CN110258352A - Construction method of steel-concrete composite bridge with two spans - Google Patents

Abstract

The invention discloses the steel reinforced concrete combined bridge construction methods that two bridgings of one kind are done, including step, 1. 2. pre-manufactured steel beam element is constructed bridge pier, Bridge Erector is erected at main bridge first, 3. two cross-locations lift first in place across girder steel, supporting leg edge is set to move along the bridge to the first girder steel bottom plate across pier top position, it is reserved to set up space, then 4. lifting second welds first across girder steel in place, two across girder steel, complete the 5. installation first simultaneously of two system transforms across girder steel " Simply supported non-uniform ", two across prefabricated bridge, and in adjusting 6. the position of supporting leg passes through Bridge Erector and lifts across girder steel hogging moment area concrete at the 7. vertically and horizontally wet joint concrete of two bridge panel of continuous placing and pier top position simultaneously to two, it completes preceding two and 8. repeats the second ~ seven step across construction, complete the construction of integrin bridge.The construction speed of steel reinforced concrete combined bridge can be substantially improved in the present invention, improve the stress of composite structure, be a kind of steel reinforced concrete combined bridge construction method of brand new ideas.

Description

Construction method of steel-concrete composite bridge with two spans

technical field

The invention relates to a construction method of a steel-concrete composite beam, in particular to a construction method of a two-span steel-concrete composite bridge.

Background technique

Steel-concrete composite bridges have many advantages such as light weight, large spanning capacity, and fast construction progress. They have very obvious economic benefits and competitiveness in transportation construction. At present, the country is vigorously promoting the construction of steel-concrete composite beam bridges. Since the construction sequence and construction method will affect the completed state and mechanical characteristics of the steel-concrete composite girder bridge, it is necessary to select an appropriate construction method based on the actual situation.

At present, there are three commonly used construction methods: ① Bracket construction: first erect temporary mounting brackets, then install steel beams on the brackets, and then pour concrete bridge decks. After the concrete reaches the design strength and integrates with the steel beams into a whole, remove the brackets , the load is shared by the steel-concrete composite structure. From the analysis of the utilization rate of materials alone, the advantages of bracket construction are more obvious, but it has higher requirements on the site, especially in the case of crossing deep valleys and bridges with high piers, it is very uneconomical to use bracket construction. ②Pushing construction: set up a steel guide beam in front of the steel girder, erect a temporary pier if necessary, then push the steel girder into place by jacking up, then install the bridge deck on the steel girder, and cast in-situ wet joints. When the main girder is erected by this construction method, the force on the steel girder is relatively unfavorable, and there are positive and negative bending moments. Therefore, it is often necessary to increase the size and cross-section of the steel girder. This construction method is generally only used in special cases. ③Bridge erecting machine construction: The bridge erecting machine is used to hoist and install the steel girders, and then install the bridge deck, and reproduce the wet joints of the poured bridge deck to form a composite structure. With this construction method, the construction speed is relatively fast. The self-weight of the steel girders and bridge decks in the early stage are all borne by the steel girders, and the bridge decks are not stressed. When the bridge erecting machine is hoisting, each span is hoisted and constructed hole by hole, that is, after erecting a steel beam each time, it is necessary to wait for the wet joints of the horizontal bridge deck to be poured before proceeding to the next span. construction, therefore, the construction speed of the wet joint link of the bridge deck directly affects the construction progress of the entire project; and, during the construction process, only one hole of the bridge erecting machine is functioning at a time, resulting in a low utilization rate of the bridge erecting machine Thirdly, in the construction of multi-span continuous beams with equal spans, the side spans of the steel beams are most unfavorable for stress, and it is also necessary to prevent cracking in the negative moment zone of the bridge pier top.

Contents of the invention

The invention provides a construction method for a two-span steel-concrete composite bridge, aiming to solve the problems of low equipment utilization rate, slow construction speed and unfavorable stress on steel girders and side spans existing in the construction of existing bridge erecting machines.

To achieve the above object, the present invention can take the following technical solutions:

The steel-concrete composite bridge construction method that two spans of the present invention is connected, comprises the steps:

The first step is to prefabricate steel girder units according to the bridge design plan, and set temporary hanging pieces on the flanges of steel girders;

In the second step, after the construction of the foundation piles and piers of the bridge is completed, the bridge erecting machine is advanced to the first and second span positions of the main bridge, and the front, middle and rear legs of the bridge erecting machine stand on the pier cover beam respectively. Among them, the middle outriggers are two pairs of telescopic outriggers that slide along the longitudinal direction of the bridge, and the length of the supporting beam of the bridge erecting machine other than the front outriggers is 0.2~0.3 times that of the single-span steel beam;

The third step is to hoist the first-span steel girder into place, then move the middle outrigger along the direction of the bridge to the steel girder floor at the top of the first-span pier, reserve space for erection, and then hoist the second-span steel girder into place ;

The fourth step is to longitudinally weld the steel beams of the first and second spans to complete the system conversion of the two-span steel beams from "simply supported to continuous";

The fifth step is to install the prefabricated bridge decks of the first and second spans at the same time; during this process, the middle outriggers are sequentially raised from the position of the bottom plate of the steel beam on the pier top, and the bridge decks supported on both sides of the pier top are respectively moved along the bridge direction superior;

The sixth step is to connect the buckle at the end of the sling of the bridge erecting machine to the hanging pieces on the steel beams of the first and second spans respectively, and then lift the steel beams of the two spans at the same time, and make the cable force of the slings stretch to the set point. Lock after setting the value, wherein, the cable force value of the sling along the bridge to the two sides of the pier top is greater than the cable force value of the mid-span sling;

The seventh step is to adopt a one-time pouring method to continuously pour the vertical and horizontal wet joint concrete of the first and second span bridge decks, as well as the concrete in the negative moment area at the top of the pier. After the cast-in-place concrete reaches the design strength, the lifting The connection between the cable and the steel beam hanger;

The eighth step is to make the bridge erecting machine move forward, and every time two spans are moved forward, the construction shall be carried out according to the method described in the second to seventh steps until the erection of the integrated bridge is completed.

Compared with the existing construction method, the construction method of the present invention has the following advantages:

1) The present invention changes the original construction method, which uses adjacent two-span steel girders as a unit, continuous hoisting, and one-time pouring of concrete for the wet joints of the two-span bridge deck and the negative moment area of the pier top. The construction speed of the steel girder remains unchanged, but half of the time for waiting for the bridge deck concrete to reach the design strength is saved, which is equivalent to doubling the entire construction speed, which greatly improves the utilization rate of equipment, saves construction costs, and generates direct economic benefits;

2) The present invention pulls back the steel girders of two adjacent spans at the same time through the sling of the bridge erecting machine, which improves the stress on the side span steel girders when installing the prefabricated bridge deck and the wet joint of the cast-in-place bridge deck. For the cable force, the cable force near the top of the pier is greater than the mid-span cable force, and a pre-compression is formed within the range of the pier top after the tension of the sling is released, which improves the cracking problem in the negative moment area of the pier top;

3) In the process of steel girder erection, the present invention adds a lengthening section at the tail of the bridge erecting machine, which improves the hoisting distance of the equipment and meets the needs of continuous erection and pouring of two spans;

4) In the construction process of the present invention, the longitudinal connection of the steel main girder is firstly carried out to complete the system conversion of "simply supported to continuous", and then the bridge deck is installed, that is: erecting the steel main girder→simply supported to continuous→installing the bridge deck ; while the previous construction method is: erect steel main girder → install bridge deck → simply supported and become continuous; using the construction method of the present invention can improve the overall mechanical performance of the steel main girder in the continuous span, for the force of the side span produce improvements.

In summary, the present invention can greatly improve the construction progress of steel-concrete composite bridges, not only can produce direct economic benefits, but also the construction method can improve the stress state of the composite structure, and is a new construction method for steel-concrete composite bridges , has broad application prospects in long-span steel-concrete composite bridges.

Description of drawings

Fig. 1～7 is the construction steps figure of the present invention.

Fig. 8 is a cross-sectional schematic diagram of the steel beam unit used in the construction of the present invention.

Fig. 9 is a schematic structural view of the bridge erecting machine used in the construction of the present invention (the beam transporter is omitted).

Fig. 10 is a schematic cross-sectional view of the bridge erecting machine in Fig. 3 when hoisting the steel girder.

Fig. 11 is a schematic cross-sectional view of the bridge erecting machine in Fig. 5 lifting the lifting point of the steel girder.

Fig. 12 is a schematic diagram of the connection structure between the middle leg and the supporting beam in Fig. 9 .

Detailed ways

The construction method of the two-span steel-concrete composite bridge of the present invention is suitable for the situation that the steel girder unit span is 30-120m. Taking the steel-concrete continuous composite bridge with six spans and one connection as an example below, the construction method of the present invention will be described in more detail.

As shown in Figure 1-7, the present invention mainly comprises the following steps:

In the first step, according to the bridge design scheme, the steel beam unit 1 shown in Fig. 8 is prefabricated. The steel beam unit 1 mainly includes a web 1.1 and a flange 1.2, and a temporary hanging piece 1.3 is welded on the flange 1.2.

In the second step, after the construction of the bridge foundation piles and bridge piers is completed, the bridge erecting machine 2 is put in place.

As shown in Figure 9, the bridge erecting machine 2 includes a supporting beam 2.4 with a front outrigger 2.1, a middle outrigger 2.2, and a rear outrigger 2.3. 0.3 times the length of the steel girder unit 1, it is used to increase the hoisting and transportation distance of the bridge erecting machine 2; in order to solve the problem of the position of the middle outrigger 2.2 when the two-span steel girders are continuously hoisted, the middle outriggers 2.2 are two pairs The telescopic support leg that slides is set, and the longitudinal travel wheel 2.2b driven by motor 2.2a at the top of each middle support leg 2.2 is connected with the slide rail 2.2c that is arranged on the bottom surface of the support beam 2.4, and the middle support leg 2.2 and the support beam A movable latch 2.2d (see Fig. 12 ) for locking the position is arranged between 2.4. When erecting steel girders, the two pairs of center legs 2.2 are all supported on the bottom plate of the steel beams that have been erected on the top of the pier (see Figure 3); on the prefabricated bridge decks on the left and right sides (see Figure 5). The supporting beam 2.4 is equipped with a sliding lifting device 2.5 that can move along the direction of the bridge and across the bridge, which includes a pair of longitudinal guide rails located on the supporting beam 2.4. The longitudinal guide rails are slidably provided with a mobile hoist with an electric rope drawer on the top. Crossbeam, the hoisting hook that is used for hoisting steel beam is installed on the hoisting crossbeam that links to each other with electric rope take-up machine. On the supporting beam 2.4 between the front outrigger 2.1 and the rear outrigger 2.3, multiple groups of winding devices 2.6 arranged at intervals along the length direction of the bridge are installed, and each group of winding devices 2.6 has at least two devices, which are respectively installed on sliding Lifting device 2.5 both sides. Specifically, each winding device 2.6 is connected to the support beam 2.4 through a horizontal pulley with a locking block, and the end of the sling 2.7 of each winding device 2.6 is provided with a suspension buckle 2.8. In order to improve the problem of cracking in the negative moment area of the pier top, according to the position of the hoisting sling device, it is divided into the pier top area and mid-span area, and the cable force value F1 of the pier top hoisting sling device and mid-span The cable force value F2 of the sling device is different. Below the supporting crossbeam 2.4, a beam transport vehicle 2.9 is set.

The bridge erecting machine 2 is in place, even if the bridge erecting machine 2 advances to the first and second spans of the main bridge, so that the front outrigger 2.1, the middle outrigger 2.2, and the rear outrigger 2.3 stand on the corresponding pier cover beam respectively, at this time The extended section a of the support beam 2.4 is located outside the front leg 2.1 (see Figure 1).

The third step is to hoist the steel beam of the first span into place, then move the middle outrigger 2.2 along the direction of the bridge to the steel beam floor at the top of the pier of the first span, reserve space for erection, and then hoist the steel beam of the second span into place .

Specifically, the beam truck 2.9 transports the steel girder of the first span to the bottom of the extended section a of the supporting beam 2.4, uses the hoisting device 2.5 to hoist the front end of the steel beam, and the rear end of the steel beam is still placed on the beam truck 2.9 (see Figure 1). Slowly move forward, and when the rear end of the steel girder reaches the hoisting range of the 2.4 extension section of the supporting beam, lift the rear end of the steel girder (see Figure 2) and hoist the steel beam of the first span into place (see Figure 3); after that, the middle The two pairs of outriggers of outrigger 2.2 are lifted up one by one, move along the bridge direction and support on the steel beam floor of the first span that has been erected (see Figure 3). The cross section of the support is shown in Figure 10, and then follow the above steps to The beam transport vehicle 2.9 and the hoisting device 2.5 cooperate to carry the second-span steel girder and hoist it in place (see Figure 4).

The fourth step is to longitudinally weld the steel beams of the first and second spans to complete the system conversion of the two-span steel beams from "simply supported to continuous";

The fifth step is to install the prefabricated bridge decks 3 of the first and second spans at the same time; during this process, the two pairs of middle outriggers 2.2 are sequentially raised from the position of the bottom plate of the steel beam on the top of the pier, moved along the direction of the bridge and supported on the top of the pier respectively On the deck 3 of the first and second spans on both sides (Fig. 5), the cross-sectional schematic diagram of the support is shown in Fig. 11;

In the sixth step, after connecting the buckle 2.6 at the end of the sling 2.7 of the bridge erecting machine 2 to the hanging piece 1.3 on the first and second span steel beams, pull the first and second span steel girders at the same time, and make the sling 2.7 The cable force is locked after being stretched to the set value, wherein the cable force value F1 of the cable hanging along the bridge to the top of the pier is greater than the cable force value F2 of the mid-span hanging cable (see Figure 5);

The seventh step is to continuously pour the vertical and horizontal wet joint concrete 4 of the first and second span bridge decks. After the cast-in-place concrete reaches the design strength, release the connection between the sling 2.7 and the steel beam hanging piece 1.3 (see Figure 6) ;

The eighth step is to make the bridge erecting machine 2 move forward, and every time two spans are moved forward, the construction is carried out according to the method described in the second to seventh steps until the erection of the integrated bridge is completed (see Figure 7).

The construction method of the steel-concrete composite beam of the present invention is explained in principle below.

In terms of force, the improvement of side span force can be explained by the following calculation. Taking the steel-concrete composite beam with a span of 50m as an example, two lifting points are set in the middle of the span, and the calculation and analysis are carried out according to the single-span construction and two-span continuous construction respectively. The stress conditions at different stages are compared as follows:

Table 1 Comparison of main calculation results (unit: MPa)

From the above calculation and comparison results, it can be seen that the two-span continuous pouring construction method has no obvious impact on the construction stage, but in the completed bridge state, the stress of the steel girder and concrete bridge deck has been greatly improved, reducing The force of the side span is reduced, which is very beneficial to the force of the side span of the bridge with equal span arrangement. In the final state of the bridge, the maximum tensile stress level of the mid-span steel girder is about 45% lower than that of the traditional construction without supports, and the maximum compressive stress of the upper edge concrete is about 43% higher, which is more favorable for the structure.

In terms of construction, using the conventional single-span construction method, it is necessary to pour the concrete bridge deck after the erection of the main girder of the first span is completed, and the average construction progress is about 9 days/hole. The wet joints of two spans were poured at the same time, and the average pouring progress was 6 days/hole, which greatly improved the construction progress and saved construction costs. Now take the steel-concrete composite beam with a hole of 80m as an example to compare the construction progress.

Table 2 Comparison of single hole construction progress

To sum up, the method of the present invention can improve the utilization index of materials, and at the same time, can improve the stress of steel girders and concrete bridge decks, without adding special construction procedures and construction machinery and equipment, and has a series of advantages such as convenient construction.

Claims (1)

1. A steel-concrete composite bridge construction method that two spans are connected, is characterized in that: comprise the steps: The first step is to prefabricate steel girder units according to the bridge design plan, and set temporary hanging pieces on the flanges of steel girders; In the second step, after the construction of the foundation piles and piers of the bridge is completed, the bridge erecting machine is advanced to the first and second span positions of the main bridge, and the front, middle and rear legs of the bridge erecting machine stand on the pier cover beam respectively. Among them, the middle outriggers are two pairs of telescopic outriggers that slide along the longitudinal direction of the bridge, and the length of the supporting beam of the bridge erecting machine other than the front outriggers is 0.2~0.3 times that of the single-span steel beam; The third step is to hoist the first-span steel girder into place, then move the middle outrigger along the direction of the bridge to the steel girder floor at the top of the first-span pier, reserve space for erection, and then hoist the second-span steel girder into place ; The fourth step is to longitudinally weld the steel beams of the first and second spans to complete the system conversion of the two-span steel beams from "simply supported to continuous"; The fifth step is to install the prefabricated bridge decks of the first and second spans at the same time; during this process, the middle outriggers are sequentially raised from the position of the bottom plate of the steel beam on the pier top, and the bridge decks supported on both sides of the pier top are respectively moved along the bridge direction superior; The sixth step is to connect the buckle at the end of the sling of the bridge erecting machine to the hanging pieces on the steel beams of the first and second spans respectively, and then lift the steel beams of the two spans at the same time, and make the cable force of the slings stretch to the set point. Lock after setting the value, wherein, the cable force value of the sling along the bridge to the two sides of the pier top is greater than the cable force value of the mid-span sling; The seventh step is to adopt a one-time pouring method to continuously pour the vertical and horizontal wet joint concrete of the first and second span bridge decks, as well as the concrete in the negative moment area at the top of the pier. After the cast-in-place concrete reaches the design strength, the lifting The connection between the cable and the steel beam hanger; The eighth step is to make the bridge erecting machine move forward, and every time two spans are moved forward, the construction shall be carried out according to the method described in the second to seventh steps until the erection of the integrated bridge is completed.