, and is of a conical structure which is communicated along an axis after combination, one end with a large opening is sleeved outside the wing plate, and the other end of the protective cover is sleeved outside the first steel strand 10.

5. The prestress construction method for railway continuous beam according to claim 4, wherein the connector 20 comprises a first corrugated tube 1, a second corrugated tube 11 and a restraining ring 9;

first bellows 1 and second bellows 11 all are the hollow tube, and both are pre-buried respectively first bellows 1 is pre-buried in A section case roof beam, with through-hole meets in the anchor backing plate 3, second bellows 11 overlap in safety cover 7 is close to the one end of B section case roof beam 11 outside cover of second bellows is equipped with restraint circle 9, restraint circle 9 is cyclic annular, be used for with second bellows 11 fastening.

6. The prestress construction method for railway continuous beam according to claim 4, wherein the connector 20 comprises an exhaust hole 5 and a working jaw 12;

the exhaust hole 5 penetrates through the protective cover 7 and is positioned outside the connecting body 4;

the working clamping piece 12 is arranged in a through hole through which the connecting body 4 penetrates, and wraps the second steel strand bundle 14 in the through hole.

Background

Along with the high-speed development of the domestic railway technology, a railway which takes a bridge as a carrier is paved in a crowded area of coping with urban buildings, particularly in a station entering area, more and more railway stations which are designed to enter the station by adopting an elevated bridge mode are designed, the construction mode is characterized in that the bridge is long in span and consists of segmental support cast-in-place continuous box girders, the bridge in the station entering area is generally designed into a turnout form according to the train running requirements, the bridge in the continuous structure form needs to reduce the prestress loss due to complex stress and large live load unbalance loading influence, the prestress rib is generally lengthened by using a connector, and the process control is strengthened and the construction quality of the turnout continuous girder is ensured due to complex working procedures and high technical requirements.

The existing prestressed tendon lengthening construction method mainly has the following defects: (1) the prestressed tendon lengthening device is divided into a front part and a rear part, so that the construction process is complicated, the structure is complex, and the construction efficiency is reduced; (2) the connecting device is not pre-arranged in the main body structures such as the box girder and the like, so that the effect of reducing the prestress loss is poor, and the long-time service life is difficult to ensure; (3) when the front beam and the rear beam are constructed, the rear beam construction can be started only after the front beam is constructed, and the construction efficiency is low.

Disclosure of Invention

Aiming at the defects or the improvement requirements in the prior art, the invention provides a railway continuous beam prestress construction method, which adopts the construction sequence of stretching the two ends of a front beam and stretching the single end of a rear beam, and lengthens the prestress steel strand bundles of the front beam and the rear beam through a connector pre-arranged in the front beam, thereby effectively reducing the prestress loss.

In order to achieve the aim, the invention provides a railway continuous beam prestress construction method, which comprises the following construction sequences:

s100: the prestress tensioning and grouting of the A-section box girder are completed, a connector is pre-buried at the end part of the A-section box girder, a second steel strand bundle penetrates through the A-section box girder, one end of the second steel strand bundle is fixed in the connector, and the prestress tensioning and grouting of the A-section box girder and concrete grouting are performed by using the second steel strand bundle;

s200: mounting a B-section box girder prestressed pipeline;

s300: finishing blanking of the steel strand of the B-section box girder, blanking the first steel strand bundle, and binding iron wires to prevent loosening and winding;

s400: completing the strand pulling of the steel strand of the B-section box girder, and using a winch or a steel strand pulling machine to enable the first steel strand to pass through the B-section box girder pre-stressed pipeline;

s500: completing the installation of the connector of the B-section box girder, manufacturing a B-section box girder steel strand extrusion head at the end of the first steel strand bundle, and connecting the B-section box girder steel strand extrusion head with the second steel strand bundle through the connector;

s600: the prestressed tensioning and grouting of the B-section box girder are completed;

s700: completing concrete pouring and maintenance of the B-section box girder;

s800: and (5) completing the tensioning and grouting of the B-section box girder concrete.

Further, step S500 specifically includes the following steps:

s501: manufacturing a B-section box girder steel strand extrusion head, wherein the extrusion head comprises an extrusion sleeve and an extrusion spring, the extrusion spring is tightly sleeved on the surface of the end part of the first steel strand bundle in a screwing mode, the extrusion sleeve is sleeved outside the extrusion spring and assembled into a combined body, the reserved part of the first steel strand bundle exceeds the extending section of the extrusion sleeve, the combined body is installed into the sleeve of the extruder to be extruded, the extrusion sleeve is deformed inwards, and the first steel strand bundle is fastened on the end part of the first steel strand bundle;

s502: connect B festival section case roof beam steel strand wires and connector, the connector is including anchor backing plate, connector and the pterygoid lamina of fixed connection in proper order, the anchor backing plate with the through-hole that runs through is established to the connector, second steel strand bundle passes the through-hole is fixed in connector tip, the pterygoid lamina centers on the connector outside is fixed, is equipped with the U-shaped of a plurality of equipartitions on it and separates the groove, the extrusion head carry is fixed in on the pterygoid lamina.

Further, the step S501 includes:

after the assembly is assembled, the assembly is placed in the sleeve, the extrusion spring extends out of the sleeve, and clean engine oil is brushed on the extrusion sleeve before extrusion.

Further, the connector includes a helical rib, a protective cover, a fastening bolt, a first strap, a second strap, and a third strap;

the spiral ribs are pre-embedded in the A-section box girder and are arranged around the periphery of the anchor backing plate;

the first strapping band secures the extrusion head outside the connector body around the extension, the second strapping band secures the extrusion head outside the connector body around the extrusion sleeve, and the third strapping band secures around the first strand of steel at the bottom end of the flap;

the protective cover is formed by combining two halves of the protective cover with the shell through the fastening bolt, the protective cover is of a conical structure which is communicated along the axis after combination, one end with a large opening is sleeved outside the wing plate, and the other end of the protective cover is sleeved outside the first steel strand.

Further, the connector comprises a first bellows, a second bellows, and a confinement ring;

the first corrugated pipe and the second corrugated pipe are hollow pipes, the first corrugated pipe and the second corrugated pipe are embedded respectively in the A-section box girder and connected with the through hole in the anchor backing plate, the second corrugated pipe is sleeved at one end, close to the B-section box girder, of the protective cover, the restraint ring is sleeved outside the second corrugated pipe and used for fastening the second corrugated pipe, and the restraint ring is annular.

Further, the connector comprises an exhaust hole and a working clip;

the exhaust hole penetrates through the protective cover and is positioned at the outer side of the connecting body;

the working clamping piece is arranged in the through hole through which the connecting body penetrates, and wraps the second steel strand bundle in the through hole.

In general, compared with the prior art, the above technical solution contemplated by the present invention can achieve the following beneficial effects:

1. the connector for lengthening the prestressed steel stranded wire harness provided by the invention is of an integrated structure, does not need to be assembled in a matching way, and can be directly mounted and fixed on the connector after the connector is mounted on the box girder steel stranded wire subjected to prestress tensioning.

2. The steel strand bundle lengthening connector provided by the invention can be pre-arranged on a front construction beam in a continuous beam, and after the front construction box beam completes double-end prestress tensioning, the steel strand penetrating and single-end tensioning of a rear construction box beam are completed, so that the prestress loss in the construction process is less, the steel strand bundle connection is more stable, and the effect of a prestress system is enhanced.

3. The construction method provided by the invention can synchronously carry out the beam penetrating of the prestressed steel strand and the manufacturing of the extrusion head for the rear beam when waiting for the tensioning and the grouting of the front beam, and the construction efficiency is improved and the construction period is shortened by synchronously carrying out the beam penetrating and the manufacturing of the extrusion head for the rear beam.

Drawings

FIG. 1 is a schematic process diagram of a method for pre-stressing a railway continuous beam according to an embodiment of the present invention;

FIG. 2 is a semi-sectional view of a connector 20 according to a prestressing method for constructing a continuous railway beam according to an embodiment of the present invention;

FIG. 3 is a cross-sectional view C-C of a connector 20 according to a prestressing method for a continuous railway girder according to an embodiment of the present invention;

FIG. 4 is a schematic structural view of a connector 20 wing plate according to a prestress construction method for a continuous railway beam of the embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a continuous beam of the prestress construction method for a railway continuous beam according to the embodiment of the invention;

FIG. 6 is a sectional view D-D of a continuous beam of a railway continuous beam prestress construction method according to an embodiment of the present invention.

In all the figures, the same reference numerals denote the same features, in particular: 1-a first corrugated pipe, 2-a spiral rib, 3-an anchor backing plate, 4-a connector, 5-an exhaust hole, 6-an extrusion sleeve, 7-a protective cover, 8-a fastening bolt, 9-a restraining ring, 10-a first steel strand bundle, 11-a second corrugated pipe, 12-a working clamping piece, 13-a wing plate, 14-a second steel strand bundle, 15-a steel strand channel, 16-a first bundling belt, 17-a second bundling belt, 18-a third bundling belt, 19-an extrusion spring, 20-a connector, 41-a first round platform and 42-a second round platform.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

As shown in fig. 1-6, the present invention provides a railway continuous beam prestress construction method, wherein a-section box girder has completed prestress tensioning and grouting, a B-section box girder is a rear construction section box girder, the bridge only relates to a longitudinal prestress system, wherein the a-section prestress system is completed by bidirectional tensioning, the B-section prestress system is completed by single-end tensioning, the construction method comprises the following steps in sequence:

s100: the prestress tensioning and grouting of the A-section box girder are completed;

s200: mounting a B-section box girder prestressed pipeline;

s300: finishing blanking of the steel strand of the B-section box girder, as shown in figure 4, firstly blanking a first steel strand bundle 10 according to the required length provided by design, before the first steel strand bundle 10 is blanked, the quality of the first steel strand bundle is checked, the first steel strand bundle is checked disc by disc in appearance, broken steel wires, transverse steel wires and steel wires which are mutually crossed are not required, the surface of the steel plate can not be provided with lubricant, oil stain, crack, small thorn, split and mechanical damage, the surface is allowed to have slight rust, but the pit can not be rusted to be visible to the naked eye, preferably, a grinding wheel cutting machine is adopted for cutting, the burrs on the cut surface are removed, when the wire scattering phenomenon occurs after cutting, binding iron wires at the positions 5 cm away from the two ends of the cutting point before cutting, and then cutting, wherein the iron wires are bound firmly within the range 20 cm away from the cut after cutting is finished, and the iron wires are bound every other meter after straightening and straightening to prevent the first steel strand bundles 10 from being loose and winding each other;

s400: and (3) finishing the threading of the steel strand of the B-section box girder, as shown in fig. 5-6, in order to finish the prestress tensioning and grouting of the A-section box girder, threading the first steel strand bundle 10 in the B-section box girder, preferably, a winch can be selected to drag the threading or a steel strand threading machine to thread, when the winch is used for threading, sleeving a conical lantern ring at one end of the first steel strand bundle 10, driving a rigid wedge into the conical lantern ring, then tightly fastening the first steel strand bundle and the lantern ring, reserving the steel strand in advance when threading the end, drawing the steel strand of the winch through the other end of the pipeline, connecting the steel wire rope with the steel strand at the threading end of the first steel strand bundle 10, and starting the winch to draw the first steel strand bundle 10 through the pipeline. The ends of several first steel strand bundles 10 can be staggered and placed, a lead is inserted, the whole bundle of steel strands and the lead are welded into a whole by adopting a welding method, the length of the lead is 2-3 m longer than that of a pipeline, particularly, before tensioning, the welded joint is cut at a position 20 cm behind the welded joint, and preferably, the steel strands near the welded joint can be sprinkled with water for cooling. When the strand pulling method of the steel strand pulling machine is used, a first steel strand bundle 10 is hung at the end head of a beam B, the first steel strand bundle is fixed by a steel strand cage at a position about 10 meters away from the beam, further, the steel strand pulling machine is installed in place, the forward and reverse rotation is debugged, whether the direction is consistent with the strand pulling direction or not is checked, after the error is determined, the end head of the first steel strand bundle 10 penetrates through a pinch roller of the steel strand pulling machine, the power supply of the steel strand pulling machine is switched on, the strand pulling construction is started, when the first steel strand bundle 10 is pulled to the other end, the leakage length of the steel strand is reached, and finally, the steel strand pulling machine is switched off and the first steel strand bundle 10 is cut to complete the strand pulling work;

before the prestress and grouting of the B-section box girder, the A-section box girder and the B-section box girder are connected by a prestressed steel strand to reduce the prestress loss;

s500: b, installing a connector of the section box girder;

the step S500 includes the following steps S501 and S502:

s501: manufacturing a B-section box girder steel strand extrusion head, as shown in figures 4-5, after a first steel strand bundle 10 finishes penetrating in the B-section box girder, manufacturing the extrusion head at the end of the first steel strand bundle 10 close to the A-section box girder, preferably, the extrusion head comprises an extrusion sleeve 6 and an extrusion spring 19, the extrusion sleeve 6 is a cylindrical sleeve, the size of a central through hole is adapted to the size of a steel strand in the first steel strand bundle 10, preferably, the extrusion sleeve 6 is manufactured by a No. 45 steel vehicle, the extrusion spring 19 is wound into a two-half barrel shape by a hard steel wire, the diameter of the extrusion spring 19 is adapted to the size of the steel strand in the first steel strand bundle 10 to play a role in enhancing the gripping force of the extrusion sleeve 6, particularly, a newly purchased or overhauled extruder should perform an idle running test, after the extruder is connected with a matched oil pump, starting the oil pump to run for 2-3 min in an idle running, after the equipment normally operates, the control valve can be operated to enable the oil cylinder of the extruder to reciprocate for 2-3 times in a no-load mode, gas in a pipeline is discharged, whether leakage exists between an oil way and a sealing element of the oil cylinder is observed, whether the piston operates smoothly is determined, the phenomena of blocking and crawling are avoided, in the no-load operation mode, the extending distance of the ejector rod is within a design allowable range so as to avoid damaging the equipment, when all the parts are normal, a load test can be carried out, the ejector rod is taken down before the load test is carried out, a steel plate with the thickness larger than 5 centimeters is additionally arranged between an extrusion die and the piston, then oil is supplied to the extruder, the oil pressure is slowly increased to a rated pressure, the load is stably maintained, whether leakage exists between the oil way and the sealing element is observed, all the parts can be decompressed to finish the test, and the extruder can be formally used. Further, an extruder is used for manufacturing an extrusion head, before extrusion is carried out, whether the end part of the steel strand is neat, whether the diameter is matched and whether the specification meets the requirements or not is checked, preferably, antirust oil is coated on the extrusion sleeve 6 and plays a role in lubrication during extrusion, if soil and sand are adhered to the surface of the extrusion sleeve, the extrusion sleeve must be cleaned by diesel oil, otherwise, an extruder die is easy to damage, firstly, the extrusion spring 19 is installed and tightly screwed on the steel strand to ensure no gap, then, the steel strand penetrates through an extruder die hole, is sleeved on the extrusion sleeve 6 and is inserted into a processing station of the extruder, particularly, the assembled extrusion spring 19 extends out of two sides of the extrusion sleeve 6, the extending length cannot be less than 14 millimeters, when the length of the extrusion spring 19 is insufficient, two extrusion sleeves can be spliced and lengthened, finally, a thin layer of clean engine oil is brushed outside the extrusion sleeve 6, and after an extrusion element is in place, operating an extruder oil pump to extend an ejector rod, tightly ejecting an extrusion sleeve 6 on a die, observing whether the steel strand is centered or not in the process, otherwise, taking measures to centralize the steel strand, observing the maximum numerical value of an extruder pressure gauge in the extrusion process, wherein the gauge pressure is in a specified range, returning the extruder when the pressure is reduced from a peak value or the ejector rod stroke is in place, and continuously finishing the whole extrusion process without stopping. The end face of the extrusion head is checked after extrusion is finished to ensure that the end face is basically flat without cracks or gaps, the outer diameter size of the extrusion head is checked at the same time, the extrusion head is required to be dismounted and manufactured again if the end face is unqualified, meanwhile, a tension test of the extrusion head is periodically carried out to ensure the extrusion quality, preferably, the extrusion spring 19 is required to be still visible at two ends of the extrusion sleeve 6 after extrusion is finished, the exposed length of the extrusion spring is not less than 2 mm, and the length of the steel strand end exposed out of the extrusion sleeve 6 after extrusion is 1-5 mm.

S502: connecting the B-section box girder steel strand with the connector, as shown in FIGS. 2-5, after the manufacturing of the extrusion head is completed, connecting the first steel strand bundle 10 close to the A-section box girder end with the connector 20 preset on the A-section box girder, thereby connecting the second steel strand bundle 14 with the first steel strand bundle 10, achieving the purpose of lengthening the A-section box girder prestressing tendons, effectively reducing the loss of the prestressing force of the A-section box girder and the B-section box girder, wherein the connector 20 comprises a first corrugated pipe 1, a spiral tendon 2, an anchor backing plate 3, a connecting body 4, an exhaust hole 5, an extrusion sleeve 6, a protective cover 7, a bolt 8, a restraining ring 9, the first steel strand bundle 10, a second corrugated pipe 11, a work clamping piece 12, a wing plate 13, a second steel strand bundle 14, a first binding band 16, a second binding band 17 and a third binding band 18, wherein the second steel strand bundle 14 is completely tensioned on the A-section box girder, first bellows 1 is used for parcel protection second steel strand 14, and anchor backing plate 3 is pre-buried plays fixed whole connector 20 on A segmental box roof beam, fixed stretch-draw back simultaneously the effect of second steel strand 14, and anchor backing plate 3 is the well logical structure of ladder enlarged form, and second steel strand 14 passes anchor backing plate 3, reachs and passes pterygoid lamina 13 and use taper work clamping piece 12 to be fixed in pterygoid lamina 13, and it has spiral muscle 2 to encircle in anchor backing plate 3 periphery, because the power of prestressed concrete in the stretch-draw in-process is very big, adopts spiral muscle 2 to prevent anchor backing plate 3 is in when carrying out the prestressing force stretch-draw because of the too big crushing concrete of local pressure is used for improving the compressive strength of concrete behind the anchor, prevents that the concrete under the anchor from taking place local destruction under the effect of tensile stress. Further, the connecting body 4 is a main structure for fixing the first steel strand bundle 10, preferably, the connecting body 4 includes a first round table 41 and a second round table 42 connected together, wherein the periphery of the second round table 42 is provided with a U-shaped partition groove, the size and number of the notches are the same as the specification of the steel strands forming the first steel strand bundle 10, the extrusion heads of the steel strands at the end of the first steel strand bundle 10 are respectively hung at the notches at the periphery of the second round table 42, at this time, the extrusion sleeve 6 is pulled to play a role in fixing the first steel strand bundle 10, particularly, the body edge is provided with a convex thin wall which can limit the movement of the extrusion sleeve 6, prevent the first steel strand bundle 10 from slipping from the wing plate 13, the side wall of the first round table 41 is tangent to and clings to the edge of the extrusion sleeve 6, also play a role in limiting the extrusion sleeve 6, particularly, both the side surface of the first round table 41 and the end surface of the second round table 42 are inclined, make extrusion cover 6 better laminating on pterygoid lamina 13, further, because the extrusion head preparation steel strand wires end surpasss extrusion cover 6 terminal surface, use first strapping 16 to encircle the steel strand wires excess portion of hanging on first round platform 41 and fix, likewise, on extrusion cover 6 and the steel strand wires of second round platform 42 bottom, use second strapping 17 and third strapping 18 respectively to fasten, preferably, above-mentioned strapping all can adopt thin iron wire, scribble rust-preventive oil and carry out rust-preventive treatment after tying up. Further, after all the extrusion sleeves 6 are hung on a wing plate 13 and fixed, a protection cover 7 is used for wrapping and protecting the part of the wing plate 13 and the tail part of the first steel strand 10, the protection cover 7 is of a horn-shaped conical structure and can be split into two halves and fastened through a bolt 8, particularly, an exhaust hole 5 is formed in the protection cover 7 and used for exhausting redundant gas during grouting, a restraining ring 9 is arranged at the tail part of the protection cover 7 and used for tightening the protection cover 7 to be attached to the first steel strand 10 inside, meanwhile, the second corrugated pipe 11 is tightened to be connected with the protection cover 7, finally, a closed space is formed inside the connector 20, the functions of preventing rainwater corrosion, prolonging the service life and preventing prestress loss are achieved, the connector 20 adopts a semi-open porous hanging mode, the process is simple, the connector is preset on a box girder in the previous construction, and when the box girder prestress rib of the section is fixed through tensioning, the construction of the box girder at the rear construction section can be synchronously carried out, the integral design reduces the prestress loss in a multi-section continuous girder with longer span, the box girder prestressed tendons at the rear construction section can be directly connected with the prestressed tendons at the front section without waiting after the box girder prestressed tendons are penetrated, and the construction efficiency is improved;

s600: the prestressed tensioning and grouting of the B-section box girder are completed;

s700: completing concrete pouring and maintenance of the B-section box girder;

s800: and (5) completing the tensioning and grouting of the B-section box girder concrete.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.