Pre-tightening type steel hoop pier energy dissipation reinforcing device and design method thereof

Abstract

The invention discloses a pre-tightening type steel hoop pier energy dissipation reinforcing device and a design method thereof.The device comprises a steel hoop splicing piece and a pre-tightening force connecting assembly, a rubber pad is attached to the inner side of the steel hoop splicing piece, and the steel hoop splicing piece comprises a vertical main steel plate and a plurality of strip steel plates; the method comprises the steps that firstly, the total shear bearing capacity and the anti-bending inertia moment which need to be achieved after the pier is reinforced are determined; secondly, the distance between two strip steel plates on the outermost side of a steel hoop splicing piece is determined; 3, the number of strip steel plates and the strip distance are determined; 4, determining the width and the thickness of the strip steel plate; and 5, determining the width of the vertical main steel plate. The steel hoop with the pre-tightening force can provide better constraint for a crack damage area or a damaged plastic hinge area of the pier, so that concrete in the area is in a three-way stress state, and the reinforcing mode can achieve the effects of improving the bearing capacity of the pier and enhancing the anti-seismic energy consumption capacity of the pier.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge pier reinforcement, and in particular relates to a pre-tightened steel sleeve bridge pier energy dissipation reinforcement device and a design method thereof. Background Art

[0002] Bridges are important transportation hubs connecting two sides of the river, carrying vehicles and pedestrians. However, during the use of bridges, due to the influence of factors such as traffic loads and natural disasters, cracks, deformations, and damage may occur on bridge piers, thus affecting the safety and stability of the bridges. At the same time, with the increase in service life and traffic loads, some bridge piers have problems such as damage, insufficient energy consumption, and insufficient bearing capacity, and effective reinforcement measures are urgently needed.

[0003] The traditional pier reinforcement method has a long construction period and may affect the traffic conditions of the bridge. At the same time, the traditional steel hoop reinforcement of bridge piers requires a large amount of steel and labor, is difficult to construct, has high costs, and cannot provide better constraints for the crack damage area of ​​the pier or the damaged plastic hinge area.

[0004] Therefore, it is an urgent need in the current bridge reinforcement field to develop a bridge reinforcement device that is easy to construct, effectively reinforces the damaged area of ​​the bridge pier, and has significant energy consumption. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a pre-tightened steel sleeve bridge pier energy dissipation reinforcement device in view of the deficiencies in the above-mentioned prior art. The pre-tightened steel sleeve can perfectly adapt to any rectangular or circular bridge pier and fit tightly with the bridge pier. The steel sleeve splicing parts are connected by a pre-tightening device, so that the construction process is simple and the connection is tight. The steel sleeve with pre-tightening force can provide better constraints for the crack damaged area or the damaged plastic hinge area of ​​the pier, so that the concrete in this area is in a three-dimensional stress state. This reinforcement method can improve the bearing capacity of the bridge pier and enhance the seismic energy dissipation capacity of the bridge pier.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a pre-tightened steel hoop bridge pier energy dissipation reinforcement device, characterized in that: it comprises at least two steel hoop splicing pieces with hoops arranged outside the bridge pier, the steel hoop splicing piece is a U-shaped half hoop, each adjacent two steel hoop splicing pieces are pre-tightened and connected by a pre-tightening force connection assembly, and a plurality of steel hoop splicing pieces are connected to form a steel hoop, and a rubber pad is attached to the inner side of the steel hoop splicing piece;

[0007] The steel sleeve splicing piece includes a vertical main steel plate, and a plurality of strip steel plates are respectively arranged on both sides of the vertical main steel plate, and the plurality of strip steel plates are arranged at equal intervals along the height direction of the vertical main steel plate, and the strip steel plates are connected to the vertical main steel plate as a whole;

[0008] An anchoring steel plate for anchoring and connecting with the pedestal is fixedly provided at the bottom of the vertical main steel plate.

[0009] The above-mentioned pre-tightened steel sleeve bridge pier energy dissipation reinforcement device is characterized in that: the pre-tightening force connection assembly includes a plurality of pre-tightening bolts, and the number of the pre-tightening bolts is equal to and corresponds to the strip steel plates in the steel sleeve splicing piece.

[0010] The above-mentioned pre-tightened steel sleeve bridge pier energy dissipation reinforcement device is characterized in that: an ear plate for installing pre-tightening bolts is arranged on the end of the strip steel plate away from the vertical main steel plate, and the ear plate is provided with bolt through holes for the pre-tightening bolts to pass through.

[0011] The above-mentioned pre-tightened steel sleeve bridge pier energy dissipation reinforcement device is characterized in that the anchoring steel plate is anchored on the cap by a plurality of anchoring bolts.

[0012] The above-mentioned pre-tightened steel sleeve bridge pier energy dissipation reinforcement device is characterized in that the number of the steel sleeve splicing parts is two.

[0013] At the same time, the present invention also discloses a design method for a pre-tightened steel sleeve bridge pier energy dissipation reinforcement device, which is characterized in that the method comprises the following steps:

[0014] Step 1: Determine the total shear bearing capacity V required after pier reinforcement u and bending moment of inertia EI 总 ;

[0015] Step 2: Determine the spacing between the two outermost strip steel plates of the steel sleeve splice: According to the equivalent plastic hinge length L of the pier p , determine the height of the bridge pier reinforcement area, and determine the distance D between the uppermost strip steel plate and the lowermost strip steel plate of the steel sleeve splice according to the height of the bridge pier reinforcement area;

[0016] Among them, the height of the pier reinforcement area is greater than the equivalent plastic hinge length L of the pier p ;

[0017] Step 3: Determine the number of strip steel plates and the strip spacing: Based on the condition that the core concrete area is an effective constraint area, determine the strip net spacing S PJ The value range of

[0018] According to the distance D between the uppermost strip steel plate and the lowermost strip steel plate of the steel sleeve splicing part and the strip net distance S PJ The value range is based on the maximum strip spacing principle and combined with the strip clearance S PJ Smaller than the stripe spacing S spThe number of strip steel plates and the strip spacing S are determined based on the theoretical basis. sp ;

[0019] Step 4: Determine the width and thickness of the strip steel plate: When using steel hoops to reinforce reinforced concrete beams for shear resistance, the bearing capacity of the inclined section conforms to the formula V u =V RC +V cf , and then calculate the shear bearing capacity V that the steel hoop needs to provide cf ; Among them, V RC is the shear bearing capacity of the pier before reinforcement;

[0020] According to the formula The sum of the cross-sectional areas of the steel ferrules at the same cross section is calculated. b,sp , and according to formula A b,sp =2×b sp ×t sp , determine the width b of the strip steel plate sp and thickness t sp ; where ψ vb is the shear strength reduction factor related to the bonding method and stress conditions of the steel hoop; f sp h is the yield strength of the steel plate used in the steel hoop; sp It is the vertical height of the bond between a single leg of the steel sleeve splice and the concrete on the side of the beam;

[0021] Step 5: Determine the width of the vertical main steel plate: Calculate the bending strength of the section based on the flat section assumption, and the bending inertia moment EI of the vertical main steel plate reinforcement 加固 =EI 总 -EI 混 , among which, EI 混 is the bending moment of inertia of the pier itself;

[0022] According to the formula EI 加固 =2×A×E2'×l 2 , calculate the reference value of the cross-sectional area A of the vertical main steel plate, and then determine the thickness and width of the vertical main steel plate according to the reference value of the cross-sectional area A of the vertical main steel plate, so that the thickness and width of the vertical main steel plate are both integers and the product of the two is not less than the reference value of the cross-sectional area A of the vertical main steel plate; where E2' is the elastic modulus of the vertical main steel plate, and l is the distance from the centroid of the vertical main steel plate to the neutral axis of the pier cross section.

[0023] The above-mentioned design method of a pre-tightened steel sleeve bridge pier energy dissipation reinforcement device is characterized in that: in step 2, the equivalent plastic hinge length L of the bridge pier p =min(L p1 ; L p2 ), where Lp1 and L p2 These are two methods for calculating the plastic hinge length;

[0024] When 0.08H+0.022f y d s ≥0.044f y d s When L p1 =0.08H+0.022f y d s ; When 0.08H+0.022f y d s <0.044f y d s When L p1 =0.044f y d s ;

[0025]

[0026] Where H is the height of the pier, b is the short side of the rectangular cross section of the pier or the diameter of the circular cross section, and f is y is the standard value of tensile strength of longitudinal reinforcement of bridge piers, d s is the diameter of the longitudinal reinforcement of the pier;

[0027] The spacing between the uppermost strip steel plate and the lowermost strip steel plate of the steel sleeve splicing piece is greater than the equivalent plastic hinge length of the pier.

[0028] The above-mentioned design method of a pre-tightened steel sleeve bridge pier energy dissipation reinforcement device is characterized in that: in step 3, the middle section of the two steel sleeve splicing parts is the section with the smallest effective constraint area, that is, the control section, which is called the effective constraint section length L of the steel sleeve PJ ,and

[0029] At the same time, in order to make the core concrete area an effective constraint area, L PJ >b-2δ, we can get S PJ <4δ; where δ is the thickness of the protective layer of the pier.

[0030] The design method of the above-mentioned pre-tightened steel sleeve bridge pier energy dissipation reinforcement device is characterized in that: in step 4, the shear bearing capacity V before the pier reinforcement RC =V C +V S +V N ;

[0031] Among them, the shear resistance of concrete in the pier Shear resistance of the web reinforcement in the pier Shear force V caused by the axial pressure of the pier itself N =0.07N;

[0032] Therefore

[0033] Wherein, λ is the shear span ratio of the pier structure. When λ is less than 1.5, λ is 1.5; when λ is greater than 3, λ is 3.

[0034] f t is the concrete tensile strength value of the pier;

[0035] b0 is the effective width of the pier cross section;

[0036] h0 is the effective length of the pier cross section;

[0037] f yv is the design value of the tensile strength of the pier stirrups;

[0038] A SV is the total effective area of ​​stirrups in the shear section of the pier;

[0039] s is the spacing of pier stirrups;

[0040] N is the design value of the axial pressure of the pier.

[0041] The above-mentioned design method of a pre-tightened steel sleeve bridge pier energy dissipation reinforcement device is characterized in that: in step 5, the bending inertia moment of the bridge pier itself

[0042] Where, E1 is the elastic modulus of the pier concrete, E2 is the elastic modulus of the pier steel bar, h is the cross-sectional length of the pier, n is the number of longitudinal bars in the pier, i is the number of longitudinal bars in the pier, i and n are both positive integers, and i≤n, A i is the cross-sectional area of ​​the i-th longitudinal reinforcement in the pier, l i It is the distance between the i-th longitudinal reinforcement in the pier and the median line of its cross section.

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] 1. The present invention forms a steel hoop with preload by connecting a plurality of steel hoop splicing parts through a preload connection assembly, which can provide better constraints for crack damage areas or damaged plastic hinge areas of the pier, so that the concrete in the area is in a three-dimensional stress state, thereby improving the bearing capacity of the pier and enhancing the seismic energy absorption capacity of the pier.

[0045] 2. The setting of the pre-tightening force connection assembly of the present invention can more simply apply the pre-tightening force so as to improve the energy dissipation effect of the bridge pier, and at the same time make the steel sleeve tightly connected to the bridge pier.

[0046] 3. The present invention forms a steel sleeve splicing piece by arranging a plurality of strip steel plates on both sides of the vertical main steel plate, which can effectively save steel materials and improve the reliability of the steel sleeve.

[0047] 4. The present invention can make the connection between the steel hoop and the bridge pier tighter by arranging a rubber pad on the inner side of the steel hoop splicing piece.

[0048] In summary, the pre-tightened steel sleeve used in the present invention can perfectly adapt to any rectangular or circular pier and fit tightly with the pier. The steel sleeve splicing parts are connected by a pre-tightening device, which makes the construction process simple and the connection tight. The steel sleeve with pre-tightening force can provide better constraints for the crack damaged area or damaged plastic hinge area of ​​the pier, so that the concrete in this area is in a three-dimensional stress state. This reinforcement method can improve the bearing capacity of the pier and enhance the seismic energy absorption capacity of the pier.

[0049] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic structural diagram of the pre-tightened steel sleeve bridge pier energy dissipation reinforcement device of the present invention.

[0051] Figure 2 for Figure 1 Top view of the .

[0052] Figure 3 This is an exploded view of the connection structure between the bridge pier and the steel hoop of the present invention.

[0053] Figure 4 It is a flowchart of the method of the present invention.

[0054] Description of reference numerals:

[0055] 1—bridge pier; 2—capping platform; 3—steel sleeve splicing piece;

[0056] 31—vertical main steel plate; 32—strip steel plate; 4—rubber pad;

[0057] 5—anchor steel plate; 6—anchor bolt; 7—ear plate;

[0058] 8—pre-tightening bolt; 81—pre-tightening component body; 82—stud;

[0059] 83—Nut. DETAILED DESCRIPTION

[0060] like Figures 1 to 3A pre-tightened steel hoop bridge pier energy dissipation reinforcement device is shown, comprising at least two steel hoop splicing pieces 3 arranged outside the bridge pier 1, the steel hoop splicing piece 3 is a U-shaped half hoop, each adjacent two steel hoop splicing pieces 3 are pre-tightened and connected by a pre-tightening force connection assembly, and a plurality of steel hoop splicing pieces 3 are connected to form a steel hoop, and a rubber pad 4 is attached to the inner side of the steel hoop splicing piece 3;

[0061] The steel sleeve splicing piece 3 includes a vertical main steel plate 31, and a plurality of strip steel plates 32 are respectively arranged on both sides of the vertical main steel plate 31. The plurality of strip steel plates 32 are arranged at equal intervals along the height direction of the vertical main steel plate 31, and the strip steel plates 32 are connected to the vertical main steel plate 31 as a whole;

[0062] An anchoring steel plate 5 for anchoring and connecting with the cap 2 is fixedly provided at the bottom of the vertical main steel plate 31 .

[0063] In actual use, the vertical main steel plate 31 and the multiple strip steel plates 32 connected thereto are integrally formed, the strip steel plates 32 on both sides of the vertical main steel plate 31 are symmetrically arranged, the top of the uppermost strip steel plate 32 is flush with the top of the vertical main steel plate 31, and the bottom of the lowermost strip steel plate 32 is flush with the bottom of the vertical main steel plate 31, and the two steel hoop splicing parts 3 cooperate to wrap around the plastic hinge or damaged area of ​​the pier 1.

[0064] In specific implementation, the number of steel hoop splicing pieces 3 is preferably two. When the cross-sectional size of the bridge pier to be reinforced is larger, in order to facilitate processing, the number of steel hoop splicing pieces 3 can be increased to 3, 4, 5 or 6. Five strip steel plates 32 are respectively arranged on both sides of the vertical main steel plate 31.

[0065] It should be noted that by connecting multiple steel sleeve splicing parts 3 through a preload connection assembly to form a steel sleeve with preload, better constraints can be provided for the crack damage area or damaged plastic hinge area of ​​the pier 1, so that the concrete in this area is in a three-dimensional stress state, which can improve the bearing capacity of the pier 1 and enhance the seismic energy absorption capacity of the pier 1.

[0066] In specific implementation, the setting of the pre-tightening force connection assembly can more simply apply the pre-tightening force so as to improve the energy dissipation effect of the bridge pier 1, and at the same time make the steel sleeve tightly connected to the bridge pier 1.

[0067] During specific implementation, the rubber pad 4 is vulcanized and bonded to the inner side of the steel sleeve joint piece 3. The provision of the rubber pad 4 prevents the steel sleeve from damaging the pier 1 and also makes the connection between the steel sleeve and the pier 1 tighter.

[0068] It should be noted that when the pier is circular, the vertical main steel plate 31 and the strip steel plate 32 are both arc-shaped plates, and when the cross-section of the pier is rectangular, the vertical main steel plate 31 is a flat plate, and the strip steel plate 32 is bent into an L shape.

[0069] In this embodiment, the pre-tightening force connection assembly includes a plurality of pre-tightening bolts 8 , and the number of the pre-tightening bolts 8 is equal to and corresponds one to one to the number of the strip steel plates 32 in the steel sleeve splicing piece 3 .

[0070] In actual use, the pre-tightening bolt 8 can be a turnbuckle bolt, a common bolt and a nut.

[0071] In this embodiment, the pre-tightening bolt 8 is composed of a pre-tightening component body 81, two studs 82 arranged at both ends of the pre-tightening component body 81, and nuts 83 that cooperate with the two studs 82. Both ends of the pre-tightening component body 81 are provided with internal threaded holes that cooperate with the studs 82, and one end of the two studs 82 is respectively threadedly connected to the internal threaded holes at both ends of the pre-tightening component body 81.

[0072] In this embodiment, a lug plate 7 for installing a pre-tightening bolt 8 is provided on one end of the strip steel plate 32 away from the vertical main steel plate 31 , and a bolt through hole for the pre-tightening bolt 8 to pass through is opened on the lug plate 7 .

[0073] In actual use, the two ear plates 7 at corresponding positions on the two steel sleeve splicing pieces 3 are respectively located at the two ends of the pre-tightening component body 81, and are fastened with two nuts 83 on the outside; that is, the ear plate 7 is passed through the stud 82 and is located between one end of the pre-tightening component body 81 and a nut 83.

[0074] During specific implementation, the ear plate 7 and the strip steel plate 32 are integrally formed.

[0075] In this embodiment, the anchoring steel plate 5 is anchored on the base 2 by a plurality of anchoring bolts 6 .

[0076] In actual use, the anchoring steel plate 5 is perpendicular to the axial direction of the pier 1. For the plastic hinge area of ​​the pier 1 or the insufficient energy dissipation reinforcement, the form of a cap 2 can be adopted. The steel hoop is fixed on the cap 2 through the anchoring bolts 6 and the anchoring steel plate 5 to achieve better energy dissipation effect.

[0077] When the present invention is actually used, first, holes are drilled in the longitudinal direction of the pier 2 of the pier that needs to be reinforced. Ordinary cracks and pier damage do not require the pier to be connected. Two steel sleeve splicing pieces 3 are buckled and sleeved on the outside of the pier 1. The steel sleeves are anchored on the pier 2 using anchor bolts 6 and anchor steel plates 5. Pre-tightening force is applied by the pre-tightening force connection assembly so that the two steel sleeve splicing pieces 3 are tightly clamped on the pier 1.

[0078] like Figure 4A design method for a pre-tightened steel sleeve bridge pier energy dissipation reinforcement device is shown, the method comprising the following steps:

[0079] Step 1: Determine the total shear bearing capacity V required after pier reinforcement u and bending moment of inertia EI 总 ;

[0080] Step 2: Determine the distance between the two outermost strip steel plates of the steel sleeve splice: According to the equivalent plastic hinge length L of pier 1 p , determine the height of the reinforcement area of ​​the pier 1, and determine the distance D between the uppermost strip steel plate 32 and the lowermost strip steel plate 32 of the steel sleeve splicing member 3 according to the height of the reinforcement area of ​​the pier 1;

[0081] The height of the reinforced area of ​​pier 1 is greater than the equivalent plastic hinge length L of pier 1. p ;

[0082] Step 3: Determine the number of strip steel plates and the strip spacing: Based on the condition that the core concrete area is an effective constraint area, determine the strip net spacing S PJ The value range of

[0083] According to the spacing D between the uppermost strip steel plate 32 and the lowermost strip steel plate 32 of the steel sleeve splicing part 3 and the strip net distance S PJ The value range is based on the maximum strip spacing principle and combined with the strip clearance S PJ Smaller than the stripe spacing S sp The number of strip steel plates 32 and the strip spacing S are determined based on the theoretical basis. sp ;

[0084] Step 4: Determine the width and thickness of the strip steel plate: When using steel hoops to reinforce reinforced concrete beams for shear resistance, the bearing capacity of the inclined section conforms to the formula V u =V RC +V cf , and then calculate the shear bearing capacity V that the steel hoop needs to provide cf ; Among them, V RC is the shear bearing capacity of pier 1 before reinforcement;

[0085] According to the formula The sum of the cross-sectional areas of the steel ferrules at the same cross section is calculated. b,sp , and according to formula A b,sp =2×b sp ×t sp , determine the width b of the strip steel plate 32 sp and thickness t sp ; where ψ vbis the shear strength reduction factor related to the bonding method and stress conditions of the steel hoop, determined according to Table 1; f sp h is the yield strength of the steel plate used in the steel hoop; sp It is the vertical height of the bond between a single leg of the steel sleeve splice and the concrete on the side of the beam;

[0086] Table 1 Shear strength reduction factor ψ vb value

[0087]

[0088] Step 5: Determine the width of the vertical main steel plate: Calculate the bending strength of the section based on the flat section assumption, and the bending inertia moment EI of the vertical main steel plate 31 reinforcement 加固 =EI 总 -EI 混 , among which, EI 混 is the bending moment of inertia of pier 1 itself;

[0089] According to the formula EI 加固 =2×A×E'2×l 2 , calculate the reference value of the cross-sectional area A of the vertical main steel plate 31, and then determine the thickness and width of the vertical main steel plate 31 according to the reference value of the cross-sectional area A of the vertical main steel plate 31, so that the thickness and width of the vertical main steel plate 31 are both integers and the product of the two is not less than the reference value of the cross-sectional area A of the vertical main steel plate 31; wherein, E2' is the elastic modulus of the vertical main steel plate 31, and l is the distance from the centroid of the vertical main steel plate 31 to the neutral axis of the cross-sectional area of ​​pier 1 in the same cross-sectional area.

[0090] In the specific implementation, in step 2, the equivalent plastic hinge length L of pier 1 is p =min(L p1 ; L p2 ), where L p1 and L p2 These are two methods for calculating the plastic hinge length;

[0091] When 0.08H+0.022f y d s ≥0.044f y d s When L p1 =0.08H+0.022f y d s ; When 0.08H+0.022f y d s <0.044f y d s When L p1 =0.044f y d s ;

[0092]

[0093] Where H is the height of pier 1, in cm, b is the short side dimension of the rectangular cross section of pier 1 or the diameter of the circular cross section, in cm, and f is y is the standard value of tensile strength of longitudinal reinforcement of pier 1, in MPa, d s is the diameter of the longitudinal reinforcement of pier 1, in cm;

[0094] The distance between the uppermost strip steel plate 32 and the lowermost strip steel plate 32 of the steel sleeve splicing component 3 is greater than the equivalent plastic hinge length of the pier 1 .

[0095] In actual use, the height of the reinforcement area of ​​pier 1 should be set with reference to the height of the plastic hinge of the pier.

[0096] In the specific implementation, in step 3, the middle section of the two steel sleeve splicing pieces 3 is the section with the smallest effective constraint area, that is, the control section, which is called the effective constraint section length L of the steel sleeve. PJ ,and

[0097] At the same time, in order to make the core concrete area an effective constraint area, L PJ >b-2δ, we can get S PJ <4δ; wherein, δ is the thickness of the protective layer of pier 1.

[0098] In the specific implementation, in step 4, the shear bearing capacity V of the pier 1 before reinforcement is RC =V C +V S +V N ;

[0099] Among them, the shear resistance of the concrete in pier 1 Shear resistance of the web reinforcement in pier 1 Shear force V caused by the axial pressure of pier 1 itself N =0.07N;

[0100] Therefore

[0101] Wherein, λ is the shear span ratio of the pier 1 structure. When λ is less than 1.5, λ is 1.5, and when λ is greater than 3, λ is 3.

[0102] f t is the concrete tensile strength of pier 1, which is the actual test value. t =0.88×0.395f cu 0.55 According to the measured compressive strength of concrete cube fcu Conversion;

[0103] b0 is the effective width of the cross section of pier 1;

[0104] h0 is the effective length of the cross section of pier 1;

[0105] f yv is the design value of the tensile strength of the stirrups of pier 1;

[0106] A SV is the effective total area of ​​stirrups in the shear section of pier 1, in mm 2 ;

[0107] s is the stirrup spacing of pier 1;

[0108] N is the design value of the 1-axis pressure of the pier. If N>0.3f c A, then take N = 0.3f c A,f c is the axial compressive strength of concrete, according to f t =0.88×0.76f cu Conversion.

[0109] In actual use, when the cross-section of pier 1 is rectangular, b0 is the short side dimension of the cross-section of pier 1, and h0 is the product of the long side dimension of the cross-section of pier 1 and the shear strength reduction coefficient; when the cross-section of pier 1 is circular, the cross-section of pier 1 is converted into a square for calculation.

[0110] In the specific implementation, in step 5, the bending strength of the cross section is calculated based on the plane cross section assumption. Since the force on the pier 1 is slightly eccentric, the entire cross section is basically compressed, so the bending strength is calculated based on the entire cross section. The bending inertia moment of the pier 1 itself is

[0111] Where, E1 is the elastic modulus of the concrete of pier 1, E2 is the elastic modulus of the steel bars of pier 1, h is the cross-sectional length of pier 1, n is the number of longitudinal bars in pier 1, i is the number of longitudinal bars in pier 1, i and n are both positive integers, and i≤n, A i is the cross-sectional area of ​​the i-th longitudinal reinforcement in pier 1, l i It is the distance between the i-th longitudinal reinforcement in pier 1 and the neutral axis of the cross section of pier 1.

[0112] In actual use, when the cross section of the pier 1 is circular, the cross section of the pier 1 is converted into a square for calculation.

[0113] In this embodiment, since the steel plate is too thick to bend easily, for the bridge pier 1 with a circular cross section of no more than 1m in diameter or a rectangular cross section of no more than 1m in length, a steel hoop made of a 5mm thick steel strip is used. For the bridge pier 1 with a circular cross section of more than 1m in diameter or a rectangular cross section of more than 1m in length, a steel hoop made of a 10mm thick steel strip is used. The energy dissipation effect of mild steel is good, and Q235 steel is used to make the steel hoop.

[0114] A bridge pier with a shear span ratio of 4.72 is used as an experimental case. The side length is 502mm. The longitudinal reinforcement of the pier column is 16 HRB400 steel bars with a diameter of 16mm. The cross-sectional reinforcement ratio is 1.28%, the original size reinforcement ratio is 1.31%, and the protective layer thickness is 36mm. The stirrup diameter is 8mm. The stirrup spacing in the densified area is set to 35mm, the stirrup spacing in the non-densified area is set to 70mm, and the axial compression ratio is 10%. This case is an example of calculating the bending and shear strength by increasing 10%.

[0115] After calculation, 0.08H+0.022f y d s =32.80cm;

[0116] 0.044f y d s =0.044×360×1.6=29.63cm;

[0117] So 0.08H+0.022f y d s >0.044f y d s , L p1 =0.08H+0.022f y d s =32.8;

[0118]

[0119] Then L p =min(L p1 ; L p2 )=32.8, so the plastic hinge height of pier 1 is 32.80cm. Since the plastic damage area of ​​the pier is very large, it is necessary not only to reinforce the plastic hinge area, but also to treat the reinforcement height. In this case, the spacing D between the uppermost strip steel plate 32 and the lowermost strip steel plate 32 of the steel sleeve splice 3 is designed to be 50cm.

[0120] In addition, S PJ <4δ is S PJ<144cm, in this case, 5 steel strips are used, and the strip spacing is selected as 125mm. Since the strip net distance is less than the strip spacing, the strip net distance is less than 144mm.

[0121] After calculation,

[0122] V N =0.07N=141.57kN;

[0123] V RC =835.5kN, since this case is to increase the bending and shear strength calculation by 10%, V cf =0.1V RC , so V cf =83.55kN, and due to the thickness t of the strip steel plate 32 sp =5mm, from which the strip width can be obtained The strip width value is rounded up after calculation to 21 mm.

[0124] After calculation, EI 混 =1.92×10 14 N·mm 2 Since this case is to increase the bending and shear strength calculation by 10%, EI 加固 =0.1EI 混 =2×A×E2'×l 2 =1.92×10 13 N·mm 2 , solid A=761mm 2 Since the thickness of the strip steel plate 32 is 5 mm, the principle of rounding up is adopted, and the width of the vertical main steel plate 31 is 160 mm.

[0125] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A pre-tightened steel sleeve bridge pier energy dissipation reinforcement device, characterized in that: The invention comprises at least two steel hoop splicing pieces (3) with hoops arranged outside the bridge pier, wherein the steel hoop splicing pieces (3) are U-shaped half hoops, and each two adjacent steel hoop splicing pieces (3) are pre-tightened and connected by a pre-tightening force connection assembly, and a plurality of steel hoop splicing pieces (3) are connected to form a steel hoop, and a rubber pad (4) is attached to the inner side of the steel hoop splicing piece (3); The steel sleeve splicing piece (3) comprises a vertical main steel plate (31), and a plurality of strip steel plates (32) are respectively arranged on both sides of the vertical main steel plate (31), and the plurality of strip steel plates (32) are arranged at equal intervals along the height direction of the vertical main steel plate (31), and the strip steel plates (32) are connected to the vertical main steel plate (31) as a whole; An anchoring steel plate (5) for anchoring connection with the base (2) is fixedly provided at the bottom of the vertical main steel plate (31).

2. A pre-tightened steel sleeve bridge pier energy dissipation reinforcement device according to claim 1, characterized in that: The pre-tightening force connection assembly comprises a plurality of pre-tightening bolts (8), the number of the pre-tightening bolts (8) being equal to and corresponding to the strip steel plates (32) in the steel sleeve splicing piece (3).

3. A pre-tightened steel sleeve bridge pier energy dissipation reinforcement device according to claim 2, characterized in that: An ear plate (7) for installing a pre-tightening bolt (8) is arranged at one end of the strip steel plate (32) away from the vertical main steel plate (31), and a bolt through hole for the pre-tightening bolt (8) to pass through is opened on the ear plate (7).

4. A pre-tightened steel sleeve bridge pier energy dissipation reinforcement device according to claim 1, characterized in that: The anchoring steel plate (5) is anchored on the base (2) via a plurality of anchoring bolts (6).

5. The pre-tightened steel sleeve bridge pier energy dissipation reinforcement device according to claim 1 is characterized in that: The number of the steel hoop splicing pieces (3) is two.

6. A design method for the pre-tightened steel sleeve bridge pier energy dissipation reinforcement device as claimed in claim 5, characterized in that: The method comprises the following steps: Step 1: Determine the total shear bearing capacity V required after pier reinforcement u and bending moment of inertia EI 总 ; Step 2: Determine the distance between the two outermost strip steel plates of the steel sleeve splice: According to the equivalent plastic hinge length L of the pier (1): p , determining the height of the reinforcement area of ​​the pier (1), and determining the distance D between the uppermost strip steel plate (32) and the lowermost strip steel plate (32) of the steel sleeve splicing piece (3) according to the height of the reinforcement area of ​​the pier (1); The height of the reinforced area of ​​the pier (1) is greater than the equivalent plastic hinge length L of the pier (1). p ; Step 3: Determine the number of strip steel plates and the strip spacing: Based on the condition that the core concrete area is an effective constraint area, determine the strip net spacing S PJ The value range of According to the distance D between the uppermost strip steel plate (32) and the lowermost strip steel plate (32) of the steel sleeve splicing piece (3) and the strip clearance S PJ The value range is based on the maximum strip spacing principle and combined with the strip clearance S PJ Smaller than the stripe spacing S sp The number of strip steel plates (32) and the strip spacing S are determined based on the theoretical basis. sp ; Step 4: Determine the width and thickness of the strip steel plate: When using steel hoops to reinforce reinforced concrete beams for shear resistance, the bearing capacity of the inclined section conforms to the formula V u =V RC +V cf , and then calculate the shear bearing capacity V that the steel hoop needs to provide cf ; Among them, V RC is the shear bearing capacity of the pier (1) before reinforcement; According to the formula The sum of the cross-sectional areas of the steel ferrules at the same cross section is calculated. b,sp , and according to formula A b,sp =2×b sp ×t sp , determine the width b of the strip steel plate (32) sp and thickness t sp ; where ψ vb is the shear strength reduction factor related to the bonding method and stress conditions of the steel hoop; f sp h is the yield strength of the steel plate used in the steel hoop; sp It is the vertical height of the bond between a single leg of the steel sleeve splice and the concrete on the side of the beam; Step 5: Determine the width of the vertical main steel plate: Calculate the bending strength of the section based on the flat section assumption, and the bending moment of inertia EI of the vertical main steel plate (31) reinforcement 加固 =EI 总 -EI 混 , among which, EI 混 is the bending moment of inertia of the pier (1) itself; According to the formula EI 加固 =2×A×E2'×l 2 , calculate the reference value of the cross-sectional area A of the vertical main steel plate (31), and then determine the thickness and width of the vertical main steel plate (31) according to the reference value of the cross-sectional area A of the vertical main steel plate (31), so that the thickness and width of the vertical main steel plate (31) are both integers and the product of the two is not less than the reference value of the cross-sectional area A of the vertical main steel plate (31); wherein E2' is the elastic modulus of the vertical main steel plate (31), and l is the distance from the centroid of the vertical main steel plate (31) to the neutral axis of the cross section of the pier (1).

7. The design method of a pre-tightened steel sleeve bridge pier energy dissipation reinforcement device according to claim 6 is characterized in that: In step 2, the equivalent plastic hinge length L of the pier (1) is p =min(L p1 ; L p2 ), where L p1 and L p2 These are two methods for calculating the plastic hinge length; When 0.08H+0.022f y d s ≥0.044f y d s When L p1 =0.08H+0.022f y d s ; When 0.08H+0.022f y d s <0.044f y d s When L p1 =0.044f y d s ; Where H is the height of the pier (1), b is the short side dimension of the rectangular cross section or the diameter of the circular cross section of the pier (1), and f is y is the standard value of tensile strength of longitudinal reinforcement of pier (1), d s is the diameter of the longitudinal reinforcement of the pier (1); The distance between the uppermost strip steel plate (32) and the lowermost strip steel plate (32) of the steel sleeve splicing piece (3) is greater than the equivalent plastic hinge length of the bridge pier (1).

8. The design method of a pre-tightened steel sleeve bridge pier energy dissipation reinforcement device according to claim 6 is characterized in that: In step 3, the middle section of the two steel sleeve splicing pieces (3) is the section with the smallest effective restraint area, that is, the control section, which is called the effective restraint section length L of the steel sleeve. PJ ,and At the same time, in order to make the core concrete area an effective constraint area, L PJ >b-2δ, we can get S PJ <4δ; wherein δ is the thickness of the protective layer of the pier (1).

9. The design method of a pre-tightened steel sleeve bridge pier energy dissipation reinforcement device according to claim 6 is characterized in that: In step 4, the shear bearing capacity V of the bridge pier (1) before reinforcement is RC =V C +V S +V N ; Among them, the shear resistance of the concrete in the pier (1) Shear resistance of the middle reinforcement of the bridge pier (1) The shear force V caused by the axial pressure of the bridge pier (1) itself N =0.07N; Therefore Wherein, λ is the shear span ratio of the pier (1) structure. When λ is less than 1.5, λ is 1.5; when λ is greater than 3, λ is 3; f t is the concrete tensile strength value of the pier (1); b0 is the effective width of the cross section of the pier (1); h0 is the effective length of the cross section of the pier (1); f yv is the design value of the tensile strength of the stirrups of pier (1); A SV is the total effective area of ​​stirrups in the shear section of pier (1); s is the spacing of stirrups of pier (1); N is the design value of the axial pressure of the pier (1).

10. The design method of a pre-tightened steel sleeve bridge pier energy dissipation reinforcement device according to claim 6, characterized in that: In step 5, the bending moment of inertia of the bridge pier (1) itself is Wherein, E1 is the elastic modulus of the concrete of the pier (1), E2 is the elastic modulus of the steel bars of the pier (1), h is the cross-sectional length of the pier (1), n ​​is the number of longitudinal bars in the pier (1), i is the serial number of the longitudinal bars in the pier (1), i and n are both positive integers, and i≤n, A i is the cross-sectional area of ​​the i-th longitudinal reinforcement in the pier (1), l i is the distance between the i-th longitudinal reinforcement in the pier (1) and the median line of its cross section.

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