Simple-supported-to-continuous pier top longitudinal connection structure for bearing improvement of existing concrete t-beam

Abstract

The utility model discloses a kind of simply supported continuous pier top longitudinal connection structures of bearing promotion of existing concrete T beam, including the joint between the adjacent two-span concrete simply supported beam, NC is formed NC pouring section at joint place pouring;The upper part of the end of the two-span concrete simply supported beam near the joint is chiseled to form UHPC pouring area;The upper area of NC pouring section and two UHPC pouring area pour UHPC integrally to form UHPC pouring part;UHPC pouring part is pre-embedded with pre-embedded tensioning steel that crosses joint.The utility model is excellent in structure quality, splicing is reliable, stress performance, durability is good, very adapt to the needs of construction development.

Description

Technical Field

[0001] This utility model belongs to the field of construction, and in particular relates to a longitudinal connection structure for the top of a simply supported variable continuous pier for the load-bearing lifting of existing concrete T-beams. Background Technology

[0002] Currently, my country's large-scale construction of new bridge infrastructure has been largely completed, and the upgrading and maintenance of existing bridges has become a new focus in the field of bridge engineering. Investigations of actual projects have revealed that when load-bearing capacity calculations are performed according to current standards such as the General Specifications for Highway Bridge and Culvert Design (JTG D60-2015) and the Specifications for Highway Reinforced Concrete and Prestressed Concrete Bridge and Culvert Design (JTG 3362-2018), some existing multi-span simply supported concrete beam bridges cannot meet the current standard requirements and require reinforcement. When reinforcing these bridges, a relatively economical and reasonable solution is to cast T-shaped joints between adjacent simply supported beams to form a longitudinal connection, transforming the structure from a simply supported beam bridge to a continuous beam bridge. This alters the bridge's stress characteristics and enhances its load-bearing capacity.

[0003] For some simply supported beam bridges using concrete T-beam sections, the longitudinal connection structure can adopt a composite joint form of ultra-high performance concrete (UHPC) and ordinary concrete (NC). Ultra-high performance concrete (UHPC) is far superior to ordinary concrete in terms of mechanical properties and durability. With the same bending resistance, the weight of a UHPC structure is only half that of a reinforced concrete structure. Applying UHPC to bridge structures can reduce the structural thickness and significantly reduce the structure's self-weight. Furthermore, based on the stress characteristics of the T-beam section, using a composite joint form of ultra-high performance concrete and ordinary concrete can effectively reduce costs while meeting the joint load-bearing capacity requirements.

[0004] This utility model addresses the needs of my country's infrastructure development, specifically the engineering problem of existing multi-span simply supported concrete beam bridges failing to meet current specifications for load-bearing capacity and requiring reinforcement. With the goals of improving structural quality and reducing construction costs, it proposes a longitudinal connection structure for simply supported to continuous pier tops suitable for enhancing the load-bearing capacity of existing concrete T-beams. This utility model boasts excellent structural quality, reliable splicing, and good stress and durability, making it highly suitable for the needs of construction development. Utility Model Content

[0005] To address the aforementioned issues, this utility model provides a simply supported variable continuous pier top longitudinal connection structure for supporting the lifting of existing concrete T-beams.

[0006] To achieve the above-mentioned technical effects, the technical solution of this utility model is as follows: A longitudinal connection structure for a simply supported to continuous pier top with existing concrete T-beam load-bearing capacity includes a joint between two adjacent spans of simply supported concrete beams 3, where NC is poured to form an NC pouring section 2; the upper part of the ends of the two spans of simply supported concrete beams 3 adjacent to the joint is chiseled to form a UHPC pouring area; the area above the NC pouring section 2 and the two UHPC pouring areas are poured with UHPC to form a UHPC pouring part 1; and pre-embedded tensile steel bars 6 spanning the joint are pre-embedded in the UHPC pouring part 1.

[0007] In a further improvement, the number of pre-embedded tensile steel bars 6 is n: in, q n For equivalent uniformly distributed load, l 0 For single-span calculation, e Let be the distance from the neutral axis of the simply supported beam section to the top surface of the simply supported beam. d The distance from the pre-embedded tensile reinforcement bar 6 to the top surface of the simply supported beam, f pd The design value of the tensile strength of the pre-embedded tensile reinforcement 6; A 0 This refers to the cross-sectional area of ​​a single pre-embedded tensile steel bar 6.

[0008] In a further improvement, the contact portion between the UHPC casting section 1 and the NC casting section 2 forms a toothed interlaced structure.

[0009] In a further improvement, several transverse diaphragms are fixed on both sides of the lower part of the simply supported concrete beam 3; the transverse diaphragms on both sides of the joint are fixedly connected by longitudinal reinforcing bolts 5.

[0010] In a further improvement, NC is laid on top of the UHPC casting section 1 to form the bridge deck pavement layer 4.

[0011] In a further improvement, the length of the UHPC casting zone is one-quarter of the span of the simply supported concrete beam.

[0012] Advantages of this utility model: 1. The UHPC-NC combined simply supported variable continuous pier top longitudinal connection structure of this utility model adopts UHPC material. The compressive strength, tensile strength and toughness of UHPC are much greater than those of ordinary concrete and high-performance concrete, thus giving this utility model excellent stress performance.

[0013] 2. The UHPC-NC combined simply supported variable continuous pier top longitudinal connection structure of this utility model adopts UHPC material. The durability of UHPC can reach more than 200 years, which makes the durability of this utility model far better than that of ordinary concrete joints.

[0014] 3. The UHPC-NC combined simply supported variable continuous pier top longitudinal connection structure of this utility model is convenient and quick to construct. While ensuring quality, it also reduces the requirements for transportation and hoisting equipment, greatly reduces the pressure of transportation and hoisting, and can significantly shorten the construction period.

[0015] 4. This utility model adopts a combination of multiple connection methods, such as pre-embedded tensile reinforcement and cast UHPC wet joints, which effectively reduces the risk of concrete cracking in weak areas of the structure.

[0016] 5. The UHPC-NC combined simply supported to continuous pier top longitudinal connection structure of this utility model has an aesthetically pleasing appearance. Due to the use of UHPC, the self-weight of the superstructure can be effectively reduced while ensuring the structural bearing capacity. In addition, its superior construction features enable it to meet the needs of infrastructure development. It has strong applicability and can be widely used in the simple support to continuous reinforcement and renovation of existing simply supported beam bridges using concrete T-beams. Attached Figure Description

[0017] Figure 1 This is a three-dimensional structural schematic diagram of the present invention; Figure 2 This is a schematic diagram of the longitudinal bridge elevation of this utility model; Figure 3 This is a schematic diagram of the bridge deck pavement rebar installation according to this utility model; Figure 4 This is a schematic diagram of the elevation of the bridge deck pavement rebar installation according to this utility model; Figure 5 This is a schematic elevation view of the longitudinal reinforcing bolt arrangement between the transverse partitions of this utility model; Figure 6 The figure below is a reference diagram for calculating the reasonable prestressing force estimation method in this utility model. Detailed Implementation

[0018] The technical solution of this utility model will be specifically described below through specific embodiments and in conjunction with the accompanying drawings.

[0019] Example 1 like Figure 1 and Figure 2 As shown, the longitudinal connection structure of the UHPC-NC combined simply supported variable continuous pier top of the concrete T-beam proposed in this utility model mainly consists of the UHPC casting section 1 and the NC casting section 2. All of the above components are cast on-site using formwork. Figure 5As shown, before pouring the NC section of the joint, longitudinal reinforcing bolts 5 are drilled and arranged on the end diaphragms of the original two spans of concrete T-beams to strengthen the longitudinal bond strength between the NC section of the joint and the original diaphragms. The size and number of bolts can be determined according to the actual project needs. The attached drawings of this utility model are for reference only. At the same time, the flange plates of the original simply supported concrete T-beams 3 and part of the bridge deck pavement near the pouring area are removed. The removal range is about 1 / 4 of the span of the original simply supported beams in the two adjacent spans, so as to achieve the purpose of pre-embedding prestressing tendons and using UHPC material to replace the original material to bear the load. After the template is built between the diaphragms of the two adjacent spans according to the actual project dimensions, the NC section of the joint is poured. The interface between the NC section of the joint and the UHPC section is treated as follows. Figure 4 The toothed staggered structure shown increases the contact area between the two materials, enhancing interfacial bonding performance. After the NC portion of the joint is cast and formed, a template is erected for the casting of the UHPC portion of the flange plate and the installation of the pre-embedded tensile reinforcement 6. After the reinforcement installation is completed, the casting and curing of the UHPC portion of the entire simply supported to continuous connection structure is completed. After the casting of the combined connection structure is completed, the bridge deck pavement layer 4 is then completed. This utility model uses UHPC material to replace the original NC material to bear the load, forming a T-shaped joint, enhancing the load-bearing capacity after the transformation from a simply supported beam system to a continuous beam system, and improving the stress characteristics of existing bridges; in response to the stress characteristics of the negative bending moment zone of the continuous beam, after removing the T-beam flange plate and part of the bridge deck pavement near the negative bending moment zone, pre-embedded prestressed tendons are installed in advance to enhance the crack resistance of the joint. The newly cast joint uses UHPC material in the T-beam flange plate portion and NC material in the web plate and other parts. It can save costs and fully utilize the excellent performance of UHPC, reducing the risk of cracking in the negative bending moment zone at the pier top connection.

[0020] The structure proposed in this invention has a problem with the placement of prestressing tendons in practical applications. To address this problem, a practical and reasonable method for estimating the prestressing force is proposed. For example... Figure 6 As shown, after the conversion from simply supported to continuous beam, according to relevant theories of structural mechanics, a negative bending moment M will be generated at the supports of the continuous beam structure. d Its theoretical size is: in q n To comprehensively consider the equivalent uniformly distributed load after the newly poured UHPC portion of the T-beam, the bridge deck pavement layer, and the second-phase load, l 0 Calculate the span for a single span. For the resulting negative bending moment... M d To partially offset the negative bending moment, prestressed tendons are used to prevent cracking of the flange concrete in the negative bending moment zone. in f pd This refers to the design value of the tensile strength of the prestressed tendons used. A p The total cross-sectional area of ​​all prestressing tendons configured. y This represents the distance from the prestressing tendon to the neutral axis of the T-beam section. e This is the distance from the neutral axis of the cross section to the top surface. d Where n is the distance from the prestressing tendon to the top surface, and n is the number of prestressing tendons to be installed. A 0 This represents the cross-sectional area of ​​a single prestressed tendon. f pd and A 0 All of these can be determined by the type of prestressing tendon to be used, and then the calculation can be performed. n The value can be: Based on this, the number of prestressing tendons to be used can be determined to ensure that the configured prestressing force can offset the maximum negative bending moment in the negative bending moment zone, and the final reinforcement scheme can be determined in combination with the cross-sectional dimensions.

[0021] The above is only one specific implementation method of this utility model, but the design concept of this utility model is not limited thereto. Any non-substantial modifications made to this utility model using this concept shall be considered as infringing on the protection scope of this utility model.

Claims

1. A longitudinal connection structure for a simply supported, variable-continuity pier top with existing concrete T-beam load-bearing lifting, characterized in that, The joint is located between two adjacent spans of simply supported concrete beams (3). NC is poured at the joint to form the NC pouring section (2). The upper part of the ends of the two spans of simply supported concrete beams (3) adjacent to the joint is chiseled to form the UHPC pouring area. UHPC is poured in the area above the NC pouring section (2) and the two UHPC pouring areas to form the UHPC pouring part (1). The UHPC pouring part (1) is pre-embedded with pre-embedded tensile steel bars (6) that cross the joint.

2. The simply supported variable continuous pier top longitudinal connection structure for load-bearing lifting of existing concrete T-beams as described in claim 1, characterized in that, The number of the pre-embedded tensile steel bars (6) is n: in, q n For equivalent uniformly distributed load, l 0 For single-span calculation, e Let be the distance from the neutral axis of the simply supported beam section to the top surface of the simply supported beam. d The distance from the pre-embedded tensile reinforcement (6) to the top surface of the simply supported beam, f pd The design value of the tensile strength of the pre-embedded tensile reinforcement (6); A 0 The cross-sectional area of ​​a single pre-embedded tensile steel bar (6).

3. The simply supported variable continuous pier top longitudinal connection structure for load-bearing lifting of existing concrete T-beams as described in claim 1, characterized in that, The contact portion of the UHPC casting section (1) and the NC casting section (2) forms a toothed interlaced structure.

4. The simply supported variable continuous pier top longitudinal connection structure for load-bearing lifting of existing concrete T-beams as described in claim 1, characterized in that, Several transverse diaphragms are fixed on both sides of the lower part of the simply supported concrete beam (3); the transverse diaphragms on both sides of the joint are fixedly connected by longitudinal reinforcing bolts (5).

5. The simply supported variable continuous pier top longitudinal connection structure for load-bearing lifting of existing concrete T-beams as described in claim 1, characterized in that, The bridge deck pavement layer (4) is formed by paving NC on top of the UHPC casting section (1).

6. The simply supported variable continuous pier top longitudinal connection structure for load-bearing lifting of existing concrete T-beams as described in claim 1, characterized in that, The length of the UHPC casting zone is one-quarter of the span of the simply supported concrete beam (3).

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