CN112482248A - Construction method of large-span arch stiffened asymmetric-section continuous beam - Google Patents
Construction method of large-span arch stiffened asymmetric-section continuous beam Download PDFInfo
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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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Abstract
The invention discloses a construction method of a large-span arch stiffened asymmetric-section continuous beam, which comprises the following steps: s1, designing a counterweight balance load by adopting a preset method, and realizing the bending moment balance of the arch stiffening continuous beam; and S2, completing the unbalanced weight construction of the large-span arch stiffening continuous beam by adopting a preset scheme. Has the advantages that: the invention mainly introduces that under the construction conditions of large-span asymmetric section load and mobile protection, one end is prevented from generating larger unbalanced moment through subsection balance weight and mobile load allocation, so that the main beam linearity is prevented from generating larger deviation in the construction process, the full bridge is ensured to be smoothly closed, and the expected main beam bridge forming linearity is achieved; the tensile stress of the section top plate generated by the balance weight can be effectively reduced, so that the generation of cracks is prevented.
Description
Technical Field
The invention relates to the technical field of large-span continuous beams, in particular to a construction method of a large-span arch stiffened asymmetric-section continuous beam.
Background
The current construction method of the continuous beam mainly comprises the following steps: the construction is carried out by a bracket method, a pushing method, a rotating method and a cantilever pouring method. The support method needs to arrange temporary supports below the continuous beam pouring position, and when the pouring beam has a plurality of long sections, the construction method is greatly influenced by geographical environment and has long support construction time; during the construction of a pushing method and a rotating method, the additional load is large when the large-span arch stiffening unbalanced load continuous beam is constructed, the load of the midspan and the side span is unbalanced, the longer the cantilever casting is, the larger the unbalanced load is, the construction linearity is difficult to control, the unbalanced moment at two ends is difficult to balance, and the safety risk is large. The method has great defects in cost, construction period and field construction process, can not meet the field construction requirement, and is difficult to realize low-risk and high-efficiency construction for the large-span unbalanced load continuous beam.
The cantilever construction method is one of the most common construction methods of the continuous beam bridge at present, has great advantages in high altitude, large span, deep valley and special conditions, generally adopts symmetrical pouring of hanging baskets of a pair of cantilevers, but inevitably has the problem of weight symmetry of cantilever pouring beam sections due to the stress requirement of a design structure or the complexity of site construction conditions. And the defects of large material consumption, long construction time, large risk, low efficiency and the like exist in the construction process of the existing large-span arch stiffening unbalanced load continuous beam.
The existing double-line large-span arch stiffening continuous beam is designed to span the high-speed highway by adopting the arch stiffening continuous beam. Because the midspan cantilever hanging basket is constructed above the highway, the construction operation surface needs to be completely covered and protected due to safety consideration; meanwhile, due to the fact that the beam section suspender crossbeam and the box girder inner tooth blocks are not uniformly distributed, load deviation of two ends of a side span and a mid span is large, and unbalanced load of the continuous beam cantilever construction section is generated.
In addition, when the large-span arch stiffening continuous beam bridge is constructed, unbalanced stress on two sides is mainly embodied in two aspects: firstly, due to the structural design; 1) because the continuous beam on two sides of the pier stud and the arch stiffening continuous beam have different design structures, the arch stiffening continuous beam side is provided with a stiffening cross beam and an anchoring block; 2) the top surface of the No. 0 block has small eccentric load on two sides due to the design of arch foot of the arch stiffening continuous beam; and secondly, due to the construction reason, in a plurality of construction processes, the complete symmetry is only an ideal state, and even if the construction blocks poured at the two ends of the main pier are the same, the construction load is unbalanced because one side of a construction site needs to cross the highway and the safety protection shed design needs to be carried out on the hanging basket.
An effective solution to the problems in the related art has not been proposed yet.
Disclosure of Invention
Aiming at the problems in the related art, the invention provides a construction method of a large-span arch stiffened asymmetric-section continuous beam, which aims to overcome the technical problems in the prior related art.
Therefore, the invention adopts the following specific technical scheme:
a construction method for a large-span arch stiffened asymmetric-section continuous beam comprises the following steps:
s1, designing a counterweight balance load by adopting a preset method, and realizing the bending moment balance of the arch stiffening continuous beam;
and S2, completing the unbalanced weight construction of the large-span arch stiffening continuous beam by adopting a preset scheme.
Further, the preset method includes the steps that a pre-pressing block is adopted to pre-press the previous section for balancing weight before pouring, and the balancing weight with the corresponding weight of the previous section is moved to the current section before tensioning after the current section is poured.
Further, the pre-pressing block adopts a standard pre-pressing block, the weight of the pre-pressing block is 3 tons, and the calculation process of the weight of the balancing weight is as follows: and calculating the weight difference of the pouring symmetrical sections by taking each beam section as a unit, taking the middle point of the 0# block as a moment zero point, and calculating a theoretical balance weight by taking the accumulated moment on two sides as zero through the balance weight.
Further, the formula of the bending moment balance of the arch stiffening continuous beam is as follows:
ΣM1+ΣM2+M3+M4＝M5+ΣM6+M7；
wherein, the sigma 1 is the sum of the side span counterweight moments of each segment;
the sigma 2 is a sum of casting moments of each span;
m3 is a hanging basket and construction load moment;
m4 is a hanging basket counterweight moment;
m5 is 0# segment arch stiffening arch springing moment;
sigma 6 casting moment for mid-span segment (including boom beam);
m7 is the hanging basket moment with protective shed.
Further, the construction of the unbalanced weight of the large-span arch stiffening continuous beam by adopting the preset scheme further comprises the following steps:
s21, starting segment construction;
s22, standard segment construction;
s23, constructing a side span closure section;
s24, balancing the middle closure section;
and S25, removing the temporary structure and the counterweight.
Further, the construction of the starting segment further comprises the following steps:
s211, performing temporary buttress, temporary anchoring and scaffold installation and prepressing on the scaffold;
s212, after the pier top permanent support is in place, casting a 0# beam section and an arch stiffening continuous upper arch springing on the support, and stretching and grouting the support with equal strength;
s213, sequentially replacing the hanging baskets and completing construction of the A1 or B1 beam section;
s214, mounting hanging baskets on the No. 0 block and the A1 or B1 beam section, prepressing, and simultaneously taking temporary anchoring measures for the middle pier;
s215, symmetrically pouring A2 or B2 beam sections on the hanging basket in a cantilever manner;
s216, tensioning and anchoring the longitudinal prestressed steel bundles and the vertical and horizontal prestressed tendons of the A1 or B1 beam section;
s217, in the pouring process, the A1 side span beam segment is close to the A2 side span beam segment, and the weights are pressed one by one according to symmetrical balance.
Further, the standard segment construction also comprises the following steps:
s221, after the longitudinal prestress construction of the section is completed, moving the hanging basket to the next section;
s221, symmetrically pouring An or Bn beam section on the hanging basket in a cantilever manner, and tensioning and anchoring longitudinal prestressed steel beams of the An or Bn beam section and vertical and horizontal prestressed tendons of the An-1 or Bn-1 beam section;
s223, eliminating unbalanced weight of each section in a mode of configuring a pre-pressing block on a beam surface of the corresponding beam section on site according to the moment difference of the symmetrical sections;
s224, in the pouring process, corresponding weights are added on the side span An-1 beam section close to the side span An beam section one by one according to symmetrical balance;
and S225, repeating S221, S222, S223 and S224 in sequence until the side span closure segment.
Furthermore, the construction of the side span closure section adopts a spiral steel pipe and profile steel form for supporting, 5 steel pipes with the diameter of 630mm and the wall thickness of 8mm are adopted to form a support, the transverse distance of the steel pipes is 3.1m, double I-shaped steel I56a is placed at the top of each steel pipe to serve as a bearing cross beam, an I25a distribution beam is longitudinally arranged on the bearing cross beam, and a bottom die system is installed on the distribution beam.
Further, the middle closure section counterweight further comprises the following steps:
s241, dismantling a temporary bracket beside the side pier and releasing the temporary locking of the side pier support;
s242, moving the middle hole hanging basket, and pouring B19 beam section concrete;
and S243, carrying out bridge line type joint measurement, and determining elevations and position deviations of two ends of the closure section.
Further, the step of removing the temporary structure and the counterweight further comprises the following steps:
s251, removing the temporary buttress on the middle pier, finishing the system conversion, and removing the hanging basket;
s252, tensioning and anchoring the residual prestressed steel beams of the bottom plate;
s253, symmetrically and simultaneously tensioning the symmetrical span steel bundles, and alternately tensioning the side span steel bundles and the main span steel bundles;
s254, tensioning the top plate steel bundle;
s255, removing the symmetrical weight of the hoisting point beam.
The invention has the beneficial effects that:
the invention mainly introduces that under the construction conditions of large-span asymmetric section load and mobile protection, one end is prevented from generating larger unbalanced moment through subsection balance weight and mobile load allocation, so that the main beam linearity is prevented from generating larger deviation in the construction process, the full bridge is ensured to be smoothly closed, and the expected main beam bridge forming linearity is achieved; the tensile stress of the section top plate generated by the balance weight can be effectively reduced, so that the generation of cracks is prevented.
The invention adopts a construction method of 'symmetrical pouring and segmental loading' for pouring the unbalanced load continuous beam by cantilever of a large-span arch stiffened asymmetric cross-section continuous beam, and solves the problem that the unbalanced load construction method is generated due to design or construction reasons of the arch stiffened continuous beam, the method needs to consider the unbalanced load of an arch springing of top face arch stiffening when the 0# block is poured during the construction of the 0# block and the 1# block, a temporary support and a temporary anchoring system are arranged for balancing, cantilever hanging baskets are installed by using the 0# and the 1# top face beam faces after the pouring is finished, and the unbalanced moment of each segment is counteracted in a mode of arranging a pre-pressing block on the corresponding beam segment beam face during the segmental cantilever construction through moment balance calculation. Counterweight loading is mainly divided into two categories: the first is an additional balance weight which is used for offsetting unbalanced load generated by the displacement of the cantilever hanging basket during the construction of the closure section; two are balance weight, and the design of jib crossbeam has been encircleed jib department because of encircleing stiffening one side structure and putting more energy into, lead to the cross-section difference of strideing in the limit, need adopt counter weight to make the limit stride reach moment balance, and balance weight does not unload when closing a dragon section concreting, treats that the concrete strength reaches 100%, unloads after the prestressing force stretch-draw is whole to be accomplished. By the method, the main beam can be prevented from being linearly deviated greatly in the construction process, construction monitoring and counterweight adding are mainly performed in the construction process, the structure is ensured to be in a balanced state, and the instability phenomenon is avoided.
In addition, the invention also has the following advantages: the construction of the cantilever method generally adopts symmetrical pouring of a pair of hanging baskets of the cantilever, and has great advantages on some special terrains and special conditions; the height difference of two sides of the closure section can be accurately adjusted by adjusting the balancing weight, namely, the adjustment precision is high, the operation is easy, and the construction precision can be improved; the stress of the top plate of the section of the continuous beam is gradually increased along with the increase of the counterweight; compared with a centralized counterweight, the segmental counterweight can effectively reduce the tensile stress of the top plate of the section and prevent the generation of cracks; the problem that a large unbalanced bending moment is generated at one end during continuous asymmetric construction is solved through the segmental balance weight, large deviation of the main beam linearity in the construction process is prevented, smooth closure of a full bridge is guaranteed, and the expected main beam bridge forming linearity is achieved; the construction process solves the problems of low energy consumption, high precision, rapidness and low risk of the cast-in-place construction of the large-span unbalanced continuous beam bridge.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a flow chart of a method for constructing a large-span arch stiffened asymmetric-section continuous beam according to an embodiment of the present invention;
FIG. 2 is a diagram of a configuration of a pre-compaction block in a construction method for a large-span arch stiffened asymmetric-section continuous beam according to an embodiment of the present invention;
FIG. 3 is one of arrangement diagrams of No. 0 blocks of supports in a construction method of a large-span arch stiffened asymmetric-section continuous beam according to an embodiment of the present invention;
FIG. 4 is a second layout diagram of a No. 0 block support in a construction method of a large-span arch stiffened asymmetric-section continuous beam according to an embodiment of the present invention;
FIG. 5 is a construction drawing of a standard section in a construction method of a large-span arch stiffened asymmetric-section continuous beam according to an embodiment of the present invention;
FIG. 6 is one of schematic diagrams of an edge-span cast-in-place section in a construction method of a large-span arch stiffened asymmetric-section continuous beam according to an embodiment of the invention;
FIG. 7 is a second schematic view of an edge-span cast-in-place section in a construction method of a large-span arch stiffened asymmetric-section continuous beam according to an embodiment of the invention;
FIG. 8 is a schematic view of an edge-span closure in a construction method of a large-span arch stiffened asymmetric-section continuous beam according to an embodiment of the present invention;
FIG. 9 is a schematic view of a balance weight in a method for constructing a large-span arch stiffened asymmetric-section continuous beam according to an embodiment of the present invention;
FIG. 10 is a second schematic view of the balance weight in the construction method of the large-span arch stiffened asymmetric-section continuous beam according to the embodiment of the present invention;
FIG. 11 is a schematic mid-span cradle closure in a method of constructing a large-span arch stiffened asymmetric-section continuous beam according to an embodiment of the present invention;
fig. 12 is a schematic mid-span weight in a construction method of a large-span arch stiffened asymmetric-section continuous beam according to an embodiment of the present invention.
Detailed Description
For further explanation of the various embodiments, the drawings which form a part of the disclosure and which are incorporated in and constitute a part of this specification, illustrate embodiments and, together with the description, serve to explain the principles of operation of the embodiments, and to enable others of ordinary skill in the art to understand the various embodiments and advantages of the invention, and, by reference to these figures, reference is made to the accompanying drawings, which are not to scale and wherein like reference numerals generally refer to like elements.
According to the embodiment of the invention, a construction method for stiffening the asymmetrical-section continuous beam by the large-span arch is provided.
The invention will be further explained with reference to the accompanying drawings and specific embodiments, and as shown in fig. 1, a construction method of a large-span arch stiffened asymmetric-section continuous beam according to an embodiment of the invention includes the following steps:
s1, designing a counterweight balance load by adopting a preset method, and realizing the bending moment balance of the arch stiffening continuous beam;
the method is very critical to control of generation of unbalanced moment in symmetrical pouring construction of the continuous beam cantilever, and how to effectively control the unbalance of the cantilever beam pouring moment in actual construction is a construction key point of cantilever construction. The mode that corresponds synchronous construction of span in the festival section during general accessible adjustment string basket bottom counter weight and construction reaches balancedly, nevertheless encircles the continuous asymmetric section of putting more energy into to the large-span and hardly realizes, and the control degree of difficulty also increases along with the increase of cantilever construction festival section length, and along with the increase of festival section length, the sensitivity of unbalanced bending moment and unbalance loading weight also increases simultaneously. Therefore, when each symmetrical section is constructed and the basket is moved to the lower section, the moment balance of the side span and the mid span is always kept. Therefore, the invention adopts a preset method, so that the balanced construction of two ends can be realized when each symmetrical beam section is constructed.
And S2, completing the unbalanced weight construction of the large-span arch stiffening continuous beam by adopting a preset scheme.
In one embodiment, as shown in fig. 1, the presetting method is to perform pre-pressing counterweight on the previous segment before casting by using a pre-pressing block, and move a counterweight block with a corresponding weight of the previous segment to the current segment before tensioning after the current segment is cast.
In one embodiment, the pre-pressing block is a standard pre-pressing block and weighs 3 tons, and the weight of the balancing weight is calculated by the following steps: and calculating the weight difference of the pouring symmetrical sections by taking each beam section as a unit, taking the middle point of the 0# block as a moment zero point, and calculating a theoretical balance weight by taking the accumulated moment on two sides as zero through the balance weight.
In one embodiment, the formula for balancing the bending moment of the arch stiffened continuous beam is as follows:
ΣM1+ΣM2+M3+M4＝M5+ΣM6+M7；
wherein, the sigma 1 is the sum of the side span counterweight moments of each segment;
the sigma 2 is a sum of casting moments of each span;
m3 is a hanging basket and construction load moment;
m4 is a hanging basket counterweight moment;
m5 is 0# segment arch stiffening arch springing moment;
sigma 6 is the mid-span segment casting moment;
m7 is the hanging basket moment with protective shed.
In one embodiment, the implementation of the unbalanced weight construction of the large-span arch stiffening continuous beam by using the preset scheme further includes the following steps:
s21, starting segment construction;
s22, standard segment construction;
s23, constructing a side span closure section;
s24, balancing the middle closure section;
and S25, removing the temporary structure and the counterweight.
In one embodiment, as shown in fig. 3-4, the construction of the launch segment further comprises the steps of:
s211, performing temporary buttress, temporary anchoring and scaffold installation and prepressing on the scaffold;
s212, after the pier top permanent support is in place, casting a 0# beam section and an arch stiffening continuous upper arch springing on the support, and stretching and grouting the support with equal strength;
s213, sequentially replacing the hanging baskets and completing construction of the A1 or B1 beam section;
s214, mounting hanging baskets on the No. 0 block and the A1 or B1 beam section, prepressing, and simultaneously taking temporary anchoring measures for the middle pier;
s215, symmetrically pouring A2 or B2 beam sections on the hanging basket in a cantilever manner;
s216, tensioning and anchoring the longitudinal prestressed steel bundles and the vertical and horizontal prestressed tendons of the A1 or B1 beam section;
s217, in the pouring process, the A1 side span beam segment is close to the A2 side span beam segment, and the weights are pressed one by one according to symmetrical balance.
The support for the 0# block and the 1# block is composed of an upper longitudinal beam, a cross beam and an upright column, wherein the upright column of the support for the 0# block is also used as a temporary buttress, and during construction, three-spliced I56a steel is placed at the top end of each row of temporary buttress along the bridge direction for 2m downwards to form a support system as a bracket. When the No. 0 beam section is poured, the formal support and the temporary buttress are in place firstly, and the movable support is locked.
In one embodiment, as shown in fig. 5, the standard segment construction further comprises the steps of:
s221, after the longitudinal prestress construction of the section is completed, moving the hanging basket to the next section;
s221, symmetrically pouring An or Bn beam section on the hanging basket in a cantilever manner, and tensioning and anchoring longitudinal prestressed steel beams of the An or Bn beam section and vertical and horizontal prestressed tendons of the An-1 or Bn-1 beam section;
s223, eliminating unbalanced weight of each section in a mode of configuring a pre-pressing block on a beam surface of the corresponding beam section on site according to the moment difference of the symmetrical sections;
s224, in the pouring process, corresponding weights are added on the side span An-1 beam section close to the side span An beam section one by one according to symmetrical balance;
and S225, repeating S221, S222, S223 and S224 in sequence until the side span closure segment.
During the installation of the steel bar, a prepressing block of 1/2 weight is configured on the previous segment. In the concrete pouring process, the weight of the prepressing blocks is added in the configuration table of the gravity center position of the previous section one by one, and the counterweight blocks with the corresponding weight of the previous section are moved to the current section before tensioning after the current section is poured. The pre-pressing block should be placed at the center of the segment as much as possible, and symmetry is guaranteed, so that unbalance loading is avoided.
In one embodiment, as shown in fig. 6-10, the construction of the side span closure section is supported by adopting a spiral steel pipe + profile steel form, a support is formed by adopting 5 steel pipes with the diameter of 630mm and the wall thickness of 8mm, the transverse distance between the steel pipes is 3.1m, double-spliced I56a I-shaped steel is placed at the top of each steel pipe to serve as a bearing cross beam, an I25a distribution beam is longitudinally arranged on the bearing cross beam, and a bottom die system is installed on the distribution beam.
The side span closure counterweight loading is mainly divided into two types, wherein one type is an additional counterweight and the other type is a balance counterweight. And standard pre-pressing blocks are adopted for counterweight loading. The side span additional balance weight is unloaded according to the pouring volume in the concrete pouring process, the balance weight is not unloaded when the side span closure section concrete is poured, and the unloading is carried out after the prestress tension is started when the concrete strength reaches 100%.
During the period of counterweight and unloading, the closing section should keep two ends symmetrically, namely, a section on the mid-span closing section is simultaneously loaded with the balance counterweight. Unloading the balance weight on the side of the side span in the concrete pouring process synchronously:
(1) if the range is within the allowed range (+ -2 cm), no additional weight loading is carried out;
(2) if the height difference exceeds the allowable range and the beam bottom at the end of the previous section is higher than the theoretical value, additional balance weight is applied to the previous section, and the specific quantity is determined according to the actual height difference and the simulation calculation of the monitoring unit;
(3) if the height difference exceeds the allowable range and the beam bottom at the end part of the previous section is lower than the theoretical value, the previous section is realized by reducing the balance weight, and the side span closure section balance weight adopts a form of early loading to counteract the beam body deformation caused by load increase during concrete pouring of the closure section. The method is characterized in that a pre-pressing block equivalent to the weight of 1/2 concrete of the side span closure section is respectively configured on a section of beam surface on the side span closure section and the side span closure section before the side span closure steel bar construction, the balance weight is unloaded in the concrete pouring process, the unloading speed is basically synchronous with the pouring speed, only the balance weight on the side span is unloaded during the side span closure, and the balance weight on the side span is reserved.
In one embodiment, as shown in fig. 11-12, the mid-closure-section counterweight further comprises the steps of:
s241, dismantling a temporary bracket beside the side pier and releasing the temporary locking of the side pier support;
s242, moving the middle hole hanging basket, and pouring B19 beam section concrete;
wherein, the big mileage side is hung the basket and is retreated a lesson section from the end, hangs the basket and wholly reduces 0.8 meters before retreating, guarantees simultaneously end basket and outer sliding beam level, guarantees that the basket of hanging retreats smoothly. The small mileage side hanging basket front moving rice closing section is characterized in that a bottom die system is anchored by using 32mm finish rolling deformed steel bars and reserved holes of bottom plates of adjacent sections on two sides, and a side die is anchored by using 32mm finish rolling deformed steel bars and reserved holes of top plates of adjacent sections on two sides.
And S243, carrying out bridge line type joint measurement, and determining elevations and position deviations of two ends of the closure section.
The mid-span closure counterweight loading is mainly divided into two types, wherein one type is an additional counterweight, and the other type is a balance counterweight. The balance weight has already been finished in mid-span project festival section loading when the side span closure construction, need move the balancing weight to the adjacent festival section of closure section and increase and decrease the balancing weight according to measured data. The additional balance weight is determined according to the height difference of the mid-span beam bottom of the adjacent sections of the closure section after the side span prestress tensioning, the elevations of the beam ends on two sides are measured before the mid-span closure, data are fed back to a monitoring unit, and the monitoring unit provides additional configuration values of the two corresponding ends. When the height difference of the two ends is less than 2cm, the two ends can be directly closed without adopting an additional counterweight. The main factors causing the height difference of the two ends of the closure section to exceed the limit are as follows: construction deviation of adjacent sections of the closure section, and height difference change caused by forward movement and backward movement of hanging baskets on two sides.
The additional balance weight is unloaded in the concrete pouring process, and the unloading speed is basically synchronous with the pouring speed.
In one embodiment, said removing the temporary structure and the counterweight further comprises the steps of:
s251, removing the temporary buttress on the middle pier, finishing the system conversion, and removing the hanging basket;
s252, tensioning and anchoring the residual prestressed steel beams of the bottom plate;
s253, symmetrically and simultaneously tensioning the symmetrical span steel bundles, and alternately tensioning the side span steel bundles and the main span steel bundles;
s254, tensioning the top plate steel bundle;
s255, removing the symmetrical weight of the hoisting point beam.
In summary, with the aid of the technical scheme, the invention mainly introduces the technical scheme that under the conditions of large-span asymmetric cross-section load and mobile protection construction, a large unbalanced moment is prevented from being generated at one end by segmental balance weight and mobile load distribution, so that large deviation of the main beam linearity in the construction process is prevented, smooth closure of a full bridge is ensured, and the expected main beam bridge forming linearity is achieved; the tensile stress of the section top plate generated by the balance weight can be effectively reduced, so that the generation of cracks is prevented. The invention adopts a construction method of 'symmetrical pouring and segmental loading' for pouring the unbalanced load continuous beam by cantilever of a large-span arch stiffened asymmetric cross-section continuous beam, and solves the problem that the unbalanced load construction method is generated due to design or construction reasons of the arch stiffened continuous beam, the method needs to consider the unbalanced load of an arch springing of top face arch stiffening when the 0# block is poured during the construction of the 0# block and the 1# block, a temporary support and a temporary anchoring system are arranged for balancing, cantilever hanging baskets are installed by using the 0# and the 1# top face beam faces after the pouring is finished, and the unbalanced moment of each segment is counteracted in a mode of arranging a pre-pressing block on the corresponding beam segment beam face during the segmental cantilever construction through moment balance calculation. Counterweight loading is mainly divided into two categories: the first is an additional balance weight which is used for offsetting unbalanced load generated by the displacement of the cantilever hanging basket during the construction of the closure section; two are balance weight, and the design of jib crossbeam has been encircleed jib department because of encircleing stiffening one side structure and putting more energy into, lead to the cross-section difference of strideing in the limit, need adopt counter weight to make the limit stride reach moment balance, and balance weight does not unload when closing a dragon section concreting, treats that the concrete strength reaches 100%, unloads after the prestressing force stretch-draw is whole to be accomplished. By the method, the main beam can be prevented from being linearly deviated greatly in the construction process, construction monitoring and counterweight adding are mainly performed in the construction process, the structure is ensured to be in a balanced state, and the instability phenomenon is avoided.
In addition, the invention also has the following advantages: the construction of the cantilever method generally adopts symmetrical pouring of a pair of hanging baskets of the cantilever, and has great advantages on some special terrains and special conditions; the height difference of two sides of the closure section can be accurately adjusted by adjusting the balancing weight, namely, the adjustment precision is high, the operation is easy, and the construction precision can be improved; the stress of the top plate of the section of the continuous beam is gradually increased along with the increase of the counter weight; compared with a centralized counterweight, the segmental counterweight can effectively reduce the tensile stress of the top plate of the section and prevent the generation of cracks; the problem that a large unbalanced bending moment is generated at one end during continuous asymmetric construction is solved through the segmental balance weight, large deviation of the main beam linearity in the construction process is prevented, smooth closure of a full bridge is guaranteed, and the expected main beam bridge forming linearity is achieved; the construction process solves the problems of low energy consumption, high precision, rapidness and low risk of the cast-in-place construction of the large-span unbalanced continuous beam bridge.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. A construction method for a large-span arch stiffened asymmetric-section continuous beam is characterized by comprising the following steps:
s1, designing a counterweight balance load by adopting a preset method, and realizing the bending moment balance of the arch stiffening continuous beam;
and S2, completing the unbalanced weight construction of the large-span arch stiffening continuous beam by adopting a preset scheme.
2. The construction method of a large-span arch stiffened asymmetric cross-section continuous beam according to claim 1, wherein the presetting method is to adopt a pre-pressing block to pre-press and balance the previous section before casting, and move a balance weight block with corresponding weight of the previous section to the current section before tensioning after the current section is cast.
3. The construction method of a large-span arch stiffened asymmetric cross-section continuous beam as claimed in claim 2, wherein said pre-pressing block is a standard pre-pressing block and has a weight of 3 tons, and the calculation process of the weight of said counter weight block is: and calculating the weight difference of the pouring symmetrical sections by taking each beam section as a unit, taking the middle point of the 0# block as a moment zero point, and calculating a theoretical balance weight by taking the accumulated moment on two sides as zero through the balance weight.
4. The construction method of a large-span arch stiffened asymmetric cross-section continuous beam according to claim 3, wherein the formula of the bending moment balance of the arch stiffened continuous beam is as follows:
ΣM1+ΣM2+M3+M4＝M5+ΣM6+M7；
wherein, the sigma 1 is the sum of the side span counterweight moments of each segment;
the sigma 2 is a sum of casting moments of each span;
m3 is a hanging basket and construction load moment;
m4 is a hanging basket counterweight moment;
m5 is 0# segment arch stiffening arch springing moment;
sigma 6 is the mid-span segment casting moment;
m7 is the hanging basket moment with protective shed.
5. The construction method of a large-span arch stiffened asymmetric cross-section continuous beam as claimed in claim 1, wherein said performing the unbalanced weight construction of the large-span arch stiffened continuous beam by using the preset scheme further comprises the steps of:
s21, starting segment construction;
s22, standard segment construction;
s23, constructing a side span closure section;
s24, balancing the middle closure section;
and S25, removing the temporary structure and the counterweight.
6. The construction method of a large-span arch stiffened asymmetric cross-section continuous beam according to claim 5, wherein said construction of a startup section further comprises the steps of:
s211, performing temporary buttress, temporary anchoring and scaffold installation and prepressing on the scaffold;
s212, after the pier top permanent support is in place, casting a 0# beam section and an arch stiffening continuous upper arch springing on the support, and stretching and grouting the support with equal strength;
s213, sequentially replacing the hanging baskets and completing construction of the A1 or B1 beam section;
s214, mounting hanging baskets on the No. 0 block and the A1 or B1 beam section, prepressing, and simultaneously taking temporary anchoring measures for the middle pier;
s215, symmetrically pouring A2 or B2 beam sections on the hanging basket in a cantilever manner;
s216, tensioning and anchoring the longitudinal prestressed steel bundles and the vertical and horizontal prestressed tendons of the A1 or B1 beam section;
s217, in the pouring process, the A1 side span beam segment is close to the A2 side span beam segment, and the weights are pressed one by one according to symmetrical balance.
7. The construction method of a large-span arch stiffened asymmetric cross-section continuous beam according to claim 5, wherein said standard section construction further comprises the steps of:
s221, after the longitudinal prestress construction of the section is completed, moving the hanging basket to the next section;
s221, symmetrically pouring An or Bn beam section on the hanging basket in a cantilever manner, and tensioning and anchoring longitudinal prestressed steel beams of the An or Bn beam section and vertical and horizontal prestressed tendons of the An-1 or Bn-1 beam section;
s223, eliminating unbalanced weight of each section in a mode of configuring a pre-pressing block on a beam surface of the corresponding beam section on site according to the moment difference of the symmetrical sections;
s224, in the pouring process, corresponding weights are added on the side span An-1 beam section close to the side span An beam section one by one according to symmetrical balance;
and S225, repeating S221, S222, S223 and S224 in sequence until the side span closure segment.
8. The construction method of the large-span arch stiffening asymmetric cross-section continuous beam according to claim 5, characterized in that the construction of the side-span closure section is supported by adopting a spiral steel pipe and profile steel form, 5 steel pipes with the diameter of 630mm and the wall thickness of 8mm form a support, the transverse distance of the steel pipes is 3.1m, double I56a I-shaped steel is placed at the top of the steel pipes to serve as a bearing cross beam, an I25a distribution beam is longitudinally arranged on the bearing cross beam, and a bottom die system is installed on the distribution beam.
9. The construction method of a large-span arch stiffened asymmetric cross-section continuous beam according to claim 5, wherein said middle closure section counterweight further comprises the steps of:
s241, dismantling a temporary bracket beside the side pier and releasing the temporary locking of the side pier support;
s242, moving the middle hole hanging basket, and pouring B19 beam section concrete;
and S243, carrying out bridge line type joint measurement, and determining elevations and position deviations of two ends of the closure section.
10. The construction method of a large-span arch stiffened asymmetric cross-section continuous beam according to claim 5, wherein said dismantling of temporary structures and counterweights further comprises the steps of:
s251, removing the temporary buttress on the middle pier, finishing the system conversion, and removing the hanging basket;
s252, tensioning and anchoring the residual prestressed steel beams of the bottom plate;
s253, symmetrically and simultaneously tensioning the symmetrical span steel bundles, and alternately tensioning the side span steel bundles and the main span steel bundles;
s254, tensioning the top plate steel bundle;
s255, removing the symmetrical weight of the hoisting point beam.
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| CN202011417358.6A CN112482248A (en) | 2020-12-04 | 2020-12-04 | Construction method of large-span arch stiffened asymmetric-section continuous beam |
| PCT/CN2021/076553 WO2022116394A1 (en) | 2020-12-04 | 2021-02-10 | Construction method for continuous beam having asymmetrical cross section stiffened by large-span arch |
| JP2021019582A JP2022089733A (en) | 2020-12-04 | 2021-02-10 | Large span arch stiffening asymmetric section continuous beam construction method |
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| CN202011417358.6A CN112482248A (en) | 2020-12-04 | 2020-12-04 | Construction method of large-span arch stiffened asymmetric-section continuous beam |
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| WO2022116394A1 (en) | 2022-06-09 |
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