CN103388376B - A kind of Wavelike steel webplate girder construction improving fatigue resistance - Google Patents

Abstract

The invention discloses a corrugated steel web beam structure with improved fatigue resistance, which comprises two flange plates (2) and a corrugated web (1) arranged between the two flange plates (2), at least one A reinforcing plate (3) is provided on the outer side of the flange plate (2), and the projection of the reinforcing plate (3) on the flange plate (2) is a waveform. The present invention adopts the above-mentioned structure, which can effectively alleviate the stress concentration of the steel girder flange plate near the inclined section of the corrugated web and the transition between the straight section and improve the fatigue resistance of the corrugated steel web girder.

Description

A Corrugated Steel Web Beam Structure with Improved Fatigue Strength

technical field

The invention relates to the field of buildings and bridge structures, in particular to a corrugated steel web beam structure with improved fatigue resistance.

Background technique

Welded corrugated steel web girders used in buildings and bridges are often subjected to alternating and repeated loads during the service period, so it is necessary to fully consider the fatigue safety of the joints between corrugated steel webs and steel girder flange plates. The corrugated steel web steel girder is mainly welded by corrugated steel plate and steel girder flange plate. Since the corrugated steel web has a high shear buckling strength and has the characteristics of free expansion and contraction similar to the accordion effect under the longitudinal tensile deformation, the tensile stress generated by the bending moment in the plane is mainly borne by the steel beam flange. In terms of structure, the inclined section of the corrugated steel web forms a certain angle with the direction of the longitudinal tensile stress, so that the stress flow transmitted on the steel flange plate is hindered to a certain extent. This causes localized stress concentrations. When the intersection angle is large, the stress concentration in the area between the inclined section of the corrugated steel web and the edge of the flange plate of the steel beam is more prominent, and it is easier to form structural fatigue weak parts, resulting in premature fatigue failure.

In the application of steel-concrete composite beams, the web is connected to the upper and lower concrete decks, and its connection is the most important structural part. It must have a good ability to transmit the longitudinal horizontal shear force and resist the bending moment perpendicular to the longitudinal direction. To ensure the safety of the composite beam. Flange-type shear connectors can provide better bearing capacity to resist transverse bending moment and longitudinal shear force, and have been widely used in steel-concrete composite beams. For example, in the invention of application number 201020185948.6 titled "A Shear Connector" announced by the Chinese Patent Office on 2010.12.15, it is formed by directly opening holes on the corrugated steel web and welding the flange plate on the corrugated steel plate. However, in recent years, domestic and foreign fatigue test studies have found that the flange plate of the tension steel beam connected to the corrugated steel web is still prone to fatigue cracking and affects the fatigue strength of the composite beam, while the existing methods are mainly to ensure static safety. Strength, but not more related to the fatigue performance of the beam.

Experience has shown that fatigue cracks initiate on the flange of the steel beam connected to the web due to stress concentration, and lead to fatigue cracking at the connecting weld under repeated stress (such as wheel load), which is very harmful and difficult to repair. In addition, during the welding of processing and manufacturing, if there is a local unfused part in the welding itself, it is easy to form natural initial cracks and develop into crack sources, which will aggravate fatigue cracking.

Contents of the invention

The invention provides a corrugated steel web girder structure with improved fatigue resistance, and solves the problem that the corrugated steel web slant section and the flange plate of the corrugated steel web girder in the past have a large intersection angle. Stress concentration is prone to occur at the connection weld near the transition part between it and the straight section, which will lead to fatigue cracking, which is harmful and difficult to repair; at the same time, there are local unfused parts in the welding itself, which tend to form natural initial cracks and develop into Crack source, local prominent stress concentration causes fatigue cracking to aggravate.

In order to solve the technical problem, the present invention is mainly realized through the following technical solutions: a corrugated steel web beam structure with improved fatigue strength, including two flange plates and a corrugated web arranged between the two flange plates, corrugated web The plate includes a longitudinal straight section and an inclined section, and the outer side of the at least one flange plate is provided with a reinforcement plate, and the projection of the reinforcement plate on the flange plate is a waveform. Under the action of in-plane bending moment, the lower flange of the steel girder is often used to bear the tensile stress, and the stress concentration on the flange of the steel girder is mostly located near the inclined section of the corrugated web and its transition to the straight section, which is easy to cause Fatigue damage occurs in these areas. When the tensile stress flow is transmitted on the steel beam tension flange after the reinforcement plate is added, the corrugated web and the reinforcement plate can better control the tensile stress flow in the tension flange. Layer-to-layer shunting, so as to well relieve the stress concentration of the steel beam flange plate near the inclined section of the corrugated web and the transition between the straight section; usually, the corrugated web and the flange plate are connected by welds , a weld will be formed on the flange plate, and the reinforcement plate and the flange plate can also be connected through the weld. The connection method can be fillet welding or butt seam welding, and welding with corrugated web and flange plate Same welding method.

Further, the reinforcing plate is perpendicular to the flange plate. After the reinforcement plate is perpendicular to the flange plate, the laminar flow of tensile stress can be better realized.

Further, the projection of the reinforcement plate on the flange plate and the projection of the corrugated web on the flange plate are located on the same coordinate axis, with a difference of 1/2 wavelength. The reinforcement plate and the corrugated web are in reverse symmetry, that is, the peaks of the reinforcement plate correspond to the troughs of the corrugated web, and the troughs of the reinforcement plate correspond to the peaks of the corrugated web. At this time, the tensile stress shunting effect is better.

Further, several shear studs are also included, and the shear studs transversely penetrate the reinforcement plate. When this part is applied to the steel-concrete composite beam structure, the role of the shear studs and through steel bars is to enable the embedded reinforcement plate to better resist horizontal shear force, improve the crack resistance of the concrete slab, and improve the durability of the structure.

Further, the shear stud is fixed to the reinforcing plate by fusion welding or penetration welding.

Penetration welding means that the studs (welding nails) are welded to the workpiece (steel beam) through the "galvanized sheet" and melted together with the galvanized sheet. There are mainly two methods: 1. First punch (punching) holes in the welding part of the galvanized sheet, and then weld the studs on the workpiece. The advantage of this method is that the welding quality can be easily guaranteed; The galvanized sheet is burnt through, and then the studs are welded on the workpiece. The advantage of this method is that the galvanized sheet perforation and the stud welding are completed in one go, which is simple and time-saving.

For fusion welding, the premise is to penetrate without burning through. During the welding process, the weldment at the stud joint is heated above the melting point, and the welding rod is melted at the same time to complete the welding method to the molten state, which can form a firm welded joint. Since the workpieces to be welded are closely attached together, under the action of temperature field, gravity, etc., without pressure, the molten liquid of the two workpieces will mix, which has high thermal efficiency, little influence by external climate conditions, and high welding speed. Fast and other advantages.

Further, the shear nails run through the straight section of the reinforcement plate, and the shear nails are perpendicular to the straight section of the reinforcement plate. Since the shear studs running through the straight section of the stiffener are perpendicular to the direction of the longitudinal tensile stress of the flange, they can maximize their resistance to shear force. At the same time, no shear studs are installed on the inclined section of the reinforcement plate, which can avoid structural difficulties caused by being too close to the longitudinal through steel bars.

Further, it also includes several through steel bars, the through steel bars longitudinally penetrate the inclined section of the reinforcing plate, and the through steel bars are perpendicular to the shear studs.

Further, the corner junction between the inclined section and the straight section of the corrugated web and the corresponding reinforcing plate adopts a circular arc transition, and the radius of curvature of the arc is equal to or greater than the parallel distance between two adjacent straight sections. half. The parallel distance between two adjacent straight sections mentioned in this plan is the peak-to-peak value of the waveform where the corrugated web or stiffener is located, that is, the sum of the absolute values of the positive and negative peak values.

Further, a notch is provided on the reinforcing plate, and a transitional arc plate is connected to the notch, and the radius of the circle where the transitional arc plate is located is equal to or greater than 150 mm. Affected by the structure, the tensile stress on the flange plates of different sections is different, that is, the flange plates in some areas need to be provided with reinforcement plates, while the flange plates in other areas do not need to be provided with reinforcement plates. In order to make the two There is a certain transition in the area, and the direction of setting the transitional arc plate is particular. It is best to set the transitional arc plate in the direction of longitudinal tensile stress (the longitudinal direction of the beam, that is, the direction perpendicular to the cross section of the beam), Avoid unnecessary stress concentration due to the obstruction of the stress flow on the steel flange by the transitional arc plate; in addition, the setting of the transitional arc plate is to make the stress transition smooth and avoid stress concentration, and the radius is too small to make the transition unsatisfactory. To better performance, it will cause unnecessary stress concentration; the material of the transition arc plate can be consistent with the material of the reinforcement plate.

Further, the flange plate corresponding to the corrugated corner of the corrugated web or reinforcing plate is treated by shot peening. Shot peening, also known as shot peening, is one of the effective methods to reduce fatigue of parts and improve service life.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) The present invention effectively alleviates the stress concentration of the steel girder flange plate near the inclined section of the corrugated web and its transition to the straight section by setting the corrugated reinforcing plate anti-symmetrically to the corrugated web, thereby effectively The fatigue strength of the corrugated steel web girder is greatly improved.

(2) In the present invention, shear nails are set on the reinforcing plate, thereby enhancing the resistance ability of the horizontal shear force in the concrete flange plate, meeting the requirement of resisting the horizontal shear force in the concrete flange plate, and adding vertical through steel bars, Together with the shear studs, the reinforced concrete shear pins are formed to further enhance the resistance to horizontal shear forces.

(3) During factory prefabrication, corrugated stiffeners can be made with the same materials and methods as corrugated webs and their connecting welds, which is convenient for fabrication and processing; and when the existing corrugated steel web girders are transformed, it can be The outer side of the steel beam tension flange plate at the corresponding position is provided with corrugated reinforcement plates that are anti-symmetrical to the corrugated web, and the structural construction and transformation are simple.

(4) In the present invention, the corrugated reinforcement plates are antisymmetrically arranged along the width centerline of the tension flange plate of the steel beam, which can better reduce the local distortion and deformation of the tension flange plate after welding the single-sided corrugated plate.

(5) The technical solution of the present invention has good designability and economical efficiency, and is suitable for segmental reconstruction of the fatigue and vulnerable sections of beams with large spans, and can also be used for local anti-fatigue strengthening of existing corrugated steel web beam structures.

Description of drawings

Fig. 1 is the overall structure schematic diagram of embodiment 1 of the present invention;

Fig. 2 is the schematic structural view of the reinforced plate of embodiment 1 of the present invention;

FIG. 3 is a schematic diagram of the overall structure of Embodiment 6 of the present invention;

FIG. 4 is a schematic diagram of the overall structure of Embodiment 8 of the present invention;

Figure 5 is a comparison of the fatigue data of the tensile stress region of the corrugated steel web beam structure before and after structural improvement.

Detailed ways

The present invention will be further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

Example 1:

As shown in Figure 1 and Figure 2, this embodiment includes two flange plates 2 and a corrugated web 1 arranged between the two flange plates 2, at least one flange plate 2 is provided with a reinforcing plate 3 on the outside, The connection between the reinforcement plate 3 and the flange plate 2 is realized through the weld 4, and the projection of the reinforcement plate 3 on the flange plate 2 is a waveform, and the tensile stress generated by the in-plane bending moment is mainly borne by the flange plate 2, often Only one side of the flange plate 2 will be subjected to tensile stress, while the other side will be subjected to compressive stress, so the reinforcement plate 3 is only placed on the side of the flange plate 2 subject to tensile stress, and the force is passed through the corrugated web 1 and the reinforcement The plate 3 can realize the diversion of the tensile stress, that is, no stress concentration will occur on the flange plate 2, thereby effectively improving the fatigue resistance of the corrugated steel web girder. In addition, if both sides of the flange plates 2 are subject to tensile stress, the reinforcement plates 3 are provided on the outer sides of the two flange plates 2 to simultaneously divert the tensile stress on both sides.

Example 2:

In this embodiment, on the basis of the embodiment 1, the reinforcing plate 3 is made perpendicular to the flange plate 2 to improve the tensile stress shunting effect of the reinforcing plate 3 on the flange plate 2 .

Example 3:

In this embodiment, on the basis of Embodiment 2, the projection of the reinforcing plate 3 on the flange plate 2 and the projection of the corrugated web 1 on the flange plate 2 are located on the same coordinate axis, and the difference is 1/2 wavelength. The difference between the two projections is half a wavelength, which just makes the peak of the reinforcing plate 3 correspond to the trough of the corrugated web 1, and the trough of the reinforcing plate 3 corresponds to the peak of the corrugated web 1, and the corrugated web 1 and the reinforcing plate 3 are anti-symmetrical, and can be changed The tensile stress can be shunted well, and the stress concentration of the steel beam flange plate near the inclined section of the corrugated web and its transition to the straight section can be relieved.

Example 4:

This embodiment is further improved on the basis of embodiment 3. In order to enhance the resistance of the horizontal shear force in the concrete flange plate, a number of shear nails 5 are added to the reinforcement plate 3, and the shear nails 5 penetrate through the reinforcement plate 3 transversely.

Example 5:

This embodiment is further optimized on the basis of Embodiment 4, specifically: the shear nail 5 is fixed to the reinforcing plate 3 by fusion welding or penetration welding, and the shear nail 5 runs through the straight section of the reinforcing plate 3, And perpendicular to the straight section; in addition, holes can also be made on the reinforcing plate 3, and the shape of the hole can be a shape such as overall circle, opening circle, ellipse, trapezoid, etc., and then the shear nail 5 passes through the hole, together with the concrete Reinforced concrete shear pins are formed to resist greater horizontal shear forces.

Embodiment 6:

As shown in Figure 3, on the basis of Embodiment 5, this embodiment adds a number of penetrating steel bars 6, and the penetrating steel bars 6 run through the inclined section of the reinforcing plate 3 longitudinally. Longitudinal penetrating steel bars 6 are used to enhance the resistance to bending moments at right angles to the longitudinal direction, and the quantity and arrangement of longitudinal penetrating steel bars 6 can be adjusted according to specific requirements.

Embodiment 7:

This embodiment is improved on the basis of Embodiment 6, and the through steel bars 6 are perpendicular to the shear studs 5, so as to ensure that the transverse and longitudinal resistance of the flange plate 2 is enhanced.

Embodiment 8:

As shown in Figure 4, on the basis of Embodiment 7, this embodiment is provided with a notch on the reinforcing plate 3, which is formed by breaking the original entire reinforcing plate 3, and then through the transition arc plate 7, the broken The open two sections of reinforcing plates 3 are connected, and the radius of the circle where the transition arc plate 7 is located is equal to or greater than 150mm. Therefore, for the case of a large beam span, the structural improvement for increasing the fatigue strength can only be carried out on the fatigue vulnerable section of the corrugated steel web beam, that is, the reinforcement plate 3 is arranged on the flange plate 2 corresponding to the fatigue vulnerable section , the places that do not need to be strengthened are transitioned through the transition arc plate 7, so that the structural design scheme can meet the economical requirements at the same time.

Embodiment 9:

In addition to the above embodiments, by enlarging the arc radius of the longitudinal straight section and the inclined section of the corrugated web 1 and reinforcing plate 3 at the corner of the corrugation, it is also helpful to improve the fatigue life and reduce the stress concentration at this position. The arc radius can be extended to a maximum value limited by the sloped segment of the waveform.

Example 10:

In addition, shot peening treatment is used to provide proper surface treatment on the surface of the steel beam flange plate at the transition part of the inner and outer circular arc corners of the wave to further improve the fatigue strength of the welded connection. Secondly, it also increases the local surface hardness. As a preference, shot peening treatment is applied At the beginning and end of the wave-like inclined section, the improved structure of the invention makes the stress distribution of the steel beam flange plate along the wave-shaped web more uniform.

As shown in Figure 5, it can be seen from the data comparison that after the standard welding method is adopted and the structure is improved, the difference in the fatigue strength of the joint with the waveform inclined section angle of 60 degrees can be found by comparing with the standard curve of the AASHTOLRFD fatigue specification. The fatigue data of the improved structure of the present invention rises from below the B level to above the B level, and the anti-fatigue strength is obviously improved.

The present invention has been described through the above-mentioned embodiments, but it should be understood that the above-mentioned embodiments are only for the purpose of illustration and description, and are not intended to limit the present invention to the scope of the described embodiments. In addition, those skilled in the art can understand that the present invention is not limited to the above-mentioned embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the requirements of the present invention. within the range.

Claims (9)

1. A corrugated steel web beam structure with improved fatigue strength, including two flange plates (2) and a corrugated web (1) arranged between the two flange plates (2), the corrugated web ( 1) It includes a longitudinal straight section and an inclined section, characterized in that: the outer side of the at least one flange plate (2) is provided with a reinforcement plate (3), and the reinforcement plate (3) is on the flange plate (2) The projection of the reinforcement plate (3) on the flange plate (2) and the projection of the corrugated web (1) on the flange plate (2) are located on the same coordinate axis, and the difference is 1/2 wavelengths. 2. A corrugated steel web beam structure with improved fatigue resistance according to claim 1, characterized in that: the reinforcement plate (3) is perpendicular to the flange plate (2). 3. A corrugated steel web beam structure with improved fatigue strength according to claim 1, characterized in that it also includes several shear studs (5), and the shear studs (5) transversely penetrate through the reinforcement plate ( 3). 4. A corrugated steel web beam structure with improved fatigue resistance according to claim 3, characterized in that: said shear studs (5) are welded to the reinforcing plate (3) by fusion welding or penetration welding fixed. 5. A corrugated steel web beam structure with improved fatigue strength according to claim 3 or 4, characterized in that: the shear stud (5) penetrates the straight section of the reinforcement plate (3), and The shear stud (5) is perpendicular to the straight section of the reinforcing plate (3). 6. A corrugated steel web girder structure with improved fatigue strength according to claim 5, characterized in that it also includes several penetrating steel bars (6), and the penetrating steel bars (6) longitudinally penetrate through the reinforcing plate (3 ), and the through reinforcement (6) is perpendicular to the shear stud (5). 7. A corrugated steel web beam structure with improved fatigue resistance according to claim 1, characterized in that: the inclined section and the straight section of the corrugated web (1) and the corresponding reinforcing plate (3) The transition between the corners adopts a circular arc, and the radius of curvature of the circular arc is equal to or greater than half of the parallel distance between two adjacent straight segments. 8. A corrugated steel web beam structure with improved fatigue resistance according to claim 1, characterized in that: there is a notch on the reinforcing plate (3), and a transitional arc plate (7) is connected to the notch , the radius of the circle where the transition arc plate (7) is located is equal to or greater than 150mm. 9. A corrugated steel web beam structure with improved fatigue strength according to claim 1, characterized in that: the corrugated web (1) or the corresponding flange plate ( 2) Shot blasting is used at all places.