Arrangement optimization method of assembled simply supported beam in small-radius section beam body

Abstract

According to the beam body arrangement optimization method of the assembly type simply supported beam in the small-radius section, the same-span beam body of the large-span and small-radius simply supported beam of a road is generally arranged by adopting a bisection medium-loss method, and the length of the large-span and small-radius same-span beam is greatly changed; the small radius is accompanied by a large cross slope working condition, and the wing plate and the diaphragm plate both need a large cross slope adjustment amount. Determining the length of the equal-section section of the beam of the span according to the shortest equal-section section of the beam end of the curve inner edge beam of the beams of different spans; the lengths of different beams with the same span are adjusted through the lengths of the beam end uniform-section sections; the plane arrangement of the beam middle diaphragm plate is vertical to the beam body axis; left and right transverse diaphragms at the beam ends of the single-piece middle beams are obliquely crossed, oblique crossing steel bars are reserved on the transverse diaphragms at the beam ends, and pouring is performed after the beam plates are hoisted to a bridge site, so that the central axes of the transverse diaphragms at the beam ends of the same-span beams are coaxial and parallel to the central axis of a supporting pier; the beam wing plates and the diaphragm plates are arranged as cross slopes; wing plate planes of the wedge-shaped parts at the ends of the beams are arranged in an oblique crossing mode and are parallel to the central axis of the supporting pier, it is guaranteed that the end faces of the beams in the same span are parallel to the central axis of the pier, the arrangement optimization method is easy to construct, and the beam bodies are good in stress.

Description

Technical Field

[0001] The present invention belongs to the technical field of bridges, and in particular relates to a method for optimizing the arrangement of a prefabricated simply supported beam in a small radius section. Background Art

[0002] Short-radius curves on highway ramp bridges are typically constructed using short-span continuous beams. However, for some special structures, such as those crossing rivers, roads, or structures, as well as for cost and construction time considerations, large-span, small-radius precast concrete simply supported beams may be used. Precast simply supported beams for circular curves can be laid out in a variety of ways, including parallel, radial, tangential, and bisecting mid-sagittal arrangements. However, for large-span, small-radius precast simply supported beams, bisecting mid-sagittal arrangements are typically used. The construction of large-span, small-radius precast simply supported beams presents challenges with demolding due to their prefabricated nature. Conventional precast structures only adjust the beam at the mid-section, with transverse slopes applied to the flanges, but not to the diaphragms. This can lead to misalignment of the diaphragms, both front-to-back and top-to-bottom, after the beams are hoisted into place. Reinforcement connections and concrete pours exhibit bending, resulting in poor stress loading on the beams in the short-radius curves, posing safety risks for subsequent operations. The ends of the beam segments are generally set in the normal direction to the axial direction of the beam body, but in the small radius curve section, it will cause interference between the flange plates of the front and rear spans, making it impossible to complete the positioning of the beam body. Summary of the Invention

[0003] In order to overcome the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a method for optimizing the arrangement of the beam body of a prefabricated simply supported beam in a small radius section, so as to solve the problem that the front and back and upper and lower diaphragms of mass-produced prefabricated simply supported beams in a small curve radius section cannot be straightened.

[0004] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: A prefabricated beam structure for optimizing the arrangement of prefabricated simply supported beams in small radius sections includes an inner side beam, a middle beam, and an outer side beam. Each beam includes a wedge-shaped end section, a uniform cross-section end section, a variable cross-section section, a medium cross-section section, an end diaphragm, a first middle diaphragm section, and a second middle diaphragm section. The inner and outer side beams also include crash barriers.

[0005] Beams of the same span are arranged along the midsagitta, with the wedge-shaped and variable-section sections at the beam ends having fixed lengths, while the medium-section section and the constant-section sections at the beam ends have adjustable lengths. The length of the constant-section section in the middle of beams of different spans is determined by the shortest constant-section section at the end of the inner edge of the curve. The lengths of different beams of the same span are adjusted based on the length of the constant-section sections at the beam ends.

[0006] The central diaphragm is arranged perpendicular to the beam axis; both the beam wings and diaphragms are sloped. The left and right sides of the beam-end diaphragms of the single-piece center beam are longitudinally diagonally intersected. Diagonal reinforcement is reserved for the diaphragms at each beam end and cast after the beam-slab bridge is hoisted to the bridge site. This ensures that the central axis of the diaphragms at the ends of each beam within the same span is coaxial and parallel to the central axis of the supporting pier on the same side. The wing panels at the wedge-shaped ends of the beams are arranged diagonally to ensure that the end faces of each beam within the same span are parallel to the axis of the supporting pier on the same side. Crash barriers are installed on the top surfaces of the inner and outer side beams, with a specific layout form of a circular curve.

[0007] The specific optimization steps are as follows: S1: Determine the layout orientation of the bridge piers of this span; S2: Determine the center axis position of the inner side beam, each middle beam, and outer side beam of this span, as well as the theoretical beam length and span of each beam; S3: Determine the length of the medium cross-section of the inner edge beam of this span. This will serve as the medium cross-section length of the beam for this span. The medium cross-section length of the inner edge beam of a curve is calculated based on the theoretical beam length, the wedge-shaped section at the beam end, and the variable cross-section. The medium cross-section length of the beam for this span = theoretical beam length of the inner edge beam of the curve / 2 - wedge-shaped section at the beam end - variable cross-section. The medium cross-section length of the beam adjusts for beam length variations between spans, ensuring that the medium cross-section lengths of different beams within the same span remain the same.

[0008] S4: Determine the length of the constant-section sections at the ends of the center beam and outer beams. The lengths of these sections are calculated based on the theoretical beam length, the medium-section section of the span, the wedge sections at the ends, and the variable-section sections. The length of the constant-section section at the ends of the beams in this span = the theoretical beam length / 2 - the length of the medium-section section of the span - the length of the variable-section section - the length of the wedge sections at the ends. The constant-section sections at the ends of the beams adjust for variations in beam length across different beams within the same span.

[0009] S5: Determine the angle of the oblique surface at the beam end based on the curve radius and span; S6: Determine the curved arrangement of the steel bars of the top surface of the inner and outer side beams against the crash wall based on the curve radius and deck width of the span.

[0010] The beneficial effects of the present invention are: 1. The length of the middle cross-section section of the beam with the same span is equal. The beam flanges and cross diaphragms are all set with transverse slopes. The cross diaphragms in the beam are perpendicular to the center line of the beam. This facilitates the demoulding of the precast beam and ensures that the cross diaphragms at corresponding positions in each beam are coaxially straight after the precast beam is erected.

[0011] 2. The cross diaphragms in the beam are partially prefabricated and partially post-cast. The axis of the prefabricated cross diaphragms in the beam is perpendicular to the axis of the beam body and is also processed with a demoulding slope to facilitate prefabrication and demoulding. The small volume of the post-cast cross diaphragms reduces the difficulty of suspending the post-cast cross diaphragms in the beam; 3. Beam end diaphragms are not cast during prefabrication at the beam yard; only diagonal reinforcement parallel to the pier axis is reserved. They are cast integrally after the prefabricated beams are erected, avoiding the difficulty in demolding caused by the diaphragm axis not being perpendicular to the beam axis during prefabrication at the beam yard. Beam end diaphragms are cast integrally within the pier cap beam, facilitating support and construction operations while ensuring the straightness of the beam end diaphragms of the same span after being cast in situ.

[0012] 4. The end face of the wing plate beam of the wedge-shaped section at the beam end and the beam centerline are adjusted from a normal plane to an oblique plane parallel to the axis of the pier, avoiding the interference problem of the flange plate after the erection of the prefabricated beam body in the small curve radius section. The oblique appearance of the beam end is beautiful and the beam joints are uniform.

[0013] 5. This layout optimization method ensures the adjustment of beam lengths of different spans and the adjustment of different beam lengths within the span. At the same time, it ensures that the cross diaphragms in the middle of the beams and the cross diaphragms at the ends of the beams of the same span are straight, which is convenient for centralized prefabrication in the beam yard and the beam body is well stressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the layout diagram of multi-span beams in a small curve radius section; Figure 2 This is a top view of a beam with a small curve radius. Figure 3 This is a side view of a beam; Figure 4 This is the cross-section of a T-beam with a small curve radius. Figure 5 This is the cross-section of a box girder with a small curve radius. Among them: 1. Bridge pier; 1-1 Centerline of bridge pier; 2. Inner side beam; 2-1 Centerline of beam body; 3. Middle beam; 4. Outer side beam; 5. Wedge section at beam end; 5-1 Oblique surface at beam end; 6. Constant cross-section section at beam end; 7. Variable cross-section section; 8. Medium cross-section section at beam end; 9. Transverse diaphragm at beam end; 9-1 Centerline of transverse diaphragm at beam end; 10. Centerline of transverse diaphragm in beam center; 10-1 Section 1 of transverse diaphragm in beam center; 10-2 Section 2 of transverse diaphragm in beam center; 11. Crash barrier. DETAILED DESCRIPTION

[0015] The following will be combined with the Figure 1-Figure 5 The present invention will be described in detail. Implementation Method

[0016] The present invention provides a method for optimizing the arrangement of a prefabricated simply supported beam in a small radius section. Taking a highway T-beam as an example, the method can be implemented as follows: The design center of a highway ramp bridge features a T-beam with a maximum span of 39m, a curve radius of 120m, a longitudinal slope of 4%, a transverse slope of 6%, a horizontal rotation angle of 9.33° at the beam end face, and a bridge deck width of 10.5m. The design uses five T-beams per span. The theoretical beam length difference between the inner curved beam (beam length 37.678m, span 36.429m) and the outer curved beam (beam length 40.848m, span 39.65m) of the same span is 3.22m. The bridge was constructed using prefabricated erection. The large longitudinal and transverse slopes, small curves, and large spans posed challenges to the prefabrication, erection, and diaphragm casting of the T-beams. Figure 1 .

[0017] In the bridge section with large span, small curve radius and large transverse slope, the plane of the pier cap beam is fan-shaped (see Figure 1 ) Horizontally inclined arrangement (see Figure 4 ).

[0018] The prefabricated T-beam structure includes: inner side beams, middle beams, and outer side beams. Each beam includes a wedge-shaped section at the end of the beam, a section with a constant cross section at the end of the beam, a variable cross section section, a medium cross section section at the end of the beam, a cross section section 1 at the middle of the beam, and two cross sections at the middle of the beam. Figure 2 . The beams of the same span are arranged in such a way that the mid-sagitta is bisected.

[0019] The wedge-shaped section and variable section section at the beam end are designed to be fixed in length for easy flow construction. The medium section section and the equal section section at the beam end are adjustable in length through the adjustment template. Figure 2 .

[0020] The theoretical span of different spans varies with the influence of curvature and variable span. The invention determines the length of the equal cross-section section in the middle of the span according to the shortest equal cross-section section at the end of the inner side beam of the curve (the length adjustment section is 0); the beam length of different spans is adjusted by the equal cross-section section of the beam, and the length of the equal cross-section section of different beams in the same span is the same. Figure 3 .

[0021] Affected by the small curve, the beam lengths of beams with the same span are different. The lengths of beams with the same span are adjusted by the lengths of the equal-section sections at the beam ends; the equal-section sections at the beam ends adjust the beam lengths of different beam pieces within the same span.

[0022] The plane layout of the middle transverse diaphragm is perpendicular to the axis of the beam body; the beam flange and transverse diaphragm are both set with transverse slopes, see Figure 4 .

[0023] The cross diaphragms at the ends of the single-piece center beam are arranged obliquely to the beam axis. When prefabricating, steel bars oblique to the beam axis are reserved for the cross diaphragms at the ends of the beams. After the beam-slab bridge is hoisted, they are cast to ensure that the central axis of the cross diaphragms at the ends of the same span is parallel to the central axis of the supporting piers. Figure 2 .

[0024] The plane of the wing plate of the wedge-shaped part of the beam end is arranged obliquely and parallel to the axis of the supporting pier, ensuring that the end surface of each beam in the same span is parallel to the axis of the pier. Figure 2 .

[0025] Preferably, the specific steps are as follows: S1: Determine the layout orientation of the bridge piers of this span; S2: Determine the center axis position of the inner side beam, each middle beam, and outer side beam of the span and the theoretical beam length of each beam; S3: Determine the length of the medium cross-section of the inner edge beam of this span as the length of the medium cross-section of the beam of this span. The length of the medium cross-section of the inner edge beam of the curve is calculated based on the theoretical beam length, the wedge section at the beam end, and the variable cross-section section of the inner edge beam; S4: Determine the length of the constant cross-section sections at the ends of the center beam and outer beams. Calculate the length of the constant cross-section sections at the ends of the center beam and outer beams based on the theoretical beam length, the constant cross-section section of the current span, the wedge section at the ends, and the variable cross-section section. Implementation Method

[0026] The present invention provides a method for optimizing the arrangement of assembled simply supported beams in small radius sections. Taking highway box beams as an example, the box beams are similar to T beams in implementation. Only the cross-sectional view is shown here. Figure 5 .

Claims

1. A method for optimizing the arrangement of a prefabricated simply supported beam in a small radius section, the structure of which comprises: Inner side beams (2), middle beams (3), outer side beams (4); each beam comprises a beam end wedge section (5), a beam end uniform cross-section section (6), a variable cross-section section (7), a beam middle cross-section section (8), a beam end transverse partition (9), a beam middle transverse partition section 1 (10-1), and a beam middle transverse partition section 2 (10-2); the inner side beams (2) and the outer side beams (4) further comprise a crash barrier (11), characterized in that the optimization sequence comprises the following steps: S1: Determine the layout orientation of the bridge pier (1) of this span; S2: respectively determine the position of the center axis (2-1) of the inner side beam (2), each middle beam (3), and the outer side beam (4) of the span and the theoretical beam length and span of each beam; S3: Determine the length of the medium cross-section section (8) of the inner side beam (2) of this span as the length of the medium cross-section section (8) of the beam of this span. The length of the medium cross-section section (8) of the curved inner side beam (2) is calculated and determined based on the theoretical beam length of the inner side beam (2), the wedge section (5) at the beam end, and the variable cross-section section (7); S4: Determine the length of the equal cross-section section (6) at the end of the middle beam (3) and the outer beam (4). The length of the equal cross-section section (6) at the end of the middle beam (3) and the outer beam (4) is determined by calculating based on the theoretical beam length, the equal cross-section section (8) of the beam in this span, the wedge section (5) at the end of the beam, and the variable cross-section section (7); S5: Determine the angle of the oblique surface (5-1) at the beam end based on the curve radius and span; S6: Determine the curve arrangement of the inner side beam (2), the outer side beam (4), and the top crash barrier (11) based on the curve radius and the bridge deck width of the span.

2. The method for optimizing the arrangement of a prefabricated simply supported beam in a small radius section according to claim 1, characterized in that: The beam end wedge section (5) and the variable cross-section section (7) are of fixed length, while the beam middle cross-section section (8) and the beam end constant cross-section section (6) are of adjustable length.

3. The method for optimizing the arrangement of a prefabricated simply supported beam in a small radius section according to claim 1, characterized in that: The center axis (10) of the second section (10-2) of the prefabricated cross diaphragm in the beam corresponding to the position of each beam body in the same span is perpendicular to the direction of the beam body axis (2-1), and the transverse bridge center axis of the first section (10-1) of the beam and the second section (10-2) of the beam corresponding to the position of each beam piece in the same span are coaxial.

4. The method for optimizing the arrangement of a prefabricated simply supported beam in a small radius section according to claim 1, characterized in that: The beam end transverse diaphragms (9) on the same side of the beam pieces of the same span are coaxial, and the center axis (9-1) of the beam end transverse diaphragms on the same side of the beams of the same span is parallel to the center axis (1-1) of the pier on the same side.

5. The method for optimizing the arrangement of a prefabricated simply supported beam in a small radius section according to claim 1, characterized in that: The beam end oblique surface (5-1) of the beam end wedge section (5) is parallel to the center axis (1-1) of the pier on the same side.

6. The method for optimizing the arrangement of a prefabricated simply supported beam in a small radius section according to claim 1, characterized in that: The anti-collision wall (11) is arranged on the top surface of the inner side beam (2) and the outer side beam (4), and the specific arrangement form is a circular curve.

7. The method for optimizing the arrangement of a prefabricated simply supported beam in a small radius section according to claim 1, characterized in that: The length calculation formula of the medium cross-section section (8) of the beam of this span in step S3 is: the length of the medium cross-section section (8) of the beam of this span = the theoretical beam length of the inner side beam (2) / 2-the wedge section (5) at the end of the beam-the variable cross-section section (7); the length of the equal cross-section section (6) at the end of the inner side beam is taken as 0; the medium cross-section section (8) of the beam adjusts the beam length change of different spans, and the length of the medium cross-section section (8) of the beam of different beams in the same span is the same.

8. The method for optimizing the arrangement of a prefabricated simply supported beam in a small radius section according to claim 1, characterized in that: The formula for calculating the length of the constant cross-section section (6) at the end of the middle beam (3) and the outer beam (4) in step S4 is: the length of the constant cross-section section (6) at the end of the beam of this piece = the theoretical beam length of this piece / 2 - the length of the medium cross-section section (8) in the beam of this span - the length of the variable cross-section section (7) - the length of the wedge section (5) at the end of the beam; the constant cross-section section (6) at the end of the beam adjusts the beam length changes of different beam pieces in the same span.

Images