Pre-pressing device suitable for large steel pipe support and pre-pressing method of pre-pressing device

Abstract

The invention relates to a prepressing device suitable for a large steel pipe support and a prepressing method of the prepressing device, which are characterized in that a plurality of groups of prepressing devices are arranged on the part with the largest stress in the large steel pipe support, and the large steel pipe support is locally prepressed by adopting a mode of synchronously jacking and reversely pressing by adopting a plurality of jacks. The pre-pressing load is 1.1 times of the maximum construction load borne by the part, with the maximum stress, of the large steel pipe support; in the pre-pressing process, the elevation of the top of the large steel pipe support is observed, a vertical deformation value is calculated, and according to the vertical deformation value, the corresponding pre-lifting amount is set in the mode that a steel plate is cushioned at the top of the large steel pipe support, so that the influence of vertical deformation of the large steel pipe support is eliminated; and meanwhile, the bearing capacity of the large steel pipe bracket can be verified by pre-pressing the part with the maximum stress in the large steel pipe bracket, so that the purpose of pre-pressing is achieved. The method has the advantages of being safe, reliable, high in practicability, high in pre-pressing efficiency, good in economic benefit, convenient, fast and capable of saving the construction period and the construction cost.

Description

Technical Field

[0001] The invention relates to the field of main tower construction in bridge engineering, and in particular to a preloading device and a preloading method suitable for a large steel pipe support. Background Art

[0002] With the vigorous development of domestic bridge engineering construction, super-large main towers are constantly breaking records in bridge construction. As an important part of the main tower, the lower crossbeam is also breaking records in terms of its structural size, and the construction difficulty is increasing. The lower crossbeam is generally constructed by cast-in-place steel pipe support. The large steel pipe support erected according to the specification requirements needs to be pre-stressed, and the pre-stressing load is not less than 1.1 times the maximum construction load that the large steel pipe support can bear, in order to test the bearing capacity of the large steel pipe support and eliminate the influence of vertical deformation of the large steel pipe support after bearing.

[0003] The traditional preloading method is overall preloading, which requires the loading of water bags and other heavy objects on the top of the support for preloading. However, for large steel pipe supports, since the overall preloading load is as high as several thousand tons, the overall loading of several thousand tons of heavy objects for preloading in a limited space at high altitude has too great a safety risk and is not feasible. Therefore, the preloading method of large steel pipe supports needs to be innovated, which can not only ensure the safety of high-altitude preloading, but also be feasible. Summary of the invention

[0004] The first object of the present invention is to provide a preloading device suitable for a large steel pipe support which has a stable structure and is easy to construct.

[0005] The second object of the present invention is to provide a safe, reliable and practical pre-stressing method suitable for large steel pipe supports.

[0006] The first object of the present invention is achieved by: A preloading device suitable for a large steel pipe support, characterized in that: the large steel pipe support comprises a crossbeam and a steel pipe column, a plurality of steel pipe columns are arranged and aligned, and a crossbeam is installed on the top of each row of steel pipe columns; a plurality of groups of preloading devices are arranged on the large steel pipe support, and each group of preloading devices consists of an anchoring system and a jack, wherein: each anchoring system consists of two embedded bases, a cushion beam, a preloading distribution beam, four precision-rolled threaded steel bars and four nuts, wherein: The jack is placed on the top of the crossbeam of the large steel pipe support. A cushion beam is arranged on the top of the jack, and a pre-stressed distribution beam is arranged on the top of the cushion beam. Four holes for inserting fine-rolled threaded steel bars are symmetrically arranged on the pre-stressed distribution beam. Two embedded bases are symmetrically embedded on the pedestal just below each pre-stressed distribution beam. Two holes are opened on the top of each embedded base, and correspond to the holes on the upper pre-stressed distribution beam; fine-rolled threaded steel bars are respectively inserted between the holes of the upper and lower corresponding embedded bases and the holes of the pre-stressed distribution beam, and nuts are installed at both ends of the fine-rolled threaded steel bars to limit and fix them.

[0007] Furthermore, the embedded base is a box-shaped structure formed by welding steel plates and steel bars.

[0008] Furthermore, the cushion beam is assembled and welded by two 45a steel sections, with a length of 1m.

[0009] Furthermore, the prestressed distribution beam is assembled and welded by four 45a beams, with a length of 0.8m.

[0010] The second object of the present invention is achieved by: A preloading method suitable for large steel pipe supports, the specific steps are as follows: A. Perform local preloading on the part of the large steel pipe support that is subject to the greatest force. The preloading load is 1.1 times the maximum construction load borne by the part. The specifications of the jack are determined according to the size of the preloading load. Install a set of preloading devices before and after the plane position of each steel pipe column included in the part. B. After the preloading device is installed, all the jacks are started synchronously. The jacks are divided into three levels, namely 0→60%→90%→100% loading to the preloading load. When the jacks are loaded synchronously, a dedicated person will give unified signal command to ensure the synchronization of loading; the total station is used to synchronously measure the elevation of the observation point on the top of the large steel pipe support, and the original elevation before loading and the elevation after 1 hour of each level of loading are recorded respectively; C. After the jack loading is completed and the elevation measurement of each observation point is completed, unloading is carried out step by step in the order of 100% → 90% → 60% → 0%; the elevation of each observation point is measured by a total station 6 hours after all unloading is completed; the difference between the elevation after unloading and the original elevation before loading is calculated, which is the inelastic deformation value; the difference between the elevation after loading and the elevation after unloading is calculated, which is the elastic deformation value; the sum of the inelastic deformation value and the elastic deformation value is the vertical deformation value; D. According to the obtained vertical deformation value, add a steel plate pad of corresponding thickness on the top of the large steel pipe support as the pre-lift of the entire large steel pipe support to eliminate the influence of the vertical deformation of the entire large steel pipe support and complete the pre-compression.

[0011] The prestressing method is to install multiple sets of prestressing devices on the most stressed part of the large steel pipe support, and locally prestress the large steel pipe support by using multiple jacks to simultaneously lift and counter-press. The prestressing load is 1.1 times the maximum construction load borne by the most stressed part of the large steel pipe support; during the prestressing process, the elevation of the top of the large steel pipe support is observed, the vertical deformation value is calculated, and according to the vertical deformation value, the corresponding pre-lifting amount is set by padding the steel plate on the top of the large steel pipe support to eliminate the influence of the vertical deformation of the large steel pipe support; at the same time, by prestressing the most stressed part of the large steel pipe support, the bearing capacity of the large steel pipe support can also be verified, thereby achieving the purpose of prestressing.

[0012] The present invention has the following advantages: 1. Safe and reliable: The present invention adopts the method of "anchoring system + jack lifting and counter-pressure" to locally pre-press the part with the greatest force in the large steel pipe support. The pre-pressing load is smaller, more reasonable and feasible, and there is no need to pile thousands of tons of heavy objects in a limited space at high altitude, with less safety risks. It solves the problem that the overall pre-pressing scheme of the traditional large steel pipe support needs to pre-press thousands of tons of load in a limited space at high altitude, which has high safety risks and is not feasible; 2. Strong practicability: The present invention can adjust the number and specifications of the jacks according to different large steel pipe supports and different preloading loads to meet the preloading load requirements, and combined with the local preloading scheme of "anchoring system + jack top-up counterpressure", it can provide thousands of tons of preloading loads under the premise of ensuring safety. The preloading is stable and reliable, and has strong practicability; 3. High preloading efficiency and good economic benefits. Compared with the traditional overall pile loading preloading scheme, the present invention does not need to pile thousands of tons of loads at high altitudes, and the loading and unloading of the preloading load can be adjusted by simply adjusting the top force of the jack. Compared with the traditional overall pile loading preloading scheme, the preloading efficiency is higher, more convenient and quick, saving construction time and construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is the elevation view of the preloading device; Figure 2 is a side view of the preloading device; Figure 3 is a top view of the preloading device; Figure 4 It is a structural schematic diagram of the prestressed distribution beam; Figure 5 It is the top view of the pre-stressed distribution beam; Figure 6 It is the side view of the pre-stressed distribution beam; Figure 7 The structural diagram of the cushion beam is shown in FIG. Figure 8 This is a top view of the cushion beam; Fig. 9 It is the side view of the cushion beam; Fig.10 It is a structural diagram of the embedded base; Fig.11 It is a top view of the embedded base; Fig.12 It is the side view of the embedded base; In the figure: 1. Jack; 2. Embedded base; 3. Pad beam; 4. Pre-loaded distribution beam; 5. Finished rolled threaded steel bars; 6. Nuts; 7. Large steel pipe support; 8. Crossbeam; 9. Steel pipe column; 10. Capping platform. DETAILED DESCRIPTION

[0014] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0015] A preloading device suitable for a large steel pipe support, the large steel pipe support 7 comprises a crossbeam 8 and a steel pipe column 9, a plurality of steel pipe columns 9 are arranged and aligned, and a crossbeam 8 is installed on the top of each row of steel pipe columns 9; a plurality of groups of preloading devices are arranged on the large steel pipe support 7, each group of preloading devices is composed of an anchoring system and a jack 1, wherein: each anchoring system is composed of two embedded bases 2, a cushion beam 3, a preloading distribution beam 4, four precision-rolled threaded steel bars 5 and four nuts 6: The jack 1 is placed on the top of the crossbeam 8 of the large steel pipe support 7. A cushion beam 3 is arranged on the top of the jack 1, and a pre-stress distribution beam 4 is arranged on the top of the cushion beam 3. Four ∅100mm holes for inserting the fine-rolled threaded steel bars 5 are symmetrically arranged on the pre-stress distribution beam 4. Two embedded bases 2 are symmetrically embedded on the pedestal 8 just below each pre-stress distribution beam 4. Two ∅100mm holes are opened on the top of each embedded base 2, and correspond to the holes on the upper pre-stress distribution beam 4; ∅40mm fine-rolled threaded steel bars 5 are respectively inserted between the holes of the upper and lower corresponding embedded bases 2 and the holes of the pre-stress distribution beam 4, and nuts 6 are installed at both ends of the fine-rolled threaded steel bars 5 to limit and fix them.

[0016] The embedded base 2 is a box-shaped structure formed by welding steel plates and steel bars.

[0017] The cushion beam 3 is assembled and welded by two 45a steel sections, with a length of 1m.

[0018] The preload distribution beam 4 is assembled and welded by four beams 45a, with a length of 0.8m.

[0019] The specification of the jack 1 is determined according to the size of the preload and the number of jacks. For example, the part of the large steel pipe support 7 that bears the greatest force is the middle part. There are three steel pipe columns and a crossbeam in a row. With the plane position of each steel pipe column in the row as the center, a group of preload devices are set in front and behind, and there are 6 groups of preload devices in total, and each group of preload devices has a jack 1. The preload of the middle part of the large steel pipe support 7 is calculated to be 1400t. Since 6*250t=1500t>1400t, the specification of the jack 1 is 250t.

[0020] A preloading method suitable for large steel pipe supports, the specific steps are as follows: A. Perform local preloading on the part of the large steel pipe support that is subject to the greatest force. The preloading load is 1.1 times the maximum construction load borne by the part. The specifications of the jack are determined according to the size of the preloading load. Install a set of preloading devices before and after the plane position of each steel pipe column included in the part. B. After the preloading device is installed, all jacks 1 are started synchronously. Jacks 1 are divided into three levels: 0→60%→90%→100%. They are loaded to the preloading load. When jacks 1 are loaded synchronously, a dedicated person will give unified signal command to ensure the synchronization of loading. The total station is used to synchronously measure the elevation of the observation point on the top of the large steel pipe support 7, and the original elevation before loading and the elevation after each level of loading is completed for 1 hour are recorded respectively. C. After the loading of jack 1 is completed and the elevation measurement of each observation point is completed, unload step by step in the order of 100% → 90% → 60% → 0%; use a total station to measure the elevation of each observation point 6 hours after all unloading is completed; calculate the difference between the elevation after unloading and the original elevation before loading, which is the inelastic deformation value; calculate the difference between the elevation after loading and the elevation after unloading, which is the elastic deformation value; the sum of the inelastic deformation value and the elastic deformation value is the vertical deformation value; D. According to the obtained vertical deformation value, a steel plate pad of corresponding thickness is added to the top of the large steel pipe support 7 as the pre-lift amount of the entire large steel pipe support 7 to eliminate the influence of the vertical deformation of the entire large steel pipe support 7 and complete the pre-compression.

[0021] The preloading method is to locally preload the most stressed part of the large steel pipe support by using a jack to lift and apply counter pressure, and the preloading load is 1.1 times the maximum construction load that the part has to bear. During the preloading process, the elevation of the top of the large steel pipe support is observed, and the vertical deformation value is calculated. According to the vertical deformation value, the corresponding pre-lift is set by padding the steel plate on the top of the large steel pipe support to eliminate the influence of the vertical deformation of the large steel pipe support. At the same time, by preloading the most stressed part of the large steel pipe support, the bearing capacity of the large steel pipe support can be verified, thereby achieving the purpose of preloading.

[0022] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A preloading device suitable for a large steel pipe support, characterized in that: The large steel pipe support includes a crossbeam and a steel pipe column. Several steel pipe columns are aligned and a crossbeam is installed on the top of each row of steel pipe columns. Several groups of pre-stressing devices are arranged on the large steel pipe support. Each group of pre-stressing devices consists of an anchoring system and a jack, wherein: each anchoring system consists of two embedded bases, a cushion beam, a pre-stressing distribution beam, four precision-rolled threaded steel bars and four nuts, wherein: The jack is placed on the top of the crossbeam of the large steel pipe support. A cushion beam is arranged on the top of the jack, and a pre-stressed distribution beam is arranged on the top of the cushion beam. Four holes for inserting fine-rolled threaded steel bars are symmetrically arranged on the pre-stressed distribution beam. Two embedded bases are symmetrically embedded on the pedestal just below each pre-stressed distribution beam. Two holes are opened on the top of each embedded base, and correspond to the holes on the upper pre-stressed distribution beam; fine-rolled threaded steel bars are respectively inserted between the holes of the upper and lower corresponding embedded bases and the holes of the pre-stressed distribution beam, and nuts are installed at both ends of the fine-rolled threaded steel bars to limit and fix them.

2. The preloading device for large steel pipe support according to claim 1 is characterized in that: The embedded base is a box-shaped structure composed of welded steel plates and steel bars.

3. The preloading device for large steel pipe support according to claim 1 is characterized in that: The cushion beam is assembled and welded from two 45a steel sections, with a length of 1m.

4. The preloading device for large steel pipe support according to claim 1 is characterized in that: The preload distribution beam is assembled and welded by four 45a steel beams, with a length of 0.8m.

5. A preloading method for a preloading device for a large steel pipe support according to claim 1, characterized in that: The specific steps are as follows: A. Perform local preloading on the part of the large steel pipe support that is subject to the greatest force. The preloading load is 1.1 times the maximum construction load borne by the part. The specifications of the jack are determined according to the size of the preloading load. Install a set of preloading devices before and after the plane position of each steel pipe column included in the part. B. After the preloading device is installed, all the jacks are started synchronously. The jacks are divided into three levels, namely 0→60%→90%→100% loading to the preloading load. When the jacks are loaded synchronously, a dedicated person will give unified signal command to ensure the synchronization of loading; the total station is used to synchronously measure the elevation of the observation point on the top of the large steel pipe support, and the original elevation before loading and the elevation after 1 hour of each level of loading are recorded respectively; C. After the jack loading is completed and the elevation measurement of each observation point is completed, unloading is carried out step by step in the order of 100% → 90% → 60% → 0%; the elevation of each observation point is measured by a total station 6 hours after all unloading is completed; the difference between the elevation after unloading and the original elevation before loading is calculated, which is the inelastic deformation value; the difference between the elevation after loading and the elevation after unloading is calculated, which is the elastic deformation value; the sum of the inelastic deformation value and the elastic deformation value is the vertical deformation value; D. According to the obtained vertical deformation value, add a steel plate pad of corresponding thickness on the top of the large steel pipe support as the pre-lift of the entire large steel pipe support to eliminate the influence of the vertical deformation of the entire large steel pipe support and complete the pre-compression.

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