NL2034933A - Construction method of lower cross beam of main tower of highway-railway dual-purpose and river-crossing A-type cable-stayed bridge - Google Patents
Construction method of lower cross beam of main tower of highway-railway dual-purpose and river-crossing A-type cable-stayed bridge Download PDFInfo
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- NL2034933A NL2034933A NL2034933A NL2034933A NL2034933A NL 2034933 A NL2034933 A NL 2034933A NL 2034933 A NL2034933 A NL 2034933A NL 2034933 A NL2034933 A NL 2034933A NL 2034933 A NL2034933 A NL 2034933A
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- 238000010276 construction Methods 0.000 title claims abstract description 113
- 230000003014 reinforcing effect Effects 0.000 claims abstract description 59
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 56
- 239000010959 steel Substances 0.000 claims abstract description 56
- 239000004567 concrete Substances 0.000 claims abstract description 38
- 238000000034 method Methods 0.000 claims abstract description 27
- 238000009415 formwork Methods 0.000 claims description 50
- 239000010410 layer Substances 0.000 claims description 14
- 239000004033 plastic Substances 0.000 claims description 9
- 238000003825 pressing Methods 0.000 claims description 8
- 238000009826 distribution Methods 0.000 claims description 6
- 230000002787 reinforcement Effects 0.000 claims description 6
- 230000036316 preload Effects 0.000 claims description 5
- 238000013461 design Methods 0.000 claims description 4
- 239000011513 prestressed concrete Substances 0.000 claims description 4
- 238000004873 anchoring Methods 0.000 claims description 3
- 230000006835 compression Effects 0.000 claims description 3
- 238000007906 compression Methods 0.000 claims description 3
- 238000003780 insertion Methods 0.000 claims description 3
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- 239000011241 protective layer Substances 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 3
- 239000004568 cement Substances 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 2
- 238000005266 casting Methods 0.000 claims 6
- 230000000630 rising effect Effects 0.000 claims 6
- 238000000465 moulding Methods 0.000 claims 1
- 239000004576 sand Substances 0.000 claims 1
- 230000009194 climbing Effects 0.000 description 15
- 238000009434 installation Methods 0.000 description 8
- 238000005259 measurement Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000005489 elastic deformation Effects 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- 244000035744 Hura crepitans Species 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 230000007812 deficiency Effects 0.000 description 2
- 239000002023 wood Substances 0.000 description 2
- 235000017166 Bambusa arundinacea Nutrition 0.000 description 1
- 235000017491 Bambusa tulda Nutrition 0.000 description 1
- 241001330002 Bambuseae Species 0.000 description 1
- 235000015334 Phyllostachys viridis Nutrition 0.000 description 1
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Classifications
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
- E01D21/00—Methods or apparatus specially adapted for erecting or assembling bridges
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
- E01D11/00—Suspension or cable-stayed bridges
- E01D11/04—Cable-stayed bridges
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
- E01D19/00—Structural or constructional details of bridges
- E01D19/14—Towers; Anchors ; Connection of cables to bridge parts; Saddle supports
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Abstract
The present invention provides a construction method of lower cross beam of main tower of highway-railway dual-purpose and river-crossing A-type cable-stayed bridge, 5 which comprises: carrying out bearing platform construction at a preset position; erecting a lower cross beam bracket after completing bearing platform construction, carrying out construction of second pre-pouring sections of the lower cross beam, carrying out construction of the first pre-pouring section after completing construction of the second pre-pouring sections, and in a process of construction of the first 10 pre-pouring section, synchronously and continuously constructing middle tower column part upwards, when completing concrete pouring of the first pre-pouring section and the second pre-pouring sections, continuously constructing the middle tower column upwards to a corresponding position of a first cross bracing, binding reinforcing bars and concrete pouring of closure sections of the first pre-pouring 15 section and the second pre-pouring sections, and carrying out pre-stress construction after installing a second cross bracing, and arranging built-in fittings on the bearing platform to connect and fix a steel pipe strut so as to ensure stability of the steel pipe strut to the lower cross beam support, and the lower cross beam is constructed by adopting a method of segmented pouring to ensure construction quality of the main 20 tower, and the tower column and the lower cross beam are constructed asynchronously, which improves the construction efficiency on the premise of ensuring the quality.
Description
Construction method of lower cross beam of main tower of highway-railway dual-purpose and river-crossing A-type cable-stayed bridge
The present invention belongs to the technical field of bridge construction, and in particular to a construction method of lower cross beam of main tower of highway-railway dual-purpose and river-crossing A-type cable-stayed bridge.
At present, the bridge towers of cable-stayed bridges, suspension bridges and other bridges containing a bridge tower structure generally have a diamond shape, an
H-shape, a herringbone shape, an A-shape, an inverted Y-shape and so on. Although there are many models, in order to increase the strength of the tower columns, a plurality of cross beams are generally provided to connect two tower columns to form a transverse support for the tower columns. The main tower of the cable-stayed bridge has a high height, and the construction of the lower cross beams is difficult. With regard to the construction schemes of the lower cross beams of the main tower with a large structural volume in the prior art, the construction is difficult, and the construction safety of the lower cross beams cannot be guaranteed.
Accordingly, there is a need to provide an improved solution to the above-mentioned deficiencies in the prior art.
The object of the present invention is to overcome the above-mentioned deficiencies in the prior art and provide a construction method of lower cross beam of main tower of highway-railway dual-purpose and river-crossing A-type cable-stayed bridge.
In order to achieve the above object, the present invention provides the following technical solutions:
A construction method of lower cross beam of main tower of highway-railway dual-purpose and river-crossing A-type cable-stayed bridge, comprising: step S1. carrying out bearing platform construction at a preset position; step S2. erecting a lower cross beam bracket after completing bearing platform construction, and the lower cross beam bracket comprising a steel pipe column, a parallel connection, a bearing beam, a distribution beam, a sand box, a bottom die and a pre-pressed bracket; and synchronously constructing a lower tower column to a corresponding section along a lower edge of the lower cross beam in the process of setting up the lower cross beam bracket; step S3. carrying out construction of second pre-pouring sections of the lower cross beam, comprising bonding of reinforcing bars corresponding to the second pre-pouring sections, pre-stress setting and formwork installation and reinforcement; continuing to lift the pouring climbing mold, and synchronously integrating the second pre-pouring sections and a corresponding section of a middle tower column with pouring; step S4. carrying out construction of the first pre-pouring section after completing construction of the second pre-pouring sections, and in a process of construction of the first pre-pouring section, synchronously and continuously constructing middle tower column part upwards; step S5. when completing concrete pouring of the first pre-pouring section and the second pre-pouring sections, continuously constructing the middle tower column upwards to a corresponding position of a first cross bracing, and installing and topping the first cross bracing; step S6. binding reinforcing bars and concrete pouring of closure sections of the first pre-pouring section and the second pre-pouring sections, synchronously constructing the middle tower column to a second cross bracing, and carrying out pre-stress construction after installing the second cross bracing; and step S7. after completing closure of the lower cross beam is closed and pre-stress construction, removing the first cross bracing and the lower cross beam bracket.
Preferably, construction of the lower tower column and the middle tower column comprises: in the process of construction of a tower base, embedding a first section of rigid skeleton and vertical reinforcing bars corresponding to the lower tower column, and pouring and forming the tower base and the first section of lower tower column at the same time; and adopting a hydraulic climbing formwork for the construction of the lower tower column from a second section, during construction, firstly pouring the first section of the lower tower column, pre-embedding a climbing cone during construction of the first section, installing a climbing formwork upper frame during construction of the second section, and completing construction of the tower column of the second section, after completing construction of the tower column of the second section, lifting the climbing formwork, installing a hanging platform, and constructing the remaining sections of the lower tower column and the middle tower column by using the climbing formwork until the main tower construction reaching a preset elevation.
Preferably, pre-pressing a bracket is performed after the bottom formwork is laid, comprising: arranging observation points, and providing a plurality of observation sections, wherein each of the observation sections arranged to correspond to two layers of observation points at the bottom of the formwork and the bottom of the bracket; loading step by step for preloading, adopting method of steel strand anti-fulcrum preloading to preload, and observing and recording settlement of the observation points during the preloading process; unloading stepwisely, unloading the preloading in several steps after the bracket settlement is stable, and the unloading process shall be done evenly and successively; and adjusting the elevation of the support and the formwork, and reserving the sinking amount of the bottom die and construction pre-camber based on the detected deformation amount and the preloading data, wherein the highest value of the pre-camber is set in the beam span, and the two end fulcrums of the beam are allocated according to the design line type.
Preferably, the observation sections are arranged at least at 1/2, 1/4 and ends of each span bracket, and each section is divided into at least left, middle and right observation points.
Preferably, the pre-pressing load is not less than 1.1 times of the maximum construction load, and the three-level loading is carried out in the order of the pre-pressing load value Oad valul 1110%, and the deformation observation of the bracket is done one hour after each level of loading is completed, and the deformation value is measured every 6 hours after the load is completed.
Preferably, before the concrete is poured, blanking points are uniformly arranged according to the concrete flow radius, a chute and a string cylinder are arranged, and when the concrete enters the formwork, free falling height of the concrete shall be controlled to be no more than 2m; the concrete is poured in layers, and thickness of each of the layers is not more than 30 cm, and the continuous construction shall be ensured during construction; and
When stirring the concrete, a vibration rod shall be inserted into the next layer to a certain depth, and the insertion points shall be uniformly moved in rows or staggered to avoid vibration leakage, and a distance between the vibration rod and the formwork shall be kept at 5~10 cm.
Preferably, a prestressed channel is installed when the reinforcing bars are bound, the prestressed channel is formed by a plastic corrugated pipe, and an end of the plastic corrugated pipe is covered after the plastic corrugated pipe is installed in the formwork.
Preferably, the lower cross beam is a prestressed concrete member; making a prestressed steel according to channel length, anchor clamp thickness, jack length, cold-drawn elongation value, elastic retraction value, tensioned elongation value and exposed length; installing the prestressed steel after binding the reinforcing bars, and sealing an opening at an end of the channel after installing the prestressed steel in the pipeline; carrying out prestressed tensioning by means of a jack, carrying out prestressed pipeline grouting within 24h after completing tensioning, removing impurities and water accumulated in the channel of the beam body before grouting, and carrying out channel grouting by means of a grouting pump, and anchoring the prestressed tensioning notch after completing the grouting.
Preferably, the rigid skeleton is a truss-type structure composed of section steel welding, the rigid skeleton is pre-embedded in the bearing platform during construction, each sections of the rigid skeleton are installed in turn according to the sectional length of the tower column during construction of the lower tower column, the rigid skeleton is connected to a height higher than the reinforcing bars to be bound before binding of the reinforcing bars, and the connectors between the rigid skeleton are installed according to thickness of the protective layer of the reinforcing bars.
Preferably, during construction of the lower tower column, pre-embedded reinforcing bars for connecting the lower cross beam are pre-embedded, the reinforcing bars of the second pre-pouring section should be installed at the same time as the reinforcing bars of the tower column, the reinforcing bars of the first pre-pouring section are independently installed, and when the reinforcing bars of the first pre-pouring section are installed, the longitudinal reinforcing bars of the joint surfaces of the first pre-pouring section and the second pre-pouring sections both extend out of the concrete joint surface, wherein 50% of the reinforcing bars extend out of 30cm, and another 50% of the reinforcing bars extend out of 120 cm, and each joint surface is provided with short reinforcing bars of 10% of the total number of longitudinal reinforcing bars.
Beneficial effects: arranging built-in fittings on the bearing platform to connect and fix a steel pipe strut so as to ensure stability of the steel pipe strut to the lower cross beam 5 support; and the lower cross beam is constructed by adopting a method of segmented pouring to ensure construction quality of the main tower, and the tower column and the lower cross beam are constructed asynchronously, which improves the construction efficiency on the premise of ensuring the quality.
The accompanying drawings, which are included to provide a further understanding of the present invention and are incorporated in and constitute a part of the present application, illustrate embodiments of the present invention and together with the description serve to explain the invention and not to limit the invention in any way.
Wherein:
Fig. 1 is a schematic diagram of division of main tower sections in a specific embodiment of the present invention;
Fig. 2 is a schematic diagram of construction of the lower cross beam in the specific embodiment provided by the present invention;
Figure 3 is a schematic diagram of distribution of the cross bracings in the specific embodiment of the present invention.
In the figures: 1-tower base; 2- lower tower column; 3- lower cross beam; 4- middle tower column; 5- closure area; 6- upper cross beam; 7- cable tower; 8- tower crown; 9- steel pipe column; 10- cross bracing; 301- first pre-pouring section; 302- second pre-pouring section; and 303- closure section.
The technical solutions in the embodiments of the present invention will be clearly and completely described below, obviously, the described embodiments are only some of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention belong to the protection scope of the present invention.
In the description of the present invention, orientations or positional relationships indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific orientation, so they cannot be understood as limitations on the Invention. The terms "connected" and "connection" used in the present invention should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate component. A skilled person can understand the specific meanings of the above terms according to specific situations.
The present invention will be described in detail below with reference to the accompanying drawings and examples. It should be noted that, in the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.
As shown in Figs 1-3, a construction method of lower cross beam of main tower of highway-railway dual-purpose and river-crossing A-type cable-stayed bridge, comprising: step SI. carrying out bearing platform construction at a preset position; step S2. erecting a lower cross beam 3 bracket after completing bearing platform construction, and the lower cross beam 3 bracket comprising a steel pipe column, a parallel connection, a bearing beam, a distribution beam, a sand box, a bottom die and a pre-pressed bracket; and synchronously constructing a lower tower column 2 to a corresponding section along a lower edge of the lower cross beam 3 in the process of setting up the lower cross beam bracket; (at this time, the fourth section of the tower column is completed). An inner mold and an outer mold are correspondingly arranged on the bottom mold, wherein the outer mold and the bottom mold are steel mold plates, and the inner mold 1s a wood mold, the inner mold is arranged inside the outer mold via the steel pipe bracket; step S3. carrying out construction of second pre-pouring sections 302 of the lower cross beam 3, comprising bonding of reinforcing bars corresponding to the second pre-pouring sections 302, pre-stress setting and formwork installation and reinforcement; continuing to lift the pouring climbing mold, and synchronously integrating the second pre-pouring sections 302 and a corresponding section of a middle tower column 4 with concrete pouring (the middle tower column 4 is partially and synchronously constructed to the sixth section). Step S4. carrying out construction of the first pre-pouring section 301 after completing construction of the second pre-pouring sections 302, and in a process of construction of the first pre-pouring section 301, synchronously and continuously constructing middle tower column 4 part upwards, (the middle tower column 4 is partially synchronously constructed to the seventh section); step S5. when completing concrete pouring of the first pre-pouring section 301 and the second pre-pouring sections 302, continuously constructing the middle tower column 4 upwards to a corresponding position of a first cross bracing 10 (namely, the middle tower column 4 is constructed synchronously to the ninth section), and synchronously installing and topping the first cross bracing; step S6. binding reinforcing bars and concrete pouring of closure sections 303 of the first pre-pouring section 301 and the second pre-pouring sections 302, synchronously constructing the middle tower column 4 to a second cross bracing 10 (constructing to the thirteenth section), and carrying out pre-stress construction after installing the second cross bracing 10; carrying out pre-stress construction after synchronously constructing and installing the middle tower column 4 with the second cross bracing 10; and step S7. after completing closure of the lower cross beam 3 is closed and pre-stress construction, removing the first cross bracing 10 and the lower cross beam bracket 3. After pouring of the lower cross beam 3 is completed and the preset strength is reached, the formwork and the steel pipe column 9 are removed. Built-in fittings on the bearing platform are arranged to connect and fix the steel pipe strut so as to ensure the stability of the steel pipe strut to support the lower cross beam 3; the middle tower column 4 and the lower cross beam 3 are constructed asynchronously, which improves the construction efficiency on the premise of ensuring the quality. In the embodiment, the second pre-pouring sections 302 correspond to two tower sections (the fifth and sixth sections), wherein the sixth section lower edge is located at a certain height as the second pre-pouring sections 302.
In another alternative embodiment, built-in fittings are embedded in a top surface of the bearing platform during construction, the built-in fittings are in structure of steel plate and anchor bar, and the foot of the steel pipe column 9 1s welded to the built-in fittings. The nine sections of the steel pipe column 9 are connected by flanges, a steel pipe is installed as a support by arranging the built-in fittings on the top surface of the bearing platform, specifically, three groups of corbel brackets are pre-embedded on two sides of the tower columns, seven rows and four columns of 630x 10mm steel pipe columns 9 are arranged on the top surface of the bearing platform, the steel pipe columns 9 are arranged at three meters apart in the longitudinal direction and six meters apart in the transverse direction, a double-spliced I63c I-shaped steel is arranged on the top of the steel pipe columns 9 as a bearing beam, and a double-spliced 1634 I-shaped steel is arranged at 3 ~60+2x140+3x60+2x140+3 x 60cm apart in the transverse direction of the bearing beam; 114 I-shaped steel on the top surface of the double-spliced 63a I-shaped steel is arranged as a distribution beam to directly bear the concrete load of the lower cross beam 3 and the construction live load transmitted from the formwork and square timber, and the longitudinal spacing along the bracket is respectively: 20 cm at the partition and stiffener, and 45 cm at other parts.
The cross-bridge double-jointed 63a H-shaped steel is processed into an arc according to the arc of 197.11m in a professional steel structure factory, and is transported to a site for assembly to adjust the change of the bottom die of the lower cross beam 3. The bottom die of the lower cross beam 3 is made of bamboo rubber plate and square wood, the side die is made of the unified customized steel formwork, and the connecting system between the longitudinal steel pipe columns 9 is connected by 20 channel steel.
Since the tower beam is constructed asynchronously, the floor bracket can be processed and installed while the tower base 1 is being constructed, and the verticality of the steel pipe bracket is controlled by hanging a vertical line during installation.
The steel pipe column 9 serves as its hoisting hole by making a hole of 3cm from its end, both hoisting holes being arranged along the central axis of the steel pipe. Prior to installation, the top surface of the built-in fittings is cleaned, the central point is calibrated, and the installation line is drawn; the tower crane is used for hoisting the steel pipe column 9 of the bottom section to perform alignment; the bottom section is overlapped with the installation line and then temporarily bolted to the built-in fittings; and the steel pipe column 9 is provided with a steel straight ladder along the side wall.
In another alternative embodiment, construction of the lower tower column 2 and the middle tower column 4 comprises: in the process of construction of a tower base 1, embedding a first section of rigid skeleton and vertical reinforcing bars corresponding to the lower tower column 2, and pouring and forming the tower base 1 and the first section of lower tower column 2 at the same time; and adopting a hydraulic climbing formwork for the construction of the lower tower column from a second section, during construction, firstly pouring the first section of the lower tower column 2, pre-embedding a climbing cone during construction of the first section, installing a climbing formwork upper frame during construction of the second section, and completing construction of the tower column of the second section, after completing construction of the tower column of the second section, lifting the climbing formwork, installing a hanging platform, and constructing the remaining sections of the lower tower column 2 and the middle tower column 4 by using the climbing formwork until the main tower construction reaching a preset elevation, at this moment, a cross bracing 10 is provided at the elevation, and the lower cross beam 3 is constructed.
Specifically, there are five cross bracings 10, and the distance between two adjacent cross bracings 10 decreases sequentially from bottom to top, and the horizontal thrust distribution of bottom to top cross braces 10 is 510 t, 580 t, 360 t, 350 t, and 200 t.
In another alternative embodiment, as the main tower is poured section by section, the arrangement of five cross bracings 10 is completed, and each of the cross bracings 10 is measured and monitored during pouring of the middle tower column 4; the first cross bracing 10 is removed after completing loading of the second cross bracing 10 from the bottom to the top, the lower cross beam 3 is poured at the position of the first cross bracing 10, and carrying out construction asynchronously by pouring the middle tower column 4 and the lower cross beam 3, so that the construction progress can be improved, and at the same time, the second cross bracing 10 gives sufficient supporting force to the main body to ensure the stability of the construction; after the middle tower column 4 is closed in the closure area 5, all the cross bracings 10 are removed, and the order of removal is according to the principle of first taking up and first removing, when the support rod is removed, the whole steel pipe is lifted by the tower crane hook, the cross braces 10 are cut along the edge of one side of the corbel fulcrum, and then the cross bracings 10 are cut along the edge of the other side of the corbel fulcrum, and the whole steel pipe is unloaded by the tower crane; the tower crane hook is used to lift the integral remaining components welded at the ends of the corbel and the support rod, the corbel pre-embedded climbing cone is removed, the tower crane 1s unloaded, and finally the platform is dismantled and the climbing cone hole 1s repaired. The steel reinforcement of the tower column is positioned with a rigid skeleton, the rigid skeleton is vertically formed with angle steel of 100x100x6mm, and both the horizontal bracing and vertical diagonal bracing are formed with angle steel of 75#75x8mm. The rigid skeleton is processed in sections according to the drawing and installed in sections and pieces. Each time the rigid skeleton is installed, a section is constructed, and the climbing frame climbs up once. After the removal is completed, the construction of the cable tower 7 and the tower crown 8 1s continued.
In another alternative embodiment, the lower cross beam 3 of the main tower is in a structure of a prestressed concrete single-box double-chamber. After the laying of the bottom formwork corresponding to the lower cross beam 3 is completed, bracket preloading is performed to eliminate the influence of non-elastic deformation such as bracket and formwork, and the actual value of elastic deformation of the bracket is measured to serve as the basis for setting the pre-arch of the beam formwork system.
Meanwhile, strength, stiffness and stress stability of the bracket are checked to verity whether the bearing capacity of the bracket can meet the design requirements and ensure the construction safety. Pre-pressing a bracket is performed after the bottom formwork is laid, comprising: arranging observation points, and providing a plurality of observation sections, wherein each of the observation sections arranged to correspond to two layers of observation points at the bottom of the formwork and the bottom of the bracket; each observation section is arranged with two layers of observation points at the bottom of the template and the bottom of the bracket. The observation points at the bottom of the formwork can be positioned by nailing into the square timber at the bottom of the formwork, and a level meter is used for settlement observation. Since the observation points are at the upper part, an inverted ruler is required for observation. The observation points at the bottom of the bracket can be positioned on the backing plate at the bottom of the bracket and the level meter is used for settlement observation. loading preloading step by step, adopting method of steel strand anti-fulcrum preloading to preload, preloading load is not less than 1.1 times of maximum construction load, and observing and recording settlement of the observation points during the preloading process; unloading, unloading the preloading by grades after the bracket settlement is stable, and the unloading process shall be evenly and successively unloading; and unloading is similar to loading, which is the reverse process of the loading procedure. The unloading process should be unloaded uniformly and sequentially to prevent the impact of sudden unloading, and place heavy objects properly so as not to affect normal construction. When unloading, each level of unloading should be observed and recorded before being unloaded to the next level of load, and the elastic recovery of the support should be measured and recorded. All measurement records are required to be reported to the test steering group on the same day, and abnormal situations found on site must be reported in time.
Adjusting the elevation of the support and the formwork, and reserving the sinking amount of the bottom die and the pre-camber of the construction based on the detected deformation amount and the pre-pressing data, wherein the highest value of the pre-camber is set in the beam span, and the two end fulcrums of the beam are allocated according to the design line type.
In another alternative embodiment, the observation sections are arranged at least at 1/2, 1/4 and ends of each span bracket, and each section 1s divided into at least left, middle and right observation points. Each observation section is arranged with two layers of observation points at the bottom of the template and the bottom of the bracket. The observation points at the bottom of the formwork can be positioned by nailing into the square timber at the bottom of the formwork, and a level meter is used for settlement observation. Since the observation points are at the upper part, an inverted ruler is required for observation. The observation points at the bottom of the bracket can be positioned on the backing plate at the bottom of the bracket and the level meter is used for settlement observation.
In another alternative embodiment, the pre-pressing load is not less than 1. 1 times of the maximum construction load, and the three-level loading is carried out in the order of the pre-pressing load value Oad valul 1110%, and the deformation observation of the bracket is observed one hour after each level of loading is completed, and the deformation value is measured every six hours after the load is completed. The preload unloading time 1s determined based on the principle of stable deformation of the bracket. When the difference between the average values of the last two settlement measurements is not greater than 2 mm, the preload unloading is terminated. After 6 hours of unloading, the elevation of each measuring point is monitored, and the elastic deformation and inelastic deformation of each monitoring point of the bracket is calculated.
In another alternative embodiment, when the tower formwork is not more than 3.5 meters in length, the pull screw adopts the standard length-to-length pull method, and the PVC casing is passed between the templates on both sides. The pull screw can be used repeatedly. When pouring a solid section with a thickness greater than 3.5 meters, use a 6-meter-long tension screw to weld with the self-provided ®25 reinforcing bar (or transverse main bar). Before concrete pouring, the feeding point shall be evenly arranged according to the concrete flow radius, and the chute and stringer shall be arranged. When the concrete enters the formwork, the free fall height of the concrete shall not exceed 2m; the concrete pouring shall be poured in layers, and the thickness of each layer shall not When the concrete is vibrated, the vibrating rod should be inserted into the next layer to a certain depth; when vibrating, the insertion points should be moved evenly, in a row or in a staggered manner, so as to avoid missing vibration, and the distance between the vibrating rod and the formwork should be mixed. The distance should be kept at 5-10cm. After the pouring is completed, the concrete is cured in two ways: watering and curing agent curing, that is, curing agent is used for curing when the temperature is lower than 5°C, and watering 1s used for curing when the temperature is higher than 5°C.
In another alternative embodiment, a prestressed channel is installed when the reinforcing bars are bound, the prestressed channel is formed by a plastic corrugated pipe, and an end of the plastic corrugated pipe is covered after the plastic corrugated pipe is installed in the formwork.
The lower cross beam is a prestressed concrete member; making a prestressed steel bundle according to channel length, anchor clamp thickness, jack length, cold-drawn elongation value, elastic retraction value, tensioned elongation value and exposed length; installing the prestressed steel bundle after binding the reinforcing bars, and sealing an opening at an end of the channel after installing the steel bundle in the pipeline; carrying out prestressed pipeline grouting within 24h after completing the tensioning, in special cases, it may be extended to 48 hours, and the cement slurry shall not be lower than M55; and carrying out prestressed tensioning by means of a jack, carrying out prestressed pipeline grouting within 24h after completing the tensioning, cleaning the channels before grouting, and carrying out channel grouting by means of a grouting pump, sequence of grouting should be injected into the lower channel first. The grouting pump adopts continuous type. The grouting of the same pipeline should be carried out continuously and completed at one time; after the grouting is completed, anchoring the prestressed tensioning notch after completing the grouting. The measurement and calculation method of the actual elongation of the steel beam: Before the prestressed tendon is stretched, it should be adjusted to the initial stress 60, and the elongation should be measured from the initial stress. In addition to the measured elongation value during tensioning, the actual elongation value should also add the calculated elongation value at the initial stress, and the elastic compression value generated during the tensioning process of the post-tensioned concrete structure can generally be omitted. The measurement of the actual elongation value adopts the method of measuring the stroke value of the jack cylinder. Under the initial stress, measure the exposed length of the oil cylinder, and measure the exposed length of the corresponding oil cylinder under the corresponding graded load.
In another alternative embodiment, the measurement control of the formwork and the connection between the new and old concrete joints and the formwork are strengthened to prevent the joints from being misplaced. Use a tower crane to hoist the formwork to be installed to the installation area, adjust the position, insert the positioning pin after precise positioning, and then install the formwork connecting bolts and tie rods. The installation of the side formwork of the beam should be carried out after the bottom plate of the beam, the reinforcement of the side plate and the prestressed bellows are completed.
In another alternative embodiment, the rigid skeleton is a truss-type structure composed of section steel welding, the rigid skeleton is pre-embedded in the bearing platform during construction, each section of the rigid skeleton is installed in turn according to the sectional length of the tower column during the construction of the lower tower column 2, the rigid skeleton is connected to a height higher than the reinforcing bars to be bound before the binding of the reinforcing bars, and the connectors between the rigid skeleton are installed according to thickness of the protective layer of the reinforcing bars. The rigid skeleton of the main tower is pre-embedded during the construction of the bearing platform. During the subsequent construction, each section of the rigid skeleton is installed in sequence according to the section length of the tower column. The length of each section of the rigid skeleton can be adjusted appropriately according to the actual situation on site. Integral tire frame and support structure installed as reinforcement. Before the reinforcing bars are bound, the rigid skeleton is raised so that it is higher than the reinforcing bars to be bound, and then the connectors between the rigid skeleton (also used as reinforcing bar positioning auxiliary aids) are installed according to the designed thickness of the reinforcing bar cover. Each section of rigid skeleton is connected by welding.
In another alternative embodiment, during construction of the lower tower column 2, pre-embedded reinforcing bars for connecting the lower cross beam are pre-embedded, the reinforcing bars of the second pre-pouring section should be installed at the same time as the reinforcing bars of the tower column, the reinforcing bars of the first pre-pouring section are independently installed, and when the reinforcing bars of the first pre-pouring section are installed, the longitudinal reinforcing bars of the joint surfaces of the first pre-pouring section and the second pre-pouring sections both extend out of the concrete joint surface, wherein 50% of the reinforcing bars extend out of 30cm, and another 50% of the reinforcing bars extend out of 120cm, and each joint surface is provided with short reinforcing bars of 10% of the total number of longitudinal reinforcing bars. The section top concrete can be chiseled manually after the concrete strength of the tower column reaches 2.5MPa, and the concrete strength must reach more than 10MPa when mechanical chiseling such as wind turbine 1s used.
When chiseling, first use a small drill to chisel out a 5cm wide chisel strip along the inner and outer contours, and then chisel off the concrete laitance on the top surface of the section.
In another alternative embodiment, a manhole is provided between the pylon and the lower beam 3 inner chambers, and all the reinforcing bars passing through the manhole are truncated, and the truncated reinforcing bars are closed at the truncation place; the upper beam 6 After the pouring is completed, the wall thickness of the lower tower column 2 and the lower cross beam 3 junction of the tower column gradually thickens within a certain range. The hollow tower column and the lower cross beam 3 can reduce the amount of concrete to the greatest extent while ensuring the strength of the cable-stayed bridge, reduce the construction volume, and speed up the construction efficiency. It can be understood that the above description is only exemplary, and this embodiment of the present application does not limit the protection scope of the present invention.
The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are within the scope of the pending rights of the present invention.
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| CN202210934676.2A CN115341472B (en) | 2022-08-04 | 2022-08-04 | Construction method for lower cross beam of main tower of highway-railway dual-purpose river-crossing A-type cable-stayed bridge |
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| NL2034933A true NL2034933A (en) | 2023-08-11 |
| NL2034933B1 NL2034933B1 (en) | 2024-01-12 |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105839536A (en) * | 2016-04-01 | 2016-08-10 | 中铁大桥局集团第五工程有限公司 | Construction method of cable-stayed bridge pylon |
| CN109338869A (en) * | 2018-11-28 | 2019-02-15 | 中国铁建大桥工程局集团有限公司 | Bracket method for synchronously constructing under a kind of Cable stayed Bridge Main Tower |
| CN110042756A (en) * | 2019-04-03 | 2019-07-23 | 中铁大桥局集团有限公司 | Bridge high tower construction method and its construction equipment |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11181725A (en) * | 1997-12-22 | 1999-07-06 | Maeda Corp | Method for constructing horizontal beam of main tower made of concrete |
| CN103437297B (en) * | 2013-09-03 | 2015-06-10 | 中铁大桥局集团有限公司 | Non-bracket closure method for upper cross beam of steel tower and construction system |
| CN106948267B (en) * | 2017-04-13 | 2019-05-14 | 中铁四局集团市政工程有限公司 | A kind of memorial archway bar formula bridge cable tower king-post method for synchronously constructing |
| CN109252444A (en) * | 2018-01-23 | 2019-01-22 | 四川公路桥梁建设集团有限公司 | A kind of lower beam special construction method under the conditions of short lower king-post strut |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105839536A (en) * | 2016-04-01 | 2016-08-10 | 中铁大桥局集团第五工程有限公司 | Construction method of cable-stayed bridge pylon |
| CN109338869A (en) * | 2018-11-28 | 2019-02-15 | 中国铁建大桥工程局集团有限公司 | Bracket method for synchronously constructing under a kind of Cable stayed Bridge Main Tower |
| CN110042756A (en) * | 2019-04-03 | 2019-07-23 | 中铁大桥局集团有限公司 | Bridge high tower construction method and its construction equipment |
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| CN115341472A (en) | 2022-11-15 |
| CN115341472B (en) | 2023-04-07 |
| NL2034933B1 (en) | 2024-01-12 |
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