EFFECTS OF SOIL BEARING STRATA ON THE STRENGTH OF CONCENTRICALLY LOADED REINFORCED CONCRETE SQUARE PAD FOOTING
Abstract
This study investigates the influence of soil bearing strataand soil compaction on the load capacity and settlement behavior of concentrically loaded reinforced concrete square pad footings measuring 230×230×150 mm with central columns of 60×60×60 mm, reinforced with eight 10 mm tension bars and 10 mm starter bars, cast using a 1:1.5:3 concrete mix and cured for 28 days; six footings were tested on six soil bearing stratacomprising five loose sand beds compacted to dry densities from 1.28 to 1.75 g/cm³ and a rigid base, using a Universal Testing Machine in accordance with ASTM C39/C39M-21, with results showing that the footing on the rigid foundation achieved the highest ultimate load of 115.8 kN with minimal settlement, while the footing on the lowest-density sand failed at 38.2 kN with significant deformation, and intermediate compaction levels showed proportional performance improvements, confirming the critical role of foundation stiffness in footing behavior; these findings align with recent work by Ebid et al. (2025), demonstrating that geotechnical reinforcement methods such as geocell confinement can increase punching capacity by 20%, enhance subgrade reaction by 90%, and reduce settlement by 70%, emphasizing the importance of proper foundation preparation and soil stabilization for ensuring the structural safety and durability of pad footings under concentric loads, consistent with guidelines from ACI 318-19, ASTM, and BS EN 1997.
KEYWORDS: Pad footing, soil bearing strata, compressive strength, settlement, load capacity, concrete mix, sand compaction
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