Bangladesh launching gantry project-HZQ50/150 bridge girder launcher

How Does HZQ50-150 Bridge Girder Launcher work?

FAQ Jun 30, 2012 No Comments

(1) The use of the bridge girder launcher

The bridge girder launcher is of non-standard equipment in worksite, some temporary works should be done in worksite in service process, which is important. Pier cap fixed block and lateral moving plan satisfy demands of the first site. In the later use, construction companies should make corresponding pier cap fixed block and lateral moving plans according to practical situation of bridge and pier caps. It demands the pier cap fixers must be stable and reliable, and piers plan can meet the demand of crossing piers for the bridge girder launcher.

main girder on the transporter

1. Crossing piers with empty load

Step 1:

After finishing installation, check the operating condition of the whole machine. If everything is ok, drive girder carrier with precast girder to rear part of bridge girder launcher to prepare for crossing piers.

Step 2:

Hydro-cylinders in front support and rear support lift main girder to a certain height, put pin roll into drivepipe. Middle support with transverse sliding rail moves forward 50m by its suspension institution. Put down middle support and transverse sliding rail to lay a solid foundation.

 

Step 3:

Hydro-cylinders in front support and rear support are driven to get pin roll out, the whole machine drop down. Main girder stands on roller wheel of middle support and rear bracket, front and rear trolley moves near to middle support. Then start roller mechanism of middle support and rear bracket to make main girder move forwards 20m, front trolley and rear trolley move backwards 20m at the same time.

 

Step 4:

Cylinder in rear bracket lifts and takes back to make main girder suspend in the air, then main girder moves forward 30m with its own suspension institution. Then keep rear bracket in a level and plug in pin roll. Take back cylinder of rear support leg to make it suspend in the air, move two trolleys move to rear part at the same time;

 

Step 5:

Start roller mechanism of middle support leg and rear bracket, make main girder move forwards 15m, two trolleys backwards 15m

 

Step 6:

Two trolleys continue to move backward to rear part of main girder, girder carrier puts precast girder in certain place, rear trolley lifts one end of girder as counterweight and fix it

 

Step 7:

Start roller mechanism of middle support and rear bracket to make main girder move forward 15m, then front support is jacked onto front abutment to meet demand of installing girder. Check operating condition of the whole machine to prepare for installing girders

 

Step 8:

After finishing crossing piers, make a comprehensive check: check whether levelness of main longitudinal girder satisfies the demand; whether bolts and pins are connected firmly; whether current circuit are correct; whether the electric wire is worn and in extrusion; whether hydraulic system works well; whether rail joint is smooth; whether limited block coupling of crane and trolley is firm; whether rail clamping device is in working position; whether skid is smooth and the gauge dimension is correct and so on;

 

Step 9:

Have a test run with no load, especially check rail layout before transverse moving; clean sundries at two sides of transverse sliding rail, then test run of the bridge girder launcher on the rail twice, check its running condition on the rail, if there is a chewing rail problem, solve it immediately. When the bridge girder launcher works normally, install the precast girder

 

Step 10:

See sketch map to learn concrete steps to cross piers

 

2. Install the precast girder

A. Carry (feed) girder and bundle the girder

Carry precast girder from precast yard to the rear part of the bridge girder launcher by using tyre girder transporter, then use lifting trolley to lift, move and drop girders. Two girder transporters with rubber tires should carry girders at same speed, when front lifting trolley lifts one end of the girder, trolley and rear girder transporter move at a speed of 4.6m/min until the rear trolley lifts the girder, then two trolleys lift and carry girders at a speed of 4.6m/min, after finishing feeding girders, two girder transporters return to carry girders at the same speed.

  1. Before the precast girder enters the bridge girder launcher, firstly check whether there are obstacles on the complete machine to hinder girders to move forward, and check whether concrete remains on top of girders is too high to affect feeding girders;
  2. Before feeding girders, check support at rear part of the bridge girder launcher to avoid too much sink at rear part of the bridge girder launcher as feeding girders
  3. There should have someone to take care of the support seat, avoid it to collide with the machine. Appoint professional drivers to operate the girder transporter;
  4. It is forbidden for somebody to stand at the rear part of girder or on the scaffold floor to move with the girder, prevent falling objects from the girder top from hurting someone;
  5. As feeding girders, the transporter should transfer the girder slowly. Assign specialist to observe to avoid the girder or transporter to collide with the bridge girder launcher;
  6. As bundling girders, set up two sides iron tiles in a level of girders and make steel wire rope between iron tiles, check whether the steel wire rope is knotted, twisted or suspended with pole;
  7. Distances from two lifting points to two ends points of the girder should be equal, so that overload will not happen due to uneven hoist force for winch;
  8. Jack line to bundle the girder should keep vertical, no inclined hanging. It is forbidden to push transversely or longitudinally the iron carrying pole in position in order to hang jack line, avoid violent swings or sudden sliding of steel wire rope to cut off the steel wire and damage the girder body

B. Lift girder and drop girder

lift and move main girder to the transporter

a. Try lifting before lifting girders any time. After bundling the girder, make winch brake test 2-3 times, then lift the girder a little, check whether steel wire rope is in order, iron tiles to protect the girder fall off or move, start formal operation after confirmation

b. Lifting winches should act uniformly with an even force. It should be prevented strictly to have a large partial load or violent swing of girder body;

c. Keep the girder in a level in the process of lifting, moving and falling down. If found the girder is inclined with naked eyes, adjust it immediately. In order to drop girder conveniently, a little but not serious tilt is allowed

d. Prevent steel wire rope being disordered or falling off. Various obstacles influencing moving girders must be cleaned

e. Arrange specialist to monitor the girder running condition on abutment as moving girders. Especially when the girder is near to be in position, watcher, commander and operating driver on abutment should be cautious and cooperate closely, avoid the girder to collide with front support leg. If necessary, abutment watcher can pull the limit switch for safety;

f. The girder is suitable to move at a higher position, moving at lower position is likely to cause crash due to violent swing;

g. The bridge girder launcher is prohibited to lift girders with over-load

h. It is strictly prohibited to push, pull laterally the girder without relative measures as dropping the girder, avoid accidents

i. As dropping girders, must take protection measures with chain block hanged in the firm place;

C.Install the middle girders

a. It is same with that above as to feed girders, bundle girders and lift girders;

b. Two trolleys longitudinally move with girders to the position of next span;

c. Drop the girder and loose it;

d. Finish installing the middle girder

 

Trolley of the bridge girder launcher

D. Install boundary girder

a. It is same with that above as to feed girders, bundle girders and lift girders;

b. Two trolleys move longitudinally to the position of next span, then fall down the girder, make the distance between the girder and the cushion stone keep 5cm (must keep the girder stable).

c. The complete machine with girder moves transversely to the position nearest to the boundary beam, drop down the boundary beam and support it, then dismantle the hanging beam

d. The bridge girder launcher moves transversely to the reverse direction, make centre line of main girder outside coincide with that of boundary beam;

e. Lift movable pulley block of lifting trolley, move transversely trolley to the upper part of one side main longitudinal girder, then two pulley blocks fall down along main girder at one side, connected with former hanging beam;

f. The complete machine with girder moves transversely to the position of boundary beam, drop it down to the right place, boundary beam installation is finished in the abutment, safe and reliable;

g. Finish installing boundary girder

h. See the sketch map to learn concrete steps of installing boundary girder

Note:

● The bridge girder launcher can lift T-type precast girder as well as box type girder, has a wide application range, but it is needed to use special slings to lift special girders;

● Orders to install concrete precast girder: firstly install boundary girders at two sides, then middle girders, finally connect them.

 

3. Operation instructions to install special spans

● Install the first span:

As installing the first span, the middle support leg usually stands on the abutment, the foundation under transverse sliding rail of middle support leg must be solid to avoid sink accident in the process of installing girders; before the front support leg moves longitudinally, adjust height of support legs, ensure the front support leg can be in position; before the bridge girder launcher moves longitudinally, make a comprehensive examination;

As installing the first girder, always keep safety in mind because the bridge girder launcher is new, unfamiliar with the situation, do not pursue speed.

●Install the last girder

As installing the last girder, the abutment is right in front, front support leg of the bridge girder launcher must move on the abutment, so lowering the height is necessary. Short sleeve is prepared for the front support leg. As installing the last girder, we can remove all middle parts of front support leg, connect short sleeve, bracket and connection crossgirder, at the same time connect connection beam and driving gearbox, see the picture at right.

●Construct upslope bridge

After assembling the bridge girder launcher, adjust the height of middle support leg and rear bracket according to bridge gradient. Before the bridge girder launcher moves longitudinally, lower the height of rear support leg, increase the height of rear bracket, make the gradient of main longitudinal girder < 0.5%, hang a winch at front part of the bridge girder launcher to avoid the machine gliding down as moving. After the front support leg is in position, adjust the height of front support leg and level the bridge girder launcher according to the height of middle support leg, then installing girders

●Construct down slope bridge

It is same to construct down slope bridge as constructing upslope bridge. Before the bridge girder launcher moves longitudinally, lower the height of rear bracket, increase the height of middle support leg, make the gradient of main longitudinal girder < 0.5%, hang winch at rear part of the bridge girder launcher to avoid the machine gliding down as moving. After the front support leg is in position, adjust the height of front support leg according to gradient, add short sleeve between inner sleeve and connection beam as there is a large slope, and add necessary connection support, level the bridge girder launcher, then install girders

●Construct curved bridge

As the bridge girder launcher constructs curved bridge, adjust the included angle between front support leg and middle support leg according to practical situation of curved radius, and adjust the direction along main girder of front support leg and middle support leg, meet the demand to construct curved bridge.

●Construct skew bridge

Keep front support and middle support parallel according to angle of skew bridge, only adjust the position of front support and middle support along the direction of main girder, which can meet the demand of skew bridge construction

●Work requirement of the bridge girder launcher

A. Before the bridge girder launcher moves longitudinally every time, all diaphragm rebar is demanded to be welded, concrete poured between two ends of diaphragm and middle diaphragm should reach strength needed, after the supervisor accepts it, the machine can move longitudinally.

B. As each girder is put in position, set up temporary support at two sides in order to make precast girder keep vertical and stable, avoid overturn and displacement. After the second girder is in position, remove temporary support, immediately weld steel bars at two ends of diaphragm to enhance stability.

 

motor for the bridge girder launcher

(2) Operation rules and attentions:

1. Structure installation

a. It is forbidden to change structure without approval from technicians and design department;

b. Connection bolts should be tightened up according to specifications and quantity demanded;

c. It is improper to tighten up bolts used as pins, must take measures to prevent nuts falling off, split cotters bolts will be better;

d. All pins should put split cotters to avoid falling off;

e. Quantity of connection bolts have to be reduced due to wrong hole, missing bolts at each joint face should not over 5% of total numbers, and missing bolts at each connection block should not more than 1;

e. All related staff being involved in bridge construction should be trained to be familiar with the bridge construction process and key link.

2. Structure use

a. When the bridge girder launcher crosses piers and install girders, we must adjust the height of front support leg or middle support leg and transverse sliding rail, make the longitudinal gradient ≤0.5%, transverse gradient ≤0.5%;

b. Appoint specialist to command and check the machine, front support leg should be stable;

c. Set up a sound check system, check the bridge girder launcher before construction, in construction and after construction for installing one girder, find out hidden trouble and deal with it in time, ensure safe construction;

d. When the bridge girder launcher is operated in the open air, normal work wind speed should be less than 6 grade; when the wind force > 6 grade, the bridge girder launcher is forbidden to work, all mechanism should be in lock condition; work should be prohibited in thunderstorm day and cut off power supply;

e. It is strictly forbidden to put weight on the bridge girder launcher at random to add the load of the machine;

f. Before using the machine, check whether the steel wire rope is worn, whether circuit is in leakage, whether brake is reliable; all reducers and exposed gear can work after being lubricated; steel wire ropes should have at least 3 laps of security circles in the drum; surface and fixed articles of steel wire rope should be checked at every shift turn. Make a detailed examination every 7-8 days;

g. Winch braking system can be used again after examination;

h. If is forbidden for the bridge girder launcher to move longitudinally as installing girders, rail layout must be smooth with enough subballast, specially assign someone to maintain the rail track;

h. Lifting and moving speed should be slow to avoid tilt and overturn;

i. After the support legs are in position, plug in security pins to avoid hydraulic cylinder bearing force for a long time;

j. When any element or pipeline is in trouble, stop the machine immediately, appoint specialist to check and maintain the machine, the operator is forbidden to dismantle the machine without permission, as checking and repairing the machine, must cut off power supply;

k. Only specialist receiving special training can operate the bridge girder launcher; the operator must be full-time qualified personnel, it is forbidden to operate the machine without related certificates or for non-operators.

l. Overload and overheight is strictly forbidden; pulling or lift objects at an angle or pile extracting is forbidden;

m. Must set up the mark to note rated lifting capacity, span, working level and manufacturer;

n. Throwing objects down from the bridge girder launcher is forbidden; lifting objects move from people’s head is forbidden; lifting working personnel with hook or on heavy objects is forbidden; putting combustibles (such as kerosene) on the machine is forbidden;

o. In one year make a safety technology check on the bridge girder launcher; as transferring the machine every time, the bridge girder launcher can work after test run according to above mentioned installation and commissioning regulations;

p. The bridge girder launcher can not lift objects, move transversely or longitudinally at the same time;

q. Staff who are familiar with crane circuit can be responsible for maintaining electrical equipment of bridge girder launcher;

r. If current-carrying part or bare conductor shell or protection cover is not complete, it is forbidden to use the bridge girder launcher;

s. If lighting is needed as maintaining, floodlight which can carry with voltage < 36v is proper;

t. All current-carrying parts on the motor, electrical equipment and electric enclosure should be connected with ground;

u. Other unmentioned matter should be in accordance with related standards and procedures.

3. Personal security

a. Prohibit double layer work;

b. Working high above the ground should fasten the safety belt tightly;

c. Strictly follow related regulations for electric safety;

d. As installing and dismantling the bridge girder launcher, it is strictly forbidden for somebody to stand on the lifting objects;

e. Set up protection rails at top of pier cap to ensure construction safety, it is strictly forbidden for somebody to stand under the bridge girder launcher.

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