There will be two nouns when bridging. Tie beams and capping beams. In fact, there is a certain difference between the two. The following is the difference between pile caps and tie beams that I have sorted out for you. I hope you like it.

The difference between capping beam and tie beam

The difference is mainly in two aspects:

First, the role is different: the role of the cap is to transfer the upper load (internal force) to the pile under the cap; The function of tie beam is to connect the ends of adjacent piles, thus enhancing the lateral stiffness of piles and improving the lateral stability of piles.

Second, the stress is different: the bearing platform not only bears the vertical force, bending moment and horizontal shear force of the column on the bearing platform, but also bears the reaction force of the pile under the bearing platform, and the stress situation is very complicated; Tie beam mainly bears axial force.

Structure of bridge bearing platform and cross beam

When the pier is high, in order to enhance the integrity between piles (columns), transverse tie beams can be set. When transverse tie beams are used to strengthen the integrity between piles, the height of transverse tie beams can be 0.8-1.0 times the pile diameter and the width can be 0.6-1.0 times the pile diameter. The strength grade of concrete should not be lower than C25. The longitudinal reinforcement shall not be less than 0.15% of the cross-sectional area of the transverse tie beam; The stirrup diameter should not be less than 8mm, the spacing should not be greater than 400 mm, and the main reinforcement of the transverse tie beam should go deep into the pile, and its length should not be less than 35 times the diameter of the main reinforcement.

The thickness and reinforcement of the cap plate should be calculated and determined according to the stress of the foundation pile. Structural requirements: the thickness of bearing base plate should be 1.0 -2.0 times the pile diameter, and not less than 1500mm; the top surface and side surface of C25 bearing platform should be provided with surface steel mesh; the cross-sectional area of each surface in both directions should not be less than 400mm, and the spacing between steel bars should not be greater than 400mm; A layer of steel mesh is set at the bottom of the pile cap, and the steel mesh is l200-1500mm in every 1m width (in all directions), and the steel bar diameter is12-16mm; When the main reinforcement at the top of the foundation pile is connected to the bearing platform, the steel mesh must pass through the top of the pile and must not be truncated, and be connected with the main reinforcement at the top of the pile; When the pile top is directly buried in the pile cap, and the compressive stress of the pile top acting on the pile cap exceeds the allowable compressive stress of the concrete of the pile cap, 1-2 layers of local steel mesh shall be added to the top surface of the pile, with the diameter of the steel mesh not less than 12mm, the length of each side of the steel mesh not less than 2.5 times the pile diameter, and the mesh size is (100 mm x/kloc-0.

The Code for Mixed Bridges of Gonggang also stipulates that when the distance between pile centers is not more than 3 times the pile diameter, the reinforced bars of the bearing platform should be uniformly arranged within the full width of the bearing platform; When the distance between the pile centers is greater than 3 times the pile diameter, the stressed steel bars should be uniformly arranged within the range of 1.5 times the pile diameter from the pile center, and the structural steel bars with reinforcement ratio not less than 0. 1% should be arranged outside this range. If there is only one direction of reinforcement in the pile cap, structural reinforcement with a diameter of not less than 12mm and a spacing of not more than 250mm shall be set in the vertical direction of the stressed reinforcement. The requirements for the spacing of steel bars are: when the steel bars are three layers or less, it should not be less than 30mm and not less than the diameter of steel bars; When more than three floors, it should not be less than 40mm and not less than 1.25 times the diameter of the steel bar. When the spacing between pile caps is equal to or greater than 3 times the pile diameter, suspenders should be set between two piles and in the middle of the pile center 1 times the pile diameter, with the diameter of suspenders not less than 12mm and the spacing not greater than 200 mm. ..

Construction scheme of tie beam of bearing platform

Firstly, earthwork excavation is carried out beside the cast-in-place pile, then a layer of C 10 concrete cushion is laid at the bottom of the foundation pit, and then construction setting-out is carried out on the cushion. According to the geometric relationship between the center position of the pile and the position of the pile cap, the outer line of the pile cap is popped up with black lines, and the redundant pile head is chiseled to the design elevation, so as to bind the reinforcement of the pile cap.

Make ribbed slab reinforcement, embed it, bind the pile cap reinforcement at the same time, control the thickness of protective layer with concrete pad, and then support the outer formwork of pile cap.

When pouring concrete, pour the platform first. After the concrete of the platform is solidified, pay off again at the top of the platform, weld the binding ribs, and then install the rib formwork. Set the rib perimeter on the platform, and use theodolite to locate the rib from two directions when pouring column concrete to ensure the verticality of the rib. When pouring column concrete, lower the casing to the bottom, and vibrate the dense concrete with the inserted vibrating rod. Concrete shall be poured in layers with a thickness of 30 cm each time.

Requirements:

1. The template should be free of dirt, mortar and other sundries, and should be thoroughly coated with release agent before use. The support shall be firm and stable, and can resist accidental collision and vibration that may occur during construction. At the same time, the support must be on the foundation with sufficient bearing capacity to ensure that excessive settlement does not occur when pouring concrete. Scaffolding should be set up to fix the ribbed slab formwork.

2. Flash butt welding and lap welding should be adopted for steel bar welding. When binding the reinforcing cage, it must be ensured that there are no more than half of the steel bar joints in the same welding section (35D or 500MM), and there must be no two joints in the same steel bar within 35D or 500MM. Steel bars shall be free from corrosion and the surface shall be clean.

3. Concrete mixing is carried out on a forced mixer. When the mixing equipment stops running for more than 30 minutes, the mixing drum should be thoroughly cleaned before mixing new concrete. When changing the cement type, the mixing equipment should be thoroughly cleaned.

4. The concrete is transported by mobile tank car, and the funnel is hoisted to the top by crane when pouring. Before pouring, the concrete temperature should be kept at 10-32 degrees. Tamp with a vibrating rod, which should be inserted vertically into the concrete and into the previous layer of concrete. In order to ensure the good combination of fresh concrete and initial concrete, the insertion depth is generally 50~ 100 mm, and the insertion rod should be used.

5, pay attention to the deformation of the template at any time when pouring concrete. After pouring, it can be cured by water or covering. During the concrete pouring of piers and abutments, concrete test blocks are made by random sampling.

Matters needing attention in pile cap construction

1. Cofferdam for pile caps and excavation of foundation pit shall comply with relevant regulations.

2. The operating platform and supporting system should be firmly connected and can bear the weight of all construction personnel, machinery and materials.

3. When taking soil, sucking mud or pumping water in the cofferdam, the stability of the cofferdam and the scouring situation in the cofferdam should be checked frequently, and measures should be taken to prevent the cofferdam from tilting.

4. Chisel out the concrete of over-poured pile head shall meet the following requirements:

(1) Grooving shall be carried out from top to bottom.

(2) When two people are working, they should echo each other and coordinate with each other. When many people work, there should be a special person to direct.

(3) The use of pneumatic tools must be carried out in strict accordance with the operating procedures, and protective equipment should be worn.

(4) When chiseling by hand, the sledgehammer must be installed firmly, and the brazing person should use a fixture, and the brazing person cannot wear gloves or operate face to face with the brazing person.

(5) Remove the dismantled fragments in time.

5. In the structure of high bearing platform, after the concrete pouring of bearing platform and pier is completed, the steel structure above the top surface of bearing platform should be removed to avoid endangering the safety of navigable ships and causing the accumulation of floating objects in flood season.

I guess you like it.

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