In the Block Reinforcement tab, you can define the reinforcement of the bucket. You can enter the horizontal and vertical stirrups separately.
The arrangement of the reinforcement varies depending on the surface texture of the bucket side. The input of both reinforcements is described in the following chapters.
Block Foundation with Rough Bucket Sides
- Vertical Reinforcement
The governing moment for the vertical reinforcement design is determined by the following formula:
To design the required steel cross-section of the vertical reinforcement, the width of an equivalent beam is required. It is calculated as:
The allowable moment MRd, which is greater than the failure moment Mgov, is then determined. This gives the required steel cross-section.
- Horizontal Reinforcement
The required steel cross-section of the horizontal stirrups Bu corresponds to the larger value of the reinforcements determined for both vertical directions.
Block Foundation with Smooth Bucket Sides
Block foundations with smooth bucket sides follow the same principle as bucket foundations with smooth bucket sides.
- Basic principle: Internal forces in block foundations
The load is transferred between the embedded column and the foundation block by a horizontal force couple. The moment ‘‘M’’ resulting from the bending moment and the horizontal force ‘‘H’’ are divided into two counteracting forces ‘‘Ho’’ (top) and Hu (bottom):
These forces act in opposite directions and it is necessary to transfer them to the concrete block via the reinforcement.
- Horizontal Reinforcement
In the horizontal plane, the foundation is considered a truss-like structural system with compression struts and tension struts. The inclination angle of the compression struts determines the required horizontal tensile force, which should be absorbed by reinforcement:
- Vertical Reinforcement
The vertical component of Ho generates splitting forces and edge forces along the bucket wall. The splitting force is usually so small that its influence can be neglected: