A method for designing the precast beam common pedestal precast camber line based on BIM design

Abstract

The present invention provides a precast beam common pedestal precast camber linear design method based on BIM design, the method is to create a rectangular concrete pedestal model with the software coordinate origin as the center in BIM design software, use the BIM model, take the origin and the pedestal top surface as the axis, obtain the coordinate point of the maximum offset value of the precast beam precast beam precast beam with the maximum span post-tensioning method, take the point as the reference point, and determine the two key coordinate points of other unequal span precast beams according to the principle of three points determining a parabola, and draw a new parabola based on the known coordinate points using a spline curve to meet the requirements of the precast beam design after the prestressing tensioning of all unequal span precast beams, and then calculate the coordinate points of every two meters on the parabola based on the BIM model as construction control points. This solves the problem that the traditional precast beam pedestal can only meet the precast beam precast beam design requirements of a single length. It belongs to the field of precast beam construction.

Description

Technical Field

[0001] The invention relates to a precast beam common pedestal pre-camber line design method based on BIM design, and belongs to the field of precast beam construction. Background Art

[0002] With the rapid development of my country's infrastructure industry, prefabricated bridge construction is becoming more and more widely used. Affected by the terrain factors of on-site construction, design units often design prefabricated beams of different lengths to meet on-site construction needs. At the same time, in order to offset the deflection of the beam under load, a correction amount opposite to the displacement direction is usually reserved along the bottom of the beam during beam form design. The correction amount changes parabolically from the center of the beam to the ends of the beam on both sides, which is the change in the pre-camber line.

[0003] At present, the traditional precast beam pedestal can only meet the precast beam precast beam design requirements of a single length. The use of traditional pedestals, on the one hand, requires a large amount of space and has high construction costs. For some projects with small sites and large construction production quantities, when only a small number of precast beams of different span lengths need to be constructed and produced, setting up a single pedestal for construction cannot meet the normal needs of construction and production. Second, when it is desired to use a shared pedestal for construction, the traditional pedestal precast degree line type value is generally based on the precast degree parabolic type of the two precast beams. Under the premise of meeting the error of ±10%, a new precast degree parabola is redesigned. The traditional parabolic design is only selected based on the construction experience to apply the formula. When there are three types of beams to be precast together or the length of the beams is very different, the precast degree parabola selected based on experience may not meet the precast degree design value of all beams. Summary of the invention

[0004] The present invention provides a method for designing a precast beam common pedestal precast camber line based on BIM design, so as to solve the problem that a traditional precast beam pedestal can only meet the precast beam precast camber design requirements of a single length, and the pedestal utilization rate and turnover rate are low.

[0005] In order to achieve the above purpose, a precast beam common pedestal precast linear design method based on BIM design is proposed. In this method, a rectangular concrete pedestal model is created in the BIM design software with the software coordinate origin as the center. The length h1 is the length of the longest precast beam required. The upper surface straight line of the rectangular pedestal is used as the reference line to offset downward to obtain the maximum precast offset value L1 of the longest precast beam required. The offset value L1 is the precast design value of the longest precast beam required, and the coordinates of point A (-h1 / 2, 0) and point A are obtained. 1The coordinates of point (h1 / 2, 0) and point D (0, -L1) are obtained based on the straight line, and then the coordinates of two points corresponding to the offset value and length of other precast beams are offset. Then, a new pre-camber parabola is drawn through the above coordinate points using a spline curve. This pre-camber parabola satisfies the requirement that the middle part of the bottom of the precast beam is arched upward under force after the prestressed tendons of the unequal-span precast beams are tensioned, and the bottom of the beam is kept horizontal.

[0006] Based on the BIM model, the coordinate points every two meters on the parabola are calculated as construction control points. When constructing the concrete pedestal, the surveyor releases the elevation based on the coordinate points for the on-site concrete pedestal pouring construction.

[0007] There are three types of precast beams required, with lengths of 25 meters, 30 meters, and 40 meters respectively. The pre-camber design values ​​of the three precast beams are 19 mm, 21 mm, and 27 mm respectively. The maximum height of the pedestal is 400 mm. The pedestal is designed in common. In Inventor software, a 40-meter-long rectangular concrete pedestal model is created with the software coordinate origin as the center. The upper surface straight line of the rectangular pedestal is used as the reference line and offset downward by 27 mm to obtain the maximum pre-camber offset value of the 40-meter precast beam. The coordinates of point A (-2000, 0) and point A are obtained. 1 The coordinates of point A are (2000, 0) and point D are (0, -27). Based on this straight line, the offsets are 19 mm and 21 mm, resulting in straight lines of 25 m and 30 m. The coordinates of point B are (-1500, -6) and B 1 Point (1500, -6), Point C (-1250, -8), C 1 Point (1250, -8), through the above coordinate points, a new pre-camber parabola line shape is obtained to meet the construction requirements;

[0008] Based on the BIM model, the coordinate points every two meters on the parabola are calculated as construction control points. When constructing the concrete pedestal, the surveyor releases the elevation according to the coordinate points for the on-site concrete pedestal pouring construction;

[0009] The other construction steps of precast beams can be carried out according to normal construction.

[0010] Compared with the prior art, the present invention utilizes BIM design software such as Inventor to design a pre-camber parabolic line shape that can meet the construction requirements according to the required precast beam size in the software, and then selects construction control points based on the BIM model for construction. This solves the problem of pre-camber line shape design for common pedestals of precast beams with multiple lengths, and is suitable for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic diagram of a pre-camber parabola obtained in an embodiment of the present invention;

[0012] Figure 2 This is a schematic diagram of the 40-meter-long precast beam after prestressing construction (the filling part is the precast beam);

[0013] Figure 3 This is a schematic diagram of a 40-meter-long precast beam before prestressing construction (the filling part is a precast beam);

[0014] Figure 4 This is a schematic diagram of a 30-meter-long precast beam before prestressing construction (the filling part is a precast beam). DETAILED DESCRIPTION

[0015] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0016] Example 1

[0017] The present embodiment provides a method for designing the pre-arch linear shape of a common pedestal for precast beams based on BIM design. The implementation scheme is demonstrated by taking a common concrete pedestal for precast beams with length differences of 22 meters, 28 meters, and 34 meters as a design case, wherein the pre-arch design values ​​of the precast beams are 19 mm, 21 mm, and 27 mm, respectively, and the maximum height of the pedestal is 400 mm.

[0018] 1) Design of the shared pedestal. In Inventor software, a 34-meter-long rectangular concrete pedestal model is created with the software coordinate origin as the center. The upper surface straight line of the rectangular pedestal is used as the reference line and offset downward by 27 mm to obtain the maximum pre-camber offset value of the 40-meter precast beam. The coordinates of point A (-1700, 0) and point A 1 The coordinates of point A are (1700, 0) and point D are (0, -27). Based on this straight line, the offsets are 19 mm and 21 mm, resulting in straight lines of 22 meters and 28 meters. Then the coordinates of points B are (-1400, -6) and B 1 Point (1400, -6), Point C (-1100, -8), C 1 Point (1100, -8), through the above coordinate points, a new pre-camber parabola line shape is obtained to meet the construction requirements;

[0019] 2) Based on the BIM model, the coordinate points every two meters on the parabola are calculated as construction control points. When constructing the concrete pedestal, the surveyor releases the elevation according to the coordinate points for the on-site concrete pedestal pouring construction;

[0020] 3) The other construction steps of precast beams can be carried out according to normal construction.

[0021] Example 2

[0022] Refer to the attached Figures 1 to 4This embodiment provides a method for designing the pre-camber linear shape of a common pedestal for precast beams based on BIM design. The implementation scheme is demonstrated by taking a common concrete pedestal for precast beams with length differences of 25 meters, 30 meters, and 40 meters as a design case. The pre-camber design values ​​of the precast beams are 19 mm, 21 mm, and 27 mm, respectively, and the maximum height of the pedestal is 400 mm.

[0023] 1) Design of the shared pedestal. In Inventor software, a 40-meter-long rectangular concrete pedestal model is created with the software coordinate origin as the center. The upper surface straight line of the rectangular pedestal is used as the reference line and offset downward by 27 mm to obtain the maximum pre-camber offset value of the 40-meter precast beam. The coordinates of point A (-2000, 0) and point A 1 The coordinates of point A are (2000, 0) and point D are (0, -27). Based on this straight line, the offsets are 19 mm and 21 mm, resulting in straight lines of 25 m and 30 m. The coordinates of point B are (-1500, -6) and B 1 Point (1500, -6), Point C (-1250, -8), C 1 Point (1250, -8), through the above coordinate points, a new pre-camber parabola line shape is obtained to meet the construction requirements;

[0024] 2) Based on the BIM model, the coordinate points every two meters on the parabola are calculated as construction control points. When constructing the concrete pedestal, the surveyor releases the elevation according to the coordinate points for the on-site concrete pedestal pouring construction;

[0025] 3) The other construction steps of precast beams can be carried out according to normal construction.

[0026] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for designing the precast beam common pedestal pre-camber line based on BIM design, characterized in that: The method is to create a rectangular concrete pedestal model in the BIM design software with the software coordinate origin as the center, the length h1 is the length of the longest precast beam required, and the upper surface straight line of the rectangular pedestal is used as the reference line to offset downward to obtain the maximum pre-camber offset value L1 of the longest precast beam required. The offset value L1 is the pre-camber design value of the longest precast beam required, and the coordinates of point A (-h1 / 2, 0) and point A are obtained. 1 The coordinates of point (h1 / 2, 0) and point D (0, -L1) are obtained based on the straight line, and then the coordinates of two points corresponding to the offset value and length of other precast beams are obtained. Then, a new pre-camber parabola line type is obtained by drawing a spline curve through the above coordinate points. The pre-camber parabola line type satisfies the requirement that the middle part of the bottom of the precast beam is arched upward by force after the prestressed tendons of the unequal span precast beams are tensioned, and the bottom of the beam is kept horizontally straight. Based on the BIM model, the coordinate points every two meters on the parabola are calculated as construction control points. When constructing the concrete pedestal, the surveyor releases the elevation based on the coordinate points for the on-site concrete pedestal pouring construction.

2. According to the method for designing the precast beam common pedestal pre-camber line type based on BIM design according to claim 1, it is characterized by: There are three types of precast beams required, with lengths of 25 meters, 30 meters, and 40 meters respectively. The pre-camber design values ​​of the three precast beams are 19 mm, 21 mm, and 27 mm respectively. The maximum height of the pedestal is 400 mm. The pedestal is designed in common. In Inventor software, a 40-meter-long rectangular concrete pedestal model is created with the software coordinate origin as the center. The upper surface straight line of the rectangular pedestal is used as the reference line and offset downward by 27 mm to obtain the maximum pre-camber offset value of the 40-meter precast beam. The coordinates of point A (-2000, 0) and point A are obtained. 1 The coordinates of point A are (2000, 0) and point D are (0, -27). Based on this straight line, the offsets are 19 mm and 21 mm, resulting in straight lines of 25 m and 30 m. The coordinates of point B are (-1500, -6) and B 1 Point (1500, -6), Point C (-1250, -8), C 1 Point (1250, -8), through the above coordinate points, a new pre-camber parabola line shape is obtained to meet the construction requirements; Based on the BIM model, the coordinate points every two meters on the parabola are calculated as construction control points. When constructing the concrete pedestal, the surveyor releases the elevation according to the coordinate points for the on-site concrete pedestal pouring construction; The other construction steps of precast beams can be carried out according to normal construction.

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