When the precast beam and slab of the upper structure are not in place accurately or the beam and slab are not closely attached to the support, the beam and slab must be hoisted in place or padded with steel plates to eliminate the gap.
Process flow: installation of bolt anchored pot type rubber bearing: Top reserved hole cleaning of pier and abutment → measurement and setting out → mixing epoxy mortar → installation of anchor bolt → leveling of epoxy mortar → bearing installation.
The specified value or allowable deviation of 1 bearing center and main beam center line (mm) 22 bearing deflection along the bridge direction (mm) 103 height (mm) meets the design requirements.
The consolidation of the bearing anchor bolt shall be carried out after the position of the bearing and anchor bolt is adjusted accurately.
After the bearing falls off the beam, the bottom surface of the bearing shall be closely attached to the top surface of the pier and abutment bearing pad stone.
(3) If the above conditions cannot be met after the support is adjusted to drop the beam, especially when the relative height difference of the fulcrum at the same end of the beam exceeds 2mm, the beam must be hoisted again, and the beam shall be dropped after the adjustment is in place, so that the box beam can be in place to meet the above requirements.
precautions 1.
④ The embedded depth of the bearing anchor bolt and the exposed length of the bolt must meet the design requirements.
The relative height difference of the fulcrum at the same end of the beam body shall not exceed 2mm.
4、 Quality inspection and inspection standard see table 4-1 for the quality standard of bearing installation.
3、 Disclosure contents 1.
(3) Prepare materials and mixing machines for high-strength grouting without shrinkage between the grouting support plate and the top surface of the pad stone in advance.
Before the installation of the support, each relative sliding surface shall be carefully cleaned with acetone or alcohol, and the oil storage tank of the tetrafluoro sliding plate shall be filled with silicone grease lubricant after cleaning, and the silicone grease shall be kept clean.
Material requirements: the bearing shall be provided with packing list, product certificate and bearing installation and maintenance rules.
Then, gravity grouting shall be carried out between the lower base plate of the support and the bearing pad stone, and in the anchor bolt hole.
4.
2.
The longitudinal axis of the upper and lower parts of the support must be aligned.
The performance of the leveling mortar for the base plate of the bearing shall meet the design requirements, and the grouting shall be dense without holes.
(2) According to the position of the span and in combination with the specific construction drawings, the type of support of the box girder of the span shall be accurately checked.
Three legs are not allowed for the whole hole box girder to eliminate the uneven reaction force.
Bearing materials The specification and quality must meet the requirements of the design and relevant specifications, and can only be installed after passing the acceptance.
2.
preparation basis: technical code for construction of highway bridges and culverts (jtg/t3650-2020), standard for quality inspection and evaluation of Highway Engineering (jtgf80/1-2017) and pot type rubber bearings for highway bridges (jt/t391).
Construction preparation (1) according to the construction drawings of each bridge, the concrete strength, plane position, top elevation, reserved anchor bolts and embedded steel base plates of the bearing pad stone shall be rechecked and checked, and the bearing shall be installed after confirming that they meet the design requirements.
If not specified, ± 54 bearing four corner height difference (mm) bearing pressure ≤ 5000kN ＜ 1 bearing pressure >5000kn ＜ 2 v.
4.
(4) Reliable measures shall be taken for the top surface of the formwork and pad stone for gravity grouting of the support, such as setting a layer of rubber leak proof strip at the bottom and fixing the formwork with expansion screws to prevent slurry leakage during gravity grouting.
The reserved anchor bolt hole, the gap between the top surface of bearing pad stone and the bottom surface of bearing shall be filled with pressure grouting, and the grouting pressure shall not be less than 1.0MPa.
II.
When the temperature during installation is different from the design requirements, the pre deflection of the bearing along the bridge direction shall be set through calculation.
5.
3.
(4) Chisel the bearing pad stone surface, remove the sundries in the reserved anchor bolt hole, and wash the surface with water.
The specification, quality and relevant technical performance indicators shall comply with the provisions of the current highway bridge bearing standards and meet the design requirements.
Safety requirements (1) before taking the post, all technicians, constructors and labor teams participating in the construction shall be organized to learn safety operation knowledge and receive special training; The full-time safety officer shall carry out safety technical disclosure layer by layer..
6、 Safety quality and environmental protection construction 1.
3.
See table 4-1 for the specified value of bearing installation or allowable deviation items.
Technical disclosure for installation and construction of bridge bearings I.
Grouting shall be carried out from the center of the support to all sides until all grouting materials are filled.
The Teflon sliding plate and stainless steel plate on the sliding surface shall not be scratched and must be coated with silicone grease before installation.
After the grouting material reaches the strength, the formwork shall be removed and the grout leakage shall be supplemented.
After the support is installed at the bottom of the box girder, the connecting bolts between the support and the beam body shall be tightened ② After the support is installed, the longitudinal and transverse anchor momentum of the center of the upper base plate and the lower base plate of the fixed support and the transverse misalignment of the center line of the movable support shall not be greater than 3mm, the sum of the longitudinal misalignment of the center line of the movable support and the allowable deviation of the design calculation value shall be ± 3mm, and the torsional deviation of the center line of the lower plate of the fixed support and the movable support shall be 1mm ③ When erecting the box girder, according to the location and elevation of measurement and positioning, the box girder shall be dropped on the jack first, and then accurately placed.
Operation process (1) connection and installation of bearing and box girder bottom ① the connection between bearing and box girder bottom shall be installed on the beam storage pedestal, and the position of movable bearing and fixed bearing shall be rechecked according to the longitudinal slope of the line to see whether they comply with the design, especially the unidirectional movable bearing shall pay attention to the unidirectional direction.
Scope of application: it is applicable to the installation of pot type rubber bearings in highway and urban bridge engineering.
The temporary jack can only be removed when the strength of the grouting material is greater than 20MPa, and the bridge erecting machine is forbidden to go through the hole before removing the temporary Jack.
The bearing shall be free from deflection, uneven stress and void.
(2) inspection after beam falling: immediately check whether the bearing cross line and bridge expansion joint meet the following requirements after beam falling: the error between the center line of the beam and the design position shall not exceed 3mm, and the error between the center line of the bottom surface of the bearing and the top surface of the abutment bearing pad stone shall not exceed 3mm.
Finally, tighten the anchor bolts of the lower support plate, and remove the temporary connecting angle steel of the upper and lower cover plates of the support.
It is not allowed to use crowbars to move the beam and slab.
When there is no reliable thermal insulation measures and the thermal insulation performance of grouting materials has not been tested and verified, it is strictly prohibited to carry out grouting construction under negative temperature conditions.
