CN105803917A - Method for preventing lateral bending deformation of edge beam of T-shaped beam bridge through external prestressing - Google Patents

Abstract

The invention discloses a method for preventing lateral bending deformation of an edge beam of a T-shaped beam bridge. The method includes the steps that external prestressing reinforcing steel bars are installed on the external cantilever side of the prefabricated edge beam through a support, then edge-beam prestressing reinforcing steel bars are tensioned one by one; in the tensioning process, the edge beam is bent and deformed towards the external cantilever side, and when the strain value epsilon at the maximum cantilever position of an external cantilever is a strain tolerance value [epsilon], tensioning is paused; then the external prestressing reinforcing steel bars are tensioned, and the value of lateral bending deformation of the midspan of the edge beam is returned to zero through the lateral bending moment generated through the external prestressing reinforcing steel bars; the process is repeated till the edge-beam lateral bending deformation generated by tensioning the last edge-beam prestressing reinforcing steel bar is eliminated. According to the method, the lateral bending moment generated when the mass center is deviated from the center line of a web of the edge beam when the edge-beam prestressing reinforcing steel bars are tensioned is balanced through external prestressing, and lateral bending deformation can be effectively prevented during construction of the edge beam.

Description

External prestressing is utilized to prevent the method that tee girder bridge side bar lateral thrust deforms

Technical field

The present invention relates to highway bridge, particularly a kind of utilize external prestressing to prevent the method that tee girder bridge side bar lateral thrust deforms.

Background technology

Tee girder bridge is a kind of common highway bridge, tee girder bridge is in building course, its side bar is big because of slenderness ratio, lateral bending rigidity is little, and the outside cantilever lateral deviation of side bar barycenter is from side bar web centrage (see Fig. 1), causing in construction after the stretch-draw of side bar deformed bar, side bar is susceptible to the deformation of outside cantilever lateral bend.Particularly in side bar age less time prestressed reinforcement of tensioning bigger than age time prestressed reinforcement of tensioning lateral thrust deformation extent many greatly.It is long to deposit the beam time, and the lateral thrust deformation extent of side bar can be gradually increased with the prolongation depositing the beam time.

The side bar of tee girder bridge occurs lateral thrust to deform in construction, side bar can be made to produce crack, have a strong impact on the construction quality of side bar and the durability of side bar.

At present, it is prevented that tee girder bridge side bar produces the method for lateral thrust deformation and specifically includes that

1, when the side bar of prefabricated tee girder bridge, increase lateral support, reduce the slenderness ratio of tee girder bridge side bar；

2, strictly side bar deformed bar cable tensios control, prematurely prestressed reinforcement of tensioning are carried out by designing requirement；

3, after completing deformed bar stretch-draw, prefabricated side bar in factory the resting period less than 60 days, and erection after should connect the diaphragm plate between each side bar as early as possible, to increase its lateral confinement, it is prevented that its lateral thrust deformation continue development.

Above method is not because all considering side bar barycenter deviation this leading factor causing side bar lateral thrust to deform of side bar web centrage, therefore it has certain limitation, and the lateral thrust alleviating side bar is deformed and can only be played a role；And method 1 can only solve the lateral thrust deformation of demoulding front side beam temporarily, after form removal, side bar still can produce lateral thrust deformation；Method 2 can extend construction period.

Summary of the invention

For the above-mentioned technical problem that prior art exists, it is an object of the invention to provide and a kind of simply, effectively utilize external prestressing to prevent the method that tee girder bridge side bar lateral thrust deforms.

For achieving the above object, provided by the invention utilize external prestressing to prevent the method that tee girder bridge side bar lateral thrust deforms, comprise the steps:

Step 1, fixing body External prestressed reinforcing bar

Limit support is fixedly mounted respectively at the both ends, web side of the outer cantilever side of side bar, fixed installation intermediate support in the middle of the support of both sides, the transverse height of intermediate support is more than the transverse height of limit support, it is respectively mounted steering gear (steel pipe of a kind of bending) on the top of limit support and intermediate support, and makes the steering gear of limit support and the steering gear of intermediate support with side bar barycenter in the same plane vertical with the web side of side bar；Its two ends are temporarily fixed on the support of limit by external prestressing reinforcing bar after the steering gear of intermediate support and limit support；

Step 2, stretch-draw side bar deformed bar and external prestressing reinforcing bar

First in side bar span centre, amesdial is installed at correspondence side bar barycenter place, cantilever side, is used for recording the lateral thrust deformation values of side bar span centre in stretch-draw side bar deformed bar process；Paste foil gauge at the outer cantilever maximum cantilever place of side bar span centre, be used for monitoring the strain value ε at the outer cantilever maximum cantilever place of side bar span centre in stretch-draw side bar deformed bar process；

Then with the stretching force of setting by root stretch-draw side bar deformed bar, in stretching process, the outside cantilever lateral bend deformation of side bar, (piece deformed bar of a stretch-draw now it is likely to when the strain value ε that foil gauge monitors the outer cantilever maximum cantilever place of side bar span centre reaches strain feasible value [ε], it is likely to more than one deformed bar of stretch-draw), suspend stretch-draw side bar deformed bar, with the lateral thrust deformation values Δ of amesdial record now side bar span centre；Then stretch-draw external prestressing reinforcing bar, utilizes the lateral bending square that external prestressing reinforcing bar produces to make the lateral thrust deformation values Δ of side bar span centre make zero, and keeps external prestressing reinforced bar stretching power constant after Δ zero；Then next root side bar deformed bar of stretch-draw is continued (if the stretching force of previous side bar deformed bar of stretch-draw is not up to design stretching force by above same procedure, now it is continued stretch-draw, make stretching force reach next root side bar deformed bar of stretch-draw again after design stretching force)；So repeatedly, after last root side bar deformed bar stretch-draw till the lateral thrust deformation values of span centre makes zero；Then external prestressing reinforcing bar is temporarily anchored on the support of limit；

Described strain feasible value [ε] is tried to achieve by following formula:

$\[\mathrm{\ϵ}\]=\frac{f_{tk}}{E_c}$

In formula

E_c: side bar is adopted concrete elastic modelling quantity (MPa)；

f_tk: the standard value (MPa) of the adopted concrete tensile strength of side bar, " highway reinforced concrete and prestressed concrete bridge contain design specification " (JTGD62) inquiry can be passed through and obtain；

By side bar hoisted in position after step 3, side bar deformed bar stretch-draw；Then the transverse splicing of side bar is completed routinely；Finally external prestressing reinforcing bar, intermediate support are removed together with the support of limit, complete the constructing operation that tee girder bridge side bar prevents lateral thrust from deforming.

Compared with the existing method preventing tee girder bridge side bar from producing lateral thrust deformation, the invention has the beneficial effects as follows:

(1) by external prestressing reinforcing bar can active balance stretch-draw side bar deformed bar time because of side bar barycenter deviate side bar web centrage produce lateral moment of flexure, thus playing the effect effectively preventing side bar lateral thrust from deforming.

(2) according to strain feasible value [ε] the stretch-draw side bar deformed bar at the outer cantilever maximum cantilever place of the side bar calculated, it can be ensured that in stretching process, side bar occurs without crack.

(3) the method construction is simple, short construction period.

(4) used by, external prestressing reinforcing bar, intermediate support, limit support can have enough to meet the need use, save Master Cost.

Accompanying drawing explanation

Fig. 1 is the side view of side bar；

Fig. 2 is the front view of the outer cantilever side of side bar of fixing body External prestressed reinforcing bar；

Fig. 3 is C-C sectional drawing in Fig. 2；

Fig. 4 is A-A sectional drawing in Fig. 2；

Fig. 5 is B-B sectional drawing in Fig. 2.

In figure: 1 side bar, the outer cantilever of 1a, cantilever in 1b, 1c web, 2 side bar barycenter, 3 side bar web centrages, 4 foil gauges, 5 external prestressing reinforcing bars, 6 intermediate supports, 7 limit supports, 8 steering gears, 9 amesdials, 10 steel plates.

Detailed description of the invention

Below in conjunction with drawings and Examples, the present invention will be further described.

The present embodiment prevents side bar generation lateral thrust deformation in certain freely-supported tee girder bridge construction process for adopting the inventive method.

In conjunction with Fig. 1 to Fig. 5, this freely-supported tee girder spanning footpath is 47m, and side bar 1 adopts C50 concreting, the concrete elastic modulus E of C50_c=3.45 × 10⁴MPa, looks into " highway reinforced concrete and prestressed concrete bridge contain design specification " (JTGD62-2004) and can obtain the standard value f of concrete tensile strength_tk=2.65MPa；The lateral bending rigidity I of side bar_xx=16.71 × 10¹⁰(mm⁴), the outer cantilever 1a transverse width of side bar is 1200mm, and interior cantilever 1b transverse width is 750mm, the outside cantilever lateral deviation of side bar barycenter 2 is from side bar web centrage 3, side bar barycenter 2 is 1667mm from the height of side bar bottom, and side bar has N1～N5 deformed bar 5, designs stretching force N_pIt is 3710.7kN.

Preventing the construction method that side bar lateral thrust deforms, step is as follows:

Step 1, fixing body External prestressed reinforcing bar 5

The side of the web 1c of side bar 1 outer cantilever side utilize the steel plate 10 pre-buried when prefabricated side bar to fixedly mount limit support 7 respectively from 8.5m place, rear and front end, the web side of support middle, both sides fixedly mounts intermediate support 6, the transverse height 900mm less of the transverse height of intermediate support of limit support, the transverse height difference of the steering gear being respectively mounted steering gear 8 (steel pipe of a kind of bending), the steering gear of intermediate support and limit support on the top of limit support and intermediate support is 900mm；By the steering gear of external prestressing reinforcing bar traverse intermediate support and limit support, then external prestressing reinforcing bar is temporarily fixed on the support of limit.

Step 2, stretch-draw side bar deformed bar and external prestressing reinforcing bar

First in side bar span centre, amesdial 9 is installed at correspondence side bar barycenter place, cantilever side, is used for recording the lateral thrust deformation values of side bar span centre in stretch-draw side bar deformed bar process；Paste foil gauge 4 at the outer cantilever maximum cantilever place of side bar span centre, be used for monitoring the strain value ε at the outer cantilever maximum cantilever place of side bar span centre in stretch-draw side bar deformed bar process；The strain feasible value [ε] at the outer cantilever maximum cantilever place of side bar span centre is:

Then with the stretching force 3710.7kN that sets according to the order of N1～N5 by root stretch-draw side bar deformed bar, in stretching process, the outside cantilever lateral bend deformation of side bar, before stretch-draw after two deformed bars N1, N2, foil gauge monitors the strain value ε at the outer cantilever maximum cantilever place of side bar span centre and reaches strain feasible value [ε], now suspend stretch-draw side bar deformed bar, be 40.9mm with the lateral thrust deformation values Δ in amesdial writing edge girder span；Then stretch-draw external prestressing reinforcing bar, utilizes the lateral thrust deformation values Δ zero that the lateral bending square that external prestressing reinforcing bar produces makes side bar span centre produce, keeps external prestressing reinforced bar stretching power constant after Δ zero；Then continue by the side bar deformed bar after root stretch-draw by above same procedure, after stretch-draw to the 4th deformed bar N4, the strain value ε at the outer cantilever maximum cantilever place of side bar span centre reaches strain feasible value [ε] again, now stop stretch-draw side bar deformed bar below, lateral thrust deformation values Δ in writing edge girder span is 31.4mm, then external prestressing reinforcing bar is increased stretching force on the basis of first time stretching force, to the lateral thrust deformation values Δ zero that side bar span centre second time produces, the stretching force keeping now external prestressing reinforcing bar is constant；The 5th side bar deformed bar N5 of last stretch-draw, after N5 stretch-draw, the strain value ε at the outer cantilever maximum cantilever place of side bar span centre not up to strain feasible value [ε], is now further added by stretching force to external prestressing reinforcing bar, by ε value zero on the basis of second time stretching force；Then external prestressing reinforcing bar is temporarily anchored on the support of limit.

By side bar hoisted in position after step 3, side bar deformed bar stretch-draw；Then the transverse splicing of side bar is completed routinely；Finally intermediate support, limit support are removed together with external prestressing reinforcing bar, complete the constructing operation that tee girder bridge side bar prevents lateral thrust from deforming.

Claims (1)

1. one kind utilizes external prestressing to prevent the method that tee girder bridge side bar lateral thrust deforms, it is characterised in that comprise the steps:

Step 1, fixing body External prestressed reinforcing bar (5)

Limit support (7) is fixedly mounted respectively at web (1c) both ends, side of side bar (1) outer cantilever (1a) side, fixed installation intermediate support (6) in the middle of the support of both sides, the transverse height of intermediate support is more than the transverse height of limit support, it is respectively mounted steering gear (8) on the top of limit support and intermediate support, and makes the steering gear of limit support and the steering gear of intermediate support with side bar barycenter (2) in the same plane vertical with the web side of side bar；Its two ends are temporarily fixed on the support of limit by external prestressing reinforcing bar (5) after the steering gear of intermediate support and limit support；

Step 2, stretch-draw side bar deformed bar and external prestressing reinforcing bar

First in side bar span centre, amesdial (9) is installed at correspondence side bar barycenter (2) place in cantilever side, is used for recording the lateral thrust deformation values of side bar span centre in stretch-draw side bar deformed bar process；Paste foil gauge (4) at the outer cantilever maximum cantilever place of side bar span centre, be used for monitoring the strain value ε at the outer cantilever maximum cantilever place of side bar span centre in stretch-draw side bar deformed bar process；

Then with the stretching force of setting by root stretch-draw side bar deformed bar, in stretching process, the outside cantilever lateral bend deformation of side bar, when the strain value ε that foil gauge monitors the outer cantilever maximum cantilever place of side bar span centre reaches strain feasible value [ε], suspend stretch-draw side bar deformed bar, with the lateral thrust deformation values Δ of amesdial record now side bar span centre；Then stretch-draw external prestressing reinforcing bar, utilizes the lateral bending square that external prestressing reinforcing bar produces to make the lateral thrust deformation values Δ of side bar span centre make zero, and keeps external prestressing reinforced bar stretching power constant after Δ zero；Then next root side bar deformed bar of stretch-draw is continued by above same procedure；So repeatedly, after last root side bar deformed bar stretch-draw till the lateral thrust deformation values of span centre makes zero；Then external prestressing reinforcing bar is temporarily anchored on the support of limit；

Described strain feasible value [ε] is tried to achieve by following formula:

$\[\mathrm{\ϵ}\]=\frac{f_{tk}}{E_c}$

In formula

E_c: side bar is adopted concrete elastic modelling quantity,

f_tk: the standard value of the adopted concrete tensile strength of side bar, " highway reinforced concrete and prestressed concrete bridge contain design specification " inquiry can be passed through and obtain；

By side bar hoisted in position after step 3, side bar deformed bar stretch-draw；Then the transverse splicing of side bar is completed routinely；Finally external prestressing reinforcing bar, intermediate support are removed together with the support of limit, complete the constructing operation that tee girder bridge side bar prevents lateral thrust from deforming.