Features of foundation reconstruction in the implementation of redevelopment projects

Abstract

The conversion of mid-twentieth-century industrial buildings to commercial and public use loads the subsoil unevenly: interior bearing walls receive load increments almost twice as large as exterior ones, while the geometry of the strip footings remains unchanged. Design practice follows a sequence of code checks in which bearing pressure is compared with the design resistance of the soil first and the combined deformation of the soil and the structure is assessed second; the order of the checks governs the order in which the strengthening decision is made. An author's computational model of a four-storey industrial building on rubble strip footings has been constructed for a layered subsoil containing a soft plastic loam in the middle of the compressible zone. The bearing pressure beneath the most heavily loaded interior wall exceeds the design resistance by 2,9%, the maximum additional settlement reaches 23,9 mm against a limit of 20 mm, and the relative difference in settlement between the exterior and interior walls amounts to 0.00223 against an admissible 0.0010. The threshold load increment is 53,5% for differential deformation, 61,5% for absolute settlement and 65,6% for design resistance. The gap of 12,1 percentage points shows that the strength check of the footing base loses its governing role in reconstruction and yields it to the criterion of differential deformation; the extent of foundation strengthening is set by the distribution of load increments among sections.