What are Counterforts?

What are Counterforts?

A counterfort retaining wall is a cantilever wall with counterforts, or buttresses, attached to the inside face of the wall to further resist lateral thrust. Some common materials used for retaining walls are treated lumber, concrete block systems, poured concrete, stone, and brick.

Why does Counterforts are provided in retaining walls?

Counterfort Retaining Walls The counterforts tie the slab and base together, and the purpose of them is to reduce the shear forces and bending moments imposed on the wall by the soil. A secondary effect is to increase the weight of the wall from the added concrete.

What is the spacing of the counterfort slabs?

The existing counterforts are 18 in. (460 mm) thick and spaced every 11 ft (3.4 m). The counterfort spacing–to–base length ratio can be calculated by dividing the spacing between the counterforts by the total length of the base slab.

Why shear key is provided?

Shear key is provided to increase the resistance to sliding. The shear key is generally an extension of the vertical stem and extends below the bottom of the base. The main purpose of the installation of shear keys is to increase the extra passive resistance developed by the height of shear keys.

What is a cantilever wall?

Cantilever walls are walls that do not have any supports and thus lead to an open unobstructed excavation. Cantilever walls laterally restrain the retained side of the excavation by the passive resistance provided below the excavation depth.

What are RC walls?

Reinforced concrete (RC) is a versatile composite and one of the most widely used materials in modern construction. Reinforced concrete can be precast or cast-in-place (in situ) concrete, and is used in a wide range of applications such as; slab, wall, beam, column, foundation, and frame construction.

What is the purpose of diaphragm wall?

Diaphragm walls are underground structural elements commonly used as retention systems and permanent foundation walls. They can also be used as groundwater barriers.

What is surcharge in retaining wall?

Surcharge: The vertical load imposed on retained soil that may impose a lateral force in addition to lateral earth pressure of retained soil. For example: Sloping retained soil; structure footings supported by the retained soil; adjacent vehicle loads supported by retained soil.

How does a cantilever retaining wall work?

Cantilever retaining walls Cantilever walls are built using reinforced concrete, with an L-shaped, or inverted T-shaped, foundation. The vertical stress behind the wall is transferred onto the foundation, preventing toppling due to lateral earth pressure from the same soil mass.

What is meant by panel of flat slab?

Flat slab is a reinforced concrete slab supported directly by concrete columns without the use of beams. Flat slab is defined as one sided or two-sided support system with sheer load of the slab being concentrated on the supporting columns and a square slab called ‘drop panels’.

What is the purpose of a key in concrete footing?

RE: Foundation Wall Keyways Keyways are used for alignment and when the resteel is insufficient to resist shearing forces through the plane of the key. They really do not negatively affect the moment capacity of the wall joint.

What’s a shear key?

The shear key is a part of the structural element mostly used to make the structure stable against the lateral loads. Depending on the type of construction and nature of the loading, the application of shear is different. Mostly the shear keys are constructed between two structural elements.

What are the parts of a counterfort wall?

The stem of the counterfort wall can be analog to the two-way slab with three fixed ends as well as a free end, which transfers its load at the base of the stem in form of bending moments and then transfers to the base slab. 2) Base slab: The base slab is the footing of the counterfort wall which supports the stem and counterforts.

What is the minimum thickness of a counterfort?

Thickness of counterfort must be greater than 0.3. Assume suitable value. Thickness of stem = 0.1m – 0.2m Effective span ,l = Minimum of (c/c between counterfort , l 0 + thickness of stem) Note: Maximum bending moment occurs at support. And the stem is considered as a slab supported by counterfort as support.

How are counterforts used to strengthen a retaining wall?

Strengthening a retaining wall with counterforts changes the structural behavior of the retaining wall. In conven- tional cantilever retaining wall systems, the face panel is the load-resisting component.

How tall is The counterfort retaining wall in Chicago?

The existing structure chosen for this study is a cast-in- place concrete counterfort retaining wall in Chicago, Ill. The wall is 21 ft 6 in. (6.55 m) high measured from the bottom of the base to the top of the wall. The total width of the base slab is 16 ft (4.9 m).

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