In which situation cantilever retaining wall is designed?
Under normal conditions, Earth pressure at normal is such that the wall deflects slightly which results in active earth pressure. Thus, Cantilever retaining wall is mainly designed for Active Earth Pressure..
What are the steps in the design of a cantilever retaining wall?
The design involves two major steps: the first one is the evaluation of the stability of the whole structure under the service loads, which includes the overturning , sliding and bearing failure modes, and the second one is the design of the different components, such as the stem, heel and toe for bending and shear, .
What is the design code for cantilever retaining wall?
[1] Indian standard code used for designing retaining wall – IS 456:2000 for concrete design. [2] IS 1893 Part-III used for design of bridges and retaining wall..
What is the design of retaining wall?
A typical retaining wall has four main components: the Stem is the vertical member holding the backfill, the Toe is the portion of the footing at the front of the wall, the Heel is the portion of the footing at the backfill side, and the Shear Key projects down under the footing..
What is the design procedure of cantilever retaining wall?
The design involves two major steps: the first one is the evaluation of the stability of the whole structure under the service loads, which includes the overturning , sliding and bearing failure modes, and the second one is the design of the different components, such as the stem, heel and toe for bending and shear, .
What is the formula for retaining wall design?
Design Procedure for Earth Retaining Wall η = (45o + β/2) – ϕ/2 – sin-1 (sin β/ sinϕ) where β represents inclination of backfill and ϕ is the angle of wall friction. Step 3: Check for stability using weight of soil, earth pressure and weight of wall based on the component dimensions of the structure..
Cantilever retaining wall: It is the most common type of retaining wall and its height ranges up to 10-25 feet (3 to 8m).
Composed of a stem and base slab of concrete, a cantilever retaining wall is the most common type of retaining wall used for commercial projects. The bottom of the cantilever wall is often imbedded deeply into the soil, which acts as a weight to stop the wall from sliding.
The basic principle for the design of the Retaining Wall is that the reinforced concrete stem and footing flexure and shear design strength must e at least equal to the factored moment and shears determined from the analysis. The wall stem is designed as a cantilever, fixed at the footing.
Feb 2, 2023This design example focuses on the analysis and design of a tapered cantilever retaining wall including a comparison with model results from the
Analytical Model
Sketches of the retaining wall forces should be considered to properly distinguish the different forces acting on our retaining wall as tackled in the previous article, Retaining Wall: A Design Approach. Based on our example in Figure A.1, we have the forces due to soil pressure, due to water and surcharge load to consider. Figure A.3 below is most.
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Approximate Proportions of A Cantilever Retaining Wall
The next thing to consider is the assumptions that we can make in terms of the geometry of the retaining wall that we are designing. Given the height, H of the retaining wall, we can assume or counter check our initial design considerations should at least according to the following geometric proportions:. 1) Base width:L= 0.5H to 2/3H. 2) Thickness.
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Can a cantilever retaining wall be precast?
Cantilever retaining walls can be precast in a factory or formed on site and considered economical up to about 25 ft in height. This design example focuses on the analysis and design of a tapered cantilever retaining wall including:
a comparison with model results from the engineering software programs spWall and spMats
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Check For Bearing Pressure Under Footing
The foundation bearing capacity usually governs the design of the wall. The soil, particularly under the toe of the foundation, is working very hard to resist the vertical bearing loads, sliding shear, and to provide passive resistance to sliding. The bearing capacity of the soil should be calculated taking into account the effect of simultaneous h.
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Check The Required Length of The Base
If qumin is in tension check the required length otherwise ignore if it is in compression. Since our qumin is tension (+), the value of L must be computed as follows: Figure A.5-Pressure Diagram under Tension From Figure A.5: Solve for Eccentricity: e=M/P = 0.181 where: 1. 1.1. a=length of pressure 1.2. qe= qumax 1.3. b=1 meter strip 1. 1.1. a= 1.7.
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Check The Wall Thickness For Shear
The nominal shear is equal to the lateral forces on the retaining wall, neglecting the effect of passive pressure which will give us:. 1) Nominal Shear, Vn= 20.05kN. 2) Ultimate Shear, Vu = 1.6Vn = 32.08kN For the thickness of the wall to be safe in shear, the ultimate shear, Vu should less than the allowable shear, Vallow as recommended by the ACI 3.
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Design Parameters
Soil Bearing Capacity, qall : 100 kPa
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Design The Wall Stem For Flexure
Nominal Moment, Mn= 10.88kNm
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Stability Check
There are two checks to consider the stability of the retaining wall. One is the check for an overturning moment and the other one is the check for sliding. The weight of the retaining wall including the gravity loads within it plays a vital role in performing the stability check. Refer to Figure A.4 for the mass or weight calculations. Figure A.4-.
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Values of Coefficient of Pressure, Ka and Kp
According to Rankine and Coulomb Formula, the following are the equation in calculating the coefficient of pressure: Ka= (1-sin ф)/(1+sin ф) Ka= 0.33 Kp= (1+sin ф)/(1-sin ф) Kp= 3 Substituting the values, we have the following results: 1. 1.1. Pa1=1/2 ɣkaH2 = 11.88kN 1.2. Pa2=1/2 ɣHw2= 5kN 1.3. Pa3=ωkah= 3.17 kN 1.4. Pp=1/2 ɣkpHp2= 9.72kN
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What is a cantilever wall stem?
Usually the cantilever wall stem is of concrete block construction rising from an in-situ concrete foundation. The following worked example is for a free-standing cantilever wall that is considered sufficiently flexible for active soil pressures to be used for design.
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What is a tapered cantilever retaining wall?
This design example focuses on the analysis and design of a tapered cantilever retaining wall including:
a comparison with model results from the engineering software programs spWall and spMats
The retaining wall is fixed to the reinforced concrete slab foundation with a shear key for sliding resistance.
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What is the unit weight of a cantilever retaining wall?
The cantilever retaining wall shown below is backfilled with granular material having a unit weight, ρ, of 19 kNm−3 and an internal angle of friction, , of 30 . Assuming that the allowable bearing pressure of the soil is 120 kNm−2, the φ coefficient of friction is 0.4 and the unit weight of reinforced concrete is 24 kNm−3 .
Design example of cantilever retaining wall
British hardened field defences of World War II
British hardened field defences of World War II were small fortified structures constructed as a part of British anti-invasion preparations. They were popularly known as pillboxes, a reference to their shape.
