The project is located in the Thar coal mine area of Pakistan, where the local environment is harsh. The total weight of the steel structure of the main warehouse is about 9000 tons, with 4917 components and the largest single component weighing 27.3 tons. The steel structure has the advantages of high strength, good material, stable quality, high degree of industrialization, fast construction speed, ease of assembly and disassembly, expansion, and so on. This kind of structure is widely used in structures with large spans and heavy loads. It is often widely used in the main workshop, large sports venues, high-voltage substations, bridges, supermarkets, and other large places. Secondly, Chinese construction steel types are various, the price is stable, and the output is the most in the world. With the continuous development of science and technology, a large number of new technologies related to steel structures appear, thus promoting the extensive application of steel structures, which also creates a good condition for expanding its development prospects.
When hoisting a steel structure coal yard warehouse, it is necessary to make sufficient preparation before construction, mainly to prepare construction technology, site environment, and equipment, and coordinate the relationship between it and nearby buildings.
First of all, familiar with the steel structure construction drawings of the main coal storage warehouse, obtain the steel structure installation drawings and processing details; Secondly, check steel components and all spare parts, including high-strength bolts, joint plates, etc. against steel structure installation drawing, processing detail drawing and packing list; Thirdly, I organized site managers and team leaders to make technical disclosure, and got familiar with construction sequence, process, and quality standards. Finally, the construction of floor slab, stud welding, secondary grouting, steel space frame plate installation, anti-corrosion coating, and other procedures of operation instructions.
The first step is to check the crane route’s road condition and the components’ place condition before hoisting. Lay the track plate on the crane route. The second step is to prepare the relevant data of civil construction and carry out the acceptance of foundation and anchor bolts. The acceptance scope is as follows: the center line of each foundation shall be popped out with ink lines, the distance between foundations, the diagonal dimension deviation, and the exact retest of the dimension deviation of each axis. The size deviation should be strictly controlled within the range of ±3mm. The third step is to clean the foundation after acceptance and to chisel the surface. When chiseling the surface, it is necessary to punch out the pockmarked surface. The acceptance range of the foundation surface is: the depth and width of the shear groove, to avoid the steel column can not be lowered. The fourth step, remove the debris on the component surface before hoisting; The protective film on the surface of the anchor bolts should be cleaned, and 4 leveling nuts should be installed on each pillar foot. The leveling nuts should be distributed in a dispersed manner, and the design elevation of the pillar bottom plate should be uniformly adjusted. Fifth, the hoisting of the second and third layers of steel structure should be carried out after grouting at the foot of the column, otherwise, it must be laid at the foot of the column flat cushion iron and wedge cushion iron, cushion iron set along the four sides of the foot of the column, no less than 4 groups. The composite length of the cushion iron should not be less than 100mm, and the cushion iron should be exposed 10 ~ 20mm outside the bottom of the column.
First, the stacking requirements of steel structure: the stacking site has been leveled, and a large number of steel structure materials can be stacked. The components should be classified and stacked according to the hoisting sequence. In the process of component stacking, each layer should be separated by the road, and the corresponding height also needs to be within a reasonable range. General and minor components shall not be higher than 1.5m in three layers, and large components are generally single layers when they are on each other. And set a certain distance between each pile component, about 1.5 ~ 2m, and set a certain unloading space. In addition, it is necessary to divide the area of the storage yard and record the corresponding component area code accurately. Timely record of incorrect delivery numbers and quantity. Second, the requirements of the steel structure transfer process: according to the component inspection quality standards, check and record item by item, notify the technical department of unqualified products, and do a good job of identification. During loading, unloading, and transportation, the problem of damaging components shall not occur. The components of the reverse transport need to be processed based on the relevant standards and specifications, and the reverse transport needs to be stacked should be cushion wood, a strict binding treatment, to avoid loosening in transit. Columns and beams are placed in the same lifting position to support subsequent operations. In the process of loading and unloading and lifting, steel pipe Angle (inner rubber) should be used to prevent damage to paint and wire rope.
First of all, the column lifting work: before the column lifting, the ladder, a self-locking device supporting safety rope, foot, and hand hoop, cable wind, connecting plate, etc. should be set correctly, and the direction indicated on the column should be checked. 1m elevation line, center line identification, etc. should be marked clearly with red paint, and 200mm high wooden parallel to the column when lifting. The direction pad is placed at the bottom of the column, and the crawler crane is directly lifted into place. If the connecting plate is set at the bottom of each layer of columns, it needs to be applied to the 50t crane during hoisting to avoid problems related to the bending and deformation of the connecting plate. After lifting, observe the stability and binding fastness of the crane. When any danger is found, stop immediately and start lifting again. When the bottom column is in place, the center line of the column must be aligned with the positioning axis of the foundation, and the 1-meter elevation line must be checked. After the column is in place, tighten the anchor bolts and nuts, and pull the cable with a loose hook. Secondly, in the process of steel column correction, the corresponding work mainly includes the adjustment of column elevation, column axis and column perpendicularity.
Measurement plays a direct role in determining installation quality.
① Elevation control: the elevation of the steel column is mainly adjusted by the nut at the bottom of the column. Before hoisting, the leveling nut should be installed according to the requirements, and the distance between the actual elevation and the design elevation should be adjusted. In the hoisting process of the column, the elevation is corrected by the level. In the case of obvious deviation, it is necessary to lift the column again and adjust the nut height again.
(2) column base axis position adjustment: when the steel structure column bottom and foundation axis do not coincide, it is necessary to loosen the anchor bolt, appropriate toggle, or knock to control the plane displacement of the column bottom to meet the requirements.
The column body perpendicularity correction: this correction process is mainly to adjust the vertical and horizontal perpendicularity deviation, through the two maintain the vertical theodolite to find the vertical. In the correction process, the jack and crowbar are used for fine-tuning, and the bottom column plate is adjusted to lower the flat nut while fine-tuning. When the perpendicularity meets the requirements, insert the cushion iron under the steel column and tighten the column nut for fixing.
The hoisting sequence of the main and secondary beams is to first lift the transverse main beam, then the longitudinal main beam, and finally the secondary beam. The beam lifting adopts two-point binding lifting, and the connecting plate and the joint of the beam before lifting are installed correctly. Feet and hands tied, horizontal safety rope set. The steel beam is lashed with soft ropes or lashing belts. The lashing points are shown in the figure below. The Angle of the rope should be 60 degrees.
Second, after lifting, pour the beam into place between the two columns. If it is not easy to pour into place, one of the columns can be slightly pulled apart by the cable wind to increase the distance between the columns.
Third, when the beam is in place, it is first positioned by punching nails, and then temporary bolts are installed. After steel beam hoisting, install bolts in time and keep the direction of bolt perforation consistent. The initial and final screwing of high-strength bolts meets the specification requirements.
If it is found that the independent hoisting of inter-column supports does not meet the requirements during the hoisting operation, the combination of inter-column supports and beams should be carried out on the ground first, and then installed. After the column support and beam assembly lifting, using a two-point lifting hook, can set the gourd (gourd selection can bear the combined weight as the premise), so as to adjust, adjust the slope after lifting to ensure that the corresponding installation Angle to meet the requirements. During the hoisting process of the inter-column beam, the number of temporary bolts should be properly controlled, not less than one-third of the number of bolt holes. And through the initial tightening wrench tightening treatment, some cases need to be controlled by 1t hoist. When the single-column inner strut and inter-column beam are hoisted together, one end shall be filled with temporary bolts. The other end in the distance from the bottom 1/4 of the hanging wire rope and hoist, and the beam between the column after tightening together hoisting.
Before hoisting the crane beam, mark the positioning axis on the bull leg surface, and remeasure the elevation of the bull leg surface. If it is excessive, it is necessary to set the appropriate gasket during the beam hoisting. The crane beam needs to be fully fixed after hoisting. The crane beam shall be arranged close to the installation place, and the center of gravity of the control beam shall coincide with the installation center properly. The mode of installation from one end to the other or from two ends to the middle can be selected. When the beam is lifted to 20cm away from the support surface, the corresponding beam is controlled to align with the center line of the support surface by manpower straightening, and then falling under the condition of low speed. If there is any deviation, lift it slightly and put it down after proper correction. The uneven support is treated by the gasket. The main correction items are center line, axis spacing, perpendicularity, etc.
In this process, the main is to correct the lateral displacement. Crane beam elevation correction, in the process of this operation, is mainly to install a level on a crane beam in the middle, measure the corresponding level point on the column, and then through the sample rod to measure the water level to the beam surface auxiliary rail height. Calibrate each beam according to the measured elevation. When correcting, it is pried up by a crowbar, and at the same time, the crane beam is lifted by hanging an inverted chain to pad the plate side, and then the subsequent operation is carried out. When correcting the elevation, the verticality is measured at both ends of the crane beam by the ruler. When it is found that the deviation is obvious, the wedge steel plate is properly corrected. The crane beam is usually moved horizontally by a prying rod and chain backing. In the process of correcting the span of the crane, the corresponding operations are as follows: First, the corresponding track axis is released on the ground at both ends of the hoisting track based on the column axis, and then the distance between the two axes is measured with a steel ruler, and then the line setting and hanging hammer of the theodolite are used to correct. In the case of obvious deviation found in the detection, the crowbar can be straightened, or the bolt can be used for lateral top straightening, or the lever can be selected to lift the corresponding crane beam, and the proper straightening can be carried out with the crowbar. After the correction of the crane beam, the fasteners of the crane beam and column leg should be fixed. Generally, the welding method is selected.