Steel column installation

1.Installation sequence of steel column:

① Foundation setting out → ② binding → ③ hoisting → ④ correction → ⑤ final fixation.

2.Steel column installation method:

(1) Setting out:

a. Elevation control:

In this project, according to the depth of the concrete cup mouth, the bottom elevation of the steel column, and the embedded elevation of the bottom of the cup mouth during the construction of the concrete foundation, the top elevation of the “middle reinforcement” is based on the bottom elevation of the steel column, and the elevation error of the iron parts is controlled within ± 1 mm.

In order to ensure that the steel column is accurately and firmly placed on the embedded φ 30 “middle reinforcement” in the foundation, a 20 thick steel plate is welded at the bottom of the H-shaped steel column, as shown in the following figure. 

During the installation of steel column, the cup mouth of the foundation shall be cleaned up first, and the embedded elevation in the foundation shall be checked to control the actual height of the “middle reinforcement” (φ 30 reinforcement). Since the elevation of the “middle reinforcement” has been accurately controlled during the foundation construction, no iron pad is needed.With this method, the treatment of steel column base is simple, fast and efficient.The construction is fast and the stress is reasonable. When the column is hoisted, the elevation can be adjusted freely in several directions.

b. Before installation, the longitudinal and transverse datum lines of foundation plane shall be placed on the top of cup mouth with woodworking ink fountain as the steel column installation positioning line.

(2) Column binding and hoisting

A. after the steel column enters the site, place the steel column according to the hoisting plan, and check whether the model and number are correct.The plane position of steel column after entering the site is shown in the figure below.

B. before the column is lifted, a horizontal line shall be drawn with red oil paint from the bottom of the column up to 2300mm, so as to review the plane elevation datum before and after installation and fixation.

C. the column installation belongs to vertical vertical hoisting. In order to keep the lifted column droop and facilitate its placement, the binding point is determined to be at the lower part of the corbel.In order to prevent the sharp edges and corners on the edge of the column and damage the lifting rope during hoisting, the rubber belt of the old car is used to separate the rope and cover it at the corner rope.Pay attention to binding firmly and easy to remove.

D. the temporary steel ladder and high strength bolt shall be bound on the steel column to install the fixture of working platform.

E. in order to avoid the free swing of the suspended column, the upper part of the column bottom should be tied with hemp rope, which can be used to tie down the sliding rope and adjust the direction.

F according to the site conditions, the rotating method is adopted for hoisting

After the preparation before hoisting is ready, the trial hoisting shall be carried out first. When the lifting height of steel column is 200 mm from the ground, the hoisting shall be stopped to check whether the rigging is firm and whether the crane is stable.After confirming that there is no problem, the crane can be slowly lifted, rotated to the top of the cup mouth, and then slowly lowered. When the distance between the bottom of the column and the design position is 40-100 mm, adjust the two datum lines of the column body and the foundation to reach the accurate position, command the crane to descend into position, and fix the column temporarily with steel wedge (or wood wedge) and wind rope, and remove the hook after reaching safety.

·Key points of rotation method: the method of hoisting the column around the base of the column by rotating the crane while lifting the hook is called rotation method, as shown in figure a below.In order to improve the hoisting efficiency when hoisting the column with the rotating method, when the steel column enters the site, the three points of the column binding point, the center of the column foot and the center of the cup foundation shall be on the arc with the crane stop point as the circle center and the distance from the stopping point to the binding point (i.e. the rotation radius of the hanging column) as the radius, as shown in Figure B below. 

The hoisting of steel column is shown in the following figure: 

(3) Preliminary correction of column: the side with large deviation shall be corrected first, and then the side with small deviation shall be corrected.

a. The correction of columns generally includes plane position, elevation and perpendicularity.

b. When the steel column is hoisted in place, it belongs to one-time alignment, which generally does not need to be corrected again.As for the elevation of the column, the elevation has been accurately controlled by the embedded “middle reinforcement” with diameter of 30 before hoisting, which generally only needs to be checked and no further correction is required.Therefore, the steel column correction is mainly to correct the perpendicularity and recheck the elevation.

c. In this project, the perpendicularity of the column is observed and calibrated by two theodolites.

·First of all, place the screws of the base line on the horizontal side of the column, and then fix the screws on the horizontal side of the column.

·Measure the center line of the column and observe it from bottom to top.If the longitudinal center line is aligned, that is, the column is vertical. If not, adjust the column until it is aligned with the longitudinal center wire of the theodolite.

·Measure the transverse line in the same way so that the center line of the other side of the column is perpendicular to the horizontal axis of the baseline.After the column is accurately positioned, the column can be fixed.

·Steel column perpendicularity correction: distance adjusting screw rod and steel wedge are used. As the contact surface of long side of column is small, cushion plate shall be set during construction. The details are as follows.

The manufacturing dimension of steel wedge is shown in the figure below

(4) Final correction and fixation of steel column:

After the steel column is hoisted in place, the column calibration mainly includes the elevation adjustment and verticality correction; the correction method can use the wind rope, Jack, crowbar and steel wedge (or wood wedge) and other tools to apply vertical and lateral forces of pulling, jacking, supporting and prying on the steel column.

Adjust the verticality of the column, positioning axis and elevation.After confirming that there is no error, the gap between the steel column and the foundation cup mouth shall be poured with C40 fine aggregate concrete.The expansive high strength grouting material is preferred.

Protection of field components

1）Members shall be unloaded carefully to prevent damage and collision and extrusion between components.

2）The components should be stacked neatly in the designated site, and the number of layers of steel beams should not be more than 3, so as to prevent the components from extrusion and deformation.

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

Placement of components and site requirements

1）When the component is unloaded, the component is directly unloaded near the installation position and is within the radius of rotation of the crane.The number shall be clearly marked with an obvious color pen to facilitate hoisting.

2）The components shall be placed in order in the site, and a certain gap shall be reserved between adjacent components for easy binding.

3）The site is required to be solid and level, not to pollute components due to rain and snow, and to be able to walk 30 tons of cars.

Steel structure installation

Preparation before hoisting steel column

Before hoisting the steel column, the cable wind rope shall be tied on the column body, the lifting point shall be selected at the bracket position, the double steel wire rope shall be set up at the upper and lower position, and the next work can be started after the snap ring is inspected as qualified.Before hoisting the steel column, the positioning axis, foundation axis and elevation, cup mouth size and cup bottom elevation must be inspected and handed over for acceptance, and the number, overall dimension, screw hole position and diameter of the steel column shall be comprehensively reviewed.After confirming that the requirements of the design drawings are met, the installation center line of the upper and lower ends of the steel column and the elevation line of the lower end of the column shall be drawn. 

Steel column hoisting

(1) steel column installation method

Before lifting the steel column, board shall be placed at the column base to prevent damage to the column base and other structures.

Special hoisting steel wire rope is used for steel column binding, and wood square or rubber is needed for binding to prevent damage to steel column.

The 25 ton truck crane is used for hoisting the steel column. When lifting the steel column, the crane should lift the hook and rotate the arm to make the steel column vertical off the ground.

(2) positioning adjustment and temporary fixation

When the steel column is lifted to 200 mm above the position of the foundation cup mouth, make it stable, align with the foundation cup mouth and slowly drop, and avoid bumping against the concrete edge of the foundation cup mouth during the falling process.After implementation, special angle ruler shall be used to check and adjust the steel column to make its positioning line coincide with the foundation positioning axis.During the adjustment, three people are required to operate, one to move the steel column, one to assist in stabilization, and the other to carry out detection.The positioning error should be controlled within 2mm. 

(3) when the steel column elevation is adjusted, the pad iron is placed at the bottom of the cup mouth foundation, and the elevation of the steel column bottom plate is used as the top elevation of the pad iron, so that the elevation of the steel column can meet the design elevation requirements after the steel column is in place. The elevation reference point is calibrated on the column body, and then the installation elevation after the installation is measured with the level.

(4) the steel column perpendicularity shall be adjusted preliminarily with a level ruler.Then, two theodolites are used to observe the two sides of the column at the same time, and the adjustment is made by means of the cable wind rope.As shown in the figure below:

Steel column verticality adjustment diagram 

(5) after the adjustment, use eight iron wedges to locate the gap between the bottom of the steel column and the cup mouth foundation, and then spot weld on the column body to make it stable.

Steel beam installation

The steel beams must be stacked neatly on site, and sleepers must be placed in the middle of each layer of steel beams. The two lifting points of steel beams should be selected on both sides of the center of gravity of the steel beams. The two lifting points should be 800 mm away from the support and the mid span, and the distance between the two lifting points should be appropriately increased according to the length of the steel beams.

To ensure safety and prevent the steel wire rope from being cut by the sharp edge of the steel beam, the steel wire rope shall be protected, and the angle of the sling shall not be less than 450. The steel beam shall be directly bound and rolled with steel wire rope or lifted with special fixture.

When lifting the two steel ropes on the beam, the two steel ropes must be hung on the two ends of the beam.To ensure safety, personnel should not stand directly under the beam.A cloth bag for placing high-strength bolts is provided at both ends of the steel beam. When the steel beam is hoisted above the position, the steel beam is put in place. The falling speed of the steel beam is controlled at 3 M / min. two installers are arranged at both ends of the column head to prepare for the installation of the steel beam.When the steel beam is close to the position in place, two installation workers should hold the upper flange of the steel beam with their hands respectively, and drag the steel beam to the position, ready to install high-strength bolts.

Installation of enclosure structure and support corner brace

1）Roof purlin installation: when the main structure forms a frame section, the roof purlin is lifted to the roof main beam by crane for manual scattered installation, or the purlin can be manually pulled onto the roof for installation with white comprehensive rope. After the installation of purlin, the purlin support shall be installed in time.

2）Wall purlin installation: when the main structure forms a frame section, the construction personnel stand on the scaffold platform and pull the wall purlin to the installation position with white comprehensive rope.

3）Corner brace installation: after the main body is welded, the corner brace is connected.

Measurement and correction of steel column

1）Steel column verticality correction

When the steel column is installed and calibrated, two theodolites are set up on the control line which is 90 degrees of each other, and the theodolite operator shall observe the small steel ruler on the top of the column, measure the steel column deviation and direct the correction.

A. control the verticality of steel columns between the first lifting sections.

The calibration of steel column B is divided into four steps: initial calibration during initial tightening, rechecking before final tightening, tracking monitoring during welding and final result measurement after welding.

Before initial screwing, the verticality can be roughly controlled with a long level ruler, and then the accurate correction can be carried out after the frame is formed.After welding, retest shall be carried out and compared with the measurement results during final tightening, so as to serve as the basis for the next construction.

Verticality measurement method of C steel column

Initial correction: the steel column perpendicularity is preliminarily adjusted with a level ruler.

Steel column perpendicularity accurate correction: the main frame hoisting takes a column net as an installation section, and waits for three consecutive complete sections to be hoisted

After forming a whole, the measurement correction can be inserted.Two theodolites are used to observe the two sides of the column at the same time, and the wind rope is used for correction and adjustment.

2、 Steel structure survey

2）Steel column elevation control

Based on the elevation datum point of the plane layer where the steel column is located, the horizontal elevation deviation value of the steel column is measured with a level gauge, and the correction is directed.

3）Steel beam measurement:

After the steel column is hoisted and calibrated, the + 1.00m control point is introduced to each steel column according to the site benchmark as the basis for the vertical transfer of elevation and the beam installation elevation; the center line of the steel beam is popped on the surface of the steel beam.

The displacement of beam position is controlled by measuring the control axis to the column body, and the accuracy of beam elevation is controlled according to the control point of column elevation.The theodolite is erected on the floor platform, and the rear cross angle is to the axis of the corresponding beam, and the theodolite is used to aim at the center line of the upper surface of the beam to the other end to see whether the number coincides with the beam axis. 

Calculation of Surveying and setting out data

In this project, the calculation of Surveying and setting out data adopts the method of computer automatic inquiry.The specific steps are as follows:

1）Establishment of data model

First of all, according to the design coordinates of buildings in the design drawings and the size relationship between them, the buildings, building axes, control lines to be lofted are drawn in proportion in AutoCAD, and the data model is established.

2）Inquiry of Surveying and setting out data

After the completion of Surveying and lofting data model drawing, AutoCAD dist and other commands are used to query the angle and distance between known basis (axis control pile, lofted axis, etc.) and the required lofting control line.

3）Advantages of computer automatic query

It is not only convenient to calculate, but also has high precision. According to the actual situation, the distance accuracy can be set to 0.1 mm, 0.01 mm, and the angle accuracy can be set to 0.0 “, 0.00″ or higher accuracy.

3、 Construction of high strength bolt

1.Preparation before installation

1）Test and inspection of high strength bolt

Anti slip coefficient test

In this project, 10.9 grade large hexagon high strength bolts are used. The anti sliding coefficient test of high-strength bolts should take the plate with the most representative thickness in the project for three groups.

The size of the specimen plate is shown in the following figure:

Axial force test

Randomly select 8 sets of bolt pairs from each batch of bolts to be installed on the construction site for re inspection.

2）Transportation and storage of high strength bolts

transport

High strength bolt connection pairs shall be manufactured and supplied by the manufacturer according to batches, with factory certificate. The form, size and technical conditions of high-strength bolt connection pairs shall comply with the provisions of national standards gb1228-1231-84 and gb3632-3633-83.Large hexagon high strength bolts for steel structures

The connection pair consists of a bolt, a nut and two washers.The use combination shall conform to the national standard, and the high strength bolt connection pairs shall be provided in the same batch.

During loading, unloading, transportation and storage, the high-strength bolt connection pair should be loaded and handled with care to prevent damage to the packing box and bolt damage.

Storage of high strength bolts in warehouse

1.The high-strength bolt connection pairs shall be cleaned and stored according to the specification, batch number, number and supply date of the packing box, and shall be stored in the indoor warehouse, and the accumulation shall not be higher than 3 layers. The indoor moisture-proof shall be kept dry for a long time to prevent rust and dirt contamination, and to prevent the torque coefficient from changing.The bottom layer shall be at least 300 mm above the ground.

2.During site installation, the quantity of high strength bolts required on that day shall be issued.The rest should be kept properly.It is not allowed to leave it disorderly, damage the thread and be contaminated by dirt.

3.The long-term storage of high-strength bolt connection pairs should be subject to comprehensive quality inspection again before use. If any abnormal phenomenon is found after unpacking, the inspection should be carried out according to the relevant provisions of national standards gb1228 ~ 1231-84 and gb3632 ~ 3633-83.It can be used after passing the identification.

3）Construction management of high strength bolt

1.Construction Manager

In the construction of this high-strength bolt, the manager of high-strength bolt shall be determined first to take charge of project management, quality management and construction guidance.

2.Weather management (climatic conditions)

In principle, the operation shall not be carried out in case of rainfall and snowfall. In case of rainfall and snowfall during the operation, it is necessary to speed up the locking of the unfinished part

3.Friction surface management

Before tightening operation, the friction surface shall be inspected first. If there are floating rust, oil, paint, residue and other attachments that reduce the bearing capacity of the friction surface, metal brush, sandpaper and oxygen acetylene flame shall be used to remove them.

4）Construction of high strength bolt

1.Final tightening of temporary bolts

Before inserting high-strength bolts, in order to make the connection tight, the temporary bolts should be used for fastening. If there is bending and warping of the material at the connection part, it needs to be corrected.

When the hole difference is less than 2mm, the cutter can be used to correct.

If the hole difference is more than 2mm, reasonable treatment methods such as panel replacement shall be adopted on the basis of consultation with management personnel, and gas cutting is not allowed for hole enlargement.

2.High strength bolt insertion

Pay attention to the installation direction of nuts and gaskets of high strength bolts, and install them according to the following figure.

When inserting the bolt, be careful not to attach rust, dust, oil, etc. on the bolt.In addition, do not force into the bolt hole during construction, so as to avoid damaging the thread.

3.Initial tightening

After locking the temporary fixing bolts, confirm the compactness of the components.

After the initial tightening, mark the bolts, nuts, gaskets and components with white marking pen

When using the inspection wrench, although the torque value can be confirmed by the contact sound, it is easy to over tighten if the force is continuously applied on the mechanism. Pay attention to this.

4）Final tightening

After the initial tightening, use a special tightening wrench to lock until the necking is broken.

In principle, the bolts inserted on the same day shall be screwed at the end of the day.

In principle, the final tightening is from the center to the end of the joint