KR20060115047A - The preflex type and loading device with 3 loading point - Google Patents

Abstract

A preflex type loading device with three loading points is provided to cut down construction cost by adjusting thickness of steel material according to distribution, and to improve structural stability without torsional deformation, local deformation or horizontal buckling by distributing load into three points. A preflex steel girder is manufactured by applying bending deformation to the steel girder with a reaction bar(2) by hydraulic jacks(3) at both ends, and load is applied to a center point of the steel girder. Load is applied alternately to the center point and both ends, and the center point is accurately dropped within the permissible limit range by applying preflex load according to change of strength of a joint portion. A loading bar(13) fixed to the ground by an earth anchor(18) is installed in the center point of the steel girder, and a lower flange(15) of an upper frame of the loading bar and a hydraulic jack(16) are mounted to the loading bar by bolting. The preflex girder is manufactured by applying load with the hydraulic jack of the loading bar.

Description

Preflex type with 3 loading points and its manufacturing method and loading device {The preflex type and loading device with 3 loading point}

1a to c is a perspective view showing a conventional technology

2a to b are cross-sectional views of a conventional preflex type

Figure 3 is a side, cross-sectional view showing a preferred embodiment of the present invention

4a to 4b is a perspective view showing an application example of the prior art and the present invention

Figures 5a to 5b is a comparison showing the cross-sectional force and cross-sectional change in the conventional two-point loading and three-point loading of the present invention

 ■ Explanation of the major symbols used in the main parts of the drawings ■

1: Type I steel 2: Reaction band

4 load cell 6 joint

DESCRIPTION OF SYMBOLS 10 Flange part welding surface 13 Loading stage 14 Lateral support 17 Sliding plate 18 Earth anchor

The present invention relates to a preflex type having three load loading points, a manufacturing method thereof, and a load device.

Preflex composition girder used in the construction of bridges (I type cross section) Compression prestressing type and re-prestress preflex composition girder (secondary compressive stress) by tensioning pre-placed PC steel wires in flanged concrete where compression is introduced by preflection. The preflex type and its manufacturing method through the management of the precise rise of the pre-synthesis type of partial prestressing to form a full prestressing) by further introducing

Looking at the technology registered in the Korean Intellectual Property Office, the application number 10-1998-0026725 is the step of connecting the first and second steels arranged in the upper and lower sides with a tight bolt at a certain point, the upper and lower steels of the first article And arranging the upper and lower side molds of article 2 in parallel at regular intervals, and the plurality of cross beams arranged at regular intervals of the upper molds of article 1 and 2 and the lower molds of articles 1 and 2, respectively. Connecting to each other using a step, installing a loading stage on the lower cross beam installed at the tight bolt position, applying a preflection load using a hydraulic jack installed between the upper and lower rigid sections of each pair corresponding to the loading position of the preflexion load. Step, pre-fabricated ball manufacturing method comprising the step of coating the concrete on the upper flange of the upper steel and the lower flange of the lower steel It's about the law,

Patent Application No. 10-2000-0070083 provides an upper and lower steel molds arranged up and down with each other, connecting the upper and lower steel molds using a fastening bolt at a predetermined point, the upper steel and corresponding to the loading position of the preflection load Installing a loading stage between the lower steel molds, and installing a hydraulic jack between the upper steel molds and the lower steel molds next to the lower steel molds to apply a preflection load to open the entire steel mold, the upper flanges of the upper steels and the lower steels The present invention relates to a method of manufacturing a preflex type in which a gap is formed in a step of covering concrete on a lower flange, and most of the methods of manufacturing an efficient preflex type are related.

In this case, deflection error of the overall steel that can be caused by dividing and moving the steel manufactured as designed in general, that is, the steel produced according to the design is assembled in the field and sag in the center due to the change in the rigidity of the assembly. The method for manufacturing the preflex type according to the initial design is not given because of the variation of the degree, and the development of technology for this is urgently required.

Accordingly, the present invention is to improve the conventional problems as described above, the active deflection deformation of the central portion during the manufacturing of the pre-flex type, to ensure the accurate introduction of the design pre-flection load, stable securing of the rigid restoring force and accurate rise management Its purpose is to make it possible, and precise construction of load and displacement allows accurate design compression force to be introduced into the lower casing concrete, improving reliability on quality and economical effect by dispersing concentrated load by added load point than before. In order to use the cross section of steel and provide structural stability, in case of manufacturing the preflex type by the conventional method, it installs a separate loading stage and hydraulic jack fixed to the ground with earth anchor at L / 2 point and flexes it according to the designed required measurement amount. It was created as a technical problem to generate | occur | produce and to construct a precision pre-fraction.

Figures 1a to c is a perspective view showing a conventional technique, Figures 2a to b is a cross-sectional view of a conventional preflex type, Figure 3 is a side, cross-sectional view showing a preferred embodiment of the present invention, Figure 4a is a prior art 4b is a perspective view showing an application example of the present invention, Figures 5a to 5b is a comparison diagram showing the cross-sectional force and the steel cross-section changes when applying the conventional two-point loading and the three-point loading of the present invention three load loading points of the present invention When explaining the preflex type and its manufacturing method and the load device in detail,

 Figures 1a ~ c shows the preflection step of the conventional preflex composite beam manufacturing process by mounting the field-type I-shaped steel (1) on the reaction table (2) using the hydraulic jack (3) at both ends of the preflection load It is a step of introducing (Pf). When the load is introduced by the load cell 4 for construction management and the design preflection load is reached, the rise of the L / 2 point, which is the end point of the steel and the center point of the steel, is measured to determine whether the required deflection (5) has occurred. You will be confirmed.

 The measured deflection of the steel (5) is not only the data on whether the required resilience of the steel is generated and the precise introduction and management of the preflection load, but also after the concrete cast around the lower flange of the preflected steel is hardened. The step of introducing prestress to the lower flange concrete by removing the static moment given to the steel) and the second step of prestressing by the PC steel wire tension are important for the management of towering in the later work stages. This also affects the profile shape. Moreover, the rigid center point of the simple beam generates the maximum bending section force, so the deflection of the center point has significant meaning in terms of precise construction and quality control. In general, the steel type cannot be transported more than 30m in length, so it is usually divided into three segments of about L / 3 length (6 ') and manufactured at the factory, and then each segment is transported to the site by bolt joint or field welding. One field assembly will produce a steel mold.

2A to 2B illustrate typical assembled states of the steel, and representative cross sections and joint shapes are bolted joints of a uniform cross section as shown in FIG. 2A and welded joints of a cross-sectional laminated board structure as shown in FIG. 2B. The joint part 6 according to this segment has increased rigidity due to the plurality of the additional plates 7 and the bolts 8 in the case of bolted joints, and in the case of the welded joint of the laminated structure, welding the joints 9 of the abdomen. As a result, the rigidity in the vicinity of the seam is increased due to the excessive nonuniformity of the welded surface 10 and the end face of the flange portion and the seam. The increase in rigidity of the L / 3 point rigid joint reduces the transfer of preflection load by the hydraulic jack at the end and the bending stress in the rigid form due to the L / 4 point reaction force to the center part, thereby reducing the predetermined deflection at the center point. This will inhibit the occurrence.

In addition, as shown in FIG. 1C, the rigidity or the stiffness according to the cross section in the structure of the fabrication table where the design point 11 becomes the load point 3 and the design load point 12 becomes the point 2 and the design deflection are calculated. Since the increase in negative stiffness is not taken into account, the error of the calculated deflection and the measured deflection value during the preflection often exceeds the allowable range. In addition, in order to reduce the error of deflection, excessive loads or excessive load tolerances may cause damage to the steel or may cause problems in the construction management of subsequent stages.

3A to 3B illustrate a manufacturing method of a preflex type according to the present invention. FIG. 3A is a side view and FIG. 3B is a cutaway view of L / 2 point.

I-shaped girders (1) assembled to have a predetermined rise in the upper part are mounted on a workbench, and a preflection load (Pf) is applied to the hydraulic jacks (3) installed at both ends of the steel, and a reaction force of about L / 4 points (2) Preflection process to give flexural deformation to steel by)

At this time, install the loading stand 13 fixed to the ground with the horizontal support device 14 and the earth anchor 18 at the rigid center point, and the hydraulic jack 16 provided with the upper frame lower flange 15 and the load measuring device. After attaching downward with a fastening means such as a bolt, a sliding plate 17 is installed on the steel and the contact surface to prevent horizontal force.

Through the loading table 13 and the hydraulic jack 16 as described above, the load by the hydraulic jacks at both ends and the load by the central point hydraulic jack 16 are alternately loaded to allow accurate design center point deflection in the tolerance range. It is to allow the introduction of the preflection load.

4A shows an example in which two steel dies are conventionally inverted up and down and a load is introduced by hydraulic jacks at both ends in one set to produce a preflex type. As shown in FIG. By installing the hydraulic jacks at 2, the load points can be changed to 3 places, and the loads can be alternately loaded as described above to introduce more accurate design center point deflection and preflection loads within the tolerance range.

Figure 5 compares the cross-sectional force and the design cross-sectional example according to the conventional method (FIG. 5A) and the present invention (FIG. 5B) at the time of pre-folding. If it is the same, but three places, the change section of the cross-sectional force is additionally generated, and considering this, the steel section can be economically used, which also has the advantage of reducing construction cost.

Through the preflex type having three load loading points of the present invention and the manufacturing method thereof,

Preflection load loading point is added to the intermediate point L / 2 point of the steel, so that the accurate deflection shape and load introduction can be expected due to the active deflection deformation. It can increase, and rational adjustment of the thickness of the steel for each part according to the dispersion of the cross-sectional force is economically helpful.

In addition, the L / 4 point reaction frame structure, where large concentrated loads are applied when two loads are applied, disperses concentrated loads in three places such as torsional deformation, local deformation of steel and lateral torsional buckling. Stability and construction problems will be improved.

Claims (5)

In the method for producing a pre-flection type by bending the segmented steel to the steel by a reaction force (2) of about L / 4 points using the hydraulic jack (3) at both ends through bolts or welding, Load the load (Pt) to the center point, which is the rigid L / 2 point, By alternately loading the load at the L / 2 point and the load at both ends, Joint plate 7 due to bolted joints between segmented steels, joint plate 9 of the abdomen by welding joints, flange weld zone 10 and non-uniformity of the end face and joints Preflex type fabrication method with three load loading points including the introduction of accurate center point deflection and preflection loads in the design tolerance range The method of claim 1, The method of loading the load (Pt) at the center point, which is the rigid L / 2 point, Hydraulic jack (16) having a transverse support device (14) at the center of the steel, and a loading stand (13) fixed to the ground by an earth anchor (18), and a lower upper flange (15) and a load measuring device After attaching the bolt downward with a fastening means such as a bolt, A preflex type manufacturing method having three load loading points including loading a load through the hydraulic jack 16 of the loading table 13. In the preflation type, the segmented steel is formed by giving bending deformation to the steel by the reaction force 2 of about L / 4 point using the hydraulic jack 3 at both ends through bolts or welding, etc. Load the load (Pt) to the center point, which is the rigid L / 2 point, By alternately loading the load at the L / 2 point and the load at both ends, Joint plate 7 due to bolted joints between segmented steels, joint plate 9 of the abdomen by welding joints, flange weld zone 10 and non-uniformity of the end face and joints Preflex type with three load loading points, including those configured by introducing a precise center point deflection and a preflection load, within the tolerance range of the design against changes in stiffness that may occur. In the production of the preflex type by inverting two steel dies upside down and introducing the load by the hydraulic jacks at both ends in one pair, The hydraulic jack is installed at L / 2 between the upper dies, and the load point is set to three places, and the load points of the center and both ends are alternately loaded to introduce a more accurate design center point deflection and preflection load in the tolerance range. Manufacturing method of preflex type with three loading points including The horizontal support device 14 is installed at the center of the steel, and the loading stage 13 fixed to the ground by the earth anchor 18 is installed, and the hydraulic jack 16 provided with the upper frame lower flange 15 and the load measuring device is installed. After attaching downward by means of fastening such as bolts, the sliding plate 17 is installed on the steel and the contact surface to prevent the horizontal force, and the load point including loading the load Pt to the center point of the steel L / 2 point. Preflex type load device

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