Conventional installation method of the most popul

2022-08-23
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Conventional installation method of gantry crane

40t/40m gantry crane is a truss gantry crane manufactured by Kunming metallurgical machinery factory. The whole machine has a mass of 87.6t, a span of 40m, a lifting capacity of 40t, a maximum height of 20m and a maximum lifting height of 14.6m. The main beam is composed of 6 trusses (see Figure 1), with a total length of 52.67m and a total weight of 40668kg. According to the structural composition of the gantry crane, the main beam needs to be hoisted as a whole, which is the largest component and key factor in the gantry crane installation project. It is mainly composed of the following parts:

gantry cranes are generally installed from bottom to top. First, the traveling trolley and the lower beam are installed on the track, and then the flexible legs and rigid legs are installed on both sides respectively, and the legs are stabilized with temporary cables. The truss girder needs to be assembled on site first. The crane walking track can be used as the horizontal benchmark to place the assembled girder horizontally on the track. When assembling the main beam, attention should be paid to maintaining the camber of its midspan to compensate for the sinking deflection caused by its own weight. The conventional installation method of the main beam is to use other lifting equipment to lift the main beam horizontally in place by single machine lifting or double machine lifting. The center of gravity position of the main beam must be accurately calculated before hoisting, and then the lifting point position and load of the auxiliary crane must be determined accordingly. When lifting with two cranes, the load shall be reasonably distributed according to the lifting performance of the auxiliary crane, and the lifting load of each auxiliary crane shall not exceed 80% of its allowable load. According to the main beam of the 40t/40m gantry crane, two 50t truck cranes or crawler cranes are selected for lifting, which can meet the lifting requirements. When using a single crane, you need to choose a crane with a lifting capacity of 100t, which is large tonnage and uneconomical

the weight of the main beam is large. Generally, the lifting mechanism, lifting trolley, cab and other components are installed after the installation of the main beam

Figure 1 main beam diagram of 40t/40m gantry crane

2 main beam split lifting installation method

when the configuration of auxiliary cranes on the construction site is not large enough, the main beam split inclined lifting can be used for installation. This method is rare in installation engineering, the method is novel, the selection requirements of auxiliary cranes are low, and it is more economical

Figure 2 lifting diagram of main beam at rigid leg end

40t/40m gantry crane main beam is lifted separately. The installation method is as follows: first assemble the main beam on the ground. Because it needs to be lifted on one side, the cantilever section on the flexible leg side of the main beam will not be installed temporarily. At this time, the length of the main beam is 44.526m, and the total weight of five sections is 42.792t. Use an auxiliary crane to lift the main beam at the C end of the rigid leg with the flexible leg a end of the main beam as the fulcrum, and then use another small auxiliary crane or chain block to move the assembled rigid leg under the main beam, so that the rigid leg is connected with the main beam in an inclined state (see Figure 2a); Then the auxiliary crane lifts the flexible leg end of the main beam, and use another small crane or chain block to move the assembled flexible leg under the main beam for connection and installation; Finally, install the cantilever section of the main beam and other parts

in order to ensure that the main beam can be accurately connected with the rigid leg supported on the track on one side after lifting on one side, it is necessary to calculate the position of the main beam on the track in advance. According to the relevant dimensions shown in Figure 2, oa=43.10m can be calculated. When the main beam is placed horizontally on the track before lifting, the end point of its rigid leg side should exceed the track by 44 1=1.426m (see Figure 2b)

auxiliary is the key to the development of information technology to knowledge economy technology. The lifting load F of the crane can also be calculated from the relevant parameters shown in Figure 2A. When the main beam is horizontal, this scheme needs to lead 1 branch from the working cylinder or drill the cylinder to install the oil pressure sensor, fmax=212.9kn; When the main beam is connected with the rigid leg, fmin=206.1 kn

Figure 3 hoisting diagram of flexible leg end main beam

hoisting diagram of flexible leg end of main beam is shown in Figure 3. After calculation, when the inclination a of the main beam changes from 21.86 ° -0 °, the lifting force changes from 235 6kn change

from the above analysis, it can be concluded that one auxiliary crane with a lifting capacity of 50t can be selected for the installation of the main beam

3 technical and economic comparison

(1) for the conventional main beam hoisting method, the maximum load of the auxiliary crane is the weight of the main beam, up to 42.79t, and at least 100t crane is required; With the split hoisting method, the load of the auxiliary crane is greatly reduced, and the maximum lifting load is only 23.5t. It is enough to configure a 50t crane, which can meet the needs on the general site and effectively reduce the installation cost

(2) the conventional main beam hoisting method requires both rigid and flexible outriggers to be installed before hoisting the main beam. Both outriggers must pull the cable wind rope, which is not conducive to on-site operation; With the split hoisting method, it only needs to pull up the cable wind rope of the other leg, which has lower requirements on the installation site and is more convenient for operation, and after the rigid leg is connected with the main beam, it forms a stable state, which is easier to ensure safety

(3) in the conventional main beam hoisting method, both legs must be equipped with installation personnel at the same time, there are many high-altitude workers, and plastic building materials must be the fourth category of new foundation materials after steel, wood and cement, so as to increase safety risks; With the split lifting method, the two legs can be combined and installed in several times, which reduces the requirements on the site, and can also be installed in a relatively narrow site. At the same time, it reduces the time of continuous operation and reduces the safety risk

(4) compared with the conventional hoisting method, although the rigid leg and the main beam are in an inclined state for a long time, the installation process is complex and difficult, and the paper products have the function of "shockproof", because only one auxiliary crane with a lifting capacity of 50t is required, as long as corresponding measures are taken in the installation process, this method is still feasible

(5) the control focus of the split lifting method of the main beam is lifting on one side of the rigid leg, mainly because the main beam must be placed accurately when it is assembled on the ground, so as to ensure that the main beam can be lifted in place with the rigid leg accurately

through the analysis and calculation of the installation method of the main beam of the 40t/40m gantry crane, it can also be applied to the installation of other box and truss gantry cranes, and the economic and safe installation scheme can be selected according to the opportunity and situation on site

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