Reliability-Based Design of Reinforced Concrete Raft Footings Using Finite Element Method

In this study, a FORTRAN-based reliability-based design program was developed for the design of raft footings based on the ultimate and serviceability design requirements of BS8110 (1997). The well-known analysis of plate on elastic foundation using displacement method of analysis was used in conjunction with the design point method. The design point method was adopted for designing to a pre-determined safety level, T. Example of the design of a raft footing is included to demonstrate the simplicity of the procedure. It was found among other findings that there is a saving of about 64% of longitudinal reinforcement applied at the column face using the proposed method as compared with the BS8110 design method. Also, the depth of footing required using the proposed procedure was found to be 47% lower than in the deterministic method using BS8110. Also, considering a target safety index of 3.0 was found to be cheaper than considering a target safety index of 4.0 for the same loading, material and geometrical properties of the footing. It is therefore concluded that the proposed procedure is quite suitable for application.