(1) ingredients

According to the data of wet joint width per span, steel bars are mixed in the steel bar processing site in advance, then bent and transported to the site for binding and molding at one time. make steel

Skeleton should be carried out on a flat ground to ensure the cleanliness of steel bars. Steel bars shall be free of dust, rust, loose rust and oil stain.

Paint, grease, oil or other foreign matter, without harmful defects. The fabrication and installation of steel bars shall be carried out in strict accordance with the construction drawings and technical specifications.

Ensure the welding quality.

(2) Binding steel bar

When steel bars are bound and assembled at the site, the steel bars shall be arranged in strict accordance with the requirements of the drawings. All intersections of reinforcement shall be bound, or

Weld firmly with spot welding. In order to avoid displacement when pouring concrete, it is not allowed to install or insert steel bars after pouring concrete. In order to ensure the protective layer

Thickness, cement mortar pad should be set between reinforcement and formwork, and the pad should be firmly bound with reinforcement and staggered. Connect the beam head at the continuity

When the reinforcement is reserved, the main reinforcement is reserved for the beam head reinforcement for the convenience of construction, so when the lap welding connection is adopted, if the length does not meet 10d,

When welding the length, 5d double-sided welding will be adopted.

Second, the diaphragm wet joint template construction

Template surface should be kept bright and clean without deformation, joints should be tight. Nail a sponge between the bottom die and the side die. When the formwork is tightened, the sponge will be compressed.

It can prevent mud from leaking. In order to prevent formwork deformation and displacement, and ensure the size of components, tension is used between formwork to prevent casting.

When building concrete, the mould will expand. Apply engine oil on the inner side of the template to facilitate demoulding. After the template is installed, the position should be kept correct. come down in torrents

When it is found that the template may exceed the allowable deviation deformation value, it should be corrected in time. Precast beams are directly used for wet joints of clapboards.

The diaphragm is used as the end formwork, and two end plates are erected on the prefabricated transverse diaphragm as the side formwork.

Third, concrete pouring

Concrete is mixed in the mixing station, transported by mixer truck, and poured into the formwork through comb groove. Layered slope casting is adopted for casting.

During construction, the plug-in vibrator vibrates. When using the plug-in vibrator, the moving distance shall not exceed 1.5 times of the action radius of the vibrator, and the side formwork shall be used to ensure it.

Keep the distance of 50~ 100mm, insert the lower concrete 50~ 100mm, and slowly boost the vibration while vibrating at each place.

Move the pull rod to avoid collision with formwork, steel bars and other embedded parts. For each vibrating part, it must be vibrated until the concrete in that part is dense.

The sign of compactness is that the concrete stops sinking, there are no more bubbles, and the surface is smooth as slurry. When pouring concrete, keep the test block.

And make records. When pouring wet joints, attention should be paid to avoid the collision between the vibrator and the bottom plate.

Fourth, maintenance

Because its construction is mainly concentrated in summer, the concrete surface can be maintained by sprinkling water after the final set, and the maintenance period is not less than 7 days. in the sun

When it is strong, it can be covered with linen to prevent shrinkage cracks after sun exposure. Concrete curing and construction joints should be strengthened.

Treatment, to ensure that the concrete is not affected by exposure and external load before reaching the strength.

Extended data

1. The diaphragm is a member arranged between beams to maintain the cross-sectional shape and enhance the lateral stiffness. It acts on the live load distributed on the bridge.

Use. Diaphragm is an important part of the overall spatial structure of the bridge, and it must have sufficient strength and stiffness. The more rigid it is.

The bigger the bridge, the better the integrity of the bridge, and the main beams can work better together under the load.

The function of diaphragm is to maintain the lateral stability of bridge and ensure the integrity and mutual adjustment of main girder in T-beam and other open-section beam bridges.

The torsional stiffness of this kind of beam is improved by the uneven load of the whole beam. At the same time, the diaphragm can also be connected to the main beam in the horizontal direction.

As a whole, it bears lateral horizontal load. Setting diaphragm in the box girder can improve the torsional stability of the beam and increase the cross section.

Directional stiffness, limiting deformation stress.

2. The partition is an important part of the whole space structure and must have sufficient strength and rigidity. The more rigid it is.

The bigger the bridge, the better the integrity of the bridge, and the main beams can work better together under the load. At the same time, the diaphragm should be strong enough.

Degree transfer load. The diaphragm at the bearing is also responsible for bearing and distributing large supporting reaction.

3. In a straight beam bridge with open cross section, the spacing between internal diaphragms is generally 5m ~ 7m, the thickness is 12cm ~ 20cm, and the height is the main beam.

About three quarters of the height. The height of the end partition is usually the same as that of the main beam. This is just a general empirical dimension, and its strength and stiffness are

Whether it can play its due role requires calculation. Generally, rigid beam method and G-M method can be used to calculate the internal force of diaphragm.

Method. Firstly, the internal force influence line of diaphragm is obtained, and then the internal force is calculated by loading on the influence line.

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