Solid raft foundation
What is raft foundation?
Raft foundation is a thick concrete slab reinforced with steel which covers the entire contact area of the structure like a thick floor. Sometimes area covered by raft may be greater than the contact area depending on the bearing capacity of the soil underneath. The reinforcing bars runs normal to each other in both top and bottom layers of steel reinforcement. Sometimes inverted main beams and secondary beams are used to carry column loads that require thicker foundation slab considering economy of the structure. Both beams cast monolithically with raft slab.
Solid raft foundation
The unified solid raft foundation is the most simple foundation form and its formwork assembling as well as its reinforcement implementation do not require hard labor. Solid raft foundation
In the solid raft foundation, there is only one unified foundation slab.
The foundation slabs are reinforced with two wire meshes, one placed at the lower fibers and one at the upper fibers. Since the most intense stresses appear along the columns’ axis, their surrounding areas are usually reinforced with stronger or double grates.
The slabs’ free edges are reinforced with common hairpin bars or with a wire mesh shaped like a hairpin.
Notes:
1. On a practical level and mainly when using a folded wire mesh as a free edge’s reinforcement, the hairpin rebars are positioned in the 2nd phase, as shown in the first figure.
2. The alternative solution for providing the free edges’ reinforcement includes the formation of hooks at the ends of the upper and lower rebars as shown in the second figure. This solution compared to the hairpin solution, apart from everything else, has a higher shaping-cost but mainly it lacks a natural peripheral rebar chair.
The reinforcement of a solid raft foundation can be separated into three categories, as shown at the following figure:
(a) slabs’ reinforcement
(b) slabs’ free edges reinforcement
(c) punching shear reinforcement
Raft foundation is a thick concrete slab reinforced with steel which covers the entire contact area of the structure like a thick floor. Sometimes area covered by raft may be greater than the contact area depending on the bearing capacity of the soil underneath. The reinforcing bars runs normal to each other in both top and bottom layers of steel reinforcement. Sometimes inverted main beams and secondary beams are used to carry column loads that require thicker foundation slab considering economy of the structure. Both beams cast monolithically with raft slab.
Solid raft foundation
The unified solid raft foundation is the most simple foundation form and its formwork assembling as well as its reinforcement implementation do not require hard labor. Solid raft foundation
In the solid raft foundation, there is only one unified foundation slab.
The foundation slabs are reinforced with two wire meshes, one placed at the lower fibers and one at the upper fibers. Since the most intense stresses appear along the columns’ axis, their surrounding areas are usually reinforced with stronger or double grates.
The slabs’ free edges are reinforced with common hairpin bars or with a wire mesh shaped like a hairpin.
Notes:
1. On a practical level and mainly when using a folded wire mesh as a free edge’s reinforcement, the hairpin rebars are positioned in the 2nd phase, as shown in the first figure.
2. The alternative solution for providing the free edges’ reinforcement includes the formation of hooks at the ends of the upper and lower rebars as shown in the second figure. This solution compared to the hairpin solution, apart from everything else, has a higher shaping-cost but mainly it lacks a natural peripheral rebar chair.
The reinforcement of a solid raft foundation can be separated into three categories, as shown at the following figure:
(a) slabs’ reinforcement
(b) slabs’ free edges reinforcement
(c) punching shear reinforcement