Nails
For each nail the following bearing capacities are either computed or input:
where: | Rf | - | nailhead strength |
Rt | - | nail strength against breaking | |
Tp | - | pull-out nail bearing capacity |
Strength characteristics of a nail represent the basic parameters to compute the total bearing capacity of a nail.
The nail strength against breaking follows from:
where: | Rt | - | strength against breaking |
ds | - | nail diameter | |
fy | - | strength of nail material |
The pull-out nail bearing capacity is calculated by one of the following ways:
1. calculate from skin friction:
where: | Tp | - | pull-out nail bearing capacity [kN/m] |
d | - | hole diameter | |
gs | - | ultimate bond strength, given either as a parameter of the nail or as soil parameter. |
2. calculate from effective stress
where:
where: | Tp | - | pull-out nail bearing capacity [kN/m] |
d | - | hole diameter | |
σz | - | vertical geostatic stress | |
φ | - | effective angle of internal friction of soil | |
c | - | effective cohesion of the soil |
3. calculate according to HA 68/94
where: | Tp | - | pull-out nail bearing capacity [kN/m] |
d | - | hole diameter | |
σn | - | average radial effective stress | |
φ | - | effective angle of internal friction of soil | |
c | - | effective cohesion of soil |
Average radial effective stress σn is calculated by the following formula:
where: | σz | - | vertical geostatic stress |
where:
Nailhead strength value to be input. If the nail head is not fixed, then the strength value equals zero.