STS crane anchoring device

Nowadays, with the vigorous development of the global shipping industry, in order to improve the loading capacity of container ships, the shape of the ship is getting bigger and bigger. In order to match the container ship, the external dimensions of the quay crane are also increased. The reach has increased from 35 to 38 m to 60 to 65 m, or even more than 70 m. The lifting height on the crane rail track surface is also from about 30 m to more than 50 m. With the enlargement of the external dimensions of the quay crane, the windward area of the whole machine, the height of the wind and the wind moment have also increased a lot. Therefore, under non-working conditions (storms), the anchoring force that the anchoring device needs to resist becomes larger and larger. At present, most of the crane anchoring devices of quay cranes in the world still use the traditional insertion plate (pin) anchoring device, but the form of the crane anchoring device is restricted by the form of the pre-buried anchoring pit in the wharf.

1 The location and arrangement of the pre-embedded anchoring pit at the quay crane berth

The supporting crane anchoring device on the quay crane needs to be used in combination with the civil construction facilities (pre-embedded anchoring pit) on the wharf to play the role of windproof and anti-slip, so the two need to be matched with each other.
Usually, a quay crane is equipped with four anchoring pits at one berth, that is, a set of anchoring devices are set on the sea and landside tracks. 1 Anchor pit, see Figure 1.

single-track double anchoring pits

1, 2. Anchoring pit
Figure 1 Four anchoring pits for a quay crane berth (single-track double anchoring pits)
There are also some wharves, and two anchoring pits are arranged at the berth of each quay crane, that is, a set of anchoring devices are set on the sea and landside tracks. Each set of anchoring devices is perpendicular to the track line and on the sea side of the track. Or set up an anchor pit on the land side, see Figure 2.

anchoring pit

1. Anchor pit
Figure 2 Two anchoring pits for a quay crane berth (single track and single anchoring pit)
Three anchoring pits are arranged at a quay crane berth, and such a wharf also exists, that is, one anchoring pit is set for the seaside anchoring device, two anchoring pits are set for the landside anchoring device, or The number of anchor pits is reversed.

2 The shape and use of the embedded anchor pit in the wharf

It is more common for the pre-embedded anchoring pit of the wharf to be made into a rectangle, so the anchoring device is mostly equipped with anchoring inserts. There are also pre-embedded anchoring pits in the wharf that are made into circular or oval shapes, which account for a relatively small proportion. The insertion part of the anchoring device matching such pits is generally designed in the form of anchoring pins. From the comparison and analysis of the force situation and the field use, the anchoring device in the form of a plug is better than the anchor bolt form.

2.1 Analysis of stress situation

The force diagram and section of the anchor plate (pin) are shown in Figure 3.

The force diagram and section of the anchor plate (pin)

According to the calculation, under the same conditions, to bear the same amount of anchoring force, the floor space and mass required by the circular anchoring pin are about 1.3 times that of the rectangular anchoring insert. Considering that the footprint of the anchor pit is limited by the arrangement of the quay structure, the space available is sometimes limited. Therefore, in the same situation, the rectangular pit with a small footprint has certain advantages, and it is also advantageous for the structural arrangement of the anchoring device on the quay crane. At the same time, for most of the anchoring devices currently operated manually, the anchor plate (pin) is lighter in weight and easier to operate.

2.2 Actual usage of the terminal site

It is assumed that during the design, the same size gap is reserved between the anchor plate (pin) and the embedded anchor pit. When the actual position of the embedded anchor pit or anchor device and the theoretical position of the drawing is generated in two directions The amount of deviation of X (see Figure 4).

(a) Rectangular anchoring pit (b) Circular anchoring pit

Figure 4 Deviation between anchor plate (pin) and anchor pit

It can be seen from the comparison that under the same deviation, the rectangular anchor plate can still be inserted into the anchor hole smoothly, but the edge area of the circular anchor pin has interfered.

3 The depth of the pre-embedded anchoring pit in the wharf

Regarding the insertion depth of the anchor plate (pin), it is generally recommended to be no less than 140-150 mm, that is, the depth of the anchor pit buried in the wharf should not be less than 150 mm. In order for the anchor plate (pin) to be inserted into the dock anchor pit smoothly, a certain amount of clearance is reserved along the direction of the cart track in the design. The requirement for the insertion depth is to ensure that the anchor plate (pin) will not jump out of the anchor hole when it is stressed (the anchor plate (pin) under actual stress will have a certain inclination).

4. Stress analysis of anchoring device structure

The anchoring device is usually located directly below the lower beam on the sea and landside (some are located below the large balance beam of the cart traveling mechanism). The bollards and marine binding struts on the wharf are basically horizontal flanges as the connection form between the anchoring device and the quay crane structure. The force at the flange face of the anchoring device is shown in Figure 5.

(a) Structural form of single-track double anchor pit (b) Structural form of single-track single anchor pit (c) Structural flange surface (rotated 90°)

Figure 5 Schematic diagram of the structure of the anchoring device

Schematic diagram of the structure of the anchoring device

For the anchoring device with single track and double anchoring pits, the anchor plates (pins) on both sides are respectively subjected to force F /2 (the same direction), and the distances from the force point to the center of the flange surface are e and -e respectively, so A pair of equal and opposite torques are formed around the Z-axis in the flange plane, which eventually cancels each other out.

Under the condition that the structure, size, plate thickness, and force of the anchoring device are exactly the same, the anchoring device of the single-track single anchoring pit is better than the anchoring device of the single-track double anchoring pit, and the structure at the flange surface The stress has to bear one more torsional stress. If the structural stress value exceeds the specified allowable stress, the stress value must be reduced by increasing the plate thickness, increasing the structural section, etc. Generally, it is preferred to increase the structural section to reduce the stress value, but the size of the structural section is often limited by the overall arrangement space of the quay crane, and sometimes it cannot be made very large. Therefore, the single-track double-anchoring pit that can avoid torsional stress on the structure has more advantages than the single-track single-anchoring pit in terms of force, but the double-anchoring pit has one more than the single-anchoring pit. There are pros and cons to each factor.

5 Conclusion

1) For the location where the storm wind speed is small (non-working wind speed is 40 m/s and below), it is not a deep-water port, it is impossible to dock large ships, and the carrying capacity of the wharf is small (that is, the allowable wheel pressure is small), and small-scale ships are purchased in the planning. The pier of the bridge. Considering that the type of quay crane is small, the corresponding windward area of the whole machine is also small, and the wind speed is not large, so the actual maximum anchoring force of the monorail that needs to be resisted will not be very large. For this type of wharf, it is recommended to use the single-track single-anchoring pit form. The distance from the centerline of the anchoring pit (the direction of the sea and landside) to the center of the cart track should not be too large and can be controlled at about 500 mm.

2) For the location where the storm wind speed is high (non-working wind speed is 55 m/s and above), the deep-water port can berth large ships, and the wharf has a large carrying capacity (that is, the allowable wheel pressure is large), it is planned to purchase large, The wharf of the super-large quay crane. Considering that the type of quay crane is large, the corresponding windward area of the whole machine is also large, and if the wind speed is large, the actual maximum anchoring force of the monorail that needs to be resisted will be relatively large. For this type of wharf, it is recommended to adopt the form of single-track double anchoring pits. The anchoring pits should be rectangular pits, and the distance from the centerline of each side of the anchoring pits (sea and landside direction) to the center of the cart track should not be less than 500 mm.

3) From the point of view of not increasing the extra torque of the whole machine, the position of the anchoring pit is usually recommended to be arranged on the center line of the quay crane stand (that is, on the center line of the quay crane complete machine).