CN103061243A - Prestressed steel tube concrete combination trussed beam and construction method thereof - Google Patents

Abstract

The invention relates to a prestressed steel pipe concrete composite truss, comprising a steel pipe truss and a concrete deck, the top of the steel pipe truss is connected to the bottom of the concrete bridge deck, and the steel pipe truss is composed of two parallel upper chord steel pipes, a It is composed of a lower string steel pipe and a plurality of steel web bars symmetrically connecting the upper string steel pipe and the lower string steel pipe. The invention also relates to a construction method of the prestressed steel pipe concrete composite truss girder. The present invention can increase the overall rigidity of the steel pipe concrete composite truss beam under the premise of reducing the self-weight of the structure by applying prestress to the steel pipe concrete bottom chord steel pipe, and reduce the deformation of the steel pipe concrete composite truss beam under the structural self weight and vehicle load. To avoid cracking due to excessive deformation of the weld between the steel web and the lower chord steel pipe, the prestressed lower chord steel pipe can make the steel tube concrete composite truss beam applied to a bridge structure with a larger span.

Description

A kind of prestressed steel pipe concrete composite truss beam and its construction method

technical field

The invention relates to a prestressed steel pipe concrete composite truss beam and a construction method thereof, belonging to the technical field of civil engineering.

Background technique

Steel-concrete composite girder bridges ensure the joint stress of the steel girder and the concrete slab through connectors, which can give full play to the advantages of steel and concrete materials, and have developed rapidly in recent years. The steel pipe composite truss formed by the combination of steel pipe truss and concrete slab is a relatively reasonable composite beam bridge structure. In addition, the required structural bending stiffness can be obtained by adjusting the height of the steel pipe truss without increasing the cost. Steel pipe composite trusses have been widely used in bridge types such as continuous girder bridges, continuous rigid frame bridges, cable-stayed bridges and suspension bridges.

The steel pipe composite truss girder has a relatively prominent problem: the node area where the main and branch pipes intersect is its weak link, and the structural bearing capacity is often controlled by local node failure, resulting in the expected overall performance of the steel pipe composite truss girder cannot be fully utilized. For this reason, the local stiffness and strength of the joint area can be improved by filling concrete in the lower chord steel pipe, so as to ensure that the local failure of the joint area does not occur earlier than the overall failure, and thus another composite beam bridge structure - steel pipe concrete composite trusses. However, although CFST composite trusses can further improve the overall stiffness and bearing capacity of the structure, when the span of the trusses is large, the trusses will undergo large deformation under the joint action of the structure's own weight and vehicle loads, which cannot meet the Requirements for normal service limit state.

Contents of the invention

The present invention makes improvements to the above-mentioned defects in the application of the existing concrete-filled steel tube composite truss beams in long-span bridges, that is, the technical problem to be solved by the present invention is to provide a prestressed steel tube concrete composite truss beam with small deformation and its construction method.

In order to solve the above technical problems, the technical solution of the present invention is: a prestressed steel pipe concrete composite truss, comprising a steel pipe truss and a concrete deck, the top of the steel pipe truss is connected to the bottom of the concrete bridge deck, and the steel pipe truss The beam is composed of two parallel upper chord steel pipes, one lower chord steel pipe and a plurality of steel web bars symmetrically connecting the upper chord steel pipe and the lower chord steel pipe. The lower chord steel pipes are filled with concrete, and the lower chord steel pipes are laid with prestressed Stress tendons.

Further, the diameter D of the lower chord steel pipe is 2 to 3 times that of the steel web, the prestressed tendons are stretched by post-tensioning, the central axis of the prestressed tendons is located below the central axis of the lower chord steel pipe and the distance is e, e The value is between D/6~D/3.

Further, the concrete bridge deck covers the upper chord steel pipe, and the upper chord steel pipe is filled with concrete.

Further, the steel web rod is an empty steel pipe or a steel pipe filled with concrete inside.

Further, the top of the steel web is provided with a connecting plate to facilitate its connection with the upper chord steel pipe.

Further, the lower chord steel pipe is replaced by two parallel and interconnected thin steel pipes, and the steel web bar connects the upper chord steel pipe and the thin steel pipe on the same side.

At the same time, the present invention also provides a construction method for prestressed steel pipe concrete composite truss girder, which is carried out according to the following steps: (1) The lower chord steel pipe is manufactured by segmental welding, and the prestressed steel pipe is first placed and fixed in the lower chord steel pipe according to the designed position Then fill the concrete in the lower chord steel pipe. When the concrete strength reaches 75%, stretch the prestressed tendon to apply prestress to the lower chord steel pipe; (2) Adjust the position of the lower chord steel pipe, clean the welding part of the lower chord The rods are welded to the lower chord steel pipes; (3) The upper chord steel pipes are welded to the steel web rods, and the upper chord steel pipes, the steel web rods and the lower chord steel pipes form a steel pipe truss girder as a skeleton; (4) The bridge deck formwork is erected on the top of the steel pipe truss girders The concrete is poured to form the concrete bridge deck.

Further, in step (1), the central axis of the prestressed tendon is located below the central axis of the lower chord steel pipe with an interval of e, where e is between D/6 and D/3, where D is the diameter of the lower chord steel pipe.

Further, in step (2), the diameter D of the lower chord steel pipe is 2 to 3 times that of the steel web, and the steel web is an empty steel pipe, and concrete is filled in the empty steel pipe when the shear force is large.

Further, in step (2), the lower chord steel pipe is replaced by two parallel and interconnected thin steel pipes, and the corresponding steel web bars are welded to the thin steel pipe on the same side as the upper chord steel pipe.

Further, in step (3), when the diameter of the steel web is larger than the diameter of the upper chord steel pipe, the top of the steel web is provided with a connecting plate to facilitate its connection with the upper chord steel pipe.

Further, in step (4), the concrete bridge deck covers the upper chord steel pipe, and the upper chord steel pipe is filled with concrete.

Compared with the prior art, the present invention has the following beneficial effects: by applying prestress to the steel tube concrete bottom chord steel tube, the overall stiffness of the steel tube concrete composite truss beam can be increased under the premise of reducing the structure's own weight, and the steel tube concrete composite truss beam can be reduced. The deformation of the structure under the weight of the vehicle and the load of the vehicle can also avoid cracking due to excessive deformation at the weld between the steel web member and the lower chord steel pipe. After prestressing the lower chord steel pipe, the steel tube concrete composite truss beam can be used in bridge structures with larger spans .

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Description of drawings

Fig. 1 is a cross-sectional view of an embodiment of the present invention in the direction of a bridge.

Fig. 2 is a kind of sectional view at A-A place among Fig. 1.

Fig. 3 is another kind of sectional view of A-A place among Fig. 1.

In the figure: 1-lower chord steel pipe, 2-steel web bar, 3-upper chord steel pipe, 4-prestressed tendon, 5-concrete bridge deck, 6-connecting plate, 7-concrete.

Detailed ways

As shown in Figures 1 to 3, a prestressed steel pipe concrete composite truss includes a steel pipe truss and a concrete deck 5, the top of the steel pipe truss is connected to the bottom of the concrete bridge deck 5, and the steel pipe truss is composed of two It consists of a parallel upper string steel pipe 3, a lower string steel pipe 1 and a plurality of steel web bars 2 symmetrically connecting the upper string steel pipe 3 and the lower string steel pipe 1, the lower string steel pipe 1 is filled with concrete 7, and the lower string steel pipe 1 is laid with Apply prestressed prestressed tendon 4. Among them, it can be seen from the cross-section view of the bridge in Figure 1 that the two steel webs 2 on the same cross-section are symmetrical about the central axis of the lower chord steel pipe 1; The plurality of steel webs 2 are evenly distributed between the upper chord steel pipe 3 and the lower chord steel pipe 1, for example in a W-shape or N-shape, and of course they can also be distributed in other forms.

In this embodiment, the diameter D of the lower chord steel pipe 1 is 2 to 3 times that of the steel web 2, the prestressed tendons 4 are stretched by post-tensioning, and the central axis of the prestressed tendons 4 is located in the lower chord steel pipe 1 Below the axis and the distance is e, and the value of e is between D/6~D/3. The concrete bridge deck 5 covers the upper chord steel pipe 3 as a stressed skeleton, and the upper chord steel pipe 3 is filled with concrete 7 . The steel web bar 2 is a steel pipe, which can be filled with concrete 7 when the shear force is large; it can be an empty steel pipe when the shear force is not large. When the diameter of the steel web 2 is greater than the diameter of the upper chord steel pipe 3, in order to avoid welding difficulties at the joint between the upper chord steel pipe 3 and the steel web 2, the top of the steel web 2 is provided with a connection that facilitates its connection with the upper chord steel pipe 3 board6.

As shown in Figures 1 and 2, a construction method for prestressed steel pipe concrete composite truss girders is carried out according to the following steps: (1) The lower string steel pipe 1 is manufactured by segmental welding, and first placed in the lower string steel pipe 1 according to the designed position and fix the prestressed tendons 4, and then fill the concrete 7 in the lower string steel pipe 1, and when the strength of the concrete 7 reaches 75%, stretch the prestressed tendons 4 to apply prestress to the lower string steel pipe 1, so as to avoid post-tensioning on the steel web 2 Generate the tensile pressure of non-parallel steel pipes and reduce the initial stress of the steel web 2; (2) Adjust the position of the lower string steel pipe 1, clean the welding position of the lower string steel pipe 1, and weld the steel web 2 to the lower string steel pipe 1; (3) Weld the upper chord steel pipe 3 to the steel web 2, and the upper chord steel 3, the steel web 2, and the lower chord steel 1 form a steel pipe truss as a skeleton; (4) Build a bridge deck formwork on the top of the steel pipe truss, and pour concrete 7 to form concrete Bridge deck 5.

In step (1), the central axis of the prestressed tendons 4 is located below the central axis of the lower chord steel pipe 1 and the distance is e, and the value of e is between D/6~D/3, where D is the diameter of the lower chord steel pipe 1; In step (2), the diameter D of the lower chord steel pipe 1 is 2 to 3 times that of the steel web 2, and the steel web 2 is an empty steel pipe, and when the shear force is large, concrete 7 is filled in the empty steel pipe; in the step In (3), when the diameter of the steel web 2 is larger than the diameter of the upper string steel pipe 3, in order to avoid welding difficulties at the connection between the upper string steel pipe 3 and the steel web 2, the top of the steel web 2 is provided with a 3 connected connecting plates 6; in step (4), the concrete bridge deck 5 covers the upper chord steel pipe 3, and the upper chord steel pipe 3 is filled with concrete 7.

In particular, it should be noted that, in actual application, when the bridge deck is wide, multiple prestressed steel pipe concrete composite trusses can be installed. 3 can also be connected into one body or not connected into one body. The lower chord steel pipe 1 can be replaced by two parallel thin steel pipes connected to each other. At this time, the steel web 2 is connected to the upper chord steel pipe 3 and the thin steel pipe on the same side. When welding, the corresponding steel web 2 is welded to the upper chord. On the thin steel pipe of steel pipe 3 same side.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (10)

1. a pre-stressed steel pipe concrete makes up trusses, comprise steel pipe trusses and concrete slab, described steel pipe trusses top is connected with the concrete slab bottom, it is characterized in that: described steel pipe trusses is comprised of the symmetrical steel web member that connects wind up steel pipe and lower edge steel pipe of two parallel steel pipes that wind up, lower edge steel pipe and complex root, be filled with concrete in the described lower edge steel pipe, be equipped with in the described lower edge steel pipe and apply prestressed presstressed reinforcing steel.

2. pre-stressed steel pipe concrete according to claim 1 makes up trusses, it is characterized in that: described lower edge diameter of steel tube D is 2 ~ 3 times of steel web member, described presstressed reinforcing steel adopts post stretching stretch-draw, described presstressed reinforcing steel axis is positioned at below, lower edge steel pipe axis and spacing is e, and the e value is between D/6 ~ D/3.

3. pre-stressed steel pipe concrete according to claim 1 makes up trusses, it is characterized in that: described concrete slab coats the steel pipe that winds up, and is filled with concrete in the described steel pipe that winds up, and described steel web member is that empty steel pipe or inside are filled with concrete steel pipe.

4. according to claim 1 or 3 described pre-stressed steel pipe concretes combination trusses, it is characterized in that: described steel web member top is provided with the junction plate that makes things convenient for it to be connected with the steel pipe that winds up.

5. pre-stressed steel pipe concrete according to claim 1 makes up trusses, it is characterized in that: described lower edge steel pipe is substituted by two parallel and interconnective fine steel tubes, and described steel web member connects wind up steel pipe and the fine steel tube that is positioned at the same side.

6. the job practices of pre-stressed steel pipe concrete combination trusses, it is characterized in that, carry out according to the following steps: (1) adopts segmentation welding production lower edge steel pipe, place in the lower edge steel pipe according to the position that designs first and fixing presstressed reinforcing steel, then fill concrete in the lower edge steel pipe, when concrete strength reached 75%, tensioned prestressing bar was to apply prestressing force to the lower edge steel pipe again; (2) adjust lower edge steel pipe position, cleaning lower edge steel-pipe welding position is welded in the steel web member on the lower edge steel pipe; (3) will wind up steel-pipe welding on the steel web member, wind up steel pipe and steel web member, lower edge steel pipe form the steel pipe trusses as skeleton; (4) set up the bridge deck template at steel pipe trusses top, concreting forms concrete slab.

7. pre-stressed steel pipe concrete according to claim 6 makes up the job practices of trusses, it is characterized in that: in step (1), described presstressed reinforcing steel axis is positioned at below, lower edge steel pipe axis and spacing is e, and the e value is between D/6 ~ D/3, and wherein D is the lower edge diameter of steel tube.

8. according to claim 6 or the job practices of 7 described pre-stressed steel pipe concretes combination trusses, it is characterized in that: in step (2), described lower edge diameter of steel tube D is 2 ~ 3 times of steel web member, and described steel web member is empty steel pipe, when shearing is larger in empty steel pipe fill concrete; In step (4), described concrete slab coats the steel pipe that winds up, and is filled with concrete in the described steel pipe that winds up.

9. pre-stressed steel pipe concrete according to claim 6 makes up the job practices of trusses, it is characterized in that: in step (3), when steel web member caliber when winding up the steel pipe caliber, described steel web member top is provided with the junction plate that makes things convenient for it to be connected with the steel pipe that winds up.

10. pre-stressed steel pipe concrete according to claim 6 makes up the job practices of trusses, it is characterized in that: in step (2), described lower edge steel pipe is substituted by two parallel and interconnective fine steel tubes, and corresponding steel web member is welded on the fine steel tube with the steel pipe homonymy that winds up.

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