Construction of UHPFRC reinforced steel plate girder bridge web gap fatigue details

Abstract

A structural detail for fatigue analysis of the web gap of a UHPFRC reinforced steel plate girder bridge includes: a first ultra-high performance cement-based composite material reinforcement component at the web gap of the vertical stiffeners; the first ultra-high performance cement-based composite material reinforcement component includes ultra-high performance cement-based composite material, a first bolt connection key, and a first steel corrugated key; the first bolt connection key is located between the vertical stiffeners and the web, and the first steel corrugated key is located on the flange; ultra-high performance cement-based composite material is cast between the web, the vertical stiffeners, and the flange; the first bolt connection key and the first steel corrugated key are located within the ultra-high performance cement-based composite material; a second ultra-high performance cement-based composite material reinforcement component is located at the web gap of the horizontal node plates; the second bolt connection key is located between the vertical stiffeners and the horizontal node plates, and the second steel corrugated key is located on the web; ultra-high performance cement-based composite material is cast between the web, the vertical stiffeners, and the horizontal node plates; the second bolt connection key and the second steel corrugated key are located within the ultra-high performance cement-based composite material.

Description

Technical Field

[0001] This invention belongs to the field of bridge engineering technology, specifically relating to the construction of a UHPFRC-reinforced steel plate girder bridge web gap fatigue detail. Background Technology

[0002] With the increasing traffic volume, the fatigue problem of existing steel bridges has become increasingly prominent. In steel bridge designs prior to the 1980s, considering the potential fatigue failure caused by direct welding of vertical stiffeners to the tension flanges, the vertical stiffeners were typically shortened, leaving a gap of several centimeters between them and the flanges, thus creating the web gap of the vertical stiffeners in plate girder bridges. To avoid introducing residual welding stress at the connection between the horizontal node plate and the web of the main steel girder, holes were usually made in the horizontal node plate to allow the vertical stiffeners to pass through, resulting in the web gap of the horizontal node plate. In actual operation, under vehicle loads, deflection differences occur between the main steel girders, causing out-of-plane bending deformation at the less stiff web gaps. This leads to significant secondary stress at the welded details, causing fatigue cracks to initiate and propagate at these points, posing a potential safety hazard to the bridge. Therefore, effective reinforcement measures are needed to repair and strengthen steel bridges to address fatigue cracks caused by out-of-plane deformation. Traditional reinforcement measures for gaps in the webs of steel bridges involve installing crack arrest holes at the crack tips. However, these holes weaken the web stiffness, potentially leading to secondary structural damage. Therefore, there is an urgent need to develop a reinforcement structure that can effectively suppress the formation and propagation of out-of-plane deformation fatigue cracks at the web gaps without weakening the web stiffness. Summary of the Invention

[0003] The technical problem to be solved by this invention is to address the issue that existing steel plate girder bridge web gap out-of-plane deformation fatigue detail reinforcement technology weakens the original structural stiffness, and to provide a UHPFRC reinforced steel plate girder bridge web gap structure that is structurally reasonable, simple in construction, has superior stress performance, and is convenient to construct.

[0004] The technical solution adopted to solve the above-mentioned technical problems is: a construction for fatigue details of the web gap of a UHPFRC reinforced steel plate girder bridge. The web gap of the steel plate girder bridge includes the web gap of the vertical stiffening rib and the web gap of the horizontal node plate. The web gap of the vertical stiffening rib is formed by the web, the vertical stiffening rib and the flange plate. The web gap of the horizontal node plate is formed by the web, the vertical stiffening rib and the horizontal node plate. The reinforcement structure at the web gap of the vertical stiffening rib includes ultra-high performance cement-based composite material, bolt connection key one, and steel corrugated key one. Bolt connection key one is provided on both the web and the vertical stiffening rib at the web gap of the vertical stiffening rib. Steel corrugated key one is provided on the flange plate at the web gap of the vertical stiffening rib. Ultra-high performance cement-based composite material is cast between the web, the vertical stiffening rib and the flange plate at the web gap of the vertical stiffening rib. Bolt connection key one and steel corrugated key one are located in the ultra-high performance cement-based composite material.

[0005] The reinforcement structure at the web gap of the horizontal node plate includes ultra-high performance cement-based composite material, steel corrugated key II, and bolt connection key II. Steel corrugated key II is provided on the web at the web gap of the horizontal node plate. Bolt connection key II is provided on both the vertical stiffening rib at the web gap of the horizontal node plate and the horizontal node plate. Ultra-high performance cement-based composite material is cast between the web, vertical stiffening rib, and horizontal node plate at the web gap of the horizontal node plate. Bolt connection key II and steel corrugated key II are located in the ultra-high performance cement-based composite material.

[0006] As a preferred technical solution, the ultra-high performance cement-based composite material is a copolymerized formaldehyde fiber ultra-high performance cement-based composite material, a hybrid fiber ultra-high performance cement-based composite material, or a steel fiber ultra-high performance cement-based composite material.

[0007] As a preferred technical solution, the copolymerized formaldehyde fiber ultra-high performance cement-based composite material, 1 m 3 The copolymerized formaldehyde fiber ultra-high performance cement-based composite material is composed of materials in the following mass ratio:

[0008] 900-1100 kg of cement

[0009] 60-75 kg of silica fume

[0010] 1250–1380 kg of standard sand or river sand

[0011] Water-reducing agent component A 35-45 kg

[0012] Water-reducing agent component B 170-180 kg

[0013] 165-170 kg of water

[0014] Copolymerized formaldehyde fiber 28-45 kg.

[0015] As a preferred technical solution, the cement is P.O42.5 silicate cement; the silica fume has a particle size distribution range of 0.1–0.15 μm and a specific surface area of ​​15–27 m². 2 / g; the maximum particle size of the standard sand or river sand is less than 0.8 mm; the water-reducing agent A component is a 3301c type high-efficiency water-reducing agent; the water-reducing agent B component is microsphere powder, which is used in combination with the water-reducing agent A component; the specifications of the copolymerized formaldehyde fiber are 12 mm in length, 200 μm in diameter, 10 GPa in elastic modulus, 7.0-8.5 cN / dtex in tensile strength, and 13-15% in elongation at break.

[0016] As a preferred technical solution, the hybrid fiber ultra-high performance cement-based composite material, 1m 3 The hybrid fiber ultra-high performance cement-based composite material is composed of materials in the following mass ratio:

[0017] 900-1100 kg of cement

[0018] 60-75 kg of silica fume

[0019] 1250–1380 kg of sand or river sand

[0020] Water-reducing agent component A 35-45 kg

[0021] Water-reducing agent component B 170-180 kg

[0022] 165-170 kg of water

[0023] 10-30 kg of polyoxymethylene fiber

[0024] 75-120 kg of steel fiber.

[0025] As a preferred technical solution, the copolymerized polyoxymethylene fiber has a length of 12 mm, a diameter of 200 μm, an elastic modulus of 10 GPa, a tensile strength of 7.0–8.5 cN / dtex, and a tensile elongation of 13%–15%.

[0026] As a preferred technical solution, the cement is P.O42.5 silicate cement; the silica fume has a particle size distribution range of 0.1–0.15 μm and a specific surface area of ​​15–27 m². 2 / g; the maximum particle size of standard sand or river sand is less than 0.8 mm; the water-reducing agent A component is a 3301c type high-efficiency water-reducing agent; the water-reducing agent B component is microsphere powder, which is used in combination with the water-reducing agent A component.

[0027] As a preferred technical solution, the steel fiber is copper-plated on the surface and has a length of 13 mm and a diameter of 0.2 mm.

[0028] As a preferred technical solution, the bolted connection key one includes a screw and a nut. The screw of the bolted connection key one passes through the mounting hole of the vertical stiffening rib or the web and is fixed by the nut. The mounting hole machined on the web is preferably located at the crack tip. The steel corrugated key one is fixed to the flange plate by structural adhesive.

[0029] As a preferred technical solution, the second bolted connection key includes a screw and a nut. The screw of the second bolted connection key passes through the mounting hole of the vertical stiffening rib or the horizontal node plate and is fixed by the nut. The second steel corrugated key is fixed to the web plate by structural adhesive.

[0030] The beneficial effects of this invention are as follows:

[0031] This invention employs ultra-high performance cement-based composite material reinforcement components to strengthen the web gaps of steel plate girder bridges. The use of bolted connections and steel corrugated keys effectively reduces the thickness and weight of the reinforcement components, increases the range of stress shared by the web and the reinforcement components, and avoids the introduction of welding residual stress at the web gaps that is common in traditional reinforcement structures. Because ultra-high performance cement-based composite materials can restrain crack development and possess strong load-bearing capacity and toughness, they can effectively improve the stress performance of the web gaps, effectively inhibit the initiation and propagation of out-of-plane deformation fatigue cracks, and feature lightweight, simple construction, low cost, and excellent performance. Attached Figure Description

[0032] Figure 1 This is a structural schematic diagram of the details of the fatigue repair of the web gap of the UHPFRC reinforced steel plate girder bridge according to the present invention.

[0033] Figure 2 This is a schematic diagram of the reinforcement structure at the gap between the vertical stiffening ribs and web plates of the steel plate girder bridge of the present invention.

[0034] Figure 3 This is a schematic diagram of the reinforcement structure at the gap between the web plates of the horizontal node plate of the steel plate girder bridge of the present invention.

[0035] Figure 4 This is a three-dimensional structural schematic diagram of the steel corrugated key of the present invention.

[0036] Among them: flange plate 1; steel corrugated key 1 2; bolted key 1 3; ultra-high performance cement-based composite material 4, 7; vertical stiffening rib 5; web plate 6; steel corrugated key 2 8; horizontal node plate 9; bolted key 2 10; UHPFRC is ultra-high performance cement-based composite material. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0038] Example 1

[0039] exist Figures 1-4 In this embodiment, a fatigue detail of the web gap of a UHPFRC reinforced steel plate girder bridge is described. The web gap of the steel plate girder bridge includes the web gap of the vertical stiffener rib and the web gap of the horizontal node plate. The web gap of the vertical stiffener rib is formed by the web plate 6, the vertical stiffener rib 5 and the flange plate 1. The web gap of the horizontal node plate is formed by the web plate 6, the stiffener rib 5 and the horizontal node plate 9.

[0040] The reinforcement structure at the gap between the web plates of the vertical stiffening ribs includes ultra-high performance cement-based composite material 4, bolt connection key 3, and steel corrugated key 2. Bolt connection key 3 is installed on both the web plate 6 and the vertical stiffening rib 5 at the gap between the web plates of the vertical stiffening ribs. Bolt connection key 3 includes a screw and a nut. The screw of bolt connection key 3 passes through the mounting hole of the vertical stiffening rib 5 or the web plate 6 and is fixed with a nut. The mounting hole machined on the web plate 6 is preferably machined at the crack tip. Steel corrugated key 2 is fixed on the flange plate 1 at the gap between the web plates of the vertical stiffening ribs by structural adhesive. Ultra-high performance cement-based composite material is cast between the web plate 6, the vertical stiffening rib 5, and the flange plate 1 at the gap between the web plates of the vertical stiffening ribs. Bolt connection key 3 and steel corrugated key 2 are located in the ultra-high performance cement-based composite material 4.

[0041] The reinforcement structure at the web gap of the horizontal node plate includes ultra-high performance cement-based composite material 7, steel corrugated key 8, and bolt connection key 10. The steel corrugated key 8 is fixed to the web 6 at the web gap of the horizontal node plate by structural adhesive. Bolt connection keys 10 are installed on both the vertical stiffening rib 5 at the web gap of the horizontal node plate and the horizontal node plate 9. Bolt connection keys 10 include a screw and a nut. The screw of bolt connection key 10 passes through the mounting hole of the vertical stiffening rib 5 or the horizontal node plate 9 and is fixed by the nut. Ultra-high performance cement-based composite material 7 is cast between the web 6, the vertical stiffening rib 5, and the horizontal node plate 9 at the web gap of the horizontal node plate. Bolt connection keys 10 and steel corrugated keys 8 are located in the ultra-high performance cement-based composite material 7.

[0042] In this embodiment, the ultra-high performance cement-based composite material is a copolymerized formaldehyde fiber ultra-high performance cement-based composite material, 1m 3 The copolymerized formaldehyde fiber ultra-high performance cement-based composite material is composed of materials in the following mass ratio:

[0043] 905 kg of cement

[0044] 68 kg of silica fume

[0045] 1258 kg of river sand

[0046] Water-reducing agent component A 37.5 Kg

[0047] Water-reducing agent component B 171 kg

[0048] 165 kg of water

[0049] 28.2 kg of copolymerized formaldehyde fiber.

[0050] The cement mentioned above is P.O42.5 silicate cement; the silica fume particle size distribution ranges from 0.1 to 0.15 μm, and the specific surface area is 15-27 m². 2 / g; maximum particle size of river sand is less than 0.8 mm; water-reducing agent A is 3301c type high-efficiency water-reducing agent; water-reducing agent B is microsphere powder, which is used in combination with water-reducing agent A; the specifications of the copolymerized polyoxymethylene fiber are 12 mm in length, 200 μm in diameter, elastic modulus of 10 GPa, tensile strength of 7.0~8.5 cN / dtex, and elongation at break of 13~15%.

[0051] The preparation method of the above-mentioned copolymerized formaldehyde fiber ultra-high performance cement-based composite material is as follows:

[0052] S1. Weigh out each dry powder material and copolymerized formaldehyde fiber according to the mixing ratio. Add cement, river sand, silica fume, water-reducing agent B component and copolymerized formaldehyde fiber to a planetary mixer in sequence. Dry mix for 8-11 minutes until the copolymerized formaldehyde fiber and dry powder materials are evenly mixed to make dry material.

[0053] S2. Add half of the water-reducing agent component A and water to the dry material in sequence and stir at a constant speed for 1 to 2 minutes;

[0054] S3. Add the remaining half of the water-reducing agent component A and water to the dry material and stir at a constant speed for 1-2 minutes until the mixture is homogeneous.

[0055] S4. Continue stirring for 4 to 6 minutes. When the mixture is evenly mixed and has good fluidity, it can be discharged and stirring can be stopped.

[0056] Example 2

[0057] In this embodiment, the ultra-high performance cement-based composite material used in the construction of a UHPFRC-reinforced steel plate girder bridge web gap fatigue detail is a copolymerized formaldehyde fiber ultra-high performance cement-based composite material, 1 m 3 The copolymerized formaldehyde fiber ultra-high performance cement-based composite material is composed of materials in the following mass ratio:

[0058] 905 kg of cement

[0059] 68 kg of silica fume

[0060] 1258 kg of river sand

[0061] Water-reducing agent component A 37.5 Kg

[0062] Water-reducing agent component B 171 kg

[0063] 165 kg of water

[0064] 42.3 kg of copolymerized formaldehyde fiber.

[0065] The cement mentioned above is P.O42.5 silicate cement; the silica fume particle size distribution ranges from 0.1 to 0.15 μm, and the specific surface area is 15-27 m². 2 / g; maximum particle size of river sand is less than 0.8 mm; water-reducing agent A is 3301c type high-efficiency water-reducing agent; water-reducing agent B is microsphere powder, which is used in combination with water-reducing agent A; the specifications of the copolymerized polyoxymethylene fiber are 12 mm in length, 200 μm in diameter, elastic modulus of 10 GPa, tensile strength of 7.0~8.5 cN / dtex, and elongation at break of 13~15%.

[0066] The other components and their connection relationships are the same as in Example 1.

[0067] Example 3

[0068] In this embodiment, the ultra-high performance cement-based composite material used in the construction of a UHPFRC-reinforced steel plate girder bridge web gap fatigue detail is a copolymerized formaldehyde fiber ultra-high performance cement-based composite material, 1 m 3 The copolymerized formaldehyde fiber ultra-high performance cement-based composite material is composed of materials in the following mass ratio:

[0069] 1022 kg of cement

[0070] 75.5 kg of silica fume

[0071] 1258 kg of standard sand

[0072] Water-reducing agent component A 37.8 kg

[0073] Water-reducing agent component B 171 kg

[0074] 165 kg of water

[0075] 28.2 kg of copolymerized formaldehyde fiber;

[0076] The cement mentioned above is P.O42.5 silicate cement; the silica fume particle size distribution ranges from 0.1 to 0.15 μm, and the specific surface area is 15-27 m². 2 / g; the maximum particle size of the standard sand is less than 0.8 mm; water-reducing agent A is 3301c type high-efficiency water-reducing agent; water-reducing agent B is microsphere powder, which is used in combination with water-reducing agent A; the specifications of the copolymerized polyoxymethylene fiber are 12 mm in length, 200 μm in diameter, 10 GPa in elastic modulus, 7.0~8.5 cN / dtex in tensile strength, and 13~15% in elongation at break.

[0077] The other components and their connection relationships are the same as in Example 1.

[0078] Example 4

[0079] This embodiment describes a UHPFRC-reinforced steel plate girder bridge web gap fatigue detail construction using a hybrid fiber ultra-high performance cement-based composite material, 1 m 3 The hybrid fiber ultra-high performance cementitious composite material is composed of materials in the following mass ratio:

[0080] 905 kg of cement

[0081] 68 kg of silica fume

[0082] 1258 kg of river sand

[0083] Water-reducing agent component A 37.5 Kg

[0084] Water-reducing agent component B 171 kg

[0085] 165 kg of water

[0086] 14.1 kg of copolymerized formaldehyde fiber

[0087] 78.5 kg of steel fiber

[0088] The cement mentioned above is P.O42.5 silicate cement; the silica fume particle size distribution ranges from 0.1 to 0.15 μm, and the specific surface area is 15-27 m². 2 / g; maximum particle size of river sand is less than 0.8mm; water-reducing agent A is 3301c type high-efficiency water-reducing agent; water-reducing agent B is microsphere powder, used in combination with water-reducing agent A; copolymerized formaldehyde fiber, with a length of 12 mm, a diameter of 200 μm, an elastic modulus of 10 GPa, a breaking strength of 7.0~8.5 cN / dtex, and a breaking elongation of 13~15%; steel fiber is copper-plated steel fiber, with a length of 13 mm and a diameter of 0.2 mm.

[0089] The other components and their connection relationships are the same as in Example 1.

[0090] Example 5

[0091] In this embodiment, the ultra-high performance cement-based composite material used in the construction of a UHPFRC-reinforced steel plate girder bridge web gap fatigue detail is a hybrid fiber ultra-high performance cement-based composite material, 1 m 3 The hybrid fiber ultra-high performance cementitious composite material is composed of materials in the following mass ratio:

[0092] 905 kg of cement

[0093] 68 kg of silica fume

[0094] 1258 kg of river sand

[0095] Water-reducing agent component A 37.5 Kg

[0096] Water-reducing agent component B 171 kg

[0097] 165 kg of water

[0098] 21.2 kg of copolymerized formaldehyde fiber

[0099] 117.8 kg of steel fiber

[0100] superior The cement is ordinary Portland cement with a P.O42.5 content; the silica fume particle size distribution ranges from 0.1 to 0.15 μm, and the specific surface area is 15-27 m². 2 / g; maximum particle size of river sand is less than 0.8mm; water-reducing agent A is 3301c type high-efficiency water-reducing agent; water-reducing agent B is microsphere powder, used in combination with water-reducing agent A; copolymerized formaldehyde fiber, with a length of 12 mm, a diameter of 200 μm, an elastic modulus of 10 GPa, a breaking strength of 7.0~8.5 cN / dtex, and a breaking elongation of 13~15%; steel fiber is copper-plated steel fiber, with a length of 13 mm and a diameter of 0.2 mm.

[0101] The other components and their connection relationships are the same as in Example 1.

[0102] Example 6

[0103] In this embodiment, the ultra-high performance cement-based composite material used in the construction of a UHPFRC-reinforced steel plate girder bridge web gap fatigue detail is a hybrid fiber ultra-high performance cement-based composite material, 1 m 3 The hybrid fiber ultra-high performance cementitious composite material is composed of materials in the following mass ratio:

[0104] 1022 kg of cement

[0105] Silica fume 75.5 kg

[0106] 1258 kg of standard sand

[0107] Water-reducing agent component A 37.8 Kg

[0108] Water-reducing agent component B 171 kg

[0109] 165 kg of water

[0110] 28.2 kg of copolymerized formaldehyde fiber

[0111] 78.5 kg of steel fiber

[0112] The cement mentioned above is ordinary Portland cement with a grade of P.O42.5; the silica fume particle size distribution ranges from 0.1 to 0.15 μm, and the specific surface area is 15-27 m². 2 / g; the maximum particle size of the standard sand is less than 0.8mm; water-reducing agent A is type 3301c high-efficiency water-reducing agent; water-reducing agent B is microsphere powder, used in combination with water-reducing agent A; copolymerized polyoxymethylene fiber, with a length of 12 mm, a diameter of 200 μm, and an elastic modulus of 10 GPa. ， The tensile strength is 7.0–8.5 cN / dtex, the elongation at break is 13–15%, and the steel fiber is copper-plated steel fiber with a length of 13 mm and a diameter of 0.2 mm.

[0113] The other components and their connection relationships are the same as in Example 1.

[0114] test

[0115] To verify the strengthening effect of the present invention, the inventors conducted a strengthening effect evaluation test. Fatigue cracks were pre-induced on the I-beam specimen, and the technical solution of Embodiment 1 of the present invention was used for strengthening. Tests were then conducted on the strengthened specimens, and the test results are as follows:

[0116] I. Testing Instruments

[0117] MTS servo hydraulic control system; TDS-602 static resistance strain gauge (made in Japan); WBD type electromechanical dial indicator (made by Wenling Kete Electronic Instrument Factory, Zhejiang Province).

[0118] II. Test on the reinforcement effect at the gap between the web and the vertical stiffening ribs

[0119] 1. Specimen design parameters

[0120] The specimen was made of Q345 steel with an elastic modulus of 2.06 × 10⁻⁶. 5 MPa. The distance between the two loading points is 440mm.

[0121] 2. Test apparatus and loading procedure

[0122] The flange plate 1 of the specimen was fixed to the base with high-strength bolts. A cyclic loading was applied perpendicularly to the web plate 6 on the vertical stiffener 5 to simulate the load transmitted by the cross bracing in an actual steel bridge. During the test, the specimen was first subjected to pre-existing crack fatigue loading until cracks initiated in the web plate 6 between the vertical stiffener 5 and the flange plate 1. Before reinforcement, a static load test was conducted on the specimen with pre-existing cracks to measure the displacement and stress at each measuring point before reinforcement, for comparison with the situation after reinforcement. The specimen 1 was reinforced using the scheme described in Example 1. After the specimen reached strength, another static load test was conducted to measure the displacement and stress at each measuring point after reinforcement. Finally, cyclic loading was performed to verify the effectiveness of the reinforcement method.

[0123] 3. Experimental Results and Analysis

[0124] Table 1 shows the out-of-plane deformation amplitudes of the specimens before and after reinforcement. In Table 1, out-of-plane deformation amplitude ① is the out-of-plane deformation value at the web gap obtained by static testing before fatigue cyclic loading of the web gap, at which point the number of cycles N=0. Out-of-plane deformation amplitude ② is the out-of-plane deformation amplitude at the web gap obtained by static testing when the fatigue crack at the web gap has expanded to a certain extent and the fatigue test has stopped (i.e., the number of fatigue loading cycles before reinforcement is 1.4 million). Out-of-plane deformation amplitude ③ is the out-of-plane deformation amplitude at the web gap obtained by static testing after repair and reinforcement of the web gap. Out-of-plane deformation amplitude ④ is the data obtained by the final static test at the end of the fatigue test on the reinforced specimen (the number of fatigue loading cycles after reinforcement is 2.8 million). In Table 1, measuring points WS and WN represent the out-of-plane deformation of the web gap on the west side of the specimen in the north-south direction, respectively, and measuring points ES and EN represent the out-of-plane deformation of the web gap on the east side of the specimen in the north-south direction, respectively.

[0125] Table 1. Comparison of out-of-plane deformation amplitudes at measuring points of specimens before and after reinforcement.

[0126]

[0127] As shown in Table 1, after repair and reinforcement using the scheme of Example 1, the out-of-plane deformation amplitude of each measuring point under the same load amplitude is significantly reduced, and the out-of-plane deformation after reinforcement is very small, indicating that the reinforcement effect is good.

[0128] Table 2 compares the stress amplitude at the weld toe of web 6-vertical stiffener 5 in the web gap before and after reinforcement of the specimen. The stress amplitudes ①, ②, ③, and ④ in Table 2 have the same number of test cycles as the out-of-plane deformation amplitudes ①, ②, ③, and ④ in Table 1. Measurement points WS and WN in Table 2 are the measurement points at the weld toe of web 6-vertical stiffener 5 in the north-south direction of the web gap on the west side of the specimen, respectively. Measurement points ES and EN are the measurement points at the weld toe of web 6-vertical stiffener 5 in the north-south direction of the web gap on the east side of the specimen, respectively.

[0129] Table 2. Comparison of stress amplitude at the weld toe before and after reinforcement

[0130]

[0131] As shown in Table 2, after reinforcement using the scheme of Example 1, the stress amplitude of each measuring point is significantly reduced under the same load amplitude, and the stress at the measuring points after reinforcement is very small, indicating that the reinforcement effect is good.

[0132] Table 3 shows the variation of out-of-plane deformation amplitude at the web gap with load. Time 1, time 2, time 3, and time 4 correspond to the completion time of the number of cycles during the testing of out-of-plane deformation amplitude ①, out-of-plane deformation amplitude ②, out-of-plane deformation amplitude ③, and out-of-plane deformation amplitude ④ in Table 1, respectively. In Table 3, measuring points WS and WN represent the out-of-plane deformation of the web gap in the north-south direction on the west side of the specimen, and measuring points ES and EN represent the out-of-plane deformation of the web gap in the north-south direction on the east side of the specimen, respectively.

[0133] Table 3. Comparison of out-of-plane deformation amplitude at the weld toe before and after reinforcement

[0134]

[0135] As shown in Table 3, the out-of-plane deformation of the web gap was significantly reduced after reinforcement. Moreover, at the end of the test, the out-of-plane deformation obtained after cyclic loading was almost unchanged compared with the value obtained after reinforcement without cyclic loading, indicating that the reinforcement effect was good.

[0136] In summary, after using the reinforcement structure at the web gap of the vertical stiffening rib of the present invention to strengthen the out-of-plane deformation fatigue details of the web gap of the vertical stiffening rib, the out-of-plane deformation amplitude and stress amplitude of the specimen are significantly reduced. Moreover, the ultra-high performance cement-based composite material cast under cyclic loading does not fail, indicating that the fatigue strengthening structure is safe and reliable.

[0137] III. Test on the reinforcement effect of horizontal node plate web gap

[0138] 1. Specimen design parameters

[0139] The specimen was made of Q345 steel with an elastic modulus of 2.06 × 10⁻⁶. 5 MPa. The distance between the two loading points of the specimen reinforced in this experiment was 440 mm.

[0140] 2. Test apparatus and loading procedure

[0141] Both flanges 1 and 8 of the specimen were fixed to the base with high-strength bolts. Cyclic loading was applied perpendicularly to the web 6 on the stiffening rib 5 to simulate the load transmitted by the cross bracing in an actual steel bridge. During the test, the specimen was first subjected to pre-existing crack fatigue loading until cracks initiated in the web 6 at the gap between the stiffening rib 5 and the upper flange 1 and lower flange 8. Before reinforcement, a static load test was conducted on the specimen with pre-existing cracks to measure the displacement and stress at each measuring point before reinforcement, for comparison with the post-reinforcement state. The specimen was then reinforced with UHPFRC4 casting and cured. After the specimen reached its strength, another static load test was conducted to measure the displacement and stress at each measuring point after reinforcement. Finally, cyclic loading was performed to verify the effectiveness of the reinforcement method.

[0142] 3. Experimental Results and Analysis

[0143] The out-of-plane deformation amplitudes of the specimens before and after reinforcement are shown in Table 4. In Table 4, out-of-plane deformation amplitude ① is the out-of-plane deformation value of specimen ① under static load before and after reinforcement; out-of-plane deformation amplitude ② is the out-of-plane deformation value of specimen ② under static load before and after reinforcement; out-of-plane deformation amplitude ③ is the out-of-plane deformation value of specimen ③ under static load before and after reinforcement; out-of-plane deformation amplitude ④ is the out-of-plane deformation value of specimen ④ under static load before and after reinforcement; WU is the vertical displacement of the upper vertical stiffening rib at the tension flange end (pre-crack side) of the reinforced specimen; WB is the vertical displacement of the lower vertical stiffening rib at the tension flange end (pre-crack location) of the reinforced specimen; EU is the vertical displacement of the upper vertical stiffening rib at the compression flange end (without pre-crack location) of the reinforced specimen; and EB is the vertical displacement of the lower vertical stiffening rib at the compression flange end (without pre-crack location) of the reinforced specimen.

[0144] Table 4 Comparison of out-of-plane deformation amplitudes at measuring points of specimens before and after reinforcement.

[0145]

[0146] As shown in Table 5, after repair and reinforcement using the scheme of Example 1, the out-of-plane deformation amplitude of each measuring point under the same load amplitude is significantly reduced, and the out-of-plane deformation after reinforcement is very small, indicating that the reinforcement effect is good.

[0147] Table 5 compares the stress amplitudes at the web gap between the vertical stiffening ribs and the weld toe of the stiffening rib 5 before and after reinforcement. The stress amplitudes ①, ②, ③, and ④ in Table 5 are the same as those corresponding to the out-of-plane deformation amplitudes ①, ②, ③, and ④ in Table 1, respectively. In Table 3, measuring points WN and WS are the measuring points at the weld toe of the stiffening rib 5-web 6 in the north-south direction of the web gap on the west side of the specimen.

[0148] Table 5 Comparison of stress amplitude at the weld toe before and after reinforcement

[0149]

[0150] As shown in Table 5, after repair and reinforcement using the scheme of Example 1, the stress amplitude of each measuring point under the same load amplitude is significantly reduced, and the stress at the measuring points after reinforcement is very small, indicating that the reinforcement effect is good.

[0151] As shown in Table 5, the out-of-plane deformation of the web gap was significantly reduced after reinforcement. Moreover, at the end of the test, the out-of-plane deformation obtained after cyclic loading was almost unchanged compared with the value obtained after reinforcement without cyclic loading, indicating that the reinforcement effect was good.

[0152] In summary, after strengthening the out-of-plane deformation fatigue details of the horizontal node plate web gap using the reinforcement structure of the present invention, the out-of-plane deformation amplitude and stress amplitude of the specimen are significantly reduced. Moreover, the ultra-high performance cement-based composite material cast under cyclic loading does not fail, indicating that the fatigue strengthening structure is safe and reliable.

Claims

1. A structural detail of fatigue details of web gap in a UHPFRC reinforced steel plate girder bridge, wherein the web gap of the steel plate girder bridge includes vertical stiffener web gap and horizontal node plate web gap, wherein the vertical stiffener web gap is formed by a web (6), a vertical stiffener (5) and a flange plate (1), and the horizontal node plate web gap is formed by a web (6), a vertical stiffener (5) and a horizontal node plate (9), characterized in that: The reinforcement structure at the gap between the web plates of the vertical stiffening ribs includes an ultra-high performance cement-based composite material (4), a bolt connection key (3), and a steel corrugated key (2). The web plate (6) and the vertical stiffening rib (5) at the gap between the web plates of the vertical stiffening ribs are provided with bolt connection keys (3), and the flange plate (1) at the gap between the web plates of the vertical stiffening ribs is provided with steel corrugated keys (2). The web plate (6), the vertical stiffening rib (5), and the flange plate (1) at the gap between the web plates of the vertical stiffening ribs are filled with ultra-high performance cement-based composite material. The bolt connection key (3) and the steel corrugated key (2) are located in the ultra-high performance cement-based composite material (4). The reinforcement structure at the gap between the web plates of the horizontal node plate includes an ultra-high performance cement-based composite material (7), a steel corrugated key (8), and a bolt connection key (10). The steel corrugated key (8) is provided on the web plate (6) at the gap between the web plates of the horizontal node plate. The bolt connection key (10) is provided on both the vertical stiffening rib (5) at the gap between the web plates of the horizontal node plate and the horizontal node plate (9). The ultra-high performance cement-based composite material (7) is cast between the web plate (6), the vertical stiffening rib (5), and the horizontal node plate (9) at the gap between the web plates of the horizontal node plate. The bolt connection key (10) and the steel corrugated key (8) are located in the ultra-high performance cement-based composite material (7).

2. The structure for fatigue detailing the web gap of a UHPFRC-reinforced steel plate girder bridge according to claim 1, characterized in that: The ultra-high performance cement-based composite material is a copolymerized formaldehyde fiber ultra-high performance cement-based composite material or a hybrid fiber ultra-high performance cement-based composite material.

3. The structure for fatigue detailing the web gap of a UHPFRC-reinforced steel plate girder bridge according to claim 2, characterized in that: The copolymerized formaldehyde fiber ultra-high performance cement-based composite material, 1 m 3 The copolymerized formaldehyde fiber ultra-high performance cement-based composite material is composed of materials in the following mass ratio: 900-1100 kg of cement 60-75 kg of silica fume 1250–1380 kg of standard sand or river sand Water-reducing agent component A 35-45 kg Water-reducing agent component B 170-180 kg 165-170 kg of water Copolymerized formaldehyde fiber 28-45 kg.

4. The structure for fatigue detailing the web gap of a UHPFRC-reinforced steel plate girder bridge according to claim 3, characterized in that: The cement is P.O42.5 silicate cement; the silica fume has a particle size distribution range of 0.1–0.15 μm and a specific surface area of ​​15–27 m². 2 / g; the maximum particle size of the standard sand or river sand is less than 0.8 mm; the water-reducing agent A component is a 3301c type high-efficiency water-reducing agent; the water-reducing agent B component is microsphere powder, which is used in combination with the water-reducing agent A component; the specifications of the copolymerized formaldehyde fiber are 12 mm in length, 200 μm in diameter, 10 GPa in elastic modulus, 7.0-8.5 cN / dtex in tensile strength, and 13-15% in elongation at break.

5. The structure for fatigue detailing the web gap of a UHPFRC-reinforced steel plate girder bridge according to claim 2, characterized in that: The hybrid fiber ultra-high performance cementitious composite material, 1 m 3 The hybrid fiber ultra-high performance cement-based composite material is composed of materials in the following mass ratio: 900-1100 kg of cement 60-75 kg of silica fume 1250–1380 kg of standard sand or river sand Water-reducing agent component A 35-45 kg Water-reducing agent component B 170-180 kg 165-170 kg of water 10-30 kg of polyoxymethylene fiber 75-120 kg of steel fiber.

6. The structure for fatigue detailing the web gap of a UHPFRC-reinforced steel plate girder bridge according to claim 5, characterized in that: The copolymerized polyoxymethylene fiber has a length of 12 mm, a diameter of 200 μm, an elastic modulus of 10 GPa, a tensile strength of 7.0–8.5 cN / dtex, and a tensile elongation of 13%–15%.

7. The structure for fatigue detailing the web gap of a UHPFRC-reinforced steel plate girder bridge according to claim 5, characterized in that: The cement is P.O42.5 silicate cement; the silica fume has a particle size distribution range of 0.1–0.15 μm and a specific surface area of ​​15–27 m². 2 / g; the maximum particle size of standard sand or river sand is less than 0.8 mm; the water-reducing agent A component is a 3301c type high-efficiency water-reducing agent; the water-reducing agent B component is microsphere powder, which is used in combination with the water-reducing agent A component.

8. The structure for fatigue detailing the web gap of a UHPFRC-reinforced steel plate girder bridge according to claim 5, characterized in that: The steel fiber is copper-plated on the surface and has a length of 13 mm and a diameter of 0.2 mm.

9. The structure for fatigue detailing the web gap of a UHPFRC-reinforced steel plate girder bridge according to claim 1, characterized in that, The bolt connection key one (3) includes a screw and a nut. The screw of the bolt connection key one (3) passes through the mounting hole of the vertical stiffening rib (5) or the web plate (6) and is fixed with a nut. The mounting hole machined on the web plate (6) is preferably located at the crack tip. The steel corrugated key one (2) is fixed to the flange plate (1) with structural adhesive.

10. The structure of a UHPFRC-reinforced steel plate girder bridge web gap fatigue detail according to claim 1, characterized in that, The bolt connection key 2 (10) includes a screw and a nut. The screw of the bolt connection key 2 (10) passes through the mounting hole of the vertical stiffening rib (5) or the horizontal node plate (9) and is fixed by the nut. The steel corrugated key 2 (8) is fixed to the web plate (6) by structural adhesive.

Images