RECONSTRUCTION OF AN INDIVIDUAL FOUNDATION BENEATH A COLUMN OF A SINGLE-STOREY INDUSTRIAL FRAME BUILDING THAT HAS EXPERIENCED SETTLEMENT

Abstract

A technology is presented for the reconstruction of an individual foundation beneath a column of an industrial frame building that has undergone settlement, as well as for increasing its load-bearing capacity. For this purpose, an excavation pit is dug around the foundation, with an area 1.5–2 times greater than the area of the foundation base. A special metal lifting structure is installed, which is connected at its upper part to the column by means of anchors, while its four lower supports rest, through hydraulic jacks, on a pre-enlarged reinforced concrete footing of the foundation.

In the upper part, the metal structure is rigidly connected to the column using anchors. To relieve the axial force N from the column base and transfer it to the strengthened footing, the jacks are activated to lift and create preliminary tension in the elements of the metal structure. The force in the jacks is set to approximately 0.25N (where N is the longitudinal force in the column due to external loads). This enables the old reinforced concrete column base to be mechanically dismantled using jackhammers, thereby freeing the column from its support.

Subsequently, the column is gradually lifted by the jacks to the design elevation. The resulting gap between the footing and the column is filled with reinforced concrete or steel shims, fixing the column in the new position. A new column base is then concreted together with the column onto the enlarged footing. After the concrete of the new base reaches 70% of its design strength, the load in the jacks is released, the metal lifting structure is dismantled, and a set of construction works is carried out to backfill the excavation around the foundation.