② In order to ensure the accurate and vertical position of vertical prestressed reinforcement, positioning reinforcement is used in the middle and angle steel is used on the top.
It is required that the tie rod must be installed during the construction process to ensure the overall appearance quality of the beam body.
Before installation, both ends shall be blocked with wide adhesive tape and tied firmly with ordinary reinforcement with binding wires.
③ Transverse prestressed steel strand and corrugated pipe shall be installed after the installation of vertical and longitudinal prestressed pipes.
(1) After the bottom formwork and external formwork are installed and corrected, the bottom plate and web reinforcement shall be bound.
(3) The top surface of the support shall be kept at the same height, and longitudinal and cross beams shall be laid above it.
① resistance wire is set inside the sulfur mortar support.
The vertical prestressed reinforcement shall be cut by cutting machine, and the prestressed reinforcement shall be installed vertically in advance.
0# block bottom formwork adopts bamboo plywood, side formwork adopts hanging basket external formwork and large steel formwork, internal formwork can be assembled with steel formwork or bamboo plywood, and end formwork adopts steel formwork.
2.5 installation of prestressed tendons (pipes) continuous box girder is a three-way prestressed system with dense pipes.
The internal formwork is assembled by standard steel formwork or large bamboo plywood and supported by trusses.
The reserved holes are made of hard plastic pipes.
(4) After the laying of the support preloading bottom formwork, the preloading shall be carried out according to the design requirements.
The support elevation shall be controlled according to the design requirements, and the error shall not be greater than 5mm.
The plug plate is perforated at the position of the prestressed pipe to extend the prestressed tendon bellows.
The adjustment principle is to first ordinary reinforcement, then vertical prestressed reinforcement, and then horizontal prestressed reinforcement, so as to keep the position of longitudinal prestressed reinforcement unchanged.
According to the pre camber in the preloading analysis report, the pre camber after the prestressed construction of the whole bridge and the pre camber generated by the creep of phase II dead load concrete, the bottom formwork elevation is calculated, and the bottom formwork is adjusted to the design elevation by thickening the bottom formwork or adjusting the square timber.
During removal, power on the resistance wire to melt sulfur and fall off the support.
Then the steel pipe column shall be welded on the flange or steel plate, and the weld shall be full and dense.
Square timber shall be laid on its upper part, wedge-shaped wood blocks shall be padded, the angle of bottom formwork shall be adjusted, and then the bottom formwork shall be laid.
Prevent the deviation of Web corrugated pipe caused by moving web reinforcement in subsequent processes.
The four corners of a single support shall also be kept flat, and the error shall not exceed the specification requirements.
Because 0# it is a variable section structure, the concrete volume is large, and the side pressure has a great impact on the chamfer of the bottom plate, the side formwork of the manhole and the outer formwork.
2.4 reinforcement installation reinforcement shall be centrally processed and manufactured by the reinforcement processing workshop and transported to the site for binding and forming.
The steel pipe columns and the steel pipe columns are connected with the pier body with section steel.
The PVC pipe shall be penetrated into the pipe to keep the pipe straight.
No matter what kind of support materials and methods are used, the stiffness and stability shall be checked and calculated, and the preloading shall be carried out after the support is erected.
The temporary support can be in the form of sulfur mortar support, steel sand cylinder, etc.
When installing the support, adjust the support deviation according to the temperature during installation.
The outer formwork adopts steel formwork, and the frames on both sides are directly supported on the longitudinal beam under the wing plate.
2.3 formwork installation box girder construction formwork shall be processed according to the design drawings and specifications.
(3) After the web and diaphragm reinforcement is completed and the internal formwork is installed, the upper chamfered reinforcement of diaphragm and the lower chamfered reinforcement of top plate can be bound.
Electric welding and oxygen burning are strictly prohibited.
(1) The floor support can be steel pipe column support, Bailey frame, universal rod, etc.
When removing, open the sand outlet, the fine sand flows out, and the sleeve falls down by itself.
2.2 bearing installation (1) the permanent bearing must have inspection certificate and product certificate when leaving the factory, and be inspected according to relevant standards.
(6) When the prestressed pipe collides with the reinforcement skeleton, the reinforcement shall be moved and cut off is prohibited.
The blanking of steel strand and finish rolled deformed steel bar shall be cut by grinding wheel cutter according to the predetermined blanking length.
The support must be positioned correctly.
The gasket and nut shall be installed firmly and strengthened locally at the diaphragm.
When using other supports for construction, it is also necessary to ensure that the column is vertical, the cross brace is horizontal, and the cable-stayed connection is firm.
The bottom formwork is made of 1.5cm thick bamboo plywood, and the joints are ground with atomic ash.
(2) After the bottom plate reinforcement is bound and before the web reinforcement is installed, the internal formwork support shall be set up, which plays the role of web reinforcement scaffold.
When the deformation is stable, the counterweight shall be removed for unloading, the measurement data shall be analyzed, the camber value of the bottom formwork shall be calculated, and the elevation of the bottom formwork shall be adjusted through the bracket and wooden wedge.
② The steel sand cylinder is in the form of sleeve, and a sand outlet is set at the lower part.
The deviation of bearing along the bridge direction is almost 10mm, and the deviation across the bridge direction is no more than 2mm.
In case of contradiction between the anchor end of vertical prestressed reinforcement and the reinforcement position of pier body, the position of anchor base plate and spiral reinforcement under anchor shall be ensured to be accurate, and the reinforcement position of pier body shall be adjusted.
Before pressing, the observation points shall be arranged on the bottom formwork, and the elevation of the corresponding observation points shall be measured regularly.
It shall be pumped out after the initial setting of concrete pouring.
It can be used only after passing the inspection.
Pier body brackets are mostly processed from steel pipes, I-beams and other section steels.
When there is a conflict between the position of prestressed pipe and ordinary reinforcement, local adjustment can be carried out.
The outside of the plug plate is reinforced with transverse steel pipes.
All reinforcement shall be lifted by crane, grouped into formwork according to the sequence of installation, and shall be covered with rainproof cloth during construction interruption to prevent rain and rust.
If the requirements cannot be met, the foundation treatment must be carried out for the range of support erection.
After determining the position of the temporary support, erect the formwork, insert the resistance wire and pour sulfur mortar.
After preloading and unloading, 0# the warped parts at both ends shall be raised with wooden wedges.
The longitudinal prestressed steel strand shall be threaded through the short strand by the threading machine, and the whole strand shall be pulled through the long strand by the winch.
The installation position and elevation of temporary support must be strictly controlled.
After the inelastic deformation of the support is eliminated, the box girder concrete can be poured.
Construction of cantilever pouring continuous beam 0# section 1.0 construction process 2.0 construction methods and requirements 2.1 when erecting cantilever pouring continuous beam across highway and railway, 0# block generally adopts floor support, and some high piers rely on pier body with triangular support.
Before installation, comprehensively check whether the support parts are lost or damaged, and clean each sliding surface with acetone or ethanol.
Sand bags and concrete blocks shall be used as loads to make the load strength consistent with the load strength distribution of the beam.
Pour fine sand into the steel sleeve, connect the upper and lower sleeves, adjust the sand amount and control the height of the sand cylinder.
The duct positioning reinforcement shall be arranged according to the design requirements, and shall be properly densified at the starting point and curve.
The preloading weight is 105% ~ 110% of the dead weight of the box girder.
(2) When the steel pipe column bracket is used, the flange plate or steel plate shall be embedded on the bearing platform and pier body according to the bracket design drawing during the construction of bearing platform and pier body.
During concrete pouring, the PVC pipe shall be pumped frequently to prevent the prestressed corrugated pipe from leaking and blocking the PVC pipe.
I-beam and other section steels are generally used.
(5) During the construction of 0# block, attention shall be paid to the setting of anti-skid facilities between the embedded reinforcement mesh under the main beam support, the measuring embedded parts, the rear lifting point of the hanging basket bottom formwork platform and the reserved hole of the rear anchor bar, the embedded reinforcement of the hanging basket walkway beam, the drain hole, the vent hole, the reserved hole for support removal, the lower lifting point of the rear anchor bar and the beam concrete.
The transverse prestressed steel strand shall be threaded first and then installed..
The position shall be accurate and the installation shall be firm.
During cross water construction, according to the actual situation of the site, the floor support can be used when the cofferdam is not removed, or the pier body bracket can be directly used.
① The longitudinal prestressed longitudinal prestressed pipe shall be provided with positioning reinforcement for positioning.
(2) Temporary support temporary support is the support beam body during cantilever casting and an important component to protect the permanent support.
At the end of the box girder section, a plug steel plate is set, and the steel plate is reserved with slots to extend the longitudinal reinforcement of the box girder out of the formwork.
(4) Note that before the installation of the internal formwork, the cross points of the bound reinforcement shall be welded firmly.
The tie rod shall be reinforced with more than 20mm.
If the support does not fall on the bearing platform, the bearing capacity of the foundation must be tested to meet the settlement requirements before the support can be erected.
The supports on both sides of the T-structure are symmetrical and balanced, and the whole is stable and firm.
