CN102364012B - Method for expanding existing large-span truss - Google Patents

Method for expanding existing large-span truss Download PDF

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Publication number
CN102364012B
CN102364012B CN 201110137234 CN201110137234A CN102364012B CN 102364012 B CN102364012 B CN 102364012B CN 201110137234 CN201110137234 CN 201110137234 CN 201110137234 A CN201110137234 A CN 201110137234A CN 102364012 B CN102364012 B CN 102364012B
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China
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truss
bracing frame
slippage
span
load
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CN 201110137234
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Chinese (zh)
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CN102364012A (en
Inventor
吴伟杰
许超诣
刘中华
洪国松
李建洪
高良
郑雪祥
胡向萍
黄利顺
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浙江精工钢结构有限公司
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Abstract

The invention provides a method for expanding an existing large-span truss. The method comprises the following steps of: erecting a support frame below the existing main truss, jacking a midspan truss upwards, cutting the truss, and safely transferring all dead weight of the truss onto the support frame on the lower part and a slippage steel beam; and arranging a hydraulic crawler at a heel, making the cut truss slip by a required distance according to the slippage design requirement, arranging the truss which is required to be expanded after slipping outwards at a high altitude, and detaching the support frame and slippage facilities below the main truss. In the method, the existing large-span truss is directly expanded by cutting and slipping, so that the entire construction period is greatly shortened, and a large amount of labor force is saved. The existing truss is fully reused, so that the consumption of a large amount of steel is lowered, and resources are recycled. Factors in various aspects are fully considered in the design, so that the safety performance is high, and the quality is reliable. The construction safety is ensured, and severe accidents are avoided.

Description

A kind of existing large-span truss enlargement method

Technical field

The present invention relates to the building structure construction technical field, particularly a kind of existing large-span truss enlargement method.

Background technology

In recent years, along with the economic development of country, the name of the country living standard improves, go out administrative staff's increase, the large-scale public place that domestic part has been built can not satisfy the present stage visitors flowrate, such as railway terminal, sports palace, hospital or the like, especially railway transport capacity.Simultaneously along with the increase of the construction dynamics of the input of country to infrastructure, particularly railway station, this will have station with regard to exigence more and more and extend.

The method of tradition enlarging generally all is the building that reserve part can be reused, just all the other most of awning truss are all removed, thoroughly rebuild then, traditional handicraft not only needs the very long construction period, strengthened the input of fund simultaneously, this mode that wastes time and energy can't satisfy the demand of current society.

So the inventor proposes a kind of enlargement method that existing awning truss band is carried cutting back integral slipping, not only saves total time of construction, and former awning truss recycling can be able to be saved a large amount of steel.

But certain time limit because original station has come into operation exists complicated internal force in the awning chord member of truss.Existing large-span truss band carries the cutting technique complexity, because its distortion, stress have synergistic effect and repeatability in cutting process, cutting scheme also will be avoided cutting the unexpected release of improper generation internal force, and make the truss integral unstability except the force request that satisfies structure.Also to guarantee the preceding truss internal force minimum of each cutting by optimizing cutting sequence.Also truss to be carried out the predeformation measure simultaneously, guarantee that the absolute altitude of main couple cutting finishing back each point can adhere to specification.The above content of truss is that existing large-span truss band carries the key technology in the cutting process.Therefore, when having the cutting of above-mentioned similar structures, how to optimize cutting sequence, improve the efficient of cutting, and how distortion to control, become crucial problem.

Summary of the invention

The object of the present invention is to provide a kind of existing large-span truss enlargement method, design safety is reliable, cutting arrangement is reasonable, frictional force in the slipping is less, reduced the requirement of slippage equipment, it is reasonable to unload sequence arrangement simultaneously, effectively control structure distortion, intersect less with the civil engineering operation, give full play to the effectiveness of stepped unloading.

The present invention realizes by following technical measures: a kind of existing large-span truss enlargement method specifically comprises the steps:

(1) below existing main couple, set up bracing frame, with the jack certain distance of jacking that on bracing frame, the span centre truss made progress, this moment outside suspension column internal force minimum, the truss fractional load is transferred on the bracing frame simultaneously;

(2) after the span centre truss made progress jacking, according to finite element method (fem) analysis, outside suspension column chord member internal force was very little, adopted the magnetic force cutting machine with outside suspension column chord member and the cutting of suspension column web member, placed the slippage girder steel simultaneously at the suspension column place;

(3) analyze the little rod member of span centre truss internal force by finite element analysis software, and with its cutting;

(4) analyze the little rod member of all the other internal force in the span centre truss once more by finite element analysis software, and with its cutting, through repeatedly repeating, cut off fully until the span centre truss, this moment, the load transfer of span centre truss was to the bracing frame of bottom;

(5) the inboard suspension column chord member of cutting, truss all cut and finished this moment, and truss is conducted oneself with dignity whole safe transfers on lower support frame and slippage girder steel;

(6) hydraulic pressure creep machine is installed at the suspension column place, according to slippage designing requirement slippage required separation distance, and suspension column is welded fixing truss under the cutting;

(7) adopt mobile crane, the truss of required enlarging after high-altitude benefit dress slippage is gone out;

(8) carry out unloaded operation, remove the bracing frame and the slippage facility of main couple below.

The present invention can be further perfect in the following way:

Described bracing frame is to set up firm foundation with mechanical model, utilization MADIS software for calculation designs, and the load of considering during design comprises the influence of horizontal wind load that aerodynamic force that dead load, live load, wind load, train cross produces, geological process, support settlement, vibration effect that train crosses, top truss sliding construction process influence and the bracing frame resistance to overturning buckling analysis to the bracing frame system.

Described wind load:

ω=β zμ sμ zω 0=1.92×2.08×1.52×0.45=2.73kN/m 2

β wherein z=1+ ξ ε 1ε 2=1+1.81 * 0.51 * 1.0=1.92, μ z=1.52, μ s=2.6 * 0.8=2.08;

ω 0Be blast, get 0.45kN/m 2ξ is the pulsation enhancement coefficient, ε 1Be the pulsation influence coefficient, ε 2Be the ratio of mode factor and height variation factor of wind pressure;

Consider wind action on column, picking and placeing big coefficient is 1.1, and then line load is: 2.73 * 1.1 * 0.377=1.13kN/m, wherein 0.377m is the pipe diameter.

Described horizontal wind load, consideration train, cross train and produce Pneumatic pressure and aerodynamic suction through out-of-date blast with 300km/h, because aerodynamic suction is opposite with the suffered shearing direction of bracing frame, favourable to calculating bracing frame, so do not consider aerodynamic suction, only consider the Pneumatic pressure effect; According to relevant regulations, the maximum height that the horizontal gas dynamic pressure acts on the track top is 5m, and has or not the existence of platform shed, needs to consider multiply by 1.5 the coefficient that stops; The train center line that crosses of speed per hour 350km is 5 meters apart from the member Edge Distance, and then the horizontal gas dynamic pressure of Chan Shenging is 0.72kN/ ㎡, then calculates wind reference pressure to be:

w 0=1.5×0.72=1.08kN/㎡

According to the geometric properties of bracing frame, can calculate the following bracing frame vertical rod of the 5m height width that keeps out the wind and be: L = 0.377 + 2 + 2 2 × 0.18 = 0.8116 m

Then crossing train to the wind load that the bracing frame column produces is:

q=0.8116*1.08*1*1=0.8765kN/m。

Consider to strengthen load action when support frame as described above calculates, comparatively conservative safety degree more than needed be set, guarantee the safety in work progress of support system and steel structural roof, during calculating, consider following load combination:

①1.35D+0.98L

②1.2D+1.4L

③1.2D+1.4L+0.84W

④1.2D+0.98L+1.4W

⑤1.2D+1.4Δ

⑥1.2(D+0.5L)±1.3Eh

⑦1.0D+1.4L

⑧1.0D+1.4L+0.84W

⑨1.0D+0.98L+1.4W

⑩1.0(D+0.5L)±1.3Eh

Wherein, D represents dead load, and L represents live load, and W represents common wind load and crosses the wind load that train aerodynamic-force produces, and Eh represents horizontal earthquake action, and Δ is represented the support settlement effect.

To put in order truss structure modeling in MIDAS software before the described main couple jacking earlier, respectively main couple is made progress jacking 10mm, 20mm and 30mm, the jacking distance of outside suspension column internal force minimum when drawing upwards jacking, the jacking that then the span centre truss made progress changes step 2 over to.

Suspension column in the described step 2 is made as initiatively point of slippage, and being erected at the bracing frame place after the span centre truss cuts off is that slippage is followed a little; Initiatively the some place comprises and lays the subgrade case that fixes on the ground, is arranged in initiatively put the slippage girder steel, be installed in the active slipping mechanism of initiatively putting slippage girder steel upper support truss and be fixed on and initiatively put on the slippage girder steel, the hydraulic pressure creep machine that the promotion truss moves on the subgrade case; Follow and a little comprise a slippage girder steel of following that is arranged on the bracing frame, be installed in the slipping mechanism of following of following a slippage girder steel upper support truss.

Describedly initiatively put the slippage girder steel and lay one deck corrosion resistant plate with some slippage girder steel upper surface.

Described active slipping mechanism comprises the support that supports the truss for the treatment of slippage with to follow slipping mechanism identical, and the polyfluortetraethylene plate that pastes in the support bottom surface, is used for sliding on corrosion resistant plate.

In the described step 8 at first with whole bracing frame truss after carrying out the bracing frame complete removal in the finite element analysis software, calculate every Pin main couple span centre degree of disturbing maximum value; Then with jack on the bracing frame with upwards jacking slightly of main couple, jacking gets final product to being about to break away from bracing frame;

First truss structure is unloaded, the height of unloading be aforementioned calculation degree of disturbing peaked half; Then with the unloading of second truss structure, the height of unloading be similarly aforementioned calculation degree of disturbing peaked half; With first truss structure unload again degree of disturbing peaked half, at this moment, first truss structure is all completions of discharge, the bracing frame of its below can complete removal;

With the 3rd truss structure begin the unloading degree of disturbing peaked half, at this moment, the 3rd truss structure and the 4th truss structure absolute altitude differ degree of disturbing peaked half, the 3rd truss structure is consistent with the second truss structure absolute altitude, second truss structure and the first truss structure absolute altitude differ degree of disturbing peaked half, absolute altitude is stepped between each truss structure;

With second truss structure unload again degree of disturbing peaked half, at this moment, second truss structure is all completions of discharge, the bracing frame of its below also can complete removal; With the 4th truss structure also unloading in the manner described above, repeat above-mentioned steps then, unload every truss structure is stepped, until whole truss completions of discharge.

After adopting such scheme, the present invention has many beneficial effects:

1, the present invention directly to existing large-span truss cut, the enlarging mode of slippage, rather than existing truss removed reconstruction, thus the whole construction duration shorten dramatically, saved great amount of manpower.

2, the present invention utilizes existing truss fully again, only needs to replenish the truss part of welding enlarging distance, has saved the consumption of great deal of steel, and resource is reused, and meets requirements of the times energy-conservation in the current society.

3, the design of bracing frame has taken into full account the factor of various aspects, security performance height, reliable in quality among the present invention.In cutting and the slipping, it is thorough that each details is all considered simultaneously, ensured the safety of construction, and generation avoids a nasty accident.

4, the present invention proposes a kind of stair-stepping truss mode, and civil engineering unit can be earlier descend the step construction to the truss that has unloaded, and can accomplish that civil engineering and steel work unloaded operation carry out synchronously, has further saved the overall duration of site operation.And, determine structure unloading flow process by unloading is optimized in proper order, adopt finite element analysis software, structure unloading overall process is carried out simulation analysis, and before the truss unloading, determine the predeformation value of structure, guarantee that the levelness after the structure unloading is finished meets design requirement.The equipment that stepped unloading drops into respect to synchronous unloading is few, improves comprehensive benefit.

Description of drawings

Fig. 1 is the structural representation of step 1 in the preferred embodiment of the present invention;

Fig. 2 is the structural representation of step 2 in the preferred embodiment of the present invention;

Fig. 3 is the structural representation of step 3 in the preferred embodiment of the present invention;

Fig. 4 is the structural representation of step 4 in the preferred embodiment of the present invention;

Fig. 5 is the structural representation of step 5 in the preferred embodiment of the present invention;

Fig. 6 is the structural representation of step 6 in the preferred embodiment of the present invention;

Fig. 7 is the structural representation of step 7 in the preferred embodiment of the present invention;

Fig. 8 is an existing large-span truss schematic top plan view of the present invention

Fig. 9 is the schematic top plan view behind the existing large-span truss slippage certain distance of the present invention;

Figure 10 is the schematic top plan view that existing large-span truss of the present invention is mended the dress main couple;

Figure 11 is the schematic perspective view of bracing frame in the preferred embodiment of the present invention;

Figure 12 be preferred embodiment slippage of the present invention initiatively put follow a little with slippage in the Sliding Structures schematic diagram.

The specific embodiment

In conjunction with the accompanying drawings, preferred embodiment of the present invention is described in further details.

In the present embodiment reconstruction at the large-scale awning truss in railway terminal, its building span 64.6m as shown in Figure 1, spring of arch 19.5m, length 545m.The awning structure adopts is just putting leg-of-mutton three limb lattice truss, about 2.5 meters of the truss leg length of side, the high 4.5m of triangular truss, maximum caliber 550mm.Main couple totally 26 Pin along its length, truss Pin is apart from 22m.Roofing is a color steel sheet, and furred ceiling adopts the aluminium sheet furred ceiling.The main platform clear span is 10.5 meters, does not satisfy instructions for use, now the main platform clear span is expanded as 15 meters, and former truss span is 64.6m, and the enlarging back is 69.1m.

Adopt the technology of the present invention, job practices specifically comprises the steps:

One, bracing frame 2 is built

Bracing frame 2 is to set up firm foundation with mechanical model, and utilization MIDAS software for calculation designs.The load that will consider during design comprises the influence of horizontal wind load that aerodynamic force that dead load, live load, wind load, train cross produces, geological process, support settlement, vibration effect that train crosses, top truss sliding construction process influence and the bracing frame resistance to overturning buckling analysis to the bracing frame system.

The dead load that bracing frame 2 is subjected to is considered dead load multiplier 1.0, roofing dead load 0.8kN/ ㎡ during calculating.Side fixed end bracing frame bears vertical force 315kN, bears horizontal shear 180kN to the inside.The slippage end structure is 404kN to the axial pressure of bracing frame, considers that friction factor is 0.05 between sliding rail and the roof system, and then the kinetic force of friction during the roof system slippage is 20.2kN.

Live load is mainly considered bracing frame 2 top operators' load, when calculating bracing frame, needs to consider the construction live load of bracing frame top 3.5kN/ ㎡.

Wind load, ω 0Blast is got 0.45kN/m 2, wind load comprises and acting directly on the bracing frame 2 have according to " GBJ135-90 " GBJ135-2004 4.2.9 bar:

Wind load:

β z=1+ξε 1ε 2=1+1.81×0.51×1.0=1.92,μ z=1.52,μ s=2.6×0.8=2.08。

ω=β zμ sμ zω 0=1.92×2.08×1.52×0.45=2.73kN/m 2

Consider wind action on column, picking and placeing big coefficient is 1.1, and then line load is:

2.73×1.1×0.377=1.13kN/m。

Because in this engineering construction process, adjacent tracks is still normally used, thus need the consideration train with 300km/h through out-of-date blast.Relevant regulations according to " 300~350 kilometers passenger dedicated railway line designs of newly-built speed per hour temporary provisions " (No. [2007] 47, iron construction) file is calculated as follows through the blast that produces train:

Cross train and produce Pneumatic pressure and aerodynamic suction, favourable because aerodynamic suction is opposite with bracing frame 2 suffered shearing directions to calculating bracing frame 2, so do not consider aerodynamic suction, only consider the Pneumatic pressure effect.According to relevant regulations, the maximum height that the horizontal gas dynamic pressure acts on the track top is 5m, and has or not the existence of platform shed, needs to consider multiply by 1.5 the coefficient that stops.Table look-up and can get, the train center line that crosses of speed per hour 350km is 5 meters apart from the member Edge Distance, and then the horizontal gas dynamic pressure of Chan Shenging is 0.72kN/ ㎡, then calculates wind reference pressure to be:

w 0=1.5×0.72=1.08kN/㎡

According to the geometric properties of bracing frame 2, can calculate following bracing frame 2 vertical rods of the 5m height width that keeps out the wind and be: L = 0.377 + 2 + 2 2 × 0.18 = 0.8116 m

Then crossing train to the wind load that bracing frame 2 columns produce is:

q=0.8116*1.08*1*1=0.8765kN/m。

In view of this engineering is the railway station, in the transformation process, still to guarantee normal operation, so its safety is extremely important, need to consider the influence of geological process.According to the relevant design data, the design parameters of seismic design is: seismic fortification intensity 7 degree, the basic earthquake acceleration 0.10g of design, earthquake is divided into groups second group, site category II class.

This engineering original structure came into operation 3 years, can think that the foundation settlement on track foundation, platform basis tends towards stability, big variation can not take place in work progress.The foundation settlement that 30mm takes place than unfavorable position bracing frame 2 bearings is got in full consideration content to retain sovereignty over a part of the country during calculating, calculates.

Because the vibration that train crosses act as low frequency vibration, its frequency and support system and steel awning basic cycle difference are bigger, covibration can not take place, so do not consider the vibration effect that train crosses in this calculating.

Consider to strengthen load action during calculating, comparatively conservative safety degree more than needed is set, guarantee the safety in work progress of support system and steel structural roof.During calculating, consider following load combination:

①1.35D+0.98L

②1.2D+1.4L

③1.2D+1.4L+0.84W

④1.2D+0.98L+1.4W

⑤1.2D+1.4Δ

⑥1.2(D+0.5L)±1.3Eh

⑦1.0D+1.4L

⑧1.0D+1.4L+0.84W

⑨1.0D+0.98L+1.4W

⑩1.0(D+0.5L)±1.3Eh

Wherein, D represents dead load, and L represents live load, and W represents wind load (comprise wind load and cross the wind load that train aerodynamic-force produces), and Eh represents horizontal earthquake action, and Δ is represented the support settlement effect.

When the steel work main couple cut off, as yet not during the state of slippage because sedimentation takes place on the basis of intermediate support beam 2, this place bracing frame 2 directly bears roof system deadweight effect simultaneously, this moment the bracing frame system rod member stress maximum, be out of shape also maximum.For the stability of checking computations bracing frame system, choose this state and carry out buckling analysis.Buckling analysis considers that 1.0 dead loads+1.0 mobile load states calculate.

Bracing frame 2 specifications are 2m * 3.5m in the present embodiment, and every joint highly is 2m, and bracing frame 2 columns are Φ 377 * 16 steel pipes, and straight web member and diagonal web member all adopt Φ 180 * 12 steel pipes, and the rod member material all adopts Q235B, design strength f=215N/mm 2

In conjunction with Fig. 1 and Figure 11 in order to prevent that bracing frame 2 is in loading process, prevent that from there is the phenomenon of differential settlement in bracing frame 2, position in that bracing frame 2 is installed as setting up subgrade case on platform and the track for a train basis, firmly is connected subgrade case with platform by i iron 25.Be not subjected to the destruction of upper support shelf 2 in order to ensure track for a train and sleeper, before setting up, track for a train and sleeper all removed.Subgrade case itself is parts commonly used in the building trade, is to adopt i iron to be welded, and at i iron upper and lower surface welding steel, i iron is wrapped make.

It on the subgrade case 21 supporting frame 22.Supporting frame 22 comprises some columns 23 and plurality of cross bars 24.Fixedly connected by cross bar 24 between column 23 with level or oblique welding, form whole supporting frame 22.When whole supporting frame 22 was fixed on subgrade case 21, the foot of column 23 all should be placed in the subgrade case 21 each i iron infall in length and breadth, strengthened the ability to bear of supporting frame 22.

The outer heel post 23 of supporting frame 22, just near the column of original train protection canopy 10, the distance that should keep greater than 100mm with train protection canopy 10 guarantees that the distortion of supporting frame 22 does not influence train protection canopy 10.Supporting frame 22 corresponding slippage truss places are provided with slippage girder steel 40.

The bracing frame force analysis

1, the truss slipping is to the influence of bracing frame

1. do not begin the preceding dead load state of slippage after analyzing cutting, draw X under the standard combination, Y, Z direction displacement isogram (X is a glide direction, the longitudinal direction between each truss structure of Y, Z bracing frame sedimentation direction) by software.In the present embodiment, do not begin the deformation values less (X maximum displacement 7.3mm, Y maximum displacement 1.95mm, Z maximum displacement 75mm) of slip state lower support frame system, the requirement of related specifications is satisfied in the support system distortion, also satisfies the needs of construction precision.In addition, the stress and the stress ratio situation of output support system: support system maximum stress ratio is 0.7,0.7<<1.0, and is practical so the design safety of this bracing frame system is reliable, can satisfy the needs of this project construction.

2. slide onto the bracing frame centre position, the dead load effect is to the moment of flexure maximum of the vertical force generation of sliding rail beam, these state slippage girder steel 40 stressed maximums, under the dead load effect, analysis draws deformation values (the X maximum displacement 5.33mm of bracing frame system, Y maximum displacement 1.51mm, Z maximum displacement 77mm), the maximum stress ratio is 0.679, by The above results as seen, support system maximum stress ratio is 0.679<<1.0, so the design safety of this bracing frame system is reliable, practical, can satisfy the needs of this project construction.

When 3. moving to bracing frame center, left side, the dead load effect is to the moment of flexure maximum of the vertical force generation of sliding rail beam, under this state, sliding rail beam 40 stressed maximums, under the dead load effect, analysis draws deformation values (the X maximum displacement 5.52mm of bracing frame system, Y maximum displacement 1.52mm, Z maximum displacement 87mm), the maximum stress ratio is 0.661, by The above results as seen, 0.661<<1.0, so the design safety of this bracing frame system is reliable, practical, can satisfy the needs of this project construction.

4. the conclusion analyzed of work progress

By the aforementioned calculation analysis as seen, in the sliding construction process, the distortion of bracing frame system is less, and all directions are out of shape all less than 6mm, and the rigidity aspect satisfies construction requirement.In each construction state, support system rod member stress ratio is 0.7 to the maximum, and rod member intensity also satisfies related request.So above computational analysis shows that the design safety of this bracing frame system is reliable, and is practical.

2, support system stability analysis

By above calculating as can be known, when the steel structural roof truss cut off, as yet not during the state of slippage because sedimentation takes place on the basis of intermediate support beam, this place bracing frame directly bears roof system deadweight effect simultaneously, this moment the bracing frame system rod member stress maximum, be out of shape also maximum.For the stability of checking computations bracing frame system, choose this state and carry out buckling analysis.

Buckling analysis considers that 1.0 dead loads+1.0 mobile load states calculate, first buckling mode (the flexing factor 62.59), second buckling mode (the flexing factor 62.65), the 3rd buckling mode (the flexing factor 62.91).By The above results as seen, under 1.0 dead loads+1.0 mobile load effects, the flexing factor minimum of bracing frame system is 62.59, promptly under 62.59 times of 1.0 dead load+1.0 mobile load effect, flexing could take place in the bracing frame system, this shows that the resistance to overturning of bracing frame system is very high, in work progress, be difficult to take place the flexing unstability.

Two,, 50 tons jack 11 is set, on the bracing frame top with the main couple 1 certain distance of jacking upwards as Fig. 2.

Because this engineering has been moved 5 years, main couple 1 is under the dead load effect, span centre degree of disturbing is bigger, after main couple 1 cutting, the absolute altitude of truss can adhere to specification, also to guarantee simultaneously internal force minimum in the truss cutting process, therefore before cutting, need to adopt large-scale finite element analysis software to carry out computational analysis in the cutting process.

In computation model, adopt bearing forced displacement 10mm, 20mm and 30mm respectively, compare analysis respectively, when finding to make progress jacking 30mm, therefore main couple suspension column 30 place's internal force minimums determine that the numerical value that main couple 1 makes progress jacking is 30mm.

Three, as shown in Figure 3, after adopting the magnetic force cutting machine that outside suspension column chord member 3 and 4 cuttings of suspension column web member are finished, stability in order to ensure the truss suspension column, at truss suspension column 30 place's mounting slip girder steels 5, slippage girder steel 5 is connected with truss suspension column 30 original structures, attachment rail beam on slippage girder steel 5 can make things convenient for the installation of hydraulic pressure creep machine 12 simultaneously.

Four, in conjunction with Fig. 4, the cutting of main couple chord member 6 and web member 7.After the chord member cutting of the suspension column outside finishes, adopt finite element analysis software to analyze, find span centre upper chord 6 and web member 7 internal force minimums, begin cutting cutting span centre upper chord 6 and web member 7, begin to cut two of span centre lower chord 8(then), cut two of inboard suspension column chord member 9(at last).

Five, referring to Fig. 5, main couple 1 slippage.After main couple 1 all cut and finishes, its load was all transferred on the lower support frame system.Suspension column 30 places arrange hydraulic pressure creep machine 12, with truss 1 along the certain distance of station one side slip.13 truss structures of slippage for the first time, slippage weight is about 1300 tons, after slippage for the first time finishes, 13 truss structures of slippage symmetry again, slippage weight is about 1300 tons, adds up to the slippage gross weight to be about 2600 tons.

Six, as Fig. 6, the truss after the dress slippage is gone out is mended in the high-altitude.

After truss 1 slippage puts in place, can set about carrying out the benefit bar installation of truss 1, filling a vacancy of truss 1 interlude adopts mobile crane mode in bulk to install, and undertaken by the order of web member behind the first chord member.When the truss suspension column is installed, should in advance suspension column be placed on the stone bolt on cushion cap basis temporary fixedly, treat after the truss slippage puts in place suspension column to be mentioned, dock welding with chord member of truss, and fix, so that be in the milk from now in the spot welding of heel slab underlay upper padding plate.The truss that is connected with station adopts whole hanging method to install, and carries out assembly unit earlier near the platform truss before installing, and installs with mobile crane then.

Seven, shown in Figure 7, remove the bracing frame and the slippage facility of main couple below.The main couple slippage finishes, and after the agent structure installation, need carry out the integral body unloading to established main structure.50 tons of mobile cranes of field by using are removed bracing frame.

The dismounting mode is also different with traditional approach, adopts stepped unloading manner.In conjunction with Fig. 8~Figure 10, at first with the calculating of whole bracing frame truss after carrying out the bracing frame complete removal in the finite element analysis software, drawing every Pin main couple span centre degree of disturbing maximum value is 40mm.Then with jack on the bracing frame with upwards jacking slightly of main couple, jacking gets final product to being about to break away from bracing frame.

Behind first truss structure 1a unloading 20mm, can be with second truss structure 2a unloading 20mm; Then the first truss structure 1a is unloaded 20mm again, at this moment, the first truss structure 1a all completions of discharge, the bracing frame 11 of its below can complete removal.

The 3rd truss structure 3a is begun to unload 20mm, and at this moment, the 3rd Pin 3a and the 4th truss structure 4a absolute altitude differ 20mm, the 3rd Pin 3a is consistent with the second truss structure 2a absolute altitude, the second truss structure 2a and the first truss structure 1a absolute altitude differ 20mm, and absolute altitude is stepped between each truss structure, all differs 20mm.

The second truss structure 2a is unloaded 20mm again, at this moment, the second truss structure 2a all completions of discharge, the bracing frame of its below also can complete removal; With the 4th truss structure 4a also unloading in the manner described above, repeat above-mentioned steps, then until whole truss completions of discharge.Adopt finite element analysis, each truss structure is when support displacement 20mm, and maximum distortion 42mm, maximum stress ratio are 0.265 much smaller than 1, and it is safe and reliable therefore unloading according to this scheme.

What also need here to propose is, in the present invention, the suspension column place is provided with hydraulic pressure creep machine 12 as slippage point initiatively, and at bracing frame upper support slippage truss, is to follow a little as slippage.For reducing the frictional force in the slippage, the Sliding Structures that adopts in the present embodiment is referring to Fig. 1 and Figure 12.

Initiatively putting 30 places comprises subgrade case 31, initiatively puts slippage girder steel 5, initiatively slipping mechanism 32, hydraulic pressure creep machine 12.

Subgrade case 31 is laid and is fixed on platform, arranges on subgrade case 31 and initiatively puts slippage girder steel 5, and what initiatively put 5 employings of slippage girder steel is i iron, lays one deck corrosion resistant plate 33 at the upper surface of i iron.Initiatively slipping mechanism 32 is erected at and initiatively puts on the slippage girder steel 5, initiatively slipping mechanism 32 mainly is directly to contact with treating mobile main couple 1 suspension column 30, mainly comprise and support the support 34 for the treatment of mobile main couple 1 suspension column 30, the bottom surface of support 34 is the plane, and pastes one deck polyfluortetraethylene plate 35.Polyfluortetraethylene plate 35 fits tightly with above-mentioned corrosion resistant plate 33 and contacts.Hydraulic pressure creep machine 12 is fixed on initiatively to be put on the slippage girder steel 5, and mobile main couple 1 is treated in its application point connection simultaneously, promotes this and treats mobile main couple 1 slippage.

Follow a slippage girder steel 40 and initiatively to put slippage girder steel 5 structures identical, following slipping mechanism is to support main couple lower chord 8, and structure is identical with active slipping mechanism 32 structures, does not do being repeated in this description.When slippage, corrosion resistant plate 33 and the friction between the polyfluortetraethylene plate 35 in this structure are little, have guaranteed smooth and easy, the safety of slippage, simultaneously the driving arrangement power requirement are reduced significantly, and the choice is big.

Because the complexity of job site condition, only depend on the simulation analysis of finite element ideal model, be difficult to the many invisible factor that simulated field exists, therefore also in work progress, displacement structure, internal force carried out timely monitor, to obtain the distortion and the stressing conditions of structure reality.

A. deformation monitoring: whether the main couple deformation values is consistent with desirable calculated value in the monitoring work progress, actual measurement deformation values in each cutting process and the theoretical pre-arch value of calculating are compared, so that take corresponding measure to come the control structure distortion, finish engineering construction smoothly.

B. stress monitoring: large-span truss has additivity and repeatability in cutting process, use stress monitoring

Among the present invention, the chord member of large-span truss is with when carrying cutting, structure has inconsistent phenomenon in incision, and we will be provided with jack the absolute altitude of truss is adjusted below the main couple chord member.After truss all cuts and finishes, all loads will be delivered on the bracing frame and slippage girder steel of below.

Because the particularity of truss, large-span truss is in the different cutting stages, and its distortion has synergistic effect and repeatability, so the present invention also adopts finite element analysis software, the structure cuts overall process is carried out simulation analysis, thereby determine the predeformation value of structure.The value size of the predeformation value of structure is closely related with the cutting flow process, because in the different cutting stages, the rigidity of structure self, stress have very big difference, the malformation distribution situation also has marked change.Therefore, the predeformation value of structure must be determined according to the distortion situation of structure in the cutting flow process.After finishing the cutting of span centre truss lower chord, truss can push the bracing frame of bottom under the deadweight effect, thereby can make the absolute altitude of cutting back truss be lower than design elevation, therefore, after main couple cutting finishes, at the bracing frame top jack is set, with the truss certain distance of jacking that makes progress.

In the main couple cutting process, structure has been carried out the monitoring of distortion and internal force, obtained the distortion and the stressing conditions of structure reality, when guaranteeing in the cutting process safety of structure, field actual measurement results and simulation calculation result compare, the accuracy of check work progress simulation analysis.More than the monitoring content is through whole construction course.

Claims (10)

1. an existing large-span truss enlargement method is characterized in that: comprise the steps:
The first step, below existing main couple, set up bracing frame, with the jack certain distance of jacking that on bracing frame, the span centre truss made progress, this moment outside suspension column internal force minimum, the truss fractional load is transferred on the bracing frame simultaneously;
Second step, span centre truss make progress after the jacking, and according to finite element method (fem) analysis, outside suspension column chord member internal force is very little, adopt the magnetic force cutting machine with outside suspension column chord member and the cutting of suspension column web member, place the slippage girder steel simultaneously at the suspension column place;
The 3rd step, analyze the little rod member of span centre truss internal force by finite element analysis software, and with its cutting;
The 4th step, analyze the little rod member of all the other internal force in the span centre truss once more by finite element analysis software, and with its cutting, through repeatedly repeating, cut off fully until the span centre truss, this moment, the load transfer of span centre truss was to the bracing frame of bottom;
The 5th step, the inboard suspension column chord member of cutting, truss all cut and finished this moment, and truss is conducted oneself with dignity whole safe transfers on lower support frame and slippage girder steel;
The 6th step, hydraulic pressure creep machine is installed, according to slippage designing requirement slippage required separation distance, and suspension column is welded fixing truss under the cutting at the suspension column place;
The 7th step, employing mobile crane, the truss of required enlarging after high-altitude benefit dress slippage is gone out;
The 8th goes on foot, carries out unloaded operation, removes the bracing frame and the slippage facility of main couple below.
2. a kind of existing large-span truss enlargement method as claimed in claim 1, it is characterized in that: bracing frame is to set up firm foundation with mechanical model in described the 1st step, utilization MIDAS software for calculation designs, and the load of considering during design comprises the influence of horizontal wind load that aerodynamic force that dead load, live load, wind load, train cross produces, geological process, support settlement, vibration effect that train crosses, top truss sliding construction process influence and the bracing frame resistance to overturning buckling analysis to the bracing frame system.
3. a kind of existing large-span truss enlargement method as claimed in claim 2 is characterized in that: described wind load:
ω=β zμ sμ zω 0=1.92×2.08×1.52×0.45=2.73kN/m 2
β wherein z=1+ ξ ε 1ε 2=1+1.81 * 0.51 * 1.0=1.92, μ z=1.52, μ s=2.6 * 0.8=2.08;
ω 0Be blast, get 0.45kN/m 2ξ is the pulsation enhancement coefficient, ε 1Be the pulsation influence coefficient, ε 2Be the ratio of mode factor and height variation factor of wind pressure;
Consider wind action on column, picking and placeing big coefficient is 1.1, and then line load is: 2.73 * 1.1 * 0.377=1.13kN/m, wherein 0.377m is the pipe diameter.
4. a kind of existing large-span truss enlargement method as claimed in claim 2, it is characterized in that: described horizontal wind load, consider train with 300km/h through out-of-date blast, cross train and produce Pneumatic pressure and aerodynamic suction, because aerodynamic suction is opposite with the suffered shearing direction of bracing frame, favourable to calculating bracing frame, so do not consider aerodynamic suction, only consider the Pneumatic pressure effect; According to relevant regulations, the maximum height that the horizontal gas dynamic pressure acts on the track top is 5m, and has or not the existence of platform shed, needs to consider multiply by 1.5 the coefficient that stops; The train center line that crosses of speed per hour 350km is 5 meters apart from the member Edge Distance, and then the horizontal gas dynamic pressure of Chan Shenging is 0.72kN/ ㎡, then calculates wind reference pressure to be:
w 0=1.5×0.72=1.08kN/㎡
According to the geometric properties of bracing frame, can calculate the following bracing frame vertical rod of the 5m height width that keeps out the wind and be: L = 0.377 + 2 + 2 2 × 0.18 = 0.8116 m
Then crossing train to the wind load that the bracing frame column produces is:
q=0.8116*1.08*1*1=0.8765kN/m。
5. a kind of existing large-span truss enlargement method as claimed in claim 1, it is characterized in that: consider to strengthen load action when support frame as described above calculates, comparatively conservative safety degree more than needed is set, guarantee the safety in work progress of support system and steel structural roof, during calculating, consider following load combination:
①1.35D+0.98L
②1.2D+1.4L
③1.2D+1.4L+0.84W
④1.2D+0.98L+1.4W
⑤1.2D+1.4Δ
⑥1.2(D+0.5L)±1.3Eh
⑦1.0D+1.4L
⑧1.0D+1.4L+0.84W
⑨1.0D+0.98L+1.4W
⑩1.0(D+0.5L)±1.3Eh
Wherein, D represents dead load, and L represents live load, and W represents common wind load and crosses the wind load that train aerodynamic-force produces, and Eh represents horizontal earthquake action, and Δ is represented the support settlement effect.
6. a kind of existing large-span truss enlargement method as claimed in claim 1, it is characterized in that: will put in order truss structure modeling in MIDAS software before the described main couple jacking earlier, jacking 10mm, 20mm and 30mm make progress main couple respectively, the jacking distance of outside suspension column internal force minimum when drawing upwards jacking, the jacking that then the span centre truss made progress changes step 2 over to.
7. a kind of existing large-span truss enlargement method as claimed in claim 1 is characterized in that: the suspension column in the described step 2 is made as initiatively point of slippage, and being erected at the bracing frame place after the span centre truss cuts off is that slippage is followed a little; Initiatively the some place comprises and lays the subgrade case that fixes on the ground, is arranged in initiatively put the slippage girder steel, be installed in the active slipping mechanism of initiatively putting slippage girder steel upper support truss and be fixed on and initiatively put on the slippage girder steel, the hydraulic pressure creep machine that the promotion truss moves on the subgrade case; Follow and a little comprise a slippage girder steel of following that is arranged on the bracing frame, be installed in the slipping mechanism of following of following a slippage girder steel upper support truss.
8. a kind of existing large-span truss enlargement method as claimed in claim 7 is characterized in that: describedly initiatively put the slippage girder steel and follow a some slippage girder steel upper surface and lay one deck corrosion resistant plate.
9. a kind of existing large-span truss enlargement method as claimed in claim 7, it is characterized in that: described active slipping mechanism is with to follow slipping mechanism identical, comprise the support that supports the truss for the treatment of slippage, and the polyfluortetraethylene plate that pastes in the support bottom surface, is used on corrosion resistant plate, sliding.
10. a kind of existing large-span truss enlargement method as claimed in claim 1, it is characterized in that: in the described step 8 at first with whole bracing frame truss after carrying out the bracing frame complete removal in the finite element analysis software, calculate every Pin main couple span centre degree of disturbing maximum value; Then with jack on the bracing frame with upwards jacking slightly of main couple, jacking gets final product to being about to break away from bracing frame;
First truss structure is unloaded, the height of unloading be aforementioned calculation degree of disturbing peaked half; Then with the unloading of second truss structure, the height of unloading be similarly aforementioned calculation degree of disturbing peaked half; With first truss structure unload again degree of disturbing peaked half, at this moment, first truss structure is all completions of discharge, the bracing frame of its below can complete removal;
With the 3rd truss structure begin the unloading degree of disturbing peaked half, at this moment, the 3rd truss structure and the 4th truss structure absolute altitude differ degree of disturbing peaked half, the 3rd truss structure is consistent with the second truss structure absolute altitude, second truss structure and the first truss structure absolute altitude differ degree of disturbing peaked half, absolute altitude is stepped between each truss structure;
With second truss structure unload again degree of disturbing peaked half, at this moment, second truss structure is all completions of discharge, the bracing frame of its below also can complete removal; With the 4th truss structure also unloading in the manner described above, repeat above-mentioned steps then, unload every truss structure is stepped, until whole truss completions of discharge.
CN 201110137234 2011-05-26 2011-05-26 Method for expanding existing large-span truss CN102364012B (en)

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