Method for reinforcing H-shaped steel beam bolt welding splicing joint under limitation of floor slab

Abstract

The invention discloses a method for reinforcing an H-shaped steel beam bolt welding splicing joint under the limitation of a floor slab, and the method comprises the following steps: detecting the effective depth of a joint defect welding seam, and detecting the effective depth of the joint defect welding seam, and the effective depth he of the welding seam is defined as the distance from the shallowest position of the internal defect of the welding seam to the upper surface of a base material. According to the method for reinforcing the H-shaped steel beam bolt-welding splicing joint under the limitation of the floor slab, reinforcement can be conducted without dismantling the covering object on the upper portion, the method is suitable for reinforcing the H-shaped steel beam bolt-welding splicing joint with the floor slab on the beam and the limited operation space, the residual bearing capacity of the defect welding seam is utilized, the thickness of the reinforcing plate can be reduced, and the construction difficulty is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of beam-column node reinforcement, in particular to a method for reinforcing bolt-welded spliced ​​nodes of H-shaped steel beams restricted by floor slabs. Background Art

[0002] H-shaped steel bolt-welded joints have excellent assembly performance and are the most convenient and widely used connection form in the rigid connection of steel structure beams and columns. However, during the construction process, such joints often have welding defects such as misalignment, pores, and slag inclusions, which do not meet the requirements of the acceptance specifications and seriously affect the safety of the structure. In order to ensure the safety of the structure, it is usually necessary to reinforce the beam-column joints with construction quality defects.

[0003] At present, for bolt-welded joints with weld defects, the welds are usually removed, re-welded, or the contribution of defective welds is completely ignored for equal strength reinforcement. The commonly used reinforcement methods for steel structure nodes under load in my country's "Technical Specifications for Steel Structure Reinforcement" are mainly the following: beam flange reinforcement with cover plates, beam flange reinforcement with lateral cover plates, beam flange reinforcement with haunches, beam flange reinforcement with ribs, end plate corner welding and circumference welding reinforcement, and high-strength bolt reinforcement.

[0004] The prerequisite for the implementation of the above reinforcement methods is that the nodes are exposed and there are no obstacles to the welded cover plates on the flanges. However, for most existing buildings, since the construction has been completed, the steel beams are usually covered with building floors or roof panels, as shown in the schematic diagram. Figure 1 , resulting in limited working space. If conventional reinforcement methods are used for reinforcement, the schematic diagram is as follows Figure 2 Due to the presence of floor slabs and roof slabs, the newly added cover slab cannot be welded to the parent material, and when there is a serious misalignment, the quality of the reinforcement weld is even more difficult to guarantee. If the reinforcement effect is to be guaranteed, the floor slab must be chiseled off before implementation, which is difficult to construct and requires a large amount of work. In addition, conventional reinforcement methods ignore the residual bearing capacity and require a large amount of welding work, which will introduce welding defects.

[0005] In view of this, the existing structure and defects were studied and improved, and a reinforcement method for H-beam bolt-welded joints restricted by floor slabs was proposed. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a method for reinforcing bolted and welded joints of H-shaped steel beams restricted by floor slabs, which solves the problems raised in the above-mentioned background technology.

[0007] To achieve the above purpose, the present invention is implemented by the following technical scheme: a method for reinforcing the bolted and welded joints of H-shaped steel beams restricted by floor slabs, the reinforcement method comprising the following steps: Detect the effective depth of the node defect weld. Detect the effective depth of the node defect weld, where the effective depth he of the weld is defined as follows: the distance from the shallowest position of the internal defect of the weld to the upper surface of the parent material; The effective weld part of the defective weld provides partial bending resistance, and the web and high-strength bolts bear part of the bending moment and shear force. When the defects in the flange are compressed, they can still resist the pressure, which is equivalent to an inverted T-shaped section. When analyzing the bearing capacity of the spliced ​​node with defects, the compressed flange is considered to be defect-free. Establish a finite element model with weld defects to calculate and analyze the residual bearing capacity of the node. According to the detection results of the effective depth of the defective weld of the node, use general finite element software to establish a finite element model of the node with weld defects to calculate and analyze the residual bearing capacity; Calculate the geometric dimensions of the reinforced steel plate, and use finite element software to calculate and analyze the reinforced model: first, determine the length of the reinforced plate. The reinforced plate is placed with the original butt weld as the midpoint, and the two sides of the weld are of equal length. The length of the reinforced plate is twice the height of the beam and rounded up. Continuously adjust the thickness of the plate until the load-displacement curve at failure is above the load-displacement curve of the lossless node. If the calculated reinforced plate is too thick and not suitable for welding, lengthen the reinforced plate and adjust the plate thickness for trial calculation.

[0008] Furthermore, the H-shaped steel, bolts, effective welds and cover plates are simulated using the solid element SOLID45. There is surface-to-surface contact between the nut and the cover plate, the cover plate and the web, and the hole wall and the bolt rod. The surface with a smaller contact area is defined as the contact surface, using the contact element CONTA173, and the surface with a larger area is defined as the target surface, using the target element TARGE170.

[0009] Furthermore, the ineffective welds at the flange joints are simulated using contact elements.

[0010] Furthermore, the steel adopts an ideal elastic-plastic constitutive relation and follows the Von-Mises yield criterion.

[0011] Furthermore, according to the calculated geometric dimensions of the reinforcement plate, fixed angle steels are welded at the upper and lower flange reinforcement steel plates on both sides of the web in the belly of the H-shaped steel, and positioning angle steels are welded at the positions where the reinforcement plates are to be welded on the upper and lower flanges. The length direction of the reinforcement plate is on both sides of the original weld, and the length of each side is the calculated reinforcement plate length L. The center line of the reinforcement plate in the thickness direction is 1 / 3 of the single-side width of the flange at the edge of the flange. The positioning angle steel is polished within the thickness range of the reinforcement plate close to the flange side to remove the surface coating and floating rust of the steel until the metallic luster is exposed.

[0012] Furthermore, the reinforcement steel plate is beveled and polished. The upper and lower ends of the reinforcement steel plate close to the flange edge are beveled at a bevel angle of 45°. Oil, rust, moisture and other contaminants on the bevel surface are polished clean until the metallic luster is exposed.

[0013] Furthermore, the reinforcing steel plate is placed at the position of the positioning angle steel and welded, and the reinforcing steel plate is placed at the position of the positioning angle steel in the belly of the H-shaped steel, wherein the groove side is located on the outer side of the flange plate, and the non-groove side is located on the web side.

[0014] Furthermore, the reinforcement steel plates are welded to both sides of the web by single-sided groove welding, so that the cross-section at the node changes from H-type to III-type.

[0015] The present invention provides a method for reinforcing the bolted welded joint nodes of H-shaped steel beams restricted by floor slabs, which has the following beneficial effects: when restricted by floor slabs, steel plates are welded on both sides of the web in the belly of the H-shaped steel, so that the cross section at the node is changed from H-shaped to III-shaped. Through the calculation and analysis of bearing capacity, this method is feasible to resist bending by adding two webs, and at the same time, the residual bearing capacity of defective welds is utilized, the thickness of the reinforcement plate can be reduced, the welding difficulty can be reduced, and the reinforcement can be performed without removing the upper covering, which is suitable for the reinforcement of H-shaped steel bolted welded joint nodes with floor slabs on the beams and limited operating space. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of a reinforcement condition limitation of a method for reinforcing a bolted and welded joint of an H-shaped steel beam under floor slab restriction of the present invention; Figure 2 A schematic diagram of cover plate reinforcement of a method for reinforcing bolted and welded joints of H-shaped steel beams restricted by floor slabs according to the present invention; Figure 3 A schematic diagram of the definition of effective weld depth of a method for reinforcing a bolted-welded joint of an H-beam restricted by a floor slab according to the present invention; Figure 4 A model diagram of a method for reinforcing a bolted and welded joint of an H-shaped steel beam restricted by a floor slab according to the present invention; Figure 5 A schematic diagram of mesh division of a method for reinforcing bolted and welded joints of H-shaped steel beams restricted by floor slabs according to the present invention; Figure 6 It is a schematic diagram of the relative sliding of the cover plate and the web plate of a method for reinforcing the bolted and welded joint of an H-shaped steel beam restricted by a floor slab according to the present invention; Figure 7 It is a load-displacement curve diagram of the bending bearing capacity of a H-beam bolt-welded splicing node with defects and without defects of the present invention; Figure 8 A schematic diagram of a reinforced component of a method for reinforcing a bolted and welded joint of an H-shaped steel beam restricted by a floor slab according to the present invention; Fig. 9 A schematic diagram of the welding position of the positioning angle steel of a method for reinforcing a bolted and welded joint of an H-shaped steel beam restricted by a floor slab according to the present invention; Fig.10 A load-displacement curve diagram of a beam after reinforcement in a method for reinforcing a bolted-welded joint of an H-shaped steel beam restricted by a floor slab according to the present invention; Fig.11 This is an equivalent stress cloud diagram under the ultimate load after the weld of a beam is reinforced according to a method for reinforcing a bolted and welded joint of an H-shaped steel beam restricted by a floor slab of the present invention. DETAILED DESCRIPTION

[0017] The following is a further detailed description of the embodiments of the present invention in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0018] like Figures 1 to 11 As shown, the present invention provides a technical solution: a method for reinforcing a bolted welded joint of an H-beam restricted by a floor slab, the reinforcement method comprising the following steps: detecting the effective depth of the defective weld of the node. The effective depth of the defective weld of the node is detected, wherein the effective depth he of the weld is defined as follows: the distance from the shallowest position where the internal defect of the weld appears to the upper surface of the parent material, and the weld within this range can play a normal tensile and compressive role, while the weld with defects in the remaining depth plays a compressive role.

[0019] The effective weld part of the defective weld can provide partial bending resistance. In addition, the web and high-strength bolts can also bear part of the bending moment and shear force. Although the defects in the flange cannot provide tensile resistance, it can still resist pressure when under compression, that is, it is equivalent to an inverted T-shaped section. Therefore, when analyzing the bearing capacity of defective splicing nodes, the compressed flange can be regarded as defect-free.

[0020] A finite element model with weld defects is established to calculate and analyze the residual bearing capacity of the node. According to the detection results of the effective depth of the defective weld of the node, a finite element model of the node with weld defects is established using general finite element software to calculate and analyze the residual bearing capacity.

[0021] The H-shaped steel, bolts, effective welds and cover plates are simulated by solid element SOLID45. There is surface-to-surface contact between the nut and cover plate, cover plate and web plate, hole wall and bolt rod. The surface with smaller contact area is defined as the contact surface, and the contact element CONTA173 is used. The surface with larger area is defined as the target surface, and the target element TARGE170 is used.

[0022] The invalid welds at the flange joints are simulated using contact elements, thus taking into account the compression but not tension characteristics of the defective welds. The ideal elastic-plastic constitutive relation is adopted for the steel material, following the Von-Mises yield criterion.

[0023] The following equation is generated along the axial direction using two points at the same position on both sides of the contact surface between the cover plate and the web plate: Figure 6The relationship between relative slip and load shown is used as a reference to determine whether the node has lost its bearing capacity. When the value suddenly increases, it is considered that the node has lost its bearing capacity.

[0024] Calculate the geometric dimensions of the reinforced steel plate. Usually the web is not used as a bending member. The reinforcement scheme proposed in this invention mainly relies on the web to provide bending resistance. The finite element software is used to calculate and analyze the reinforced model: First, the length of the reinforcement plate is determined. The reinforcement plate is placed with the original butt weld as the midpoint, and the two sides of the weld are of equal length. The length of the reinforcement plate is twice the height of the beam and rounded up. The thickness of the plate is continuously adjusted until the load-displacement curve at failure is above the load-displacement curve of the intact node.

[0025] If the reinforcement plate calculated by trial is too thick and not suitable for welding, lengthen the reinforcement plate and adjust the plate thickness for trial calculation.

[0026] According to the calculated geometric dimensions of the reinforcement plate, fixed angle steels are welded at the positions of the upper and lower flange reinforcement steel plates on both sides of the web in the belly of the H-shaped steel.

[0027] Weld the positioning angle steel at the position where the reinforcement plate is required to be welded on the upper and lower flanges. The length direction of the reinforcement plate is on both sides of the original weld, and the length of each side is the calculated reinforcement plate length L. The distance between the center line of the reinforcement plate in the thickness direction and the edge of the flange is 1 / 3 of the single-side width of the flange, that is, 1 / 3*(B-t1) / 2=(B-t1) / 6. The schematic diagram of the positioning angle steel is as follows: Fig. 9 .

[0028] Grind the positioning angle steel within the thickness range of the reinforcement plate close to the flange side to remove the surface coating, floating rust, etc. of the steel until the metallic luster is exposed.

[0029] Beveling and grinding the reinforcement steel plate: Beveling the upper and lower ends of the reinforcement steel plate close to the flange edge with a bevel angle of 45°. Grind away oil, rust, moisture and other contaminants on the bevel surface until the metallic luster is exposed.

[0030] Place the reinforcement steel plate at the location of the positioning angle steel and weld it: Place the reinforcement steel plate at the location of the positioning angle steel in the belly of the H-shaped steel, with the groove side located on the outside of the flange plate and the non-groove side located on the web side.

[0031] The reinforcement steel plate is welded to both sides of the web by single-sided groove welding, so that the cross section at the node changes from H-type to III-type, such as Figure 8 As shown in the figure, in this scheme, the bending resistance of the reinforced node is provided by the defective weld, the newly added web and the high-strength bolts.

[0032] After calculation and analysis, the load-displacement curve after reinforcement using this reinforcement method is above the load-displacement curve of the lossless node, such as Fig.10As shown in the figure, it shows that the type III reinforcement scheme can effectively restore the bending bearing capacity of the weld defect node. Fig.11 This is the equivalent stress cloud diagram of a beam weld after reinforcement when it is subjected to bending failure. Compared with the weld before reinforcement, it is no longer a weak part. The maximum stress area, that is, the yield failure section, is transferred to the conventional section at the end of the reinforcement plate. This reinforcement method utilizes the residual bearing capacity of the defective weld, which can reduce the thickness of the reinforcement plate and the construction difficulty. This reinforcement method can be carried out without removing the upper covering, and is suitable for the reinforcement of H-shaped steel bolt-welded splicing nodes with floor slabs on beams and limited operating space.

[0033] The embodiments of the present invention are given for the purpose of illustration and description, and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses.

Claims

1. A method for reinforcing bolted and welded joints of H-shaped steel beams restricted by floor slabs, characterized in that: The reinforcement method includes the following steps: Detect the effective depth of the node defect weld. Detect the effective depth of the node defect weld, where the effective depth he of the weld is defined as follows: the distance from the shallowest position of the internal defect of the weld to the upper surface of the parent material; The effective weld part of the defective weld provides partial bending resistance, and the web and high-strength bolts bear part of the bending moment and shear force. When the defects in the flange are compressed, they can still resist the pressure, which is equivalent to an inverted T-shaped section. When analyzing the bearing capacity of the spliced ​​node with defects, the compressed flange is considered to be defect-free. Establish a finite element model with weld defects to calculate and analyze the residual bearing capacity of the node. According to the effective depth detection results of the node defect weld, use general finite element software to establish a finite element model of the node with weld defects to calculate and analyze the residual bearing capacity; Calculate the geometric dimensions of the reinforced steel plate, and use finite element software to calculate and analyze the reinforced model: first, determine the length of the reinforced plate. The reinforced plate is placed with the original butt weld as the midpoint, and the two sides of the weld are of equal length. The length of the reinforced plate is twice the height of the beam and rounded up. Continuously adjust the thickness of the plate until the load-displacement curve at failure is above the load-displacement curve of the lossless node. If the calculated reinforced plate is too thick and not suitable for welding, lengthen the reinforced plate and adjust the plate thickness for trial calculation.

2. According to claim 1, a method for reinforcing bolted and welded joints of H-shaped steel beams restricted by floor slabs is characterized by: The H-shaped steel, bolts, effective welds and cover plates are simulated by solid element SOLID45. There is surface-to-surface contact between the nut and cover plate, cover plate and web plate, hole wall and bolt rod. The surface with smaller contact area is defined as the contact surface, and the contact element CONTA173 is used. The surface with larger area is defined as the target surface, and the target element TARGE170 is used.

3. The method for reinforcing the bolted and welded joints of H-shaped steel beams restricted by floor slabs according to claim 1 is characterized in that: The ineffective welds at the flange joints are simulated using contact elements.

4. The method for reinforcing bolted and welded joints of H-shaped steel beams restricted by floor slabs according to claim 1 is characterized in that: The steel adopts the ideal elastic-plastic constitutive relation and follows the Von-Mises yield criterion.

5. The method for reinforcing bolted and welded joints of H-shaped steel beams restricted by floor slabs according to claim 1 is characterized in that: According to the calculated geometric dimensions of the reinforcement plate, fixed angle steels are welded at the upper and lower flange reinforcement steel plates on both sides of the web in the belly of the H-shaped steel, and positioning angle steels are welded at the positions where the reinforcement plates are to be welded on the upper and lower flanges. The length direction of the reinforcement plate is on both sides of the original weld, and the length of each side is the calculated reinforcement plate length L. The distance between the center line of the reinforcement plate in the thickness direction and the flange edge is 1 / 3 of the single-side width of the flange. The positioning angle steel is polished within the thickness range of the reinforcement plate close to the flange side to remove the surface coating and floating rust of the steel until the metallic luster is exposed.

6. The method for reinforcing bolted and welded joints of H-shaped steel beams restricted by floor slabs according to claim 1 is characterized in that: The reinforcement steel plate is beveled and polished. The upper and lower ends of the reinforcement steel plate close to the flange edge are beveled with a bevel angle of 45°. The oil, rust, moisture and other dirt on the bevel surface are polished clean until the metallic luster is exposed.

7. The method for reinforcing bolted and welded joints of H-shaped steel beams restricted by floor slabs according to claim 1 is characterized in that: The reinforcement steel plate is placed at the location of the positioning angle steel and welded, and the reinforcement steel plate is placed at the location of the positioning angle steel in the belly of the H-shaped steel, wherein the groove side is located on the outside of the flange plate, and the non-groove side is located on the web side.

8. The method for reinforcing bolted and welded joints of H-shaped steel beams restricted by floor slabs according to claim 7 is characterized in that: The reinforcement steel plates are welded to both sides of the web by single-sided groove welding, so that the cross-section at the node changes from H-type to III-type.

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