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Site protection of steel structure installation

Jun 28, 2018

Protection of site components

1) the components should be unloaded carefully to prevent damage, and to prevent the components from colliding with each other and squeezing each other.

2) the members should be stacked neatly in the designated site, and the steel beams should not be stacked in more than 3 layers to prevent the members from squeezing and deforming each other.

3) the oil, sediment and dust on the surface of the components should be cleaned up before hoisting.

1.1.2 placement of components and requirements for the site

1) when the component is unloaded, the component is unloaded directly near the installation position and within the turning radius of the crane. The numbering is clearly marked with a clear color pen to facilitate hoisting.

2) the components are arranged neatly in the field, and some gaps are reserved between adjacent components, which is convenient for binding.

3) the site should be solid, smooth, not polluted by rain and snow, and be able to walk 30 tons of cars.

Steel structure installation

1.2.1 installation of main structure

1.2.1.1 installation process

1.2.1.2 preparation of steel columns before hoisting

Before the steel column is hoisted, the cable and wind rope are fastened in the column body first, the lifting point is chosen in the position of the corbel, the upper and lower position of the double wire rope is set up, and the check of the clip ring is passed before entering the next step. Before the steel column is hoisted, it is necessary to check and accept the position axis, base axis and elevation, cup size and cup bottom elevation of the steel column, and to carry out a comprehensive review of the steel column number, shape size, screw hole position and diameter, etc. After confirming compliance with the design drawings, draw the installation centerline at the upper and lower ends of the column and the elevation line at the lower end of the column

1.2.1.3 lifting of steel columns

A steel column installation method

Before lifting the steel column, a good board is fixed at the foot of the column to prevent damage to the foot of the column and other structures. Steel column binding uses special hoisting wire rope, the binding needs to cushion wood or rubber to prevent damage to the steel column. The steel column installation uses 25 ton automobile crane to carry on the hoisting, when the steel column hoisting, the crane should take the hook while, the side turns the arm, causes the steel column to leave the ground perpendicularly.

B position adjustment and temporary fixation

When the steel column is suspended to the top of the base cup, the 200mm is stabilized, and the base cup falls slowly, and the concrete edge of the base cup is avoided in the process of falling. After implementation, special angle ruler is used to check and adjust the steel column to make its positioning line coincide with the base positioning axis. The adjustment requires three people to operate, one person to move the steel column, one person to assist in stability, the other to carry out the test. The position error is controlled within 2mm.Steel column installation process.jpg

C when the steel column height is adjusted, it is necessary to place the cushion iron at the bottom of the cup mouth foundation, and use the level instrument to find out the height of the steel column bottom plate as the top surface elevation of the steel column, so that the steel column elevation meets the design elevation requirement after the steel column is in place, and the reference point of elevation is calibrated in the column body. Then the installation elevation after installation is measured by the level.

D the vertical degree of steel column is adjusted preliminarily with horizontal ruler. Then two theodolite from the two sides of the column at the same time, depending on cable wind rope adjustment.

E After adjustment, use eight iron wedges around the bottom of the steel column and the gap in the base of the cup mouth, and then spot weld the post to make it stable.

1.2.1.4 installation of steel beams

The steel beam must be neatly laid on the spot, and the middle of each layer must be cushioned with sleepers. Two hoisting points of the steel beam should be selected on both sides of the center of gravity of the steel beam, and the two lifting points should be located outside the support and the 800mm in the middle of the span. And according to the length of the steel beam to increase the distance between the two suspension points. To ensure safety, prevent steel beam sharp edge cut wire rope, to protect the wire rope, sling angle is not less than 450, steel beam is directly tied by wire rope or used special jig for lifting. Before the steel beam is hoisted, safety rope is installed on the steel beam. When lifting the steel beam, two sliding ropes are hung at the two ends of the steel beam, and the two people pull the two rope respectively. The lifting speed of the steel beam must be slow at the beginning of the hoisting. In order to ensure safety, personnel should not stand directly below the beam. When the steel beam is suspended above the position, the steel beam will begin to be in position. The falling speed of the steel beam will be controlled at 3 meters per minute, and two installers will be arranged at each end of the column at the end of the column. Ready to install steel beam. When the steel beam is near the position, the two installers shall hold the upper flange of the steel beam with their hands, and drag the steel beam to the position to prepare the installation of high strength bolts.

1.2.2 Enclosure and bracing installation

A Roof purlin installation: when the main structure forms a frame section, the roof purlin can be hoisted to the main beam of the roof with a crane and spread out artificially, or the purlin can be manually pulled up to the roof with a white rope for installation. Purlin installation completed timely purlin support installation.

B Wall purlin installation: when the main structure forms a frame section, the constructor stands on the scaffolding platform and pulls the wall purlin to the installation position with the white Headlock rope.。

C Corner installation: after the main body welding is completed, the corner bracing connection is carried out.

2.1 Steel column measurement and correction

1) Verticality Correction of Steel column

When the steel column is installed and corrected, two theodolites are set up on the control line of 90 degrees and the same direction is looked back. The theodolite operator observes the small steel ruler on the top of the column, measures the deviation of the steel column and directs the correction.

A to control the perpendicularity of the steel columns of the first hoisting Internode.

B The correction of B steel column is divided into four steps: initial screw correction; final realignment; tracking and monitoring during welding process; and measurement of final results after welding. The vertical degree can be roughly controlled by a long horizontal ruler before the initial twist, and the precision correction can be carried out after the frame is formed. After welding, it should be re-tested, and compared with the measurement results when the final twist, as the basis for the next step of construction.

C method for measuring the perpendicularity of steel columns

Initial correction: the vertical degree of steel column is preliminarily adjusted with horizontal ruler.

Steel column verticality accurate correction: the main frame hoisting with a cylindrical mesh as one installation Internode, to be continuously completed three complete Internode hoisting

After forming the whole, the measurement correction can be inserted: Simultaneous observation of two sides of the column with two theodolites, correction and adjustment using wind-collecting rope

2.Steel structure measurement

Steel structure measurement.jpg

1) steel column elevation control

Based on the reference point of the plane layer elevation of the steel column, the deviation value of the horizontal elevation of the steel column is measured with the level, and the correction is directed.

2) steel beam measurement

After the erection and correction of the steel column, the control points of + 1.00m + 1.00m are used as the basis for the vertical transfer of the elevation and the installation of the beam, and the center line of the steel beam is ejected on the surface of the steel beam. The control axis is dropped to the column body to control the deviation of the beam position, and the accuracy of the beam elevation is controlled according to the height control point of the column body. The theodolite is set up on the floor platform, and the angle of cross turns back to the axis of the corresponding beam. The theodolite is used to aim at the center line of the upper surface of the beam to the other end, to see if the number coincides with the axis of the beam.

2.2 calculation of measured lofting data

In this project, the computer automatic query method is used to calculate the measuring and lofting data. The specific steps are as follows:

1) Establishment of data model:Firstly, according to the design coordinates of the buildings in the design drawings and the relationship between the dimensions of each building, the building axis, the control line to be lofting are drawn in AutoCAD, and the data model is established.

2) query of measuring lofting data

After drawing the model of measuring and lofting data, the angle and distance between the known basis (axis control pile, lofting axis, etc.) and the control line need to be set out are obtained by using the commands of AutoCAD Dist and so on.

3) the advantage of computer automatic query

It is not only convenient to calculate, but also with high precision to obtain the needed measurement and positioning data by the method of computer automatic query. The distance precision can be set to 0.1mm, 0.01mm and angle precision to 0.0 ", 0.00" or higher precision according to the actual situation.