CN202031029U - Cross-arch rib gantry crane - Google Patents

Abstract

The utility model discloses a cross-arch rib gantry crane comprising a lifting system, a steel structure main body and a main walking system, wherein the steel structure main body consists of two parallel connected door frames, the each door frame is formed by a main beam and supporting legs which are connected by connecting frames, the steel structure main body is assembled by universal rod pieces, and the each main beam is provided with two lifting trolleys movable horizontally along the main beam. By adopting the universal rod pieces to assemble the large-span cross-arch bridge gantry crane, the cross-arch rib gantry crane of the utility model is suitable for various arch bridge engineerings with medium or small span and certain navigation requirements, and suitable for arch rib lifting constructions with complex space curves; in addition, the cross-arch rib gantry crane has more obvious applicability and economy in technology for a medium-span large inclination angle butterfly type arch bridge, thus the cross-arch rib gantry crane can be used as a recommended method for installation of the butterfly type arch bridge.

Description

Arch rib-crossing gantry crane

Technical Field

The invention relates to the technical field of gantry cranes, in particular to a gantry crane applied to the technical field of steel arch rib installation construction of butterfly arch bridges and other special-shaped arch bridges such as bird-flying type space inverted triangle moon arch bridges and the like.

Prior Art

The arch rib of the traditional arch bridge is parallel to the traffic lane, the arch rib is mainly stressed in the plane, the structure is stressed reasonably, and the arch bridge is economical and practical. The transverse stability of the arch is an important consideration of the structural design, and usually two or more arch ribs are transversely connected, and sometimes wind bracing is added to the inward inclination of the arch ribs for better stabilizing the arch ribs, so that a 'basket arch' with the inward inclination of the arch ribs is generated, and a mature bridge type is gradually developed. Some architects design an arch structure against their way, with the two ribs not being inward-sloping but outward-sloping and without a cross brace, forming an asymmetric rib butterfly arch bridge. The bridge type is in dynamic posture and an open bridge floor, has more aesthetic feeling than an inward-inclined arch bridge in modeling, and meets the requirement of people in a variable-heart state. Such as Tianjin staphylea bridge, Changjiang river bridge in Zhongshan city, and Guangxi Nanning bridge in China.

The bridge type is a multi-element space structure system formed by 2 inclined asymmetric arch ribs, a curved steel box girder and inclined suspension rods, all loads in a three-dimensional space are borne, and the stress behaviors of the whole structure and the local structure are complex. The bridge looks like a butterfly flying in a wing way, so the bridge is also named as a butterfly arch bridge.

Because the arch rib is camber and asymmetric, the arch rib shows the space stress characteristic, the stress is very complex, the cross section of the arch rib simultaneously has two-way bending, torsion, axial force, shearing force and other elements, under the action of dead load and live load, the bending moment of the camber arch rib is larger than that of the vertical arch, the camber angle is larger, the bending moment of the arch rib is larger, and under the action of self dead load, larger out-of-plane bending moment exists, the gravity center position of the asymmetric structure is very sensitive to the deformation of the structure, and different hoisting erection modes and working conditions of the steel main beam and the arch rib greatly influence the internal force of the structure, so that reasonable construction methods and steps are required to be adopted for carrying out construction monitoring. Because the in-plane rigidity of the arch rib is larger, the out-plane rigidity is small, the arch rib has no wind bracing, the transverse windward area is large, the self-weight component of the outwards inclined arch rib generates the tendency of outwards overturning the arch, the lateral restraint of the arch rib is small during construction, the transverse stability of the arch rib becomes the core problem in construction, the construction safety and quality of the bridge are directly influenced, and the key of construction is to adopt reasonable measures to ensure the out-plane stability of the inclined arch rib. And because the two steel arch ribs are respectively inclined outwards without transverse connection, the spatial relative positions of the arch rib sections have vertical inclination angles and plane torsion angles, and reliable spatial attitude adjustment and positioning adjustment measures are required for hoisting the arch rib sections.

Although the cost of the camber arch structure with a strange shape is higher than that of a conventional arch bridge, the camber arch structure is generally applied to a pedestrian bridge, a bicycle bridge, a landscape bridge or a small-span small-scale vehicle bridge, and the structure is complex in structure, difficult to construct and limited in cost due to structural dissimilarity due to small scale and limited total cost. However, butterfly arch bridges built in China are urban bridges with large vehicle loads and large spans, particularly a 300 m-span nanning bridge, steel box arch ribs with the width of 7.4m and the height of 5.6-10 m are added with shadows generated after outward inclination, so that the arch ribs are too thick and clumsy, and the outward-inclined wind-free arch ribs are completely opposite to the steady feeling of the traditional parallel arch or basket arch, so that the worry about bridge stability is that most audiences greatly reduce the aesthetic feeling. The large-span curved butterfly arch bridge not only has great disputes for many audiences due to the adoption of huge economic cost and pursuing attractive appearance, but also has high requirements on the installation and construction technology of the upper structure due to the unique stress characteristic.

For the hoisting and erecting of the bridge type, the domestic technology comprises the following steps:

(1) beam-first arch-second assembly method of large-tonnage ship engine fully supported by support

The overall construction scheme of river course closure, erection of an overwater construction trestle for the passing hoisting of a large-tonnage crane, in-situ assembly of full-cloth supports and 'beam-first and arch-second' is adopted. The installation and construction of the steel box girder adopt the installation modes of block positioning, assembling and welding, and 2 large-tonnage crawler cranes (such as 2 200t truck cranes) are used for hoisting in a double-crane four-hoisting-point mode. After the steel box girders are subjected to on-site positioning and group welding construction, a full support platform for supporting the steel arch ribs is built, the arch ribs are hoisted to the support platform in sections by a large-tonnage car crane in an alignment welding way and are folded, and the system conversion is completed. Such as Tianjin Zhigu bridge.

In addition, when the method is adopted, a large-sized floating crane is sometimes used for construction instead of a large-tonnage crane according to specific conditions.

(2) Method for erecting 'arch before beam' of transverse moving type cable crane without support inclined pulling buckle

The method adopts the overall construction scheme of 'arch first and beam later, arch support beam and steel rib arch through cable crane without support hoisting', such as Guangxi Nanning bridge. As the maximum distance between the center lines of the two outwards inclined arch ribs of the bridge reaches 92.577m, the maximum length of the arch sections reaches 21.6m, and the maximum weight is 218 tons, the temporary cable tower is used as key construction equipment in an inclined pull buckle hanging-cable hoisting system, and adopts the integrated design of a hanging tower and a buckle tower. The cable tower adopts a door type combined steel tower structure, the height is 138m, the transverse width reaches 110m, and the cable tower creates the best bridge construction in the aspects of beam width, beam maximum load, cable saddle transverse movement distance, tower crane height, steel box arch maximum hoisting weight and the like. The main span of a cable crane of the hoisting equipment is 452m, the cable crane consists of east-west cableways, and each cableway comprises two groups of main cables and is respectively responsible for hoisting arch ribs of corresponding cable areas.

The steel box arch of the bridge adopts a suspension splicing construction scheme of a bracket-free cable crane, four-point lifting and hanging arch rib longitudinal movement, positive lifting and positive falling installation and inclined pulling and buckling hanging. In order to solve the problem that the cable force of a hoisting cable at front and rear hoisting points is uneven due to the fact that the gravity center of a corresponding structure is changed along with posture adjustment in the process of adjusting variable-section box-shaped arch sections which need to be in place in the air from hoisting to installation, a turning process of firstly turning over and then turning over by using an underwater floating box platform as a support is adopted in construction, and the suspended sections are anchored on a buckling tower through buckling cables through transverse shifting and positioning of cable saddles at the top of the tower, adjustment of the lengths of the hanging belts, transverse shifting of the front and rear hanging frames and temporary auxiliary measures, so that the construction process is extremely complex. Because the steel box girder is positioned in the plane curve, and because the transverse inclination angles of the slings are different, auxiliary measures of temporary oblique slings are adopted for temporarily overcoming the transverse force of the bridge deck steel box girder during hoisting. The adjustment of the steel box arch elevation is mainly completed by tensioning a cable crane and a buckle cable, and a certain pre-lifting amount is considered; the deviation of the arch rib axis is mainly adjusted by a side cable wind cable and a transverse temporary pull cable.

The assembly method of the large-tonnage ship machine supported by the full-distributed supports through beam-first and arch-second is suitable for the conditions of medium and small span, no navigation on land or water or low navigation requirement, shallow water depth, no structure or traffic interference at the bridge position, and is also frequently used for basket arch bridges and camber symmetrical butterfly arch bridges under the conditions.

The erection method of the 'first arch and then beam' of the cross sliding type cable crane without the bracket inclined pulling buckle is more suitable for the large-span camber type asymmetric arch bridge, and is perhaps a unique method without a new choice. The method needs to solve the technical problems of uneven cable force of front and rear hoisting points caused by transverse hoisting and arch rib posture adjustment, bracket-free inclined pull buckle hanging, transverse force for hoisting the bridge deck box girder caused by different transverse inclination angles of the suspension cable and the like, and a quite large cable crane system needs to be adopted, so that the cost investment is huge.

The advantages and disadvantages of the two methods are shown in Table 1.

TABLE 1 comparison of advantages and disadvantages of the installation methods

For the butterfly arch bridge, the installation methods of the bridge deck steel box girder and the steel arch ribs are closely connected, and the two installation methods of the steel arch ribs have the most outstanding problems of inconvenient air posture adjustment and positioning of the steel arch ribs, more auxiliary measures and links for positioning, complex process, slower installation speed, large safety risk, large using amount of temporary supports, high construction cost and poor economy.

Disclosure of Invention

The invention aims to provide a gantry crane which can be applied to mounting of a steel box girder and a steel arch rib of a butterfly arch bridge.

In order to realize the purpose of the invention, the invention adopts the following technical scheme: the gantry crane comprises a hoisting system, a steel structure main body and a main walking system, wherein the steel structure main body is composed of two parallel connected gantries, each gantry is formed by connecting a main beam and supporting legs through a connecting frame, the steel structure main body is formed by splicing universal rods, and each main beam is provided with two trolleys which can horizontally move along the main beam direction.

In particular, the axes of the two gantries are spaced apart by 8 m.

The main traveling system comprises a gantry crane cart traveling trolley, the traveling trolley is in a double-track four-wheel structure and is arranged below the supporting legs, and the supporting legs are hinged with the traveling trolley through an equalizing beam.

Specifically, the traveling carriages were spaced apart by 16m in the longitudinal direction.

The gantry crane assembled by the universal rod pieces adopted by the method is convenient to assemble and disassemble and flexible to assemble, and is not limited by sites and the capacity of hoisting equipment. The universal rod piece can be temporarily rented as a turnover material, after the project is finished, a gantry crane truss can be disassembled for other projects, a travelling trolley and a crane trolley of the gantry crane can be transformed for other gantry cranes and bridge erecting machines, so that new fixed asset overstock is avoided, one-time investment of capital and overstock of materials after the project is finished are avoided, good technical and economic benefits are achieved, the cost is saved by about 300 ten thousand yuan by matching a full-hall support with a large truck crane scheme, the support saves about 150 ten thousand yuan due to reduction of about one fourth, and the rented gantry crane assembled by the universal rod piece saves about 150 ten thousand yuan compared with a newly purchased truss gantry crane (about 500 ten thousand yuan) with the same effect.

In the invention, a double-door bridge-spanning gantry crane method with the span of 62m assembled by universal rod pieces is adopted for erection, the gantry crane has the functions of longitudinal movement and transverse movement under the hoisting state, the requirements of various aerial vertical rotation, horizontal rotation and small-angle torsion around an axis of a complex-shaped member on accurate installation and positioning are met, the problems that other hoisting equipment is difficult to overcome the difficulty of three-dimensional positioning of an arch rib section are solved ingeniously by using a hoisting process with 4 independent displacement hoisting points, the space hoisting and positioning of the arch rib is easy, accurate and rapid, the installation of all structures of the whole bridge can be completed by only 3 more months by using one gantry crane, the safe and efficient process characteristics are reflected, the equipment is stable in operation, safe and reliable, the displacement is flexible, and the working efficiency is high. Compared with a full-hall support method commonly used for butterfly arch bridge construction, the method reduces two thirds of support erection quantity, the installation and use cost of the gantry crane is far lower than that of other hoisting equipment, and the engineering cost is effectively reduced.

Drawings

FIG. 1 is a schematic diagram of steps of gantry crane installation; wherein,

FIGS. 1a and 1a0 show front and side views of a tower lift construction;

FIGS. 1b and 1b0 show front and side views of a main beam assembly on the ground and legs on a trestle;

FIGS. 1c and 1c0 show front and side views of the first lifting of the main beam;

FIGS. 1d and 1d0 show front and side views of the main beam lifted a second time;

FIGS. 1e and 1e0 show front and side views of the main beam lifted into position for a third time;

FIGS. 1f and 1f0 show the girder and the legs are butt-jointed and installed;

FIG. 2 is a schematic structural view of an arch rib temporary buttress; wherein,

FIG. 2a is a schematic structural view of a temporary buttress along a vertical plane of a bridge;

FIG. 2b is a schematic structural view of a transverse bridge vertical face of the temporary buttress;

FIG. 3 is a schematic view of a gantry crane for erecting steel box girders and arch ribs; wherein,

FIG. 3a is a schematic view of a gantry crane for erecting a steel box girder and arch ribs in the transverse direction of a bridge;

FIG. 3b is a schematic view of a gantry crane for erecting steel box girders and arch ribs in the forward bridge direction;

fig. 4 is a schematic diagram showing the synchronous change of the elevation angle and the plane torsion angle when the arch rib is installed and positioned.

Fig. 4a, 4b, 4c show side views of the change in elevation angle as the rib segment is hoisted;

fig. 4d, 4e and 4f show schematic plane twist angle variations of the lifting position of the rib segment corresponding to fig. 4a, 4b and 4c, respectively;

FIG. 5 is a schematic view of the arch rib being lifted; wherein,

FIG. 5a is a schematic front view along the bridge;

fig. 5b is a schematic transverse bridge view.

Detailed Description

The present invention will now be described with reference to the specific embodiments of the present invention in the case of the bridge of the Yangtze river in Zhongshan, Guangdong province.

The steel arch bridge of Changjiang river in Zhongshan city strides over the stone flood river, and due to the requirement of urban landscape construction, the bridge is a multi-space structure consisting of 2 inclined asymmetric steel arch ribs, curved steel box girders and inclined suspension rods, and overlooks the butterfly that the bridge imitates flying in wings, so the butterfly arch bridge also is named as butterfly arch bridge, and the main span of the butterfly arch bridge is 110m and is positioned on the space curve with the vertical curve radius of 2000m and the flat curve radius of 650 m. The outer arch rib (far away from the circle center of the flat curve) of the bridge inclines outwards by 13.5 degrees, and the rise in the plane is 37.0 m; the inner arch rib (close to the center of the flat curve) inclines outwards by 35.5 degrees, and the rise in the plane is 30.0 m. The arch rib with a closed oval-shaped deformation section is adopted in the butterfly arch bridge in China for the first time, the size of the arch springing section is that the long axis is multiplied by the short axis which is 4.1569m multiplied by 3m, the size of the arch crown section is that the long axis is multiplied by the short axis which is 2.0784m multiplied by 1.5m, and the long axis of the oval section at the arch springing position rotates 90 degrees and is gradually transited to the position of the short axis of the oval section of the arch crown. 20 longitudinal stiffening ribs are distributed on the inner plane of the arch rib, and the arch rib at the arch foot section is fixedly connected with the arch seat through a bearing platform embedded rib and a steel plate. The bridge type facade and sides are shown in figure 5.

The flat steel box girder of curved bridge floor is made up of orthotropic steel plates, and is continuously integrated in the whole arch span range, and is connected with arch rib by means of strong steel cross beam at two ends, and is suspended by means of suspension rod at its edge by means of hidden transverse partition, so that the weight can be transferred to arch rib. The top full width of the steel box girder is 30.4m, the bottom plate width is 9.6m, the cantilever on each side is 10.4m, and the girder height is 2.172 m. The steel box girder subsection single piece has the maximum weight of 120t, and the steel cross girder has the weight of 426.45 t. 19 suspension rods are arranged on the outer arch, 21 suspension rods are arranged on the inner arch, LZM7-55 parallel steel wire twisted guys are adopted, the distance is 5m, the tensioning end is arranged at the position of the steel box girder, the anchoring end is arranged in the arch rib, and the anchorage devices are all cold-cast pier head anchors.

The arch foot mode that this bridge changed traditional arch bridge and fallen to the ground and take root, left and right arch rib constitutes a variable cross section closed steel ring, and both sides bend the different angle to form the bow string relation with curved bridge floor steel box girder, balanced horizontal thrust, nearly simple beam just shelved on the cushion cap of both sides. This bridge constitutes a multi-element spatial structure system by the asymmetric steel arch rib of slope, curved steel box girder and the jib of slope jointly, has increased very big degree of difficulty for the installation, mainly reflects in:

firstly, the bridge deck steel box girder is arranged along a curve, the outward inclination angle of two steel arch ribs is large, the distance between the widest positions of the two steel arch ribs is close to 60m and is asymmetric, the gravity center position of the asymmetric structure is sensitive to the deformation of the structure, and the different hoisting and erecting modes and working conditions of the steel box girder and the arch ribs have large influence on the internal force of the structure.

Secondly, in order to reduce the stress concentration phenomenon, the arch rib does not adopt a common hexagonal section, but adopts an elliptical deformation section, the long axis and the short axis of the elliptical section are gradually changed in a rotating mode from the arch foot, the direction of the arch crown is changed to 90 degrees, and the positions of the long axis and the short axis of the elliptical section are interchanged. The complex-change space curved surface structure not only causes great difficulty in manufacturing, but also provides a new technical problem for the installation of the arch rib, because the space relative position of the arch rib section has both a vertical inclination angle and a plane torsion angle, and reliable space attitude adjustment and positioning adjustment measures are required for the section hoisting of the arch rib.

The arch rib has large in-plane rigidity, small out-plane rigidity, no wind bracing of the arch rib, large transverse windward area, and the self-weight component of the outwards inclined arch rib generates the tendency of outwards overturning the arch, so that the lateral restraint of the arch rib is small during construction, the transverse stability of the arch rib becomes the core problem in construction, the construction safety and quality of the bridge are directly influenced, and the measures for ensuring the out-plane stability of the arch rib also become one of the key points of construction.

In addition, two bidirectional navigation requirements of 6.5m of clear height of a navigation hole and 16.0m of clear width of the navigation hole are required to be ensured under the bridge in the installation process of the bridge, and the factors of economy, convenience, safety and the like of construction are also considered.

In view of the above, the present invention employs the following construction steps.

(1) Installing the arch rib spanning gantry crane, wherein the installation steps are shown in each figure 1.

Firstly, constructing a gantry crane trestle, wherein a trestle support frame is formed by connecting phi 800 steel pipe piles and other section steel into a square, and steel rails are laid and installed on the trestle;

constructing a gantry crane girder lifting tower frame, specifically, building a steel pipe pile lifting frame 1 at two ends of a vertical projection position after the installation of the gantry crane girder is completed, drawing an air cable, and placing 4 trolleys of the gantry crane on the top of the lifting frame, as shown in fig. 1a and fig. 1a 0;

and assembling the gantry crane main beam 2 by using universal rods on the ground according to the vertical projection position of the gantry crane main beam after installation, and assembling the gantry crane supporting legs 4 by using the universal rods in a segmented manner. Hoisting the gantry crane cart traveling trolley, positioning according to the measurement lofting size, and fixing and locking. Gantry crane legs are mounted on the trestle 3, and the legs are anchored by wind cables when being heightened continuously, as shown in fig. 1b and fig. 1b 0.

Lifting the main beam 2 by the crane trolley for 2-3 times, as shown in fig. 1 c-1 e 0;

after the main beam 2 is lifted to the butt joint position with the supporting legs 4, the horizontal position between the main beam and the supporting legs is adjusted through the chain block and the supporting leg wind cables, and the universal rod piece connection is carried out manually, so that the butt joint installation of the main beam and the supporting legs is completed, as shown in fig. 1f and fig. 1f 0;

and finally, moving the trolley from the top of the lifting frame to the main beam, and then removing the lifting frame, thereby completing the installation of the whole gantry crane.

The installed gantry crane comprises a hoisting system, a steel structure main body, a main walking system and the like, wherein the steel structure main body is of a double-beam wide-interval conjoined gantry structure, and each gantry is formed by connecting a main beam and two support legs through a connecting frame. The center distance between the two door frames is 8 m. The steel structure main body is formed by splicing universal rod pieces. Each main beam is provided with two trolleys which can move horizontally along the direction of the main beam, and 4 independent lifting points are arranged in total so as to meet the requirement of changing the distance between the longitudinal lifting points and the transverse lifting points of the arch section with the oval deformation section and the trapezoidal plane steel box girder.

The main traveling system comprises a gantry crane cart traveling trolley which is arranged below the supporting legs of the gantry. The double-track four-wheel structure for the large trolley traveling trolley of the gantry crane is used for reducing the pressure of track wheels and has the function of realizing the horizontal movement of the gantry crane in the front and back directions. In order to realize the uniform stress of the double-track four wheels, the support legs of the gantry crane are hinged with the walking trolley through an equalizing beam 41. The balance beam is a beam-type steel member, is fixed in portal crane landing leg bottom, through the form articulated with the walking platform truck, transmits the load that the portal crane landing leg bore to the walking platform truck, realizes the even atress of walking platform truck four-wheel. The gantry crane cart walking table and the crane trolley walking mechanism adopt variable frequency control to reduce the inertia force impact during gantry crane and braking, and are convenient to accurately position through fine adjustment during installation

During hoisting operation, 4 hoisting trolleys move and shift according to different hoisting point positions of the components, so that 4 hoisting points with rectangular, trapezoidal or parallelogram vertical projection are realized, and the requirements of different hoisting point positions of various components are met.

(2) Erecting an arch rib temporary buttress as a joint positioning support of an arch rib section;

the steel arch rib adopts the form of sectional manufacture and less support installation, the arch rib sections 600 are welded on the butt joint platform in an alignment mode, the butt joint platform corresponds to arch rib section interfaces, and temporary buttresses 5 are arranged at the arch rib interface positions to serve as the butt joint platform. The structure of the temporary buttress is schematically shown in figure 2. The temporary buttress 5 adopts 4 phi 600 multiplied by 6 steel pipe piles 51 and section steel 54 to be lapped into a pile base, the top of the pile base is provided with a bracket consisting of Bailey pieces 52, the top of the bracket is provided with a bracket support 53, and the bracket support 53 is manufactured according to the curve shape of the bottom of the arch rib segment 600 so as to be convenient for hoisting and positioning the arch rib segment 600. The elevation of the bracket support 53 is set according to the elevation of the designed arch rib section and the downward deflection of the arch rib section after the bracket is removed.

The temporary supporting top of the steel box girder and the arch rib segments is provided with clamping groove steel, jacks and the like so as to finely adjust the lateral displacement and elevation of the steel box girder and the arch rib segments, a safe operation platform 55 is installed on the steel support, a wood board is fully paved, fences are arranged around the platform, and a safety net is hung. The construction of the overwater temporary buttress support is carried out by matching a 60t floating crane or a gantry crane with a 90kW vibration hammer.

(3) Installing arch ribs and steel beams of arch springing sections;

the arch foot section of the arch rib is divided into a left section and a right section for installation by taking the longitudinal axis of the bridge as a boundary. The arch foot section is hoisted from a barge stopped in a navigation hole by converting 4 hoisting trolleys of a gantry crane into two-point cranes through a carrying pole beam, the two-point cranes are moved to the position of an arch base, the lower end of the arch foot is firstly aligned with an alignment mark line on the arch base to be in place, the end lifting hook is loosened, the end is taken as a fulcrum, the other end is hoisted and moved to a bracket of a temporary buttress through walking position adjustment of the gantry crane trolley and the hoisting trolleys, and after the alignment position is measured, the arch foot at the end of the arch base is firstly subjected to primary positioning welding. The other side arch is then installed in the same manner.

After the detection confirms that the installation positioning precision of the arch springing meets the requirements, the steel beam is hoisted, the elevation (considering the pre-arch degree) is rechecked to be accurate and correct, the welding of the steel beam and the arch rib is completed, the final welding of the arch rib of the arch springing section and the pre-buried steel plate of the arch abutment is carried out, and the rigid connection of the arch abutment is completed.

(4) Mounting the middle section of the steel box girder;

after the installation of the steel beam 9 of the steel box girder 8, which is arranged at the arch rib and arch foot of the arch foot section, is finished, the steel box girder is pushed from two ends to the middle. The steel box girder segment 80 is hoisted from a barge stopped in a navigation hole by four trolleys 7 of a gantry crane through a carrying pole beam to be converted into two-point cranes, moved to an installation position, operated by a gantry crane cart traveling trolley and the trolleys, slowly dropped on a temporary buttress 85 after the plane position of the steel box girder segment 80 is adjusted, the elevation, the plane position and the boom hole position of the steel box girder segment are measured, the size error of the port position is detected, the position of the steel box girder segment is accurately adjusted through the gantry crane and a jack, and finally, positioning welding is carried out.

(5) Sequentially mounting middle sections of arch ribs from the arch springing sections;

referring to fig. 3 a-3 b, the steel arch rib segment is lifted from a barge stopped at a navigation hole by converting four trolleys of a gantry crane into two-point cranes through a carrying pole beam, moved to the surface of a steel box girder, and then is lifted by a carrying pole beam type rotatable single hook, and the steel arch rib segment is rotated by a certain angle, so that 2 pairs of lifting lugs 601 (the welding positions of the lifting lugs are determined according to the relative positions of the intersection points of the steel arch segment and the vertical projection lines of the 2 main girder axes of the gantry crane when the steel pipe arch is manufactured on a jig) of the arch rib segment are respectively positioned at the vertical projection lines 202 and 203 of the 2 main girder axes of the gantry crane and fall on a temporary bracket prepared in advance. After the shoulder pole beam is removed, four trolleys 7 of the gantry crane are operated to be respectively hooked on 4 lifting lugs 601 of the arch section. And (3) operating the gantry crane cart traveling trolley 40 and the crane trolley 7, and moving the arch rib segment 600 to the mounting point temporary buttress 5 for alignment installation.

Outer arch rib segment 620 is moved to the outer arch temporary buttress and inner arch rib segment 610 is moved to the inner arch temporary buttress. The three-dimensional positioning of the arch rib segment 600 realizes the adjustment of the elevation angle, the plane torsion angle and the micro-rotation around the arch axis through the displacement of the gantry crane cart walking trolley and the crane trolley and the lifting of four lifting points, and the crane trolley needs to be operated simultaneously to change the plane torsion angle alpha of the arch rib segment to be adapted to the elevation angle beta of the arch rib segment along with the increase of the elevation angle beta of the arch rib segment, and finally the arch rib segment is adjusted to the position required by the design to carry out the initial positioning welding of the butt joint. The angle change of the lifting process is shown in each figure of fig. 4. In the drawing, the elevation angle β is an angle between the arch rib segment 600 and a horizontal projection line thereof, and the torsion angle α is an angle between the horizontal projection line of the arch rib segment 600 and a forward direction of the bridge. 4 a-4 c show the gradual lifting of one end of an arching rib segment with a gradually increasing elevation angle after lifting; fig. 4 d-4 f show that the included angle between the arch rib segment and the forward bridge direction gradually decreases until the elevation angle beta and the torsion angle alpha accord with the preset design angle. After the middle sections of the arch ribs are hoisted, the elevations (considering the pre-camber) and the arch axes of all the erected arch rib sections are rechecked, after the arch rib sections are confirmed to be accurate, the middle sections of the arch ribs are welded in sequence from the arch foot sections, and finally, the arch crown closure sections of the outer arch and the inner arch are hoisted.

(6) Installing an arch rib closure section;

the arch rib closure section is arranged at the arch crown position, 2 trolleys of the gantry crane are converted into a rotatable single hook through a carrying pole beam to be hoisted from a barge stopped at a navigation hole, the barge is moved to the box girder surface position, rotated by 90 degrees and dropped on a temporary buttress 5 prepared in advance, four trolleys 7 of the gantry crane are operated to be respectively aligned with 4 lifting lugs 601 of the closure section to be hoisted, and the gantry crane cart walking trolley 40 and the trolleys 7 move the arch rib closure section to the closure position. The three-dimensional positioning of the arch rib closure segment realizes the positioning adjustment of the plane torsion angle and the rotation around the arch axis through the displacement of 4 hoisting points, and corrects the machining allowance through measuring and rechecking related gap data, elevation values (considering the pre-arch degree) and the arch axis, and carries out butt positioning welding in a preset designed closure temperature period, thereby completing the installation and construction of the arch rib closure segment.

(7) Pouring concrete into the arch rib of the arch springing section;

and after the arch rib is closed, pouring non-shrinkage concrete into the arch rib C50 of the arch springing section. Because the concrete in the arch rib of the arch leg section must be filled in the whole arch rib space, the concrete mixing proportion is designed by mainly considering the three aspects of optimization of the high-efficiency superplasticizer, reasonable adoption of admixture and control of the coordinated development between the concrete strength and the expansion rate.

The arch rib concrete is poured by pumping and jacking method, and is divided into two steps, the anchoring bar is inserted into the joint part of the concrete poured twice, and the surface is roughened.

(8) Constructing a steel box girder folding section;

the folding position of the steel box girder is arranged at the midspan position, and the steel box girder is folded and butted (the steel box girder is used as a rigid tie rod) after temporary prestress is applied so as to balance unbalanced thrust on the inner side and the outer side of the curved bridge. And after the closure section of the steel box girder is hoisted in place, pre-pulling the steel strand and the finish-rolled deformed steel bar which are temporarily connected with the steel box girder to a certain tonnage, and then dismantling the arch rib support. And (3) detaching the buttress supports of the arch ribs until the arch ribs are all suspended, tensioning the temporarily connected steel strands and the finish-rolled deformed steel bars to the designed tonnage, finally performing butt welding on the closure openings of the steel box girders, completing closure construction of the steel box girders, detaching the temporary connecting facilities, and cutting off the temporarily connected steel plates.

(9) Installing a suspender and adjusting the cable force;

the two ends of the suspension rods 611 and 621 are respectively in pin joint with the arch rib and the ear plate of the bridge deck steel box girder, and the tensioning adjusting end of the suspension rod is positioned on the side of the steel box girder wing plate. After all the suspenders are installed, the suspenders are gradually tensioned and adjusted to meet the design requirements. The principle of double control of the displacement of the arch rib and the steel box girder and the axial force of the suspension rod is adopted in the suspension rod tensioning construction. And finally adjusting the cable force of the suspender after the arch rib temporary support is dismantled and the steel box girder is tensioned, folded and welded.

(10) Disassembling the gantry crane;

and after the butterfly arch bridge is installed, the gantry crane is disassembled. When the disassembly is carried out, the method comprises the following steps:

the gantry crane is longitudinally moved to one end of the butterfly arch bridge, a gantry crane cart traveling trolley is locked, and a steel plate is used for wedging a gantry crane supporting leg balance beam.

Secondly, cables on the inner side and the outer side of the gantry crane supporting legs are installed, the cables are tightened by a winch and locked by a hoist, the winch is fixed with a ground anchor, and longitudinal cables are additionally arranged according to the weather conditions.

And thirdly, two temporary supports are erected in the gantry crane span, the steel box girder erected on the bridge deck supports the gantry crane girder, the temporary supports and the bridge deck steel box girder are welded and fixed, a counter-pull cable is added between the two supports for stabilization, and the top surface of each support needs to be wedged tightly with the bottom surface of the gantry crane girder.

Fourthly, four trolleys are driven into the span of the gantry crane, then the trolleys, steel rails, track beam bolts and an electrical system of the gantry crane are dismantled, and a truck crane of 40-50 t is adopted for hoisting.

The disassembly of the main beam of the gantry crane is divided into two layers, each layer is divided into three sections, each section is divided into two sections, the disassembly is carried out for 12 times, two sides of a temporary support in the span of the main beam are respectively divided into one section, one section is arranged between the two supports, the gantry crane is eccentric to the bridge floor at the far side, the length of the main beam section in disassembly is 22m, the weight is about 18.4t, the length of the middle section is 26m, the weight is about 21.6t, the length of the third section is 12m, and the weight is about 10 t; the main beams are disassembled from top to bottom, and the transverse connecting rod piece between the two main beams is disassembled before the segments are disassembled.

Disassembling the support leg of the gantry crane into a support leg upright post and a support leg base, wherein the support leg upright post is divided into three sections, namely two sections of 8m and one section of 10m, and the weight is about 9 t; the supporting leg base is disassembled into two sections, the length of each section is 9m, the height of each section is 8m, and the weight of each section is about 29 t. The support leg disassembly adjusts the cable position accordingly to the height reduction.

And seventhly, hanging the gantry crane cart walking trolley down to the ground from the trestle by using a crane to finish the disassembly of the gantry crane.

Claims (4)

1. The utility model provides a stride arch rib portal crane, includes hoist and mount system, steel construction main part and main traveling system, steel construction main part comprises the disjunctor portal of two parallels, and every portal passes through the link connection by girder and landing leg and constitutes its characterized in that: the steel structure main body is formed by assembling and splicing universal rod pieces, and each main beam is provided with two hoisting trolleys which can horizontally move along the direction of the main beam.

2. The cross-rib gantry crane of claim 1, wherein: the axial distance between the two portal frames is 8 m.

3. The cross-rib gantry crane of claim 1, wherein: the main traveling system comprises a gantry crane cart traveling trolley, the traveling trolley is in a double-track four-wheel structure and is arranged below the supporting legs, and the supporting legs are hinged with the traveling trolley through an equalizing beam.

4. The cross-rib gantry crane of claim 3, wherein: the longitudinal distance between the gantry crane cart traveling trolleys is 16 m.

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