24-09-2016, 09:33 AM
1455964977-structuraldesignofraftfoundation869.pdf (Size: 1 MB / Downloads: 36)
Abstract:
In this report, a full discussion and clarification of the design of Raft foundation in loose sand
will be shown in details. The columns loads calculation for this raft is also will be shown in
terms of the turbidity area of the columns. Final design and detailing will be shown at the
end of this report with SAFE software design out file attached.
Introduction:
This foundation will be done for a storage 5 story building. The raft will be used for
economical consideration. The justification of using raft foundation will be discussed in
columns loads section 3.2.0.
The raft foundation is a kind of combined footing that may cover the entire area under the
structure supporting several columns in one rigid body. In this project, the soil profile shows
that the bearing stress is around 100 kN/m2
. The raft foundation is usually used with this
kind of soil. The columns have high axial loads. If spread footings used, the area of the
footing required will be big as will be shown in column load section 3.2.0. In this big spread
footing condition, the raft foundation could be much practical and economical.
In this project, the raft will be designed as flat plate, which has a uniform thickness and
without any beams or pedestals.
Objective:
This report shows the structural design of the raft foundation. The raft is modeled in SAFE
software. All analysis and design are based on the ACI code. Raft foundation can be design
using several methods. In this special project the method used in the design called “the
Conventional Rigid Method” and all design steps will be shown in the report.
Manual & Computer Design:
Using the SAFE software analysis, the moments of x and y strips will be used to design the
top and the bottom reinforcement for the raft. The maximum moments in each direction
will be used to design the reinforcement in all raft strips. SAFE software design output will
be compared with the manual design for those maximum positive and negative moments
Conclusion:
At the end of this special project, we are really happy that we have been involved in the Raft
manual design. The raft foundation is considered to be a very common foundation type
especially here in Qatar.
We also have been involved in using SAFE analysis and design software which is really
professional and helped us for this project.