Measurement method for installation of steel structure buildings

Measurement method for installation of steel structure buildings

According to the Code for Acceptance of Construction Quality of Steel Structural engineering, the allowable deviation of column positioning axis is 1mm. The correct embedding of anchor bolts is an important stage in the lifting process of steel structures, including the installation and positioning of anchor bolts, the measurement of deviations between the concrete pouring process and the concrete solidification.

1) Before installing the anchor rod, mark the "ten" centerline on the anchor plate;

2) After the steel bars are tied, accurately measure the theoretical "ten" centerline of the anchor rod on the steel bars;

3) The elevation points near the anchor rod are measured by the elevation control network;

4) Install the anchor bolts with the centerline on the steel bars;

5) Two Theodolite are set in the direction of the anchor bolt centerline to accurately guide the anchor bolt installation in place; Adjust the height of anchor rod with Dumpy level;

6) Repeat the above two processes until the plane position and elevation of the anchor rod meet the specification requirements.

Measurement and calibration of steel columns

One. Theodolite calibration

During measurement and correction, two Theodolite shall be erected near the vertical and horizontal axis of the steel column, but the deflection angle shall not be greater than 15 degrees. The distance from the column is approximately 1.5 times the length of the column. During calibration, first aim at the control line at the lower part of the column, and then look up at the control line at the top of the column after the Theodolite aiming part is fixed. If overlapping, it indicates that the column is vertical in this direction. If there is no overlap, it should be adjusted until the two mutually perpendicular directions meet the requirements. After the first steel column is in place, in addition to verticality correction, the elevation of the column bottom should also be adjusted. Adjust the elevation of the first column by adjusting the nut at the bottom of the column to ensure accurate positioning of the steel beam.

When correcting the steel column with a cable wind rope, when the cable wind rope is loose, the steel column can maintain a "0" displacement state to complete the correction. If the power of the cable wind rope is very high, the column will have a significant installation internal force. Release the cable and wind rope. The position of the column will change, causing significant changes in the structure. At this point, it cannot be considered a correction.

2. Space Rendezvous Technology

Due to the limitations of construction site conditions, the following problems may occur during the construction process of the working layer: on-site control points cannot be viewed, instruments cannot be set at known points, and vision is obstructed for a long time. In order to solve the above problems, the space resection technology is adopted, the total station is set at a position with good visibility, and the "resection method" is used to obtain the center coordinates of the instrument, and then the coordinate data is used for lofting.

Measurement and Control of Steel Beam Installation

After correcting the steel column, the next process is to lift the steel beam. Before installing the main beam, welding deformation values should be reserved based on the welding shrinkage and recorded in writing. During the installation process, if the verticality of the column is reached, and the steel beam is installed and calibrated, the column should be opened to retain the welding shrinkage of the joint. At this point, the internal force generated by the column will automatically disappear after welding shrinkage.

The beam is connected to the steel column using high-strength bolts. Due to the large cross-section and stiffness of the main beam between columns, the installation of the main beam between columns will affect the verticality of the steel column. Therefore, it is necessary to further track and correct the columns. The separation span of the main beam connection, even columns with two or more spans, should be monitored simultaneously. Only by taking such measures can the installation quality of the columns be guaranteed.

After tightening the high-strength bolts, the overall observation of the steel column in the area should be carried out again and records should be kept. Based on the recorded deviation values and deviation directions, determine whether the deviation before welding needs to be adjusted locally, determine the welding sequence, welding direction, and reserved amount for welding shrinkage, and submit it to the welding team for welding.

After the high-strength bolts are finally tightened, the welded joints in the next process will shrink.