Shear force transfer coefficients
For U-type sheet piles, the reduction coefficient βB and βD is introduced to express the possible reduction of shear force transfer in the locks, or the degree of coupling in the lock between close sheet piles.
Coefficient βB is applied when calculating the moment capacity of the wall:
where: | MRd | - | is the design value of the bending resistance of the section |
βB | - | coefficient expressing the possible reduction of the section modulus of the sheet piles |
W | - | elastic section modulus |
fy | - | steel yield stress |
U-type sheet pile
The coefficient βD influences the bending stiffness of the sheet pile wall, i.e. the calculation of horizontal deformations and internal forces:
where: | I | - | moment of inertia of a continuous wall |
E | - | modulus elasticity of steel |
βD | - | coefficient expressing the possible reduction of bending stiffness in sheet piles |
The βB and βD coefficients are influenced by the following factors:
- the type of foundation soil into which the sheet piles are put in
- type of inserted element
- the number of support levels and the method of securing them in the plane of the wall
- by way of insertion
- the method of lock treatment used on site (grease lubrication, or partial connection by welding, head beam, etc.)
- the height of the cantilever of the wall (i.e. if the wall is significantly overhanging the highest or lowest overhang)
For full coupling the value βB = βD = 1.0 is used, other values can be used, e.g. recommended values according to EN 1993-5.