Raft foundations pdf

4.3 Raft foundations. Raft foundations are essentially large plan area foundations built either solidly or in cellular form. They may be employed for lightly loaded structures on soft natural ground or on other ground where weak zones exist. In this case the raft is designed to span across such zones with tolerable bearing pressures and Piled raft foundations: design and applications H. G. POULOS In situations where a raft foundation alone does not satisfy the design requirements, it may be possible to enhance the performance of the raft by the addition of piles. The use of a limited number of piles, strategically located, may improve Foundation Analysis and Desing Foundation Design -1 . engineering of foundations, not at the geotechnical engineering. This presentation relates to example computations in Chapter 5 of the FEMA P752, NEHRP Recommended Provisions: Design Examples. The conventional rigid combined footing approach is a method of analysing raft foundation using simple statics without any consideration of the elastic properties of the raft and the soil. Here the raft is analysed as a large beam member independently in both directions. The raft foundation or mat foundation is a very popular type of foundation. Before selecting raft foundation for a project, its advantages and disadvantages must be considered. Advantages of Raft Foundation. Followings are the advantages of raft foundation: design of foundation elements. Example 5.1 completes the analysis and design of shallow foundations for two of the alternative framing arrangements considered for the building featured in Example 6.2. Example 5.2 illustrates the analysis and design of deep foundations for a building similar to the one Raft foundation R A F T F O U N D A T I O N S 8 9. TYPES OF RAFT FOUNDATIONS R A F T F O U N D A T I O N S 9 10. TO DESIGN RAFT FOUNDATIONS: 1. Determine the capacity of the foundation 2. Determine the settlement of foundation 3. Determine the differential settlement 4. Determine the stress distribution beneath the foundation 5. A Structural Designer Engaged In The Design Of Raft Foundations Finds It Hard To Select The Method That Can Be Carried Out Within The Time And Cost Available For Design And Give Adequate Safety And Economy.This Book Covers Complete Design Of Raft Foundations Including Piled Rafts, Starting From Their Need, Type, All The Approaches Suggested So C. Mat Foundation (Raft Foundation) It is a combined footing that may cover the entire area under a structure supporting several columns and walls. Mat foundations are sometimes preferred for soils that have low load-bearing capacities, but that will have to support high column or wall loads. A raft or mat foundation consists of a large concrete slab or a slab and beam system resting on soil or rock and supporting all the loads through a number of columns or walls.. When the raft foundation is supported on piles, it is called a piled raft. Full Learn To Read Structural Drawing Course at the cheapest rate: bit.ly/2Xw0dkv This video show how the rebar in raft foundation are placed at the s Mat (Raft) foundations is a relatively large slab supporting the structure as a whole. •Low bearing capacity, but high structural loads •Area required for individual/combined footings > 50% of area •Heterogeneous soil profile : minimizes differential Full Learn To Read Structural Drawing Course at the cheapest rate: bit.ly/2Xw0dkv This video show how the rebar in raft foundation are placed at the s Mat (Raft) foun