Common problems and preventive measures of steel structure installation

The positioning axis of the foundation and the elevation of the supporting steel cylinder exceed the allowable deviation value of the specification

The reasons are:

There are errors and deviations in the foundation survey control network, foundation survey line, and elevation finding, foundation formwork is not firmly supported, the pouring concrete is too high, the concrete vibrates and impacts, and the formwork is displaced, causing the baseline to deviate, or use steel rulers , Theodolite, level gauge has not been verified, there are errors, or the construction drawing is wrong, the axis is wrong, it has not been strictly inspected, or the foundation supporting surface has not been rubbed and leveled twice, the concrete settlement shrinks and sinks, or it is embedded The steel plate (or support) is not fixed, etc., because the foundation positioning axis and the supporting surface are out of tolerance, it will cause the column installation axis and the supporting elevation to appear out of tolerance, which will affect the quality of the entire structure installation project.

Precaution:

The accuracy of the basic measurement control network, the instruments and measuring tools used for the basic measurement setting and leveling, etc. should be accurate. They must be checked or verified by the metrology department before use. If problems are found, they should be adjusted in time to prevent errors or cumulative errors that cause the axis and elevation to exceed Allow deviation.

The foundation formwork support must be firm, and should have sufficient strength and rigidity. When pouring concrete blanking and vibrating, it is necessary to prevent hitting the template and causing displacement. In the process of pouring concrete, the positioning axis and elevation should be checked regularly with measuring tools or hanging wires. If deviations are found, the pouring and vibrating should be stopped, and the reinforcement should be adjusted and eliminated before proceeding. Before the final setting of the concrete, the surface of the foundation concrete should be pressed and leveled twice. For pre-embedded steel plates or supports, the elevation and levelness should be corrected twice, and the bottom concrete should be dense. The steel plate of the foundation support column or the support shall be provided with necessary fixing devices to ensure the correct position and elevation.

When the vertical and horizontal axis of the foundation and the column supporting surface steel plate or the support elevation and levelness are out of tolerance, measures should be taken to deal with it according to the degree of deviation. When the over-tolerance is not serious, it can be solved by shifting the column base, reaming the hole, and filling the backing plate when installing the column. If the over-tolerance is serious and cannot be adjusted and handled, it should be studied in conjunction with relevant departments, and a feasible correction plan shall be determined before handling.