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OPTIMIZATION AND CONTROL IN CIVIL AND STRUCTURAL ENGINEERING
Edited by: B.H.V. Topping and B. Kumar
Optimum Design of Pile Supported Reinforced Concrete Footings
M.J. Fadaee* and D.E. Grierson+
*Civil Engineering Department, Shahid Bahonar University of Kerman, Iran
M.J. Fadaee, D.E. Grierson, "Optimum Design of Pile Supported Reinforced Concrete Footings", in B.H.V. Topping, B. Kumar, (Editors), "Optimization and Control in Civil and Structural Engineering", Civil-Comp Press, Edinburgh, UK, pp 147-151, 1999. doi:10.4203/ccp.60.5.2
A computer-based method is presented for the optimal design of the pile-supported reinforced concrete footings subjected to a factored column load. The design variables are the footing dimensions. the area of the required longitudinal and transverse reinforcement of the footing, and the diameter of the piles. Having the values of design variables, the other required dimensions can be found using the "CSA STANDARD A23.3-94" recommendations. The number of piles is pre-assigned. and the factored column load is divided by the number of piles to obtain the effective pile reaction. The pile diameter must be computed such that the bearing stress at the top of the pile is less than the allowable stress.
The effective depth of the footing is derived as the maximum required by: 1) one-way shear of footing corner due to reaction of a single pile, 2) two-way shear of footing due to reaction of a single pile located along the side of the footing, 3) one-way shear of the entire footing in the worst direction, 4) two-way shear about the column, 5) allowable bearing stresses over the piles, and 6) allowable bearing stress under the column. The sequential quadratic programming (SQP) method is applied to minimize the cost of the concrete and steel for the structure. For the design method the CSA STANDARD A23.3-94 Code provisions concerning the strength of the structure are taken as constraints. Constraints also impose upper and lower bounds on the design variables. The features of the design optimization method are illustrated by an example.
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