CN109001060A - A kind of drawing hoist cable pulling force width and the two-way index fatigue experimental device of anchored end corner and method - Google Patents

Abstract

The invention discloses a fatigue test device and method for two-way indicators of tension amplitude and anchoring end rotation angle of a sling, comprising a self-balancing support and a support frame, a fixed anchoring end and a connecting plate with adjustable tension, and the fixed anchoring end is connected to the self-balancing support One end of the connecting plate is connected to the other end of the self-balancing support; one end of the sling is connected to the fixed anchor end, and the other end is anchored with the connecting plate; A connector is connected to the clip. The test method includes steps such as connecting the pulling sling to the fixed anchor end and the connecting plate, adjusting the tension of the pulling sling to the minimum tension value required for the test, and applying a lateral lateral force on the suspender. The test device can truly reflect the fatigue damage of the pull sling, the force transmission is clear, the model is simple, and the operation is easy; the test method can simulate the wear fatigue at the pull sling and the anchorage end, the bending stress fatigue of the pull sling, the failure mode of the connecting piece and Rotational fatigue at the anchorage end.

Description

A two-way indicator fatigue test device for tension amplitude and anchor end rotation angle of a sling and method

technical field

The invention belongs to the technical field of bridges, in particular to a bidirectional index fatigue test device and method for the tensile amplitude of a sling and the rotation angle of an anchoring end.

Background technique

As the main stress-bearing components of suspension bridges and cable-stayed cables, the tension cables transfer the load of the stiffening girder of the suspension bridge and the main girder of the cable-stayed bridge to the main cables or bridge towers, thus ensuring the normal operation of the cable-bearing bridge. The design period of the service life of the sling is generally 30 years, but in general its service life is far below the design requirements. Load-bearing bridges tend to swing longitudinally and laterally along the bridge under dynamic loads, resulting in repeated bending of the slings. Due to the relatively high stiffness of the short slings, fatigue damage is more likely to occur. Under the action of live load, the pull sling bears the changing load, which leads to the constant change of the internal force of the steel wire in the pull sling. This change makes the steel wire undergo reciprocating pulling and pulling alternating stress, which easily leads to fatigue damage of the steel wire inside the pull sling structure.

From another point of view, the sling will produce a small corner at the anchorage of the connection with the main beam. Under the long-term dynamic load, the steel wires at the connection between the upper and lower anchor heads of the sling will be subject to reciprocating bending stress. This leads to tension and compression stress cycles in the cross-sectional stress of the steel wire, resulting in wire fatigue. In addition, due to the small corners at the anchorage, damage will occur over time.

For the straddle-type anchorage end pull sling, where the wire rope pulls the sling around the anchorage end, due to the alternating load on the sling, the straddle bend is subject to reciprocating bending loads, which is prone to bending fatigue.

Studies have shown that the most important way of pulling sling damage is fatigue damage. There are many factors affecting the fatigue performance of the cable body, which can be roughly divided into:

(1) The nature of the sling itself, such as: structure, material, strength, stiffness, oiling on the surface of the rope core, treatment process, etc.;

(2) Cable body operation factors, such as alternating stress amplitude, impact force, environment, etc.;

(3) The anchoring condition of the wire rope and the anchorage and the condition of the anchorage and the connecting pin.

In the current tension sling fatigue test, only the alternating axial load is applied to the tension sling, and there is no test device for applying bending load at the same time. The test cannot reflect the force state at the anchorage and the position where the sling bypasses the clamp.

Contents of the invention

The object of the present invention is to provide a fatigue test device and method for two-way indicators of the tension amplitude of the sling and the rotation angle of the anchoring end, and the change of the axial force and the rotation angle of the sling can be realized by applying a relatively small transverse force.

The technical scheme that realizes the object of the present invention is as follows:

A two-way indicator fatigue test device for the tension amplitude of the sling and the rotation angle of the anchoring end, including a self-balancing support and a support frame; The vertical support column also includes a fixed anchor end and a connecting plate with adjustable tension, the fixed anchor end is connected to one end of the self-balancing support through the first anchor frame, and the connecting plate is connected to the other end of the self-balancing support through the second anchor frame; One end of the sling is connected to the fixed anchor end, and the other end is anchored to the connecting plate; it also includes a cable force loading member for the sling, which includes a clip, a connecting piece and a boom, and the clip is set on the sling On the cable, the boom is connected to the clip by a connector.

Further, the fixed anchor end is a pin-connected anchor end, and the pulling sling is a pin-connecting pulling sling.

Further, the fixed anchoring end is a straddling anchoring end, and the pulling sling is a straddling anchoring end pulling sling.

An alternative to any of the above technical solutions is that the boom is replaced by a loading head, and the loading head is connected to the clip through a connecting piece.

A two-way index fatigue test method for the tension amplitude of the sling and the rotation angle of the anchorage end, including

Step 1: Connect one end of the pull sling to the fixed anchor end, and the other end to anchor with the connecting plate;

Step 2: Adjust the tension of the pulling sling to the minimum tension value required by the test;

Step 3: By applying a lateral force on the suspender, the dual-index fatigue test of the tension amplitude and the anchoring end rotation angle is realized.

Further, in the step 3, by applying a lateral force on the boom, the equipment used is a jack.

An alternative to the technical solution of the above method is that the suspender is replaced by a loading head; the step 3 is replaced by: by applying a lateral force on the loading head, a dual-index fatigue test of the tension amplitude and the anchoring end rotation angle is realized.

Further, in the step 3, by applying a lateral lateral force on the loading head, the equipment used is a fatigue testing machine or a vibration exciter.

The beneficial effects of the invention are: compared with the prior art, a test device that can truly reflect the fatigue damage of the pulling sling is designed, and has the advantages of clear force transmission, simple model, easy operation and the like. The present invention also proposes a test method that considers the stress state of the bending stress, the anchorage and the position where the sling bypasses the cable clamp, which can simulate the wear fatigue of the sling and the cable clamp, the bending stress fatigue of the sling, and the stress of the connecting piece. The failure mode and the rotational fatigue of the anchor end. The test results can provide the necessary basis for the accurate calculation and full utilization of the fatigue damage of the sling, and can also comprehensively evaluate the state of the sling during operation, so it has significant scientific value and economic benefits.

Description of drawings

Fig. 1 is the structural diagram of the fatigue test device of the pin-connected pull sling;

Fig. 2 is a structural diagram of a straddle-type pull sling fatigue test device.

In the figure, (1) pin-connected anchorage end, (2) pin-connected pull sling, (3) pin-connected pull sling cable load member, (4) self-balancing bracket and support frame, (5) fixed anchor (6) Simplified straddle-type anchorage end, (7) Simplified straddle-type anchorage end pulls the sling, (8) The straddle-type cable clamp pulls the sling to load the cable.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

The self-balancing bracket is a rectangular frame made of steel, which is used to balance the initial cable force of the pulling sling. The support frame is a vertical support column. The cable force loading member is composed of clips, connectors and suspenders (or loading heads), which can convert the concentrated force during lateral loading into a uniform force in a small range to avoid stress concentration. The anchor frame at both ends is composed of steel plates.

The self-balancing bracket and support frame are placed on the ground to bear the test reaction force and serve as an operating platform.

The pin-connected anchor end 1 is fixed at the top center of the self-balancing support, the pull sling 2 is pin-connected to the pin-connect anchor end 1, and the other end of the pull sling is anchored to the adjustable tension anchor end plate. After the suspender rod of the pin-connected sling cable force loading member is connected to the jack, it can move at any position of the sling so as to realize loading at any position. When the cable force loading member of the pin-connected sling is the loading head, the loading head can be loaded by a fatigue testing machine or a vibration exciter.

The anchor end 6 of the straddle-type pull sling is fixed at the top central position of the self-balancing support, the pull-sling 7 spans the slot in the middle of the two side walls of the anchor end 6 of the straddle-type pull sling, and the other end of the pull sling One end is anchored with a connecting plate with adjustable tension. After the suspender rod of the straddle-type anchorage end pulls the sling and loads the member connected to the jack, it can move at any position of the pull sling so as to realize loading at any position. When the straddling sling cable force loading member is the loading head, the loading head can be loaded by a fatigue testing machine or a vibration exciter.

In this way, by applying a relatively small lateral force, the repeated changes of the double index of the axial force and the rotation angle of the pulling sling are realized.

During the test, the pulling sling is fixed on the self-balancing support, the tension of the pulling sling is adjusted to the minimum tension value required by the test, and the method of applying force laterally on the pulling sling is adopted to realize the double index of the pulling force amplitude and the angle of the anchoring end stress test. On the pull sling, determine the position and the magnitude of the force that make the amplitude of the anchoring end rotation angle and the amplitude of the internal force of the pull sling meet the test requirements.

Claims (8)

1. A two-way indicator fatigue test device for pulling sling tension amplitude and anchorage end angle, is characterized in that, comprises self-balancing support and bracing frame; Described self-balancing supporting frame is the upper and lower rectangular frame parallel to each other, and bracing frame is to connect The vertical support column of the upper and lower rectangular frames; it also includes a fixed anchor end and a joint plate with adjustable tension, the fixed anchor end is connected to one end of the self-balancing support through the first anchor frame, and the joint plate is connected to the self-balancing support through the second anchor frame The other end of the balance bracket; one end of the pull sling is connected to the fixed anchor end, and the other end is anchored with the connecting plate; it also includes a pull sling cable force loading member, and the pull sling cable force loading member includes a clip, a connector and a suspender, The clip is fitted on the pull sling, and the boom is connected to the clip by a connecting piece. 2. a kind of pulling sling tension amplitude as claimed in claim 1 and the two-way index fatigue test device of anchoring end angle, it is characterized in that, described fixed anchoring end is pin joint type anchoring end (1), and described pulling sling For the pinned pull sling (2). 3. a kind of pulling sling tension amplitude as claimed in claim 1 and the two-way indicator fatigue test device of anchoring end angle, it is characterized in that, described fixed anchoring end is straddle type anchoring end (6), and described pulling sling Pull the sling (7) for the straddle anchorage. 4. A kind of pull sling tension amplitude and anchoring end rotation angle two-way index fatigue test device as described in any one of claims 1-3, it is characterized in that, described suspender is replaced by loading head, and loading head is connected by connector to the clip. 5. A two-way index fatigue test method for pulling sling tension amplitude and anchorage end rotation angle, characterized in that, comprising Step 1: Connect one end of the pull sling to the fixed anchor end, and the other end to anchor with the connecting plate; Step 2: Adjust the tension of the pulling sling to the minimum tension value required by the test; Step 3: By applying a lateral force on the suspender, the dual-index fatigue test of the tension amplitude and the anchoring end rotation angle is realized. 6. a kind of pulling sling tension amplitude as claimed in claim 5 and the two-way index fatigue test method of anchorage end angle, it is characterized in that, in described step 3, by applying transverse lateral force on suspender rod, adopted The device is a jack. 7. A kind of pulling sling tension amplitude and the two-way index fatigue test method of anchoring end angle as claimed in claim 5, it is characterized in that, described suspender is replaced by loading head; A lateral force is applied on the top to realize the double-index fatigue test of the tension amplitude and the anchoring end rotation angle. 8. a kind of pulling sling tension amplitude as claimed in claim 7 and the two-way index fatigue test method of anchorage end angle, it is characterized in that, in described step 3, by applying transverse lateral force on the loading head, adopting The equipment is a fatigue testing machine or a shaker.