In-vitro inhaul cable span expansion structure and method

Abstract

According to the in-vitro inhaul cable span expansion structure and method, the newly-arranged steel columns are connected between the upper-layer existing beams and the lower-layer existing beams of the to-be-expanded span area, and the upper-layer existing beams and the lower-layer existing beams of the to-be-expanded span area are supported through the new supports; the first to-be-disassembled section of the to-be-disassembled support is statically cut off step by step while the prestress is tensioned step by step, and the second to-be-disassembled section of the to-be-disassembled support is statically cut off after the prestress tensioning is completed and the structural deformation is stable; the transformation effects that the influence on an existing structure is extremely small, the amplitude of span expansion can be extremely large after transformation, construction is extremely convenient and fast, and the manufacturing cost is extremely low can be achieved.

Description

Technical Field

[0001] This invention relates to the field of building renovation technology, specifically to an external cable-stayed span-expanding structure and method. Background Technology

[0002] With the increasing pace of urban renewal, the demand for the renovation and reinforcement of existing buildings is growing, which also places new and higher demands on building reinforcement and renovation solutions.

[0003] Currently, there are many methods for building reinforcement and renovation, such as cross-section enlargement, concrete replacement, external prestressing, and external steel reinforcement. Among these, external prestressing involves placing prestressing tendons outside the structural members, with prestress applied to the structure through deflectors and anchors. It offers significant advantages, including combining reinforcement and unloading, substantial simultaneous improvement in strength and stiffness, and good performance of both new and old structures working together. However, traditional external prestressing methods are limited by the ultimate bearing capacity of the reinforced member, thus limiting the effective reinforcement and renovation results. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide an external cable-stayed span expansion structure and method that has minimal impact on existing structures, allows for large-scale span expansion modifications, is easy to construct, and is highly economical.

[0005] An embodiment of the present invention provides an external cable span-expanding structure, comprising: New steel columns are installed, which are connected between the existing beams of the upper and lower floors in the area to be expanded. The new support can support the existing beams of the upper and lower layers in the area to be expanded, and the span formed by the new support in the area to be expanded is greater than the original span formed by the support to be dismantled. The external prestressed cable has its turning point connected to the existing beam of the lower layer of the span area to be expanded via a turning device, and its tensioning end is anchored to the existing beam of the upper layer of the span area to be expanded, or the new support, or the connection node between the new support and the existing beam of the upper layer via an anchoring device. The number and location of the newly installed steel columns, the location of the new supports, the turning point location of the external prestressed cables, and the prestress value are all determined by calculation based on the principle that the internal forces of the existing beams of the upper and lower layers connected do not change after the span is expanded or remain within the bearing capacity range provided by the original reinforcement.

[0006] Optionally, the new support can be a reinforced existing support or a newly established support.

[0007] Optionally, the support to be dismantled is divided into a first section to be dismantled and a second section to be dismantled from top to bottom. The first section to be dismantled is statically removed in stages while the prestress is tensioned in stages, and the second section to be dismantled is statically removed after the prestressing is completed and the structural deformation is stable.

[0008] Optionally, a high-precision finite element model combining rod elements, shell elements, or solid elements is used to calculate and analyze the number and location of the newly installed steel columns, the location of the new supports, the turning point location and prestress value of the external prestressed cables, and to simulate the entire process of applying prestress in stages while simultaneously removing the supports to be dismantled in stages, and achieving a smooth transfer of load while expanding the span.

[0009] Optionally, the steering device includes a steel pipe and two steering sleeves. The steel pipe is fixedly installed through the existing beam on the lower layer. The two steering sleeves are rotatably sleeved on both ends of the steel pipe through ball bearings, and each end of the steering sleeve is provided with a limiting protrusion ring.

[0010] Optionally, the anchoring device includes a semi-circular steel pipe and two anchor plates. The semi-circular steel pipe is fixedly inserted into the existing upper beam or the new support or the connection node between the new support and the existing upper beam. The two anchor plates are respectively fixed at both ends of the semi-circular steel pipe, and the anchor plates and the semi-circular steel pipe are respectively provided with through holes for the external prestressed cables to pass through.

[0011] Accordingly, this invention also provides an external cable span widening method, which mainly includes the following steps: S1. Based on the principle that the internal forces of the existing beams in the upper and lower layers of the span to be expanded do not change after the span expansion or remain within the bearing capacity provided by the original reinforcement, calculate and analyze the number and location of the newly installed steel columns, the location of the new supports, the turning point location and prestress value of the external prestressed cables, and simulate the entire process of applying prestress in stages while removing the supports to be dismantled in stages, and achieving a smooth transfer of load while expanding the span. S2. Connect the newly installed steel columns between the existing beams on the upper and lower floors of the area to be expanded, according to the calculation results; S3. Based on the calculation results, reinforce the existing supports as the new supports or establish new supports as the new supports to support the existing beams of the upper and lower layers in the area to be expanded; the span formed by the new supports in the area to be expanded is greater than the original span formed by the supports to be dismantled; S4. Install the external prestressed cable according to the calculation results. The turning point of the external prestressed cable is connected to the existing beam of the lower layer of the span area to be expanded through the turning device. The tensioning end of the external prestressed cable is anchored to the existing beam of the upper layer of the span area to be expanded or the new support or the connection node between the new support and the existing beam of the upper layer through the anchoring device. S5. Divide the support to be dismantled into the first section to be dismantled and the second section to be dismantled from top to bottom. While the prestressing is being tensioned in stages, the first section to be dismantled is statically cut off in stages. S6. After the prestressing is completed and the structural deformation is stable, the second section to be dismantled is statically removed.

[0012] Optionally, a high-precision finite element model combining rod elements, shell elements, or solid elements can be used to calculate and analyze the number and location of the newly installed steel columns, the location of the new supports, the inflection point location of the external prestressed cables, and the prestress value.

[0013] Optionally, the existing support mentioned in step S3 is reinforced by increasing the cross-section.

[0014] Optionally, the newly established support in step S3 is made of micro-expansion concrete and is poured densely.

[0015] The embodiments of the present invention have the following beneficial effects: new steel columns are connected between the existing beams of the upper and lower layers in the area to be expanded, and the new supports are used to support the existing beams of the upper and lower layers in the area to be expanded. While the prestress is tensioned in stages, the first section of the support to be dismantled is statically cut off in stages. After the prestressing is completed and the structural deformation is stable, the second section of the support to be dismantled is statically cut off. This can achieve the effect of minimal impact on the existing structure, a large range of expanded span after the renovation, extremely convenient construction and extremely low cost. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention; Figure 2 This is a schematic diagram of the steering device in an embodiment of the present invention; Figure 3 This is a schematic diagram of the anchoring device in an embodiment of the present invention; Figure 4 This is a schematic diagram of the step-by-step removal of the support to be dismantled in an embodiment of the present invention; Figure 5 This is a schematic diagram of the expansion structure of a certain renovation project in an embodiment of the present invention; Figure 6 This is a simulation diagram of the expansion process of a certain renovation project in an embodiment of the present invention; Figure 7 This refers to the measured vertical displacement difference during the expansion process of a certain renovation project in this embodiment of the invention. The numbers in the diagram represent: 1. Existing beam; 2. Support to be dismantled; 2-1. First section to be dismantled; 2-2. Second section to be dismantled; 3. New steel column; 4. New support; 5. External prestressed cable; 6. Steel pipe; 7. Steering sleeve; 8. Ball bearing; 9. Limiting convex ring; 10. Semi-circular steel pipe; 11. Anchor plate; 12. Perforation. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of the present invention and are not intended to limit the present invention. In the present invention, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in actual use or operation, specifically the drawing directions in the accompanying drawings; while terms such as "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.

[0019] Please see Figure 1 As shown, an embodiment of the present invention provides an external cable span-expanding structure, comprising: New steel column 3 is installed and connected to the existing beams 1 of the upper and lower floors in the area to be expanded through anchor bolts and other connectors, so that the existing beams 1 of the upper and lower floors can share the load to form a prestressed composite truss.

[0020] The new support 4 can provide support for the existing beams 1 on both the upper and lower floors in the area to be expanded. The span formed by the new support 4 in the area to be expanded needs to be greater than the original span formed by the support 2 to be dismantled, so as to achieve the purpose of expanding the span. Specifically, the new support 4 can be either a reinforced existing support or a newly established support.

[0021] The external prestressed cable 5 has its turning point connected to the existing beam 1 of the lower layer in the area to be expanded via a turning device. The tensioning end of the external prestressed cable 5 is anchored to the existing beam 1 of the upper layer in the area to be expanded, or to the new support 4, or to the connection node between the new support 4 and the existing beam 1 via an anchoring device. During tensioning, the prestress on the external prestressed cable 5 can be applied to the existing beam 1 through the turning device and the anchoring device to balance the bending moment generated by the load on the beam.

[0022] Specifically, such as Figure 2 As shown, the steering device in this embodiment of the invention includes a steel pipe 6 and two steering sleeves 7. The steel pipe 6 is fixedly installed through the existing beam 1 on the lower layer (the gap between the steel pipe 6 and the post-concrete opening is filled with structural adhesive). The two steering sleeves 7 are rotatably sleeved on both ends of the steel pipe 6 via ball bearings 8. The turning point of the external prestressed cable 5 is wound around the steering sleeve 7, which can effectively solve the problem of large prestress loss caused by a large turning angle. Both ends of the steering sleeve 7 are provided with limiting protrusions 9 to prevent the external prestressed cable 5 from slipping off.

[0023] like Figure 3 As shown, the anchoring device in this embodiment of the invention includes a semi-circular steel pipe 10 and two anchor plates 11. The semi-circular steel pipe 10 is fixedly installed through the existing upper beam 1 or the new support 4, or the connection node between the new support 4 and the existing upper beam 1 (the gap between the semi-circular steel pipe 10 and the post-concrete opening is filled with M50 or larger grout). The two anchor plates 11 are respectively fixedly installed at both ends of the semi-circular steel pipe 10, and corresponding through holes 12 are opened on the anchor plates 11 and the semi-circular steel pipe 10 for the external prestressed cables 5 to pass through.

[0024] The number and location of newly installed steel columns 3, the location of new supports 4, and the location of the turning points of external prestressed cables 5 (e.g., Figure 1 The values ​​of L1, L2, etc., and prestress shown are all calculated and determined based on the principle that the internal forces of the existing beams 1 connected to the upper and lower layers do not change after the span is expanded, or remain within the bearing capacity provided by the original reinforcement (i.e., the existing beams 1 do not require additional reinforcement). The above calculation and analysis can use a high-precision finite element model that combines rod elements, shell elements, or solid elements. In the calculation, the entire process of applying prestress in stages while simultaneously removing the supports 2 to be dismantled in stages, and achieving a smooth transfer of load while expanding the span, can be accurately simulated.

[0025] Furthermore, the support 2 to be dismantled can be divided into a first section 2-1 and a second section 2-2 from top to bottom. The first section 2-1 is statically removed in stages while the prestress is being tensioned in stages to ensure a smooth transfer of load. The second section 2-2 is statically removed after the prestressing is completed and the structural deformation is stable.

[0026] For example, if prestressing requires n stages of tensioning, then it can be done as follows: Figure 4 As shown, the first section 2-1 of the support to be dismantled 2 is divided into sections 1 to n-1 from the side away from the new support 4 to the side closer to the new support 4. When cutting, starting from the second stage of prestressed step tensioning, the first section 2-1 to be dismantled is statically cut off step by step according to the numbering order 1 to n-1.

[0027] Accordingly, this invention also provides an external cable span widening method, which mainly includes the following steps: S1. Based on the principle that the internal forces of the existing beams 1 on the upper and lower floors of the area to be expanded will not change after the expansion, or will remain within the bearing capacity provided by the original reinforcement, the number and location of the newly installed steel columns 3, the location of the new supports 4, the turning point location and prestress value of the external prestressed cables 5 are calculated and analyzed. The entire process of applying prestress in stages while simultaneously removing the supports 2 to be dismantled in stages, and achieving a smooth transfer of load while expanding the span, is simulated. The above calculations, analyses, and simulations can be performed using a high-precision finite element model that combines rod elements, shell elements, or a mixture of solid elements.

[0028] S2. According to the calculation results, connect the new steel column 3 between the existing beams 1 of the upper and lower floors of the area to be expanded (generally a hinged connection is used, but a rigid connection can also be used).

[0029] S3. Based on the calculation results, reinforce the existing supports as new supports 4, or establish new supports as new supports 4, using the new supports 4 to support the existing beams 1 of the upper and lower layers in the area to be expanded. The span formed by the new supports 4 in the area to be expanded must be greater than the original span formed by the supports 2 to be demolished, in order to achieve the purpose of expanding the span. Specifically, the existing supports can be reinforced by increasing the cross-section, and the newly established supports can be made by pouring micro-expansion concrete to make it dense. The internal reinforcement of the new supports 4 must be tied and fixed to the original reinforcement of the existing beams 1.

[0030] S4. Install the external prestressed cable 5 according to the calculation results. The turning point of the external prestressed cable 5 is connected to the existing beam 1 of the lower layer of the span to be expanded through the turning device. The tensioning end of the external prestressed cable 5 is anchored to the existing beam 1 of the upper layer of the span to be expanded or the new support 4 or the connection node between the new support 4 and the existing beam 1 of the upper layer through the anchoring device.

[0031] S5. Divide the support 2 to be dismantled into the first section 2-1 and the second section 2-2 from top to bottom. While the prestress is being tensioned in stages, the first section 2-1 is statically removed in stages.

[0032] S6. After the prestressing tension is completed and the structural deformation is stable, the second section to be dismantled, 2-2, is statically removed.

[0033] Specifically, taking the renovation of an existing project as an example, the renovation project required the demolition of most of the shear walls of the existing 27m span support, expanding the span of the existing 27m span prestressed beam to 38.8m, an increase of 43.7%. This means that, without changing the load, the total bending moment in the beam after the expansion is 2.07 times the original. However, the construction unit had no intention of demolishing any part of the roof, making the renovation extremely difficult.

[0034] The external cable-stayed span expansion method provided in this embodiment of the invention was used to modify the structure. Vertical steel columns were added between the upper and lower 27m span beams, allowing the upper and lower beams to share the load and form a 38.8m span prestressed composite truss. New supports were established and external prestressing tendons were added. For example... Figure 5 As shown in the figure, the blue lines represent the newly added steel columns 3 and external prestressed cables 5 during the renovation, the area within the red box represents the support 2 to be removed, and the area within the purple box represents the location of the new support 4 to be installed.

[0035] like Figure 6 As shown, a high-precision finite element model using a mixture of rod elements, shell elements, or solid elements is employed for full-process high-precision simulation analysis to ensure that the stress of the existing beam 1 remains essentially unchanged throughout the process or remains within the bearing capacity range provided by the original reinforcement after changes, and that the existing beam 1 does not require additional reinforcement.

[0036] Depend on Figure 6 The structural analysis results show that the nominal principal stress of the concrete remains basically unchanged throughout the span expansion process, achieving the effect of maintaining the internal forces of the structure while gradually applying prestress and gradually expanding the span.

[0037] The measured vertical displacement difference during the span expansion process of this renovation project is as follows: Figure 7 As shown, whether during or after the span expansion construction, the vertical displacement of the beam mid-span is within ±1mm, which is a very small change, thus confirming the achievement of the predetermined design goal.

[0038] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core ideas of the present invention. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An external cable-stayed expansion structure, characterized in that, include: New steel columns are installed, which are connected between the existing beams of the upper and lower floors in the area to be expanded. The new support can support the existing beams of the upper and lower layers in the area to be expanded, and the span formed by the new support in the area to be expanded is greater than the original span formed by the support to be dismantled. The external prestressed cable has its turning point connected to the existing beam of the lower layer of the span area to be expanded via a turning device, and its tensioning end is anchored to the existing beam of the upper layer of the span area to be expanded, or the new support, or the connection node between the new support and the existing beam of the upper layer via an anchoring device. The number and location of the newly installed steel columns, the location of the new supports, the turning point location of the external prestressed cables, and the prestress value are all determined by calculation based on the principle that the internal forces of the existing beams of the upper and lower layers connected do not change after the span is expanded or remain within the bearing capacity range provided by the original reinforcement.

2. The external cable span-expanding structure according to claim 1, characterized in that: The new support is either a reinforced existing support or a newly established support.

3. The external cable span-expanding structure according to claim 1, characterized in that: The support to be dismantled is divided into a first section to be dismantled and a second section to be dismantled from top to bottom. The first section to be dismantled is statically removed in stages while the prestress is tensioned in stages. The second section to be dismantled is statically removed after the prestressing is completed and the structural deformation is stable.

4. The external cable span-expanding structure according to claim 3, characterized in that: A high-precision finite element model, which combines rod elements, shell elements, or solid elements, is used to calculate and analyze the number and location of the newly installed steel columns, the location of the new supports, the turning point location and prestress value of the external prestressed cables, and to simulate the entire process of applying prestress in stages while simultaneously removing the supports to be dismantled in stages, and achieving a smooth transfer of load while expanding the span.

5. The external cable span-expanding structure according to claim 1, characterized in that: The steering device includes a steel pipe and two steering sleeves. The steel pipe is fixedly installed through the existing beam on the lower layer. The two steering sleeves are rotatably sleeved on both ends of the steel pipe through ball bearings, and each end of the steering sleeve is provided with a limiting protrusion ring.

6. The external cable span-expanding structure according to claim 1, characterized in that: The anchoring device includes a semi-circular steel pipe and two anchor plates. The semi-circular steel pipe is fixedly installed on the existing upper beam or the new support or the connection node between the new support and the existing upper beam. The two anchor plates are respectively fixed at both ends of the semi-circular steel pipe, and the anchor plates and the semi-circular steel pipe are respectively provided with through holes for the external prestressed cables to pass through.

7. A method for expanding the span of an external cable, characterized in that, Includes the following steps: S1. Based on the principle that the internal forces of the existing beams in the upper and lower layers of the span to be expanded do not change after the span expansion or remain within the bearing capacity provided by the original reinforcement, calculate and analyze the number and location of the newly installed steel columns, the location of the new supports, the turning point location and prestress value of the external prestressed cables, and simulate the entire process of applying prestress in stages while removing the supports to be dismantled in stages, and achieving a smooth transfer of load while expanding the span. S2. Connect the newly installed steel columns between the existing beams on the upper and lower floors of the area to be expanded, according to the calculation results; S3. Based on the calculation results, reinforce the existing supports as the new supports or establish new supports as the new supports to support the existing beams of the upper and lower layers in the area to be expanded; the span formed by the new supports in the area to be expanded is greater than the original span formed by the supports to be dismantled; S4. Install the external prestressed cable according to the calculation results. The turning point of the external prestressed cable is connected to the existing beam of the lower layer of the span area to be expanded through the turning device. The tensioning end of the external prestressed cable is anchored to the existing beam of the upper layer of the span area to be expanded or the new support or the connection node between the new support and the existing beam of the upper layer through the anchoring device. S5. Divide the support to be dismantled into the first section to be dismantled and the second section to be dismantled from top to bottom. While the prestressing is being tensioned in stages, the first section to be dismantled is statically cut off in stages. S6. After the prestressing is completed and the structural deformation is stable, the second section to be dismantled is statically removed.

8. The method for expanding the span of an external cable according to claim 7, characterized in that: A high-precision finite element model, which combines rod elements, shell elements, or solid elements, is used to calculate and analyze the number and location of the newly installed steel columns, the location of the new supports, the inflection point location of the external prestressed cables, and the prestress value.

9. The method for expanding the span of an external cable according to claim 7, characterized in that: The existing support mentioned in step S3 is reinforced by increasing the cross-section.

10. The method for expanding the span of an external cable according to claim 7, characterized in that: The newly established support mentioned in step S3 is made of micro-expansion concrete and is poured densely.

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