Analysis and design of a concrete retaining wall
Design of a concrete retaining wall
First we need to check the stability of the retaining wall. Slopes and slides must be checked before proceeding with planning. For more details on the above exams, see Click here .
Additionally, we need to check the storage under the foundation. If the wall is supported on the ground, the bearing pressure under the wall foundation must be less than the allowable load capacity.
First we need to analyze the retaining wall and determine the bending moments and shear forces.
This can be done using analysis software such as SAP2000 or PROKON or other software or through manual calculations. If there are variations such as steps in the retaining wall and we are more focused on the wall's stress variations, we can use software such as SAP2000 or ANSIS.
Manual calculations can only be done for simple retaining walls that do not present many complications.
For example, cantilever retaining walls can be analyzed by simplifying their behavior.
We can assume the “fixed” boundary condition at the base to find the bending moments and shear forces of the wall. Once we determine the wall forces, we can determine the forces at the base of the wall.
The easiest way is to at least determine the bending moments and shear forces using software.
Project example
Consider a wall 3 m high and 2.3 m wide. Assume a friction angle of 30 degrees and the water table is 1 m above the base of the foundation. The wall thickness is considered to be 0.3 m. This analysis is carried out using the Prokon software. The input details and analysis results are as follows.
According to the analysis above, the wall and base have maximum bending moments of 39.81 kNm and 46.85 kNm, respectively. The construction of each element is in accordance with the guidelines of BS 8110 Part 01 1997.
wall design
Coverage to armor = 40 mm
Assumed diameter of main rod = 12 mm
Horizontal reinforcement diameter = 10 mm
Wall thickness = 300mm
Characteristic strength of concrete = 25
Characteristic strength of steel = 460 N/mm 2
Effective depth = 300 – 40-10-12/2
= 244mm
Bending moment = 39.81 kNm
M/bd 2 = 0.669 N/mm 2
100 As/bd = 0.158
How = 385mm 2
Provides T10 at 200mm center to center. It should also be noted that this design does not cover reinforcement requirements for concrete cracks due to thermal effects.
Basic project
Coverage to armor = 40 mm
Assumed diameter of main rod = 12 mm
Horizontal reinforcement diameter = 10 mm
Wall thickness = 300mm
Characteristic strength of concrete = 25
Characteristic strength of steel = 460 N/mm 2
Effective depth = 300 – 40-12/2
= 254mm
Bending moment = 46.85 kNm
M/bd 2 = 0.726 N/mm 2
100 As/bd = 0.172
How = 437 mm 2
Provides T10 at 175mm center to center. It should also be noted that this design does not cover reinforcement requirements for concrete cracks due to thermal effects.
