Key points of arch bridge construction

1. The main construction method of arch bridge

【Formula】The cable is strong and the suspension is less

The arch (support mode) of arch ring construction can be divided into support method, less support method and no support method; wherein support construction comprises cable hoisting, rotating body installation, stiff skeleton, cantilever pouring and cantilever installation and the combination of one or several construction methods above.

2. Basis for the selection of arch bridge construction methods

【Formula】Cross-knot Shi homonym: cross-knot

The selection of construction methods should be based on the span, structural form, on-site construction conditions, construction level and other factors of the arch bridge, and determine the reasonable construction method through the technical and economic comparison of the scheme.

3. Arch bridge arch selection

【Formula】The topography and foundation are navigable, and the material structure is strong and stable

When selecting the arch, the technical and economic comparison should be carried out in many aspects in combination with the actual conditions such as the topography, foundation, navigation requirements, and water crossing capacity of the bridge position. The main principle is that the arch should have sufficient strength, stiffness and stability, and at the same time it is required to be easy to take materials, simple in structure, clear in force, easy to make and assemble and disassemble, and can be reused.

4. General provisions for the construction of cast-in-place arch bridges

【Formula】Standardize the temperature of strong sample closing

(1) The manufacture of steel components of concrete-filled steel tubular arch bridges, rigid skeleton arch bridges and steel arch bridges shall comply with the relevant provisions of Chapter 14 of the Code for Construction and Quality Acceptance of Urban Bridge Engineering CJJ2-2008 on the manufacture of steel beams.

(2) When the prefabricated arch bridge component is hoisted, the strength of the concrete shall not be lower than the design requirements, and when the design is not required, it shall not be less than 75% of the design strength value.

(3) arch ring (arch rib) lofting should be set according to the design requirements of the pre-camber, when the design is not required, according to the size of the span, dead load deflection, arch stiffness and other factors to calculate the pre-camber, the vault should be taken to calculate the span of 1/1000 ~ 1/500. When lofting, the horizontal length deviation and arch axis deviation: when the span is greater than 20m, it shall not be greater than 1/5000 of the calculated span, and when the span is equal to or less than 20m, it shall not be greater than 4mm.

(4) The temperature of the arch ring (arch rib) sealing arch closure should meet the design requirements, and when the design is not required, it should be carried out at the local annual average temperature or 5~10 °C.

5. Cast-in-place concrete arch ring

【Formula】16 compartments are poured ribs, and the strong amplitude is divided when the dragon is closed

(1) The arch ring or arch rib concrete with a span diameter of less than 16m should be poured symmetrically and continuously from the arch feet at both ends to the vault according to the full width of the arch ring, and all should be completed before the initial setting of the concrete at the arch foot. When it cannot be completed, a partition should be reserved at the arch foot, and the partition concrete should be poured at the end.

(2) The arch ring or arch rib with a span diameter greater than or equal to 16m should be poured in sections. In the segmented position, the arch arch should be arranged at the arch stress bending point, the arch node, the arch and the arch foot, and the full cloth arch should be arranged at the vault, 1/4 span, arch foot and arch node, etc. The joint surface of each section should be perpendicular to the arch axis, and the interval groove should be reserved for each segmentation point, and its width should be 0.5~1m. When it is expected that the deformation of the arch is small, the spacer groove can be reduced or not set, and the segmented interval pouring should be adopted.

(3) The sectional pouring procedure should meet the design requirements and should be carried out symmetrically at the vault. The concrete in each section should be poured continuously at one time, and when interrupted for some reason, the construction joint should be chiseled into a plane or stepped joint surface perpendicular to the arch axis.

(4) The concrete pouring of the spacer groove should be carried out symmetrically from the arch foot to the vault. It should be carried out after the concrete segmentation of the arch ring is poured and the strength reaches 75% of the design strength and the joint surface is treated according to the construction joint.

(5) When pouring the reinforced concrete arch ring (arch rib) in sections, the longitudinal length of the steel bar shall not be used, and the steel bar joint shall be installed in several spacer grooves after pouring, and shall be welded when pouring the concrete of the spacer groove.

(6) When pouring large-span arch ring (arch rib) concrete, it is advisable to use the ring (layer) segmentation method to pour, or longitudinal frame pouring, the middle width of the first pouring of the dragon, after reaching the design requirements, and then the transverse symmetry pouring of the other widths of the dragon.

(7) the concrete strength of the arch ring (arch rib) sealing the arch closure dragon should meet the design requirements, when the design does not require, the concrete strength of each section should reach 75% of the design strength; when the arch ring stress is adjusted by the method of applying pressure with a jack before sealing the arch closing dragon, the concrete strength of the arch ring (including the poured spacer groove) should reach the design strength.

6. Technical points for the installation of prefabricated truss arches and rigid arches

【Formula】Wet connection of the ceiling, close the installation and observation

(1) When the prefabricated truss arch and rigid arch adopt horizontal prefabricated arch, in order to prevent the arch from twisting in the lifting process, the whole piece must be lifted horizontally when lifting, and then suspended and erected. In the whole process of the arch hanging over, the force of each hanging point should be uniform, and always remain in the same plane, and must not be twisted.

(2) For large-span truss composite arches and vault wet-joint concrete, it is advisable to use early-strength concrete with a higher strength than the concrete strength of the components.

(3) During the installation process, the total station should be used to observe the deflection and lateral displacement of the arch rib and arch ring, concrete cracks, pier abutment displacement, and the deformation and displacement of installation facilities.

(4) When the arch rib is hoisted and positioned, the elevation of the joint and the position of the axis should be observed to control and adjust the arch axis to meet the design requirements. After the arch rib loose cable is arched, from the construction and loading of the arch to the completion of the arch building, the deflection and lateral displacement of the 1/4 span, 1/8 span and each point of the vault should be observed at any time.

(5) The observation and control of the construction of long-span arch bridges should be carried out when the daily temperature and sunshine do not change much, so as to minimize the influence of unfavorable factors such as temperature changes.

7. Regulations on the production of steel pipe arch ribs

【Formula】The pipe is long bent, and the welding is fortified

1) The types and specifications of the arch rib steel pipe should meet the design requirements, and should be added in the factory with a product certificate.

2) The segmented length of steel pipe arch rib processing should be determined according to factors such as material, process, transportation, and hoisting. Before making, the size of the closing section should be determined according to the influence of temperature and welding deformation, and the construction details should be drawn for accurate lofting.

3) The elbow should be heated and pressed by pressing at a temperature of 800°C.

4) The welding strength of the arch rib segment should not be lower than the strength of the base metal. All welds should be visually inspected, butt welds should be 100% ultrasonic tested, and their quality should meet the design requirements and the current national standards.

5) Concrete injection holes, backflow stop valves, exhaust holes, buckle points, and hanging point gusset plates should be set on the steel pipe arch ribs

6) The exposed surface of the steel pipe arch rib should be treated with long-term protection according to the design requirements.

8. Regulations on the installation of steel pipe arch ribs

【Formula】Tie the buckle and connect the rope, and the girth welds the dragon

1) In the process of arching the steel pipe arch rib, the transverse connection should be installed at the same time, and the uninstalled connection shall not be more than one section, otherwise temporary lateral stabilization measures should be taken.

2) The welding of the girth weld between the segments should be carried out symmetrically, and the positioning plate should be used to control the weld gap, and the surfacing welding should not be used.

3) The welding or bolting operation of the closure port should be quickly completed in the period when the ambient temperature is relatively stable.

4) When the cable-stayed cable suspension method is used for construction, the safety factor should be greater than 2 when the cable is made of steel strand or high-strength steel wire bundle.

Yesterday 速记口诀4/21

1. Steel-concrete combined beam composition

Steel girder shear bridge deck

2. Scope of application of steel-concrete knot (group) beam

The large span of the city affects the reduction of its own weight

3. The basic process flow of steel-concrete knot (group) beam

Pre-shear frame plate pouring joints (or mold reinforcement), watering tension and dismantling temporary support

4. Technical points of steel-concrete knot (group) beam

The bracket is accepted and mixed, and the pouring is monitored and dropped by the table

Three days ago, shorthand mantra 4/19

1. Cast-in-situ prestressed concrete continuous beam by bracket method

The foundation is arranged, the landing frame is dismantled, the pre-arch is eliminated, and the sinking is avoided

2. Pouring a prestressed concrete continuous beam on the moving formwork

Long group seams, poor built-in

3. Design and assembly of hanging baskets

Quality-ratio variable tilt anchor limit inspection

4. Pouring paragraph

Top 0 overhang

5. Suspension pouring sequence

0 side neutralization

6. Check the content of the beam section before pouring concrete

The backboard rib tube is buried, and the machine is mixed with the seam

7. The tensile sequence of the longitudinal prestressed tendons of the roof and web of the prestressed concrete continuous beam

Pull symmetrically up and down, left and right

8. Prestressed concrete continuous beam closure sequence

Edge times

9. Closing regulations for continuous beams (T structures).

Duan Changguan is even loose, and the warm mix is pre-pressurized

10. System conversion regulations for continuous beams (T structures).

Tension and grouting are about to be released

11. Provisions for the adjustment of the bearing reaction force of continuous beams (T structure).

High dominant

12. Elevation control of cantilever pouring method

The temperature has been poured pre-deformed

Seven days ago, shorthand mantra 4/15

1. Bridge maintenance

Maintenance and other technical day maintenance, minor damage repair is small, and the general repair is high

2. Requirements for bridge reconstruction design and construction

The bridge line is divided into a bridge, the aperture of the upper and lower mechanisms is high, and the settlement of the structure is small

3. Common maintenance and reinforcement techniques

Viscosity pre-modification

4. The connection mode of the old and new bridges

The board box is hinged with the T beam rigid

5. General provisions for cofferdam construction

Shiwei demolition is high, and the prevention is reduced in the plane

6. The scope of application of various types of cofferdams

The water depth and flow rapidly permeate the riverbed

7. Construction requirements for earth cofferdams

Clean fill rammer, top wide slope margin

8. Construction requirements for soil bag weirs

Build a wall in the side slope yard bag, and the distance between the top width and the soil is the same

9. Construction requirements for steel sheet pile cofferdam

Set up a point to twist the seam to prepare a guide, hammer down to vibrate and sink the investigation, repair and weld the pile for a long time

10. Construction requirements for reinforced concrete sheet pile cofferdam

Section stiffening angle, mold tenon water channel

11. Construction requirements for casing cofferdams

Leak-proof

12. Construction requirements for double-walled steel cofferdam

The factory is divided into joint transportation, the cable chain ingot is irrigated, and the back cover is observed

Two weeks agoShorthand mantra 4/8

1. Design and verification of templates, brackets and arches

The knot is rigid and stable, the pre-arching force of the load, the rod base is set with a symbol, and the rigidity is checked and the anti-tilt is checked

2. Construction design basis

Knot across the load place to prepare

3. Construction design content

The general situation is based on the book materials, and the safety system is required to be dismantled

4. Load combination when designing templates, brackets and arches

12 self-weight, 5 side pressure, 3 walks, 4 vibrations, 6 tilting, wind and snow heat preservation 7 water, rigid and strong static movement.

5. The deformation value of the formwork, bracket and arch

Lu Lu 4 Bai Yin 25, 500 hoops 1.5.

6. The construction precamber of the formwork, bracket and arch should be considered

Bullet non-bullet pre-sinking

7. Production and installation of brackets and arches

The pressure base is forbidden to bubble and frozen, the column is in the middle of the hole, the support is not altogether, and the pressure frame is inspected in multiple layers.

8. Template production and installation

Cooperate with the pier platform tilt and check the special argument

9. Regulations on the installation of inflatable capsule core molds

When checking for leaks and stabilizing voltage

10. Provisions for the removal of formwork, brackets and arches

非不损，承加重，芯内不塌缝。

11. Regulations on the unloading of the arch of the mortar masonry and concrete block arch bridge

Pulp 80, small finish, solid arch protection, large empty arch horizontal

12. The principle of circular dismantling of formwork, bracket and arch

Split longitudinal and horizontal