Steel column installation
- Installation sequence of steel column:
① Foundation setting out → ② binding → ③ hoisting → ④ correction → ⑤ final fixing. - Installation method of steel column:
(1) Setting out:
a. Elevation control:
In this project, according to the depth of concrete cup mouth, the elevation of steel column bottom, and the elevation control iron pieces and “center bars” are embedded in the middle of the cup mouth bottom during the construction of concrete foundation（ φ 30 reinforcement), the top elevation of “middle reinforcement” is based on the bottom elevation of steel column, and the elevation error of iron parts is controlled within ± 1mm.
To ensure that the steel column is accurately and firmly embedded in the foundation φ On the 30 “middle reinforcement”, a 20 thick steel plate is welded at the bottom of the H-shaped steel column.
When installing the steel column, clean the foundation cup and check the embedded elevation control “middle reinforcement” in the foundation（ φ 30) the actual height of the steel bar. Since the elevation of the embedded “middle reinforcement” during the foundation construction has been accurately controlled, it is not necessary to add a sizing block. This method makes the treatment of steel column base simple, fast and efficient. The construction is fast and the stress is reasonable. When the column is hoisted, it can be freely adjusted in several directions with the same elevation.
b. Before installation, use a carpenter’s ink bucket to place the vertical and horizontal axis datum lines of the foundation plane on the top of the cup mouth as the installation positioning line of the steel column.
(2) Column binding and hoisting
A after the steel column enters the site, place the steel column according to the position of the hoisting plan, and check whether the model and number are correct. See the following figure for the plane position of steel column after mobilization.
Ten installation points of frame steel structure
B before lifting the column, a horizontal line shall be drawn with red oil paint from 2300mm upward from the column bottom, so that it can be used as the datum for rechecking the plane elevation before and after installation and fixation.
C the column installation belongs to vertical hoisting. In order to keep the lifted column drooping and convenient for positioning, the binding point is determined to be at the lower part of the bracket. In order to prevent sharp edges and corners at the edge of the column from damaging the lifting rope during hoisting, the rubber belt of the old car shall be used to separate it and be sleeved at the edges and corners of the lifting rope. Note that the binding is firm and easy to remove.
D. the steel column shall be bound with temporary steel ladder and fixture for high-strength bolt installation platform.
E in order to avoid the free swing of the lifted column, the hemp rope shall be tied at the upper part of the column bottom as a restraining slip rope to adjust the direction.
F rotation method shall be adopted for hoisting according to site conditions:
After the preparations before hoisting are completed, the trial hoisting shall be carried out first. When the steel column is lifted 200mm above the ground, the hoisting shall be stopped to check whether the rigging is firm and whether the crane is stable. After it is confirmed that there is no problem, the crane can be commanded to slowly lift, rotate to the top of the cup mouth, and then slowly lower. When the column bottom is 40 ~ 100mm away from the design position, adjust the two datum lines of the column body and foundation to reach the accurate position, command the crane to lower in place, and temporarily fix the column with steel wedge (or wood wedge) and wind rope. The hook can be removed only after it is safe.
·Key points of rotation method: the method that the crane rotates while lifting the hook to make the column rotate around the column base and lift the column is called rotation method, as shown in figure a below. In order to improve the hoisting efficiency when hoisting the column with the rotation method, when the steel column enters the site, the three points of the column binding point, the column base center and the cup-shaped Foundation Center shall be on the arc with the crane stop point as the center and the distance from the stop point to the binding point (i.e. the turning radius of the hoisting column) as the radius (hereinafter referred to as three points and one arc), as shown in Figure B.
(3) Preliminary correction of column: the side with large deviation shall be corrected before the side with small deviation.
a. The column calibration generally includes plane position, elevation and perpendicularity.
b. When the steel column is hoisted in place, it belongs to one-time alignment, and it generally does not need to be recalibrated on the plane. For the elevation of the column, it has been used before hoisting φ 30. The embedded “middle reinforcement” accurately controls the elevation. Generally, it only needs to be checked and no further correction is required. Therefore, the steel column correction is mainly to correct the verticality and recheck the elevation.
c. The column correction shall be carried out simultaneously with measuring tools. In this project, the verticality of the column shall be observed, and two theodolites shall be used for measurement and correction.
·First, place the theodolite on one side of the column to align the longitudinal center wire with the baseline of the column base, and then fix the screws of the horizontal plate.
·Measure the center line of the column from bottom to top. If the longitudinal center line is aligned, that is, the column is vertical. If not, adjust the column until the longitudinal center wire of the theodolite is aligned.
·Measure the horizontal 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.
·Verticality correction of steel column: the distance adjusting screw rod and steel wedge are used. Since the contact surface of the long side of the column is small, the base plate is set during construction. The details are as follows.
(4) Final correction and fixing of steel column:
After the steel column is hoisted in place, the column correction work is mainly to adjust the elevation and verticality; The correction method can use tools such as wind rope, Jack, crowbar and steel wedge (or wood wedge) to apply vertical and lateral forces of pulling, jacking, bracing and prying to the steel column.
Adjust the verticality, positioning axis and elevation of the column. After confirmation, the gap between the steel column and the foundation cup shall be poured with C40 fine aggregate concrete. Expansion high-strength grouting materials are preferred.
Protection of site components
1) Members shall be unloaded carefully to prevent damage and mutual collision and extrusion between members.
2) The members shall be stacked neatly at the designated site, and the number of layers of steel beams shall not exceed 3, so as to prevent members from squeezing and deforming each other.
3) Before hoisting, the oil stain, sediment and dust on the component surface shall be cleaned.
Component placement and site requirements
1) When unloading the components, the components shall be directly unloaded near the installation position and within the turning radius of the crane. The number shall be clearly marked with an obvious color pen to facilitate hoisting.
2) The members shall be placed neatly in the site, and a certain gap shall be reserved between adjacent members to facilitate binding.
3) The site is required to be solid and flat, not to pollute components due to rain and snow, and can walk 30 ton vehicles.
Preparation before steel column hoisting
Before hoisting the steel column, the cable wind rope shall be tied to the column body, the lifting point shall be selected at the bracket position, and the double steel wire rope shall be set up at the upper and lower positions. The next step can be started only after the snap ring is inspected to be qualified. Before hoisting the steel column, the positioning axis, foundation axis and elevation, cup size and cup bottom elevation of the steel column must be checked and the handover acceptance must be handled, and the number, overall dimension, screw hole position and diameter of the steel column must be comprehensively rechecked. After confirming that the requirements of the design drawings are met, draw the installation center line at the upper and lower ends of the steel column and the elevation line at the lower end of the column.
Steel column hoisting
(1) installation method of steel column
Before the steel column is hoisted, the Board shall be weighed at the column base to prevent damage to the column base and other structures.
The steel column shall be bound with special hoisting steel wire rope, and the binding shall be padded with wood or rubber to prevent damage to the steel column.
The 25t truck crane shall be used for hoisting the steel column. When hoisting the steel column, the crane shall lift the hook and turn the arm at the same time to make the steel column vertically off the ground.
(2) positioning adjustment and temporary fixation
When the steel column is hoisted to 200mm above its foundation cup mouth, it shall be stabilized, and it shall fall slowly aligned with the foundation cup mouth to avoid bumping the concrete edge of the foundation cup mouth during the falling process. After implementation, use a special angle ruler to check and adjust the steel column to make its positioning line coincide with the foundation positioning axis. During adjustment, three people are required to operate, one person moves the steel column, one person assists in stabilization, and the other person performs detection. The positioning error shall be controlled within 2mm.
Ten installation points of frame steel structure
(3) when the steel column elevation is adjusted, a sizing block is placed at the bottom of the cup foundation. The elevation of the steel column bottom plate is used as the top elevation of the sizing block with a level gauge to make the elevation of the steel column meet the design elevation requirements after it is in place. The elevation reference point is calibrated on the column body, and then the installation elevation after it is installed in place is measured with a level gauge.
(4) steel column perpendicularity correction: the steel column perpendicularity shall be preliminarily adjusted with a level. Then use two theodolites to observe from both sides of the column at the same time, and adjust it by cable wind rope. As shown below:
(5) after the adjustment, use eight iron wedges to position the gap between the bottom of the steel column and the cup foundation, and then spot weld it on the column body to make it stable.
Steel beam installation
Steel beams must be stacked neatly on site. Sleepers must be placed in the middle of each layer of steel beams. Two lifting points for lifting steel beams shall be selected at both sides of the center of gravity of the steel beams. The positions of the two lifting points shall be 800mm away from the support and the midspan, and the distance between the two lifting points shall be appropriately increased according to the length of the steel beams.
To ensure safety and prevent the sharp edge of the steel beam from cutting the steel wire rope, the steel wire rope shall be protected, and the sling angle shall not be less than 450. The steel beam shall be directly rolled with the steel wire rope or lifted with a special fixture.
Before hoisting the steel beam, install the safety rope on the steel beam. During hoisting, hang two sliding ropes at both ends of the steel beam, and two people hold the two sliding ropes respectively. The hoisting speed of the steel beam must be slow. To ensure safety, personnel shall not stand directly under the beam. Cloth bags for special high-strength bolts shall be provided at both ends of the steel beam. When the steel beam is hoisted above the position, the steel beam shall be placed in place. The falling speed of the steel beam shall be controlled at 3m / min. two installers shall be arranged at both ends of the column head of the steel column to prepare for the installation of the steel beam. When the steel beam approaches the position, two installers shall hold the upper flange of the steel beam with their hands, drag the steel beam to the position, and prepare to install high-strength bolts.
Installation of enclosure structure and supporting corner brace
1) Installation of roof purlins: when the main structure forms a frame section, the roof purlins shall be hoisted to the roof main beam with a crane and installed manually. The purlins can also be manually pulled onto the roof with a white synthetic rope for installation. After the purlins are installed, the purlin support installation shall be carried out in time.
2) Installation of wall purlins: when the main structure forms a frame section, the construction personnel stand on the scaffold platform and pull the wall purlins to the installation position with a white comprehensive rope.
3) Installation of corner brace: after the main body is welded, connect the corner brace.
Measurement and correction of steel column
1) Verticality correction of steel column
During the installation and calibration of steel columns, two theodolites shall be erected on the control line with a 90 degree translation of 1 m and viewed in the same direction. The theodolite operator shall observe the small steel ruler on the top of the column, measure the deviation of the steel column and direct the correction.
A. control the verticality of the steel columns between the first hoisting sections.
The correction of B steel column is carried out in four steps: initial correction during initial tightening; Re calibration before final screwing; Tracking and monitoring during welding; Final result measurement after welding.
Before initial tightening, the verticality can be roughly controlled with a long level first, and then accurately corrected after the frame is formed. Re measurement shall be carried out after welding and compared with the measurement results during final screwing as the basis for the next construction.
Measurement method for verticality of C steel column
Initial correction: use a level to preliminarily adjust the verticality of the steel column.
Accurate correction of steel column perpendicularity: one column grid is used as an installation section for the hoisting of the main frame, and three continuous complete sections are hoisted
After forming a whole, the measurement correction can be inserted. Use two theodolites to observe from both sides of the column at the same time, and use the wind rope for correction and adjustment.
2、Steel structure measurement
Ten installation points of frame steel structure
2) Steel column elevation control
Based on the elevation datum point of the plane layer where the steel column is located, measure the horizontal elevation deviation of the steel column with a level gauge, and command the correction.
3) Steel beam measurement:
After the steel column is hoisted and calibrated, the +1.00m control point shall be measured to each steel column according to the site benchmark as the basis for vertical transmission of elevation and beam installation elevation; Snap the center line of the steel beam on the surface of the steel beam.
The control axis is projected to the column body to control the offset of the beam position; The accuracy of the beam elevation is controlled according to the column elevation control points. Set up a theodolite on the floor platform, look back at the cross angle to the axis of the corresponding beam, aim the center line of the upper surface of the beam to the other end with the theodolite, and see whether the number coincides with the beam axis.
In this project, the method of computer automatic query is adopted for the calculation of Surveying and setting out data. The specific steps are as follows:
1) Establishment of data model
First, according to the design coordinates of each building in the design drawing and the size relationship between them, draw each building, building axis, setting out control line, etc. in AutoCAD in proportion, and establish the data model.
2) Query of survey setting out data
After the surveying and setting out data model is drawn, use AutoCAD dist and other commands to query the surveying and setting out data such as the angle and distance between the known basis (axis control pile, lofted axis, etc.) and the control line to be lofted.
3) Advantages of computer automatic query
The method of computer automatic query is adopted to obtain the required measurement and positioning data, which is not only convenient for calculation, but also has high precision. According to the actual situation, the distance precision can be set to 0.1mm, 0.01mm, and the angle precision can be set to 0.0 “, 0.00” or higher.
3、High strength bolt construction
- preparation before installation
1) Test and inspection of high strength bolts
Anti slip coefficient test
Grade 10.9 large hexagon high-strength bolts are used in the project. The anti slip coefficient test of high-strength bolts shall be carried out with the most representative thickness of plates in the project, and three groups shall be made.
The bolts to be installed at the construction site shall be randomly selected, and 8 sets of bolt pairs shall be selected from each batch for re inspection.
2) Transportation and storage of high strength bolts
The high-strength bolt connection pair shall be manufactured and supplied by the manufacturer in batches. The form, size and technical conditions of the high-strength bolt connection pair with factory certificate shall comply with the provisions of the national standards gb1228-1231-84 and gb3632-3633-83. Large hexagon high strength bolts for steel structures
The connecting pair consists of a bolt, a nut and two washers. The use combination shall comply with the provisions of national standards, and the high-strength bolt connection pair shall be stored, transported and supplied in the same batch.
The high-strength bolt connection pair shall be loaded and placed with care during loading, unloading, transportation and storage to prevent damage to the packing box and bolts.
Storage of high strength bolts in warehouse - the high-strength bolt connection pair shall be cleaned according to the specification, batch number, number and supply date marked on the packing box, stored in the indoor warehouse, and the stacking shall not be higher than 3 floors. It shall be moisture-proof indoors, and shall be kept dry for a long time to prevent rust and dirt, and to prevent the torque coefficient from changing. The bottom layer shall be ≥ 300mm above the ground.
- during site installation, the quantity of high-strength bolts required for the day shall be distributed. The rest shall be kept properly. It is not allowed to put it randomly, damage the thread or be contaminated by dirt.
- before using the high-strength bolt connection pairs that have been stored for a long time, a comprehensive quality inspection shall be carried out again. If any abnormality is found after unpacking, the inspection shall also be carried out. The inspection standard shall be in accordance with the relevant provisions of the national standards gb1228~1231-84 and gb3632~3633-83. Use after passing the appraisal.
3) Construction management of high strength bolts - Construction Manager
During the construction of this high-strength bolt, the high-strength bolt manager shall be determined first to act as the project management, quality management and construction guidance personnel. - weather management (climatic conditions)
In principle, no operation shall be carried out during rainfall and snowfall. In case of rainfall and snowfall during operation, it is necessary to speed up the speed to lock the unfinished parts - friction surface management
Before tightening, the friction surface shall be checked first. If there are attachments that reduce the bearing capacity of the friction surface, such as floating rust, oil, paint, residue, etc., the metal brush, sandpaper and oxygen acetylene flame shall be used to remove them.
4) High strength bolt construction - final tightening of temporary bolts
Before inserting the high-strength bolt, the temporary bolt shall be used to tighten the connection. If the material at the connection part is bent or warped, it shall be corrected.
When the hole difference is within 2mm, it can be corrected with a reamer.
If the hole difference is more than 2mm, on the basis of consultation with the management personnel, reasonable treatment methods such as panel replacement shall be adopted for treatment, and gas cutting and hole expansion are not allowed.