When hoisting the first steel structure workshop steel column, it is necessary to add a protective sleeve on the embedded anchor bolt to avoid damaging the screw teeth of the anchor bolt when the steel column is in place. Before hoisting the steel column, the operation hanging basket and climbing ladder should be fixed on the construction column on the ground in advance. The lifting point of the steel column is at the lifting lug (the lifting lug is welded at the lifting point during the production of the column, and it can be cut after lifting). According to the weight of the steel column and the lifting weight of the crane, the lifting of the steel column can be single-machine lifting or double-machine lifting. In single lifting, wooden pads should be placed on the root of the column to lift by rotary method, and it is strictly prohibited to drag the column root; When the steel column is lifted off the ground, it is straightened in the air.
After the steel column is in place, first adjust the elevation, then adjust the displacement, and finally adjust the verticality. Columns shall be calibrated to the values specified in the code and the vertical deviation of standard columns shall be calibrated to zero. When the upper column and the lower rod are torsional dislocation, the upper and lower column can be connected to the ear plate with a backing plate for adjustment. In order to control the installation error of steel structure workshop, first determine the international quasi-column, the so-called standard column is a few columns that can control the plane outline of the frame, generally choose the plane Angle column standard column. Square frame take 4 corner columns; Rectangular frame when the ratio of the long side to the short side is greater than 2, take 6 columns; The polygon frame takes the scratch mark as the standard column.
In general, the center line of the base of the standard column is taken as the reference point, and the verticality machine of the reference column is observed by the laser theodolite. In the laser instrument measurement, in order to correct the error caused by the vibration of the steel structure and the instrument installation error, mechanical error, laser rotation 90 degrees in each measurement, a total of 4 laser points on the target, the intersection of the four laser points to measure the installation error.
In order to pass the laser beam, a small steel tube is fixed or embedded on the metal or concrete floor above the laser. For steel column elevation adjustment, after each steel column is installed, the elevation of the top of the column shall be measured once. If the elevation error exceeds 6mm, it shall be adjusted. If the error is too large, it is not suitable for one adjustment, you can adjust part of it first and wait for the next adjustment. If the adjustment is too large, the installation of the support and the elevation of the steel beam surface will be affected. The elevation of the middle frame column should be slightly higher, because the frame installation period is long, the weight of the structure is increasing, the load borne by the middle column is larger, and the foundation settlement is also large.
For the correction of the axis displacement of the steel column, the actual column center line at the top of the following steel column shall prevail, and the bottom of the steel column shall be aligned with the center line of the next steel column. When correcting the displacement, attention should be paid to the torsion of the steel column, which is detrimental to the installation of the frame.
Before steel beam hoisting, elevation and column spacing should be checked at the column leg; Before the main beam hoisting, the handrail and handrail rope should be installed on the beam. After the main beam hoisting is in place, the handrail rope and steel column should be securely tied to ensure the safety of construction personnel.
Generally, holes are made at the upper flange of the steel beam as a lifting point. The position of the lifting point depends on the span of the steel beam. In order to speed up the hoisting speed, for the secondary beams and other trabeculars with small weight, multiple slings are used to lift several beams at a time.
Sometimes the beam and column are assembled into a rack on the ground for overall lifting, so as to reduce overhead work, which can ensure the quality of the project and speed up the progress of the project. When installing the frame girder, the weld deformation should be reserved according to the weld shrinkage; When installing the main beam, the monitoring of the verticality of the column, in addition to monitoring the changes of the verticality of the two ends of the installation of the main beam column, but also monitoring the changes of the verticality of the adjacent pillars connected with the main beam, to ensure that the column in addition to the reserved weld shrinkage, all deviations need to meet the requirements of the code.
When installing the floor profiled steel plate, first draw the position line of the profiled steel plate on the beam; When laying, it is necessary to square the end slope-shaped notch of the adjacent two rows of pressing steel plates so that the reinforcement in the cast-in-place layer can pass smoothly.
After all the components of each column are installed, welded and tethered and accepted, the positioning axis of one column can be measured from the ground.
