These pads are used in similar locations to those of the mass concrete pad, but where the reduction in cost of mass concrete exceeds the cost of the additional labour and materials.
These extras would include providing the reinforcement and any extra shuttering, blinding, or working space which may prove necessary for the reinforced solution.
The plan size and shape is determined from the vertical load and allowable bearing stress in conjunction with any physical requirements. The depth and amount of reinforcement is determined from the resulting bending moments and shear force considerations (see Fig. 11.20) or from past experience. The experience basis is often used where reinforcement needs are related to variable ground for a familiar location and use or where there is a need to cater for a number of time-related variations in differential settlement.
1 Design decisions and Sizing up of the design Design decisions The decision to reinforce a concrete foundation of this type usually follows the realization that the ground conditions are variable and/or deep trench fill is...
2 Design Example 3: Reinforced strip foundation The load-bearing wall of a single-storey building is to be supported on a wide reinforced strip foundation. A site investigation has revealed loose-to-medium granular soils...
3 Design Example 4: Reinforced pad base The axially loaded pad base in Design Example 2 is to be redesigned as a reinforced base, founded in the weathered sandstone. Assuming settlements have been judged to be...
Fig. 11.20 Reinforced concrete strip design conditions. |
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