The concrete steps of a steel box arch bridge grid beam concrete cast-in-place bridge deck construction method include:
 The first step, steel template production
 1.1 According to the specifications and dimensions of the grid beam, draw the "Formwork and Installation Drawing".
 1.2 The steel template is completed by purchasing steel plates and cutting on site. During the production process, the template size and welding quality are strictly controlled.
 1.3 Intermittent welding is used between the steel template stiffener and the steel template, the weld length is 100mm, the interval is 200mm, and the welding foot size is 5mm.
 The second step, steel formwork installation
 2.1 When installing the steel template, the surveyor will set the line and mark the installation position of the steel template. Then use a crane to hoist the steel formwork to the specified position on the grid beam.
 2.2 When installing the steel formwork, pay attention to the direction so that the formwork stiffener is located outside the box girder. The welding between the template and the end beam, the main longitudinal beam, the middle beam and the small longitudinal beam adopts surrounding welding, and the welding foot size is 6mm to ensure that the welding seam does not leak.
 2.3 After the installation is completed, perform a pressure test.
 The third step, construction of cast-in-place bridge deck
 3.1 Rebar processing and installation
 3.1.1 Use conventional lashing and lap welding methods for steel reinforcement construction. The steel bars are processed centrally in the processing site. The steel bars are inspected before processing and used after they are qualified.
 3.1.2 After the steel bar skeleton is processed in the steel bar processing factory, it is transported to the site for installation, which improves the construction speed. Use a crane to hoist the steel bars to the deck of the steel box arch bridge, and pay attention to the lashing spacing when lashing. When installing steel bars, pay attention to pre-embedded anti-collision guardrails and expansion joint steel bars.
 3.2 Pouring concrete
 3.2.1 According to relevant specifications, arrange relevant personnel to follow up the whole process, and the flatness, strength and thickness of the cast-in-place slab on the bridge deck must be controlled to ensure the construction quality of the asphalt concrete surface layer on the upper part of the cast-in-place slab in the future and improve the safety of passing vehicles Performance, comfort, stability and durability of bridge engineering.
 3.2.2 The bridge deck adopts C50 polypropylene mesh fiber to compensate shrinkage concrete. The specific construction technical requirements are as follows:
 Bridge deck treatment: Before concrete pouring, clean all the debris and dust on the bridge deck.
 Installation of vibrating beam track: The vibrating beam track is laid on the steel bar along the longitudinal direction of the bridge. During the installation process, the transverse slope, flatness, longitudinal slope and elevation of the track must be controlled to ensure that the top elevation of the bridge deck The elevation of the top surface of the track is the same, and the error is controlled within the allowable range of the specification. After passing the inspection of the track elevation, install the vibrating beam on the track.
 Transportation: The concrete is mixed in the mixing station according to the mixing ratio approved by the laboratory, and the concrete tanker is transported to the site. After the concrete arrives at the site, professional and technical personnel should conduct slump detection. The slump should be controlled at 16-20cm. The concrete cannot be used when segregation occurs.
 Concrete paving: Use pump trucks to pour cast-in-place bridge deck concrete. During the concrete pouring process, proceed in sequence from one end to the other to ensure uniform concrete paving, and use vibrating beams for preliminary leveling.
 Vibration: Based on the use of a vibrating rod, the vibrating beam is used for vibrating. The sign of vibrating compaction is that the concrete has stopped sinking, no more bubbles, and the surface is flat and grouty.
 Concrete harvesting and plastering: Concrete harvesting and plastering: After the concrete is poured, the first surfacing is carried out. After the initial setting of the concrete and before the final setting, a hand-held trowel is used for secondary calendering to prevent concrete cracks. The cast-in-place bridge deck is reserved as the test piece, and the standard curing test pieces (not less than two groups) are used as the basis for the strength inspection of the slab concrete; the test pieces cured under the same conditions as the slab body (not less than two groups) are used as the strength of the cast-in-place slab Basis for testing.
 After the construction of the cast-in-place slab on the bridge deck is completed, it is covered and sprinkled with water to maintain health. Covering is carried out by a cloth-membrane method, that is, "health cloth + film", which can ensure the humidity of the concrete when the surface of the concrete is wet. The health water must meet the drinking water standard, and the health time should be at least 7 days. Vehicles are prohibited during the health maintenance period.
 After the construction of the cast-in-place bridge slab is completed, the exposed surface of the steel formwork adopts the same spraying process as the steel box arch bridge for anti-corrosion construction to ensure that the steel formwork is not corroded.
 Furthermore, the cast-in-place bridge deck concrete is polypropylene mesh fiber-compensated shrinkage concrete, and the mixing amount of polypropylene fiber is 1kg/m 3.
 Furthermore, the protective coating on the outer surface of the steel formwork is "1 inorganic zinc silicate workshop primer + 1 epoxy zinc-rich primer + 1 epoxy mica intermediate coating + 1 acrylic polysiloxane topcoat" .
 A specific embodiment is provided below.
 Follow the above steps to carry out the construction. In 1.1 of the first step, draw the "Formwork and Installation Drawing" according to the grid beam specifications. The number of statistical templates is as follows:
 The specific template plane position diagram is as figure 1 As shown, all templates are arranged in 8 rows and 19 columns. figure 1 In the orientation shown, the 1st row 1 column, the 1st row 19 columns, the 8th row 1 column and the 8th row 19 columns are the first template 1; the 1st row 2-18 columns and the 8th row 2-18 columns are The second template 2; the second row 1 column, the second row 19 columns, the 7th row 1 column and the 7th row 19 columns are the third template 3; the second row 2-18 columns and the 7th row 2-18 columns are The fourth template 4; the first column of rows 3-6 and the 19th column of rows 3-6 are the fifth template 5; the columns 3-6, 2-18 of the sixth template 6 (that is figure 1 Except for the first template 1, the second template 2, the third template 3, the fourth template 4, and the fifth template 5 marked in the middle 8 rows and 19 columns, the rest are the sixth template 6). Reference to the structure diagram of six templates Figure 2-13.
 The above-mentioned embodiments only describe the preferred mode of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, those of ordinary skill in the art have made various contributions to the technical solutions of the present invention. Variations and improvements should fall within the protection scope determined by the claims of the present invention.