CN102296751B - Prestressing anti-fatigue girder - Google Patents

Abstract

The invention belongs to the technical field of civil engineering, and in particular relates to a prestressed anti-fatigue steel beam. It consists of upper flange, lower flange, web, support stiffener and prestressed anchor plate, anchor hole, high-strength prestressed steel strand, anchor stiffener, anchor head, arc plate, support steel corbel and The anti-sideway pad is composed of prestressed steel strands inserted into the anchor holes symmetrical to the web near the tension flange, and anchored with anchor heads after tension, thereby generating prestress on the tension area of the steel beam. Considering that the compressive stress after prestress relaxation is greater than the amplitude of the self-weight pull-down stress plus the fatigue tensile stress, the lower flange of the beam will not enter tension under the combined action of its own weight and fatigue load, thus solving the fatigue problem. The present invention increases the design fatigue stress range of the lower flange from the original limit to the allowable fatigue stress range to close to the design strength f, greatly improves the fatigue resistance, changes the brittle failure of fatigue into a ductile strength problem, and almost improves the ultimate strength of the lower flange Doubled, greatly improving the material utilization rate of high-strength steel.

Description

Prestressed anti-fatigue steel beams

technical field

The invention belongs to the technical field of civil engineering, and in particular relates to a prestressed anti-fatigue steel beam.

Background technique

At present, the allowable fatigue stress amplitude of anti-fatigue steel beams (such as heavy-duty crane girders, driving main girders, bridges, etc.) is low, and high-strength steel has no advantage in fatigue resistance. The ratio of allowable fatigue stress amplitude to strength Much lower than the ratio of fatigue effects and strength effects. For the main anti-fatigue steel beams, except for Q235 steel and type 2 connections, which can simultaneously exert material strength and fatigue resistance, the materials in other cases are controlled by anti-fatigue, and the utilization rate of material strength is insufficient. The higher the material strength, the worse the connection category, and the higher the number of fatigue load repetitions, the lower the material strength utilization. In addition, the current structural fatigue failure is brittle failure, which can cause major accidents suddenly. Therefore, a method is required to prevent fatigue from becoming a controlling factor restricting the use of high-strength materials, and to avoid brittle fatigue failure of high-strength steel beams, so as to make full use of material strength, save steel, and improve the safety of structures under fatigue.

Contents of the invention

The object of the present invention is to provide a prestressed anti-fatigue steel beam.

The prestressed anti-fatigue steel beam proposed by the present invention consists of an upper flange 1, a lower flange 2, a web 3, an anchor plate 4, an anchor hole 5, a high-strength prestressed steel strand 6, an anchor stiffening plate 7, an anchor head 8. Composed of arc-shaped plate 9 and support steel corbel 10, the upper flange 1, web 3 and lower flange 2 are sequentially welded to form an H-shaped steel beam, and the two ends of the H-shaped steel beam are fixed to the support steel bull On the leg 10, anchor plates 4 are welded on both sides of the web 3 above the support steel corbel 10, and the anchor plates 4 act as stiffening plates for the steel beam support and prestressed anchor plates; The anchor plate 4 at the end is near the lower flange 2 and is respectively provided with anchor holes 5 on both sides symmetrical to the web 3. The anchor holes 5 are welded with anchorage area stiffeners 7 above and below, and the anchor plate 4 faces the end side of the H-shaped steel beam. A curved plate 9 is provided, and the protruding part in the middle of the curved plate 9 is pressed on the anchor plate 4 corresponding to the center line of the web plate 3, and one end of the prestressed steel strand 6 passes through the curved plate 9 and two anchor plates in sequence After the anchor hole 5 on the 4 is stretched, the two ends of the prestressed steel strand 6 are anchored by the anchor head 8.

In the present invention, the number of 6 prestressed steel strands is 2, and after the pretension is applied, the anchor head 8 and the anchor plate 4 generate compressive stress on the tension area of the steel beam lower flange 2 and web 3 .

In the present invention, both the steel girder and the steel strand are made of high-strength steel.

In the present invention, one end of the prestressed steel strand 6 is fixed on the arc-shaped plate 9, so if one side of the steel strand breaks, the tension of the other side of the steel strand disappears at the same time, and no lateral bending moment will be generated on the beam. .

In the present invention, the H-shaped steel beam is prestressed and stretched first, and then installed on the steel bracket 10 of the support.

In the present invention, an anti-sideshift pad 11 is tightly clamped between the middle part of the web 3 and the middle part of the prestressed steel strand 6. When the web of the H-shaped steel girder tends to move sideways, the prestressed steel strand is the opposite of the girder. The web exerts a reverse restoring force to keep the beam lower flange 2 laterally stable.

The principle of the invention is as follows: high-strength steel strands are used to apply pre-compression to the lower flange of the steel girder and the adjacent web plate with larger tensile stress. Make it consider that the compressive stress after prestress relaxation is greater than the amplitude of the self-weight pull-down stress plus the fatigue pull-down stress. Then the lower flange of the beam will not enter tension under the combined action of self-weight and fatigue load, thus solving the fatigue problem.

The advantages of the present invention are:

下翼缘设计疲劳应力幅从原局限于允许疲劳应力幅可提高到接近设计强度f，抗疲劳能力大幅提高。

The design fatigue stress amplitude of the lower flange can be increased from the original limit to the allowable fatigue stress amplitude to close to the design strength f, and the fatigue resistance ability is greatly improved.

将疲劳的脆性破坏变为强度问题，呈延性（此种情形一般先由一侧钢绞线发生疲劳破断，一侧钢绞线破断后由于弧形垫块的作用另一侧钢绞线也失去预拉力。钢梁成为无预应力普通钢梁。钢梁经设计本身可抵抗疲劳荷载标准值的静力作用。所以钢绞线疲劳破坏不会引起结构倒坍，所以只要维修即可，避免了脆性破坏）。

Turn the brittle failure of fatigue into a strength problem, showing ductility (in this case, the steel strand on one side is generally broken by fatigue, and the steel strand on one side is broken after the steel strand on the other side is also lost due to the action of the arc pad. Pre-tension. The steel beam becomes a non-prestressed ordinary steel beam. The steel beam itself can resist the static force of the standard value of the fatigue load by design. Therefore, the fatigue damage of the steel strand will not cause the structure to collapse, so it only needs to be repaired, avoiding brittle failure).

钢绞线和防侧移垫块相互作用可改善梁侧向稳定。

The interaction of steel strands and anti-sway pads improves the lateral stability of the beam.

大幅提高高强度钢材的材料利用率。

Greatly improve the material utilization rate of high-strength steel.

Description of drawings

Figure 1 is the elevation view of the prestressed anti-fatigue steel beam.

FIG. 2 is a cross-sectional view along line A-A of FIG. 1 .

Fig. 3 is a B-B sectional view of Fig. 1 .

Fig. 4 is a C-C sectional view of Fig. 1 .

FIG. 5 is a D-D sectional view of FIG. 1 .

Fig. 6 is a cross-sectional view of a prestressed anti-fatigue box steel girder.

Numbers in the figure: 1 is the upper flange, 2 is the lower flange, 3 is the web, 4 is the anchor plate, 5 is the anchor hole, 6 is the prestressed high-strength steel strand, 7 is the anchor stiffener, 8 is the anchor 9 is a curved plate, 10 is a support steel corbel, and 11 is an anti-sideshift pad.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing and example.

Embodiment 1: As shown in Figures 1-6, the device consists of an upper flange 1, a lower flange 2, a web 3, a support stiffener and a prestressed anchor plate 4, an anchor hole 5, and high-strength prestressed steel Stranded wire 6, anchor stiffening plate 7, anchor head 8, arc plate 9, support steel corbel 10 and anti-sideshift pad 11 are formed. The upper flange 1, the lower flange 2 and the web 3 form a welded H-shaped steel beam. Both ends of the H-shaped steel beam are fixed on the support steel corbel 10, and anchor plates 4 are welded on both sides of the web 3 above the support steel corbel 10. The anchor plate 4 is used both as a steel beam support stiffening plate and also as a prestressed anchor plate. One end (right end) of the H-shaped steel beam is provided with anchor holes 5 on both sides symmetrical to the web 3 at the anchor plate 4 near the lower flange, and anchor holes 5 are welded with anchorage area stiffeners 7 up and down. Beam other end (left end) is bored with anchor hole 5 equally at anchor plate 4 and the corresponding position of right end, and anchor plate is provided with an arc plate 9 to beam end side, and arc plate 9 is also drilled with same anchor hole. The protruding part in the middle of the arc plate 9 presses on the anchor plate 4 corresponding to the center line of the web 3 . The prestressed steel strand 6 is penetrated into the anchor hole 5 symmetrical to the web 3, and anchored with the anchor head 8 after stretching. After the prestressed steel strand 6 is pre-tensioned, the anchor head 8 and the anchor plate 4 generate compressive stress on the tension area of the lower flange 2 of the steel beam and the web 3 . Steel girder and prestressed steel strand 6 all use high-strength steel. One end of the prestressed steel strand 6 is fixed on the arc plate 9, so if the steel strand on one side breaks, the tension on the other side of the steel strand disappears simultaneously, so no lateral bending moment will be produced on the beam. The anti-sideshift pad 11 is tightly clamped in the center of the web 3 and the prestressed steel strand 6. When the web of the beam tends to move sideways, the steel strand exerts a reverse restoring force on the web of the beam to keep the beam Lateral stabilization of the lower flange 2 .

The above-mentioned device is used for heavy-duty work-making I-shaped steel crane girders, and the tensile stress σ _p of the lower flange 2 caused by the self-weight and the standard value of the fatigue load is calculated, and prestressed steel strands are installed on both sides of the web 3 close to the lower flange 2 Line 6, and apply pretension to it. After deducting the prestress loss, the compressive stress generated by the pretension force on the lower flange 2 is equal to σ _p , so the steel beam will not be stretched under the action of fatigue, and the fatigue resistance is naturally satisfied.

Embodiment 2: The device described in Embodiment 1 is used for the box-shaped steel girder of the bridge crane, and the prestressed steel strands 6 are arranged on both sides of the web 3 near the tension flange of the box-shaped steel beam of the bridge crane, and the It applies a pretension. Similarly, after deducting the loss of prestress, the pretension produces compressive stress on the tension flange. The steel beam is not stretched under fatigue, and the fatigue resistance is satisfactory. Due to the use of high-strength materials and improved material utilization, the weight of the box girder can be greatly reduced, which is beneficial to the reduction of long-term energy consumption of the bridge crane.

Claims (3)

1. A prestressed anti-fatigue steel beam, comprising upper flange (1), lower flange (2), web (3), anchor plate (4), anchor hole (5), prestressed steel strand ( 6), anchorage area stiffener (7), anchor head (8), arc-shaped plate (9) and support steel corbel (10), characterized in that the upper flange (1), web (3) and lower The flange (2) is sequentially welded to form an H-shaped steel beam, and the two ends of the H-shaped steel beam are fixed on the support steel corbel (10), and the two webs (3) located above the support steel corbel (10) An anchor plate (4) is welded on the side, and the anchor plate (4) acts as a steel beam support stiffener and a prestressed anchor plate; the anchor plates (4) located at both ends of the H-shaped steel beam are close to the lower flange (2) Anchor holes (5) are respectively arranged on both sides symmetrical to the web (3), and anchorage area stiffeners (7) are welded above and below the anchor holes (5), and the anchor plate (4) faces the end of the H-shaped steel beam There is an arc-shaped plate (9) on the side, and the protruding part in the middle of the arc-shaped plate (9) is pressed on the anchor plate (4) corresponding to the center line of the web plate (3), and one end of the prestressed steel strand (6) is sequentially After passing through the anchor holes (5) on the arc plate (9) and the two anchor plates (4), after tensioning, the two ends of the prestressed steel strand (6) are anchored by the anchor head (8). 2. The prestressed anti-fatigue steel beam according to claim 1, characterized in that the number of said prestressed steel strands (6) is two. 3. The prestressed anti-fatigue steel beam according to claim 1, characterized in that an anti-sideshift pad (11) is tightly clamped between the middle part of the web (3) and the middle part of the prestressed steel strand (6).

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