CN110396918B - Assembled hollow pier system equivalent to cast-in-situ and construction method thereof - Google Patents

Abstract

A prefabricated hollow bridge pier system equivalent to cast-in-place and its construction method. The system includes a prefabricated cap platform with metal bellows pre-embedded, and prefabricated pier body segments with longitudinally connected steel bars at the ends. The prefabricated pier body segments It includes prefabricated pier bottom segments, prefabricated pier middle segments, and prefabricated pier top segments that are integrally prefabricated with the pier caps, and prefabricated guide blocks for assembling adjacent prefabricated pier body segments; the construction method is to first place the prefabricated bearings. The platform is hoisted into place, and then ultra-tough fiber concrete (UTFC) grouting pipes are used to connect the prefabricated pier bottom segments and the prefabricated cap as a whole. After that, ultra-tough fiber concrete (UTFC) wet joints are used to connect adjacent prefabricated units. The connection between the pier body segments is finally assembled into the entire bridge pier. The invention has the advantages of fast construction speed, little impact on the traffic at the construction site and the surrounding environment, easy control of component quality, and good seismic resistance, high stiffness, high toughness, and durability. Good, good fatigue resistance and other characteristics.

Description

An assembled hollow bridge pier system equivalent to cast-in-place and its construction method

Technical field

The invention relates to the field of prefabricated bridge piers, and in particular to a prefabricated hollow bridge pier system equivalent to cast-in-place and a construction method thereof.

Background technique

Prefabricated bridge construction technology has been widely used in bridge engineering construction due to its short construction period, small impact on traffic, batch production of prefabricated components in factories, and easy quality control. Prefabricated bridge construction technology has become a bridge The main development trends of engineering construction. However, the seismic performance of prefabricated bridge piers is not completely clear, and its application in bridge projects in medium- and high-intensity earthquake areas is greatly restricted. The main reason is that in the current ductile seismic design of bridges, bridge piers are usually used as ductile components in the bridge structure. They dissipate seismic energy through the development of plastic hinges and thereby protect the remaining components of the bridge. The behavior of plastic hinges is also the same as in traditional integral cast-in-situ reinforced concrete ductile bridge piers. Typical characteristics under seismic loads, and the connection of prefabricated components in most current prefabricated pier systems may affect the formation of the pier's plastic hinges, which in turn affects the seismic performance of the entire bridge structure. These factors have led to the development of prefabricated pier technology. At present, it is difficult to widely promote and apply it in medium- and high-intensity earthquake areas.

The current research and development on the prefabricated bridge pier system mainly involves dividing the bridge pier vertically into a number of prefabricated pier body segments, and applying prestressing force through prestressed tendons to vertically assemble each prefabricated pier body segment into a whole bridge pier. Prestressed prefabricated pier systems are widely used in bridge projects in non-seismic fortification areas and low-intensity earthquake areas. However, for bridge projects in medium- and high-intensity earthquake areas, this type of prefabricated pier system will lose its cap and piers under the action of earthquake loads. The joints and the joints of each prefabricated pier segment are prone to stress concentration, and there are poor energy consumption performance, loss of prestress, and stress characteristics that are significantly different from traditional integral cast-in-place piers. The use of prestress increases the construction time. Difficulty and project cost, etc. These factors make it difficult to promote and use relevant research results in bridge projects in medium- and high-intensity earthquake areas. In addition, the selection of pier types at the current stage has gradually transitioned from the original gravity-type piers to light-weight piers. The connection processing between each prefabricated pier body segment in the prefabricated hollow pier is a key issue in the design. The connection structure is properly designed and No, it will directly affect the overall mechanical performance of the bridge pier as well as the construction period and on-site construction safety.

One type of prefabricated pier currently suitable for seismic areas is the equivalent cast-in-place prefabricated pier system, that is, a prefabricated pier with similar stress characteristics and seismic performance as traditional monolithic cast-in-place reinforced concrete piers, as well as predictable plastic hinge behavior. system. Research has proven that grouting pipe connections and wet joint connections are a cost-effective connection method for prefabricated bridge piers. However, these two connection types have problems such as the large connection length that may affect the plastic hinge behavior of the bridge pier. Therefore, developing an equivalent cast-in-place prefabricated pier system that is cost-effective, fast and feasible to construct is still a technical difficulty faced by the current application of prefabricated pier construction technology in bridge projects in earthquake areas.

Contents of the invention

In order to overcome the shortcomings of the existing technology, the present invention provides a cast-in-place assembled hollow pier system and its construction method, using ultra-tough fiber concrete (UTFC) grouting pipe connections and ultra-tough fiber concrete (UTFC) wet joint connections. Complete the connection between the precast pier bottom segments and the precast caps and adjacent precast pier body segments respectively, which can effectively reduce the connection length required for grouting pipe connections and wet joint connections, and improve the mechanical properties of the joints. Combined with reasonable structural design, the prefabricated hollow pier system reaches the same performance level as cast-in-place in terms of stress characteristics and seismic performance. It has good integrity, good seismic performance, high stiffness, high toughness, good durability, and practical construction. Feasibility and other advantages.

In order to achieve the above objects, the technical solution of the present invention is implemented as follows:

A prefabricated hollow bridge pier system that is equivalent to cast-in-place, including a prefabricated cap platform 1 set on the foundation soil layer. A pier is provided above the prefabricated cap platform 1. The bridge pier is assembled from prefabricated pier body segments 5. Each prefabricated pier body is The section 5 includes a prefabricated pier bottom section 16 , a prefabricated pier middle section 14 and a prefabricated pier top section 7 that is integrally prefabricated with the pier cap 6 .

The prefabricated cap 1 and each prefabricated pier segment 5 are prefabricated with ordinary reinforced concrete materials, and are equipped with longitudinal steel bars 12 and transverse stirrups 13 inside; the prefabricated cap 1 has metal bellows 2 embedded inside. , the top surface is provided with a groove 3; each of the prefabricated pier segments 5 has a hollow rectangular cross-section, and is provided with longitudinal connecting steel bars 18 and supporting tooth blocks 15 at both ends or one end.

The supporting tooth blocks 15 at the bottom of the precast pier middle section 14 and the precast pier top section 7 are pre-embedded with thick-diameter internal threads and bolts 8, and the supporting tooth blocks at the top of the precast pier bottom section 16 and the precast pier middle section 14 are pre-embedded. 15 is provided with shear nails 11 and steel plates 9 .

The precast cap 1 and the precast pier bottom segment 16 are connected by UTFC grouting pipes to complete the splicing, and the adjacent precast pier body segments 5 are connected by super tough fiber concrete UTFC wet joints to complete the splicing; the UTFC The inner cavity of the pier at the wet joint connection is provided with prefabricated guide blocks 19 for assembling each prefabricated pier segment and transverse supporting steel bars 20 for supporting the prefabricated guide blocks 19. The prefabricated guide blocks 19 are prefabricated from gypsum material, and the cross-section The form can be hollow or solid section.

In the UTFC wet joint connection, the longitudinal connecting steel bars 18 between adjacent prefabricated pier segments 5 are overlapped, welded, mechanically connected, or memory alloy connected, and the UTFC wet joint connection setting length L is as follows: Calculate to determine:

In the formula:

d is the diameter of longitudinal connecting steel bar 18;

f _s is the longitudinal connecting steel bar 18 strength, take f _s =max (1.5f _y , _fu ), where f _y is the longitudinal connecting steel bar 18 yield strength, f _u is the longitudinal connecting steel bar 18 ultimate strength;

f _UTFC is the measured compressive strength of super tough fiber concrete UTFC material for 28 days;

α is the influence coefficient of the diameter of the longitudinal connecting steel bar 18. When d=12mm, α=1.0; when d=32mm, α=1.2; when d is between 12 and 32mm, the value of α is determined by linear interpolation;

c is the influence coefficient of the longitudinal connecting steel bar 18 connection processing. When the longitudinal connecting steel bars are overlapped, welded, mechanically connected, and memory alloy connected, c is taken to be 1.0, 0.5, 0.65, and 0.87 respectively;

The longitudinal connecting steel bars 18 in the UTFC grouting pipe connection are provided with longitudinal bar stripping sections 17 of 4d length.

The construction method of the prefabricated hollow pier system based on the above equivalent to cast-in-place:

Step 1: Lift the prefabricated cap 1 into place, hoist the prefabricated pier bottom section 16 and the prefabricated cap 1 for pre-assembly, then pour UTFC4 into the pre-embedded metal bellows 2 and groove 3, and then install the prefabricated pier bottom section. Section 16 is hoisted to the predetermined position and fixed with brackets, and the prefabricated pier bottom section 16 and the prefabricated cap 1 are assembled;

Step 2: Lift the prefabricated guide blocks 19 to the lateral supporting steel bars 20 of the prefabricated pier bottom section 16, and then hoist the adjacent prefabricated pier middle section 14 to above the prefabricated pier bottom section 16. Through the prefabricated guide blocks 19 and the supporting tooth blocks 15 And the thick-diameter internal threads and bolts 8 complete the adjustment of the assembly position and verticality of the precast pier middle section 14, and the bolts and steel plates 9 are spot welded to initially fix the precast pier middle section, and then the precast guide blocks The gap between 19 and the inner wall of the connected prefabricated pier segment 5 is filled and sealed with epoxy resin glue 24, so that the prefabricated guide block 19 serves as the internal mold of the UTFC wet joint connection;

Step 3: Overlap, weld, mechanically connect, or memory alloy connect the longitudinal connecting steel bars 18 of the precast pier bottom section 16 and the adjacent precast pier middle section 14, and then tie and support the transverse stirrups 13 The outer formwork 21 is then poured with UTFC4 through the grouting port 22 until the UTFC4 emerges from the grouting port 23. It is vibrated and cured. The UTFC wet joint connection pouring is completed. At this point, the precast pier bottom segment 16 is connected with the adjacent precast pier. Section 14 is assembled;

Step 4: Repeat the above steps 2 and 3 in sequence to complete the assembly of the remaining adjacent prefabricated pier segments, and finally the entire bridge pier construction is completed.

The present invention takes advantage of the fact that the strength of UTFC material is much higher than that of ordinary concrete and conventional grouting materials. By reducing the anchoring length required for longitudinally connecting steel bars, the invention effectively reduces the connection length required for UTFC grouting pipe connection and UTFC wet joint connection; By setting a longitudinal bar stripping section of 4d length in the longitudinal connecting steel bar in the UTFC grouting pipe connection, it can effectively avoid the stress concentration of the longitudinal connecting steel bar at the splicing surface between the precast cap and the precast pier bottom segment, and prevent it from reciprocating Fatigue failure occurs under load, and the deformation of the longitudinal connecting steel bars is extended to a larger length range, thereby expanding the plastic hinge area at the bottom of the pier, slowing down the degree of concentrated damage of the plastic hinges, and improving the ductility of the prefabricated pier system; by The top surface of the precast cap is designed with shallow grooves to enhance the shear force transfer at the splicing surface between the precast pier bottom segment and the precast cap; the support teeth at one or both ends of each precast pier segment avoid post-cast UTFC wet joints The contact surface between the joint connection and the precast pier segment is completely on the same plane, which can cooperate with the shear force transmission at the UTFC wet joint connection, and by rotating the thick-diameter bolt embedded in the support tooth block at the bottom of the precast pier segment. When assembling the precast pier segments, fine-tune the verticality to ensure that the verticality meets the design requirements; the setting of precast guide blocks made of gypsum material not only serves as guide blocks when assembling the precast pier segments, but also serves as a guide for pouring UTFC The internal mold during wet joint pouring, and the lower strength of the gypsum material prevents the prefabricated guide block from affecting the overall stress performance of the pier; the UTFC grouting pipe connection at the bottom of the pier is a ductile connection, which is designed to It yields in a ductile manner under the action of high-level seismic forces, and there is still a potential plastic hinge area near the pier bottom; the UTFC wet joint connection between the precast pier segments is a strong connection. When the bottom of the pier is under the action of high-level seismic forces, When yielding, the connection is protected and remains elastic; the above detailed structural design will ensure that the mechanical properties and seismic performance of the assembled hollow pier system proposed by the present invention are similar to those of traditional monolithic cast-in-situ reinforced concrete bridge piers, that is, they achieve the same level of performance. The performance level of pouring, and both the UTFC grouting pipe connection and the UTFC wet joint connection use grouting technology to complete the pouring of UTFC. The construction is convenient and feasible. The superior mechanical properties of UTFC will ensure the stability of the connection performance; the use of prefabricated assembly construction method greatly greatly It improves the construction efficiency, shortens the construction cycle, has good economic benefits, and saves manpower and material resources to a large extent. The invention has great practical value and good economic benefits, especially in the field of bridge pier construction technology, and has broad application prospects.

Description of the drawings

Figure 1 is a schematic diagram of the structure of a cast-in-place assembled hollow bridge pier equivalent to the present invention.

Figure 2 is a layout diagram of the supporting tooth blocks at the bottom of the precast pier middle section and the precast pier top section of the present invention.

Figure 3 is a schematic diagram of the reinforcement of each prefabricated pier segment 5 of the present invention.

Figure 4 is a schematic structural diagram of the prefabricated pier bottom segment 16 of the present invention.

Figure 5 is a schematic structural diagram of the middle section 14 of the prefabricated pier of the present invention.

Figure 6 is a schematic diagram showing the arrangement of the UTFC wet joint connection prefabricated guide block 19 and the outer formwork 21 of the present invention.

Figure 7 is a top view of the installation of the UTFC wet joint connection prefabricated guide block 19 and the outer formwork 21 of the present invention.

Figure 8 is a schematic structural diagram of the UTFC wet joint connection longitudinal connecting steel bar 18 using overlap according to the present invention.

Figure 9 is a schematic structural diagram of the UTFC wet joint connection longitudinal connecting steel bar 18 using welding according to the present invention.

Figure 10 is a schematic structural diagram of the mechanical connection of the longitudinal connecting steel bars 18 of the UTFC wet joint connection according to the present invention.

Figure 11 is a schematic structural diagram of the UTFC wet joint connection longitudinal connection steel bar 18 of the present invention using memory alloy connection.

Among them: 1. Prefabricated cap; 2. Metal corrugated pipe; 3. Groove; 4. UTFC; 5. Each prefabricated pier body segment; 6. Pier cap; 7. Prefabricated pier top segment; 8. Large diameter inner Threads and bolts; 9. Steel plate; 10. Mechanical connection of longitudinal connecting steel bars; 11. Shear nails; 12. Longitudinal steel bars; 13. Transverse stirrups; 14. Prefabricated pier middle section; 15. Supporting tooth blocks; 16. Precast Pier bottom segment; 17. Stripped section of longitudinal bars; 18. Longitudinal connecting steel bars; 19. Prefabricated guide blocks; 20. Transverse supporting steel bars; 21. External formwork; 22. Grouting port; 23. Grouting outlet; 24. Ring Oxygen resin glue; 25. Overlap of longitudinal connecting steel bars; 26. Welding of longitudinal connecting steel bars; 27. Memory alloy connection of longitudinal connecting steel bars.

Detailed ways

Embodiment 1

As shown in Figure 1, a prefabricated hollow pier system that is equivalent to cast-in-place includes a prefabricated cap 1. A metal bellows 2 is embedded inside the prefabricated cap 1, and a groove 3 is provided on the top surface. Above the prefabricated cap 1 Each prefabricated pier body segment 5 is provided, and each prefabricated pier body segment 5 includes a prefabricated pier bottom segment 16, a prefabricated pier middle segment 14, and a prefabricated pier top segment 7 that is integrally prefabricated with the pier cap 6;

As shown in Figures 2 and 3, the precast cap 1 and each precast pier segment 5 are prefabricated with ordinary reinforced concrete materials, and are equipped with longitudinal steel bars 12 and transverse stirrups 13 inside. Each precast pier segment 5 is a hollow rectangular section;

As shown in Figures 4 and 5, each prefabricated pier body segment 5 is provided with longitudinal connecting steel bars 18 and supporting tooth blocks 15 at both ends or one end of the precast pier middle section 14 and the supporting tooth blocks at the bottom end of the precast pier top section 7 15 is pre-embedded with thick-diameter internal threads and bolts 8, and the supporting tooth blocks 15 at the top of the prefabricated pier bottom section 16 and the prefabricated pier middle section 14 are provided with shear nails 11 and steel plates 9;

As shown in Figures 6 and 7, the inner cavity of the pier at the UTFC wet joint connection is provided with prefabricated guide blocks 19 for assembling each prefabricated pier segment and transverse supporting steel bars 20 for supporting the prefabricated guide blocks 19. The prefabricated guide blocks Block 19 is prefabricated from gypsum material, and the cross-section form can be hollow or solid cross-section. In this embodiment, solid cross-section is selected;

When the longitudinal connecting steel bars at the UTFC wet joint connection are mechanically connected, the set length L of the UTFC wet joint is calculated and determined according to the following formula:

In the formula:

d is the diameter of longitudinal connecting steel bars;

f _s is the strength of longitudinal connecting steel bars, take f _s =max(1.5f _y , _fu ), where f _y is the yield strength of longitudinal connecting steel bars, and f _u is the ultimate strength of longitudinal connecting steel bars;

f _UTFC is the measured compressive strength of ultra-tough fiber concrete (UTFC) material for 28 days;

α is the influence coefficient of the diameter of the longitudinal connecting steel bars. When d=12mm, α=1.0. When d=32mm, α=1.2. When d is between 12 and 32mm, the value of α is determined by linear interpolation;

c is the influence coefficient of the connection processing of the longitudinal connecting steel bars. When the longitudinal connecting steel bars are mechanically connected, refer to Figure 10 and take 0.65;

The construction steps of the above-mentioned cast-in-place assembled hollow pier system of this embodiment are as follows:

Step 1: Lift the prefabricated cap 1 into place, hoist the prefabricated pier bottom section 16 and preassemble the prefabricated cap, then pour UTFC 4 into the pre-embedded metal bellows 3 and groove 3, and then install the prefabricated pier bottom section Section 16 is hoisted to the predetermined position and fixed with brackets, and the prefabricated pier bottom section 16 and the prefabricated cap 1 are assembled;

Step 2: Lift the prefabricated guide blocks 19 to the lateral support steel bars 20 of the prefabricated pier bottom section 16, and then hoist the adjacent prefabricated pier middle section 14 to above the prefabricated pier bottom section 16. Through the prefabricated guide blocks 19 and the supporting tooth blocks 15 And rotate the bolts in 8 to complete the adjustment of the assembly position and verticality of the precast pier middle section 14, and spot weld the thick diameter internal threads and the bolts and steel plates 9 in bolt 8 to adjust the precast pier middle section 14 After preliminary fixing, the gap between the prefabricated guide block 19 and the inner wall of the adjacent prefabricated pier segment 5 is filled and sealed with epoxy resin glue 24, so that the prefabricated guide block 19 serves as the internal mold for the UTFC wet joint connection;

Step 3: Perform longitudinal connecting steel mechanical connection 10 on the longitudinal connecting steel bars 18 of the precast pier bottom section 16 and the adjacent precast pier middle section 14. Refer to Figure 10, then tie the transverse stirrups 13 and support the outer formwork 21. Then pour UTFC 4 through the grouting port 22 until UTFC 4 emerges from the grouting port 23. Vibration and curing are performed. The UTFC wet joint connection pouring is completed. At this point, the precast pier bottom section 16 is connected to the adjacent precast pier middle section. 14Complete assembly;

Step 4: Repeat the above-mentioned steps 2 and 3 in sequence to complete the assembly between the remaining adjacent prefabricated pier segments 5, and finally the entire bridge pier construction is completed.

Embodiment 2

As shown in Figures 1 and 8, a prefabricated hollow bridge pier system that is equivalent to cast-in-place includes a prefabricated bearing platform 1, with a metal bellows 2 embedded inside the prefabricated bearing platform 1, and a groove 3 provided on the top surface. Each prefabricated pier body segment 5 is provided above the platform 1. Each prefabricated pier body segment 5 includes a prefabricated pier bottom segment 16, a prefabricated pier middle segment 14, and a prefabricated pier top segment 7 that is integrally prefabricated with the pier cap 6;

As shown in Figures 2 and 3, the precast cap 1 and each precast pier segment 5 are prefabricated with ordinary reinforced concrete materials, and are equipped with longitudinal steel bars 12 and transverse stirrups 13 inside. Each precast pier segment 5 is a hollow rectangular section;

As shown in Figures 4 and 5, each prefabricated pier body segment 5 is provided with longitudinal connecting steel bars 18 and supporting tooth blocks 15 at both ends or one end of the precast pier middle section 14 and the supporting tooth blocks at the bottom end of the precast pier top section 7 15 is pre-embedded with thick-diameter internal threads and bolts 8, and the supporting tooth blocks 15 at the top of the prefabricated pier bottom section 16 and the prefabricated pier middle section 14 are provided with shear nails 11 and steel plates 9;

As shown in Figures 6 and 7, the inner cavity of the pier at the UTFC wet joint connection is provided with prefabricated guide blocks 19 for assembling each prefabricated pier segment and transverse supporting steel bars 20 for supporting the prefabricated guide blocks 19. The prefabricated guide blocks Block 19 is prefabricated from gypsum material, and the cross-section form can be hollow or solid cross-section. In this embodiment, solid cross-section is selected;

When the longitudinal connecting steel bars at the UTFC wet joint connection are overlapped, the length L of the UTFC wet joint is calculated and determined according to the following formula:

In the formula:

d is the diameter of longitudinal connecting steel bars;

f _s is the strength of longitudinal connecting steel bars, take f _s =max(1.5f _y , _fu ), where f _y is the yield strength of longitudinal connecting steel bars,

f _u is the ultimate strength of longitudinal connecting steel bars;

f _UTFC is the measured compressive strength of ultra-tough fiber concrete (UTFC) material for 28 days;

α is the influence coefficient of the diameter of the longitudinal connecting steel bars. When d=12mm, α=1.0. When d=32mm, α=1.2. When d is between 12 and 32mm, the value of α is determined by linear interpolation;

c is the influence coefficient of the longitudinal connecting steel bar connection treatment. When the longitudinal connecting steel bar is overlapped, refer to Figure 8 and take 1.0;

The construction steps of the above-mentioned cast-in-place assembled hollow pier system of this embodiment are as follows:

Step 1: Lift the prefabricated cap 1 into place, hoist the prefabricated pier bottom section 16 and preassemble the prefabricated cap, then pour UTFC 4 into the pre-embedded metal bellows 2 and groove 3, and then install the prefabricated pier bottom section Section 16 is hoisted to the predetermined position and fixed with brackets, and the prefabricated pier bottom section 16 and the prefabricated cap 1 are assembled;

Step 2: Lift the prefabricated guide blocks 19 to the lateral support steel bars 20 of the prefabricated pier bottom section 16, and then hoist the adjacent prefabricated pier middle section 14 to above the prefabricated pier bottom section 16. Through the prefabricated guide blocks 19 and the supporting tooth blocks 15 And rotate the bolts in the thick-diameter internal threads and bolts 8 to complete the adjustment of the assembly position and verticality of the prefabricated pier middle section 14, and spot-weld the thick-diameter internal threads and the bolts and steel plates 9 in the bolts 8 to adjust the assembly position and verticality of the prefabricated pier segment 14 The prefabricated pier middle section 14 is initially fixed, and then the gap between the prefabricated guide block 19 and the inner wall of the adjacent prefabricated pier body section 5 is filled and sealed with epoxy resin glue 24, so that the prefabricated guide block 19 serves as a UTFC wet joint. Internal mold at the joint;

Step 3: Perform longitudinal connecting steel bar overlap 25 processing on the longitudinal connecting steel bars 18 of the precast pier bottom section 16 and the adjacent precast pier middle section 14. Refer to Figure 8, then tie the transverse stirrups 13 and support the outer formwork 21. Then pour UTFC 4 through the grouting port 22 until UTFC 4 emerges from the grouting port 23. Vibration and curing are performed. The UTFC wet joint connection pouring is completed. At this point, the precast pier bottom section 16 is connected to the adjacent precast pier middle section. 14Complete assembly;

Step 4: Repeat the above-mentioned steps 2 and 3 in sequence to complete the assembly between the remaining adjacent prefabricated pier segments 5, and finally the entire bridge pier construction is completed.

Referring to Figures 8, 9, 10, and 11, in addition to the mechanical connection processing of Embodiment 1 and the longitudinal connection of Embodiment 2, the longitudinal connecting steel bars 18 of the precast pier bottom section 16 and the adjacent precast pier middle section 14 are In addition to the steel bar overlap 25 process, the longitudinal connecting steel bar welding 26 process or the longitudinal connecting steel bar memory alloy connection 27 process can also be performed. Refer to Figure 9 for a schematic structural diagram of the UTFC wet joint connection longitudinal connecting steel bar 18 using welding according to the present invention; Figure 11 is Schematic diagram of the structure of the UTFC wet joint connection longitudinal connection steel bar 18 using memory alloy connection according to the present invention.

Principles and advantages of the invention:

The prefabricated hollow bridge pier system and its construction method proposed by the present invention are equivalent to cast-in-situ and utilize the advantages of ultra-tough fiber concrete (UTFC) materials such as high compressive strength, superior mechanical properties, and good bonding performance with steel bars, and are effective The required length of the splicing joints is shortened, and the disadvantages of the prefabricated pier technology such as the complicated steel connection structure, insufficient concrete strength, and poor joint mechanical properties in the prefabricated segments are eliminated. Through structural design, the prefabricated hollow piers are made more durable. The connection structure is simpler, the construction is convenient and feasible, the efficiency of bridge pier construction is improved, and the mechanical properties, seismic performance and plastic hinge behavior of the assembled hollow pier system proposed by the invention are similar to those of traditional integral cast-in-situ reinforced concrete bridge piers. , ultimately reaching a performance level equivalent to cast-in-place.

Ultra-tough fiber concrete (UTFC) in this field is a proprietary name. In the present invention, it generally refers to cement-based concrete using millimeter-sized particles (aggregate) and adding steel fibers. It is relatively ordinary concrete and high-performance concrete. Another type of concrete material with better comprehensive mechanical properties, such as reactive powder concrete, ultra-high performance fiber reinforced concrete, grouting fiber concrete, dense reinforced composite materials, etc., but ultra-high performance steel fiber reinforced concrete or ultra-high performance steel fiber reinforced concrete is preferred. Grouted fiber concrete.

Compared with the existing technology, the present invention sets super-tough fiber concrete UTFC at the connection point of the hollow bridge piers. The steel bars in the super-tough fiber concrete UTFC are overlapped, welded or mechanically connected, which significantly changes the structural form of the prefabricated assembled hollow bridge piers. and working status, which also makes the technical solution of the present invention have the following obvious advantages:

First of all, the super-tough fiber concrete connected hollow pier structure of the present invention is stressed together, and the stress, deformation and other indicators of the super-tough fiber concrete UTFC itself can meet the requirements of the cast-in-place hollow pier structure;

Secondly, the super tough fiber concrete UTFC of the present invention increases the stiffness of the bridge pier, ensures the bonding performance between the connecting section and the pier body section, and improves the crack resistance and durability of the connecting section.

In addition, the ultra-tough fiber concrete UTFC in the technical solution of the present invention is selected with a ratio suitable for the connection of hollow bridge piers. The particles of different particle sizes of its constituent materials are in the best proportion to form the most densely packed, which is not only easy to construct and operate, but also ensures The compactness improves the seismic performance of the bridge pier and its erosion resistance and durability under harsh environmental conditions.

The connecting section can adjust the values of different wall thicknesses and heights of the super-tough fiber concrete layer to make the curve peak value and ductility of the connected hollow pier skeleton reach or exceed the performance of cast-in-place pier columns. In summary, the super-tough fiber concrete proposed in the present invention, as a prefabricated assembled hollow bridge pier wet joint, has the advantages of large structural rigidity, good inter-layer bonding, good durability, and good fatigue resistance, and has great practical value. And good economic benefits, especially in the field of precast assembly of hollow bridge piers, it has broad application prospects. It has good seismic resistance and excellent durability. Plaster guide blocks are placed on the lower sections of the prefabricated hollow piers, and the upper and lower sections of the hollow piers are connected through supporting tooth blocks, and the longitudinal reinforcements of the upper and lower sections of the pier are laid. connection, welding or mechanical connection; install the formwork, pour the super tough fiber concrete, and use a vibration platform to vibrate it after completion; maintain the poured super tough fiber concrete, remove the formwork after the mechanical index of the concrete reaches the design requirements, and complete the entire construction.

Claims (3)

1. A prefabricated hollow bridge pier system equivalent to cast-in-place, characterized by: including a prefabricated cap platform (1), a pier is connected above the prefabricated cap platform (1), and the bridge pier is composed of each prefabricated pier body segment (5) Assembled, each prefabricated pier body segment (5) includes a prefabricated pier bottom segment (16), a prefabricated pier middle segment (14), and a prefabricated pier top segment (7) integrally prefabricated with the pier cap (6); The prefabricated capping platform (1) and each prefabricated pier segment (5) are prefabricated with ordinary reinforced concrete materials, and are equipped with longitudinal steel bars (12) and transverse stirrups (13) inside. The prefabricated capping platform (1) 1) There is a metal bellows (2) embedded inside, and a groove (3) is provided on the top surface. Each of the prefabricated pier body segments (5) has a hollow rectangular cross-section. The prefabricated pier body segments (5) Both ends or one end are provided with longitudinal connecting steel bars (18) and supporting tooth blocks (15); The supporting tooth blocks (15) at the bottom of the prefabricated pier middle section (14) and the prefabricated pier top section (7) are pre-embedded with thick-diameter internal threads and bolts (8), and the prefabricated pier bottom section (16) And the supporting tooth block (15) at the top of the prefabricated pier middle section (14) is provided with shear nails (11) and steel plates (9); The prefabricated cap (1) and the prefabricated pier bottom segments (16) are connected by ultra-tough fiber concrete (UTFC) grouting pipes to complete the splicing, and the adjacent prefabricated pier body segments (5) are connected by ultra-tough fiber concrete (UTFC) grouting pipes. The ductile fiber concrete (UTFC) wet joint connection completes the splicing. The inner cavity of the pier at the UTFC wet joint connection is provided with prefabricated guide blocks (19) for assembling each prefabricated pier segment and for supporting the prefabricated guide blocks (19). 19) transverse supporting steel bars (20), the prefabricated guide block (19) is prefabricated from gypsum material, and the cross-sectional form can be hollow or solid cross-section; In the described UTFC wet joint connection, the longitudinal connecting steel bars (18) between adjacent prefabricated pier segments (5) are overlapped, welded, mechanically connected, or memory alloy connected, and the UTFC wet joint connection is configured The length L is calculated and determined according to the following formula: In the formula: d is the diameter of the longitudinal connecting steel bar (18); f _s is the strength of the longitudinal connecting steel bar (18), take f _s =max (1.5f _y , _fu ), where f _y is the longitudinal connecting steel bar 18 Yield strength, f _u is the ultimate strength of longitudinal connecting steel bars (18); f _UTFC is the measured compressive strength of super tough fiber concrete UTFC material for 28 days; α is the influence coefficient of the diameter of the longitudinal connecting steel bar (18). When d=12mm, α=1.0. When d=32mm, α=1.2. When d is between 12 and 32mm, the value of α is determined by linear interpolation; c is the influence coefficient of the connection processing of the longitudinal connecting steel bars (18). When the longitudinal connecting steel bars are overlapped, welded, mechanically connected, and memory alloy connected, c is taken to be 1.0, 0.5, 0.65, and 0.87 respectively. 2. A cast-in-place assembled hollow bridge pier system according to claim 1, characterized in that: the longitudinal connecting steel bars (18) in the UTFC grouting pipe connection are provided with a 4d length longitudinal bar stripping section ( 17). 3. A construction method based on a cast-in-place assembled hollow bridge pier system according to claim 1, characterized in that it includes the following steps: Step 1: Lift the prefabricated cap (1) into place, hoist the prefabricated pier bottom segment (16) and the prefabricated cap (1) for pre-assembly, and then pour the embedded metal bellows (2) and the groove (3) UTFC (4), then hoist the prefabricated pier bottom section (16) to the predetermined position and fix it through the bracket, and the prefabricated pier bottom section (16) and the prefabricated cap platform (1) are assembled; Step 2: Lift the prefabricated guide blocks (19) to the lateral supporting steel bars (20) of the prefabricated pier bottom section (16), and then hoist the adjacent prefabricated pier middle section (14) to the top of the prefabricated pier bottom section (16). The assembly position and verticality of the prefabricated pier middle section (14) are adjusted through the prefabricated guide block (19) and the supporting tooth block (15) as well as the thick-diameter internal thread and bolt (8), and the bolts and steel plates are spot welded. The middle section of the prefabricated pier is initially fixed, and then the gap between the prefabricated guide block (19) and the inner wall of the connected prefabricated pier body section (5) is filled and sealed with epoxy resin glue (24), so that the prefabricated pier can be The guide block (19) serves as the inner mold for the UTFC wet joint connection; Step 3: Overlap, weld, mechanically connect, or memory alloy the longitudinal connecting steel bars (18) of the precast pier bottom section (16) and the precast pier middle section (14), and then tie the transverse stirrups (13) and support the outer formwork (21), then pour UTFC (4) through the grouting port (22) until UTFC (4) emerges from the grouting port (23), vibrate and maintain, and UTFC is wet-joined The joint pouring is completed, and the precast pier bottom section (16) and the adjacent precast pier middle section (14) are assembled; Step 4: Repeat the above-mentioned steps 2 and 3 in sequence to complete the assembly of the remaining adjacent prefabricated pier segments (5), and finally the entire bridge pier construction is completed.