Construction Preparation

1. Site Preparation
   1.1 Select a reasonable transportation route based on engineering geology, steel girder weight, and hoisting machinery, plan the on-site storage and assembly site, and ensure the site bearing capacity meets construction requirements.
   1.2 Before installing the steel girder , re-measure the elevation, centerline of the abutment and pier top, and the span of each hole. Installation can only be carried out if the errors are within the allowable deviation range.
   1.3 After the completion of temporary structures, organize acceptance.
2. Technical Preparation
   2.1 Before processing the beam, inspect the raw materials and organize on-site welding procedure qualification tests.
   2.2 Prepare an operation instruction manual for steel girder installation.
   2.3 Carry out three-level technical disclosure for steel girder installation operations.
3. Equipment Preparation
   3.1 Inspect and accept the in-plant transportation and hoisting machinery after they enter the site and are assembled to ensure they meet various requirements.
   3.2 Complete the formalities for the assembly of large lifting special equipment.

4. Material Preparation
   4.1 The steel girder must be trial-assembled before leaving the factory, and the quality of the steel beam and the delivered documents must be inspected and confirmed to be qualified.
   4.2 Welding materials, fasteners, connection plates, and coating materials used in steel girder installation construction must comply with design and technical specifications, and relevant testing experiments must be conducted.

   

Construction Key Points

1. The steel girder should be bound and fixed during transportation, and the surface paint film of the steel beam should be protected from damage.

2. Before hoisting, after the steel wire rope and lifting gear are connected and fixed to the girder segment, they can be trial-hoisted only after being inspected and accepted by on-site management personnel.

3. Blocking blocks should be set on the temporary support to ensure the accurate planar position of the girder after hoisting.

4. After each section of the steel beam is hoisted, measure and adjust it in a timely manner.

5. After the steel beam is hoisted in place, use code plates for temporary fixation to prevent component movement.

6. The on-site welding of steel girder welds should be carried out in the order required by the design. When there is no design requirement, longitudinally proceed from the mid-span to both ends, and transversely proceed symmetrically from the centerline to both sides.

7. To facilitate construction and ensure safety, manholes should be set up, and the manholes should avoid the mid-span position. After all work inside the steel girder is completed, flaw detection should be carried out after the manhole plate is reinstalled.

Quality Control

1. When using the torque method to tighten high-strength bolts, the initial tightening, re-tightening, and final tightening should be completed within the same work shift.

2. Nondestructive testing of welds should be carried out within a certain time after welding is completed, and the testing grade and frequency should comply with specification requirements.

3. Carbon arc air gouging or other mechanical methods should be used to remove welding defects. Before removing the defects, gouge a groove conducive to repair, and use a grinding wheel to remove the oxide skin on the groove surface to expose the metal luster.

4. The ambient temperature and relative humidity during painting should comply with the provisions of the paint instruction manual. When the specified number of layers cannot reach the minimum total dry film thickness, the number of paint layers should be increased.

5. The self-deformation of the girder during hoisting should be checked and calculated to prevent permanent deformation of the structure.

Finished Product Protection

1. Warning signs and height limiters should be set below the steel beam to prevent passing vehicles and machinery from damaging the steel girder .

2. Measures should be taken to prevent equipment such as air compressors from polluting the bridge deck when placed on the bridge deck.

3. During bridge deck cleaning and other construction operations, avoid hard heavy objects such as steel bars and steel plates from colliding and scratching the steel girder and damaging the steel beam coating.

4. When hoisting and welding adjacent steel girder , partitions should be set at the completed steel beams to prevent damage and burning.

Safety, Civilized Construction, and Environmental Protection

1. Wear protective clothing and masks correctly during grinding and painting operations.

2. During construction, take noise reduction and other protective measures. Construction should try to 错开 (stagger) the rest time of nearby residents.

3. When painting inside the box, space detection instruments should be prepared, and corresponding ventilation equipment and personal protective equipment should be set up. During operation, the concentration of harmful substances in the space inside the box should comply with relevant regulations.

4. When flammable gases and dust exist inside the box, instruments that can generate smoke, open flames, and electric sparks are strictly prohibited from being brought in.

5. The gas cylinders on the high-altitude work platform should be firmly tied to prevent the gas cylinders from falling from a height and exploding to cause injury. When cutting and welding operations are carried out above, the pressure gas cylinders below must take measures to isolate welding slag and molten slag.

6. A separate storage room for work clothes should be set up.

7. Steel beam installation construction has risks such as mechanical injury, high-altitude fall, and electric shock.

8. The steel girder hoisting plan should be communicated with the design institute in advance.

9. Risk assessment should be carried out before hoisting the steel girder , and corresponding control measures and emergency response plans should be formulated.

10. Fully investigate the weather, traffic control, and other special circumstances during construction, reasonably arrange the steel girder installation plan, and control the progress risk.