Online Manuals RFEM 6 | Concrete Foundations

Back to Online Manuals

132x

006025

Hedi Boukraa, M.Sc.

2025-06-12

Select Manual

Overview

Concrete Foundations Add-on

Theoretical Principles

Design Specifications

Design Properties of Single Foundations

Design

Results

Documentation

Geometry

The Geometry tab is used to enter the dimensions of the foundation plate and the bucket.

Concrete Foundations | Bucket Foundations, Tab Geometry

Variable	Designation
w_x / w_y	Dimension of the foundation plate in the x- and y-direction
t	Thickness of the foundation plate
h	Bucket height
d	Embodiment depth of the column
t_tx / t_ty	Bucket wall thickness at the top in the x- and y-direction
a_tx / a_ty	Column allowance at the top in the x- and y-direction
t_bx / t_by	Bucket wall thickness at the bottom in x- and y-direction
a_bx / a_by	Column allowance at the bottom in the x- and y-directions
α_x / α_y	Inner wall inclination in the x- or y-direction
e_x / e_y	Eccentricity in the x- or y-direction
c_x / c_y	Column dimension in the x- or y-direction

Use the button to display the dynamic model with the dimensions directly in the tab.

Bucket Foundations, Tab Geometry with Dynamic Model

Info

The column dimensions cannot be adjusted here. They can only be changed in the cross-section dialog box of the corresponding member.

Minimum Dimensions

It is necessary to observe the following minimum dimensions to ensure correct geometric design of the bucket foundation:

Embedment Depth

The embedment depth must not exceed the height of the bucket:

d \leq h

Bucket Foundations | Maximum Embedment Depth of Column

Bucket Wall Thickness Top

The minimum bucket wall thickness on the top is the maximum of four individual minimum values. The largest of these thicknesses defines the required wall thickness:

It is necessary for the bucket wall (depending on the type of the stirrup arrangement) to be dimensioned in such a way that the mandrel diameter, the diameter of the statically required vertical stirrups in the x-direction, the diameters of the horizontal stirrups in the y-direction (inside and outside), and the double concrete cover can be sufficiently taken into account:

\{\begin{cases} 2 \cdot (c_{k} + d_{m, v, x} + d_{s, v, x}) + d_{s, h, x} + \max (d_{s, h, outer}, d_{s, h, y}) + d_{s, v, y} \leq t_{tx} & stirrups enclosing the column \\ 2 \cdot (c_{k} + d_{m, v, x} + d_{s, v, x}) + d_{s, h, x} + \max (d_{s, h, x}, d_{s, h, y}) + d_{s, v, y} \leq t_{tx} & stirrups lying completely in the bucket wall \end{cases}

c_k	Concrete cover of the bucket wall
d_m,v,x	Minimum mandrel diameter of the vertical static stirrups in the x-direction
d_s,v,x	Diameter of the vertical static stirrup
d_s,h,x	Diameter of the horizontal stirrup in the X-direction (inside)
d_s,h,outer	Diameter of the outer horizontal stirrup
d_s,h,y	Horizontal stirrup in the y-direction
d_s,v,y	Diameter of the vertical stirrup in the y-direction

Bucket Foundations | Minimum Dimensions of Wall Thickness (1)

The second condition depends on the width of the column and the column allowance (top and bottom):

\frac{(2.0 \cdot a_{tx} + c_{x}) + (2.0 \cdot a_{bx} + c_{x})}{6.0} \leq t_{tx}

Bucket Foundations | Minimum Dimensions of Wall Thickness (2)

The third condition is a geometric specification that depends on the width of the column:

\frac{c_{x} + 15 cm}{3} \leq t_{tx}

Bucket Foundations | Minimum Dimensions of Wall Thickness (3)

To ensure an absolute lower limit, a minimum wall thickness of 10 cm is applied regardless of the reinforcement and geometry:

10 cm \leq t_{tx}

Bucket Foundations | Minimum Dimensions of Wall Thickness (4)

Info

The minimum dimensions of the wall thickness in the y-direction are to be considered in the same way as those in the x-direction.

Additional Minimum Dimensions

\{\begin{cases} (t_{tx} + a_{tx}) = (t_{bx} + a_{bx}) \\ (t_{t y} + a_{t y}) = (t_{b y} + a_{b y}) \end{cases}

Bucket Foundations | Bucket Width Condition

These relationships ensure that the total width of the bucket is identical in each direction at the top and bottom side.

\{\begin{cases} (t_{tx} \leq t_{bx}) & (a_{tx} \geq a_{bx}) \\ (t_{t y} \leq t_{b y}) & (a_{t y} \geq a_{b y}) \end{cases}

Bucket Foundations | Bucket Inner Wall Condition

These relations ensure that:

The wall thickness at the bottom is at least as large as the wall thickness at the top.
The column allowance at the top is at least as large as the column allowance at the bottom.

The bucket wall can either be vertical or sloped outward. An inward slope is prevented.

Rotation of Foundation via Nodal Support

The rotation of a foundation around the Z-axis is performed using the local coordinate system of the associated nodal support.
To do this, you need to create a user-defined local coordinate system and assign it to the nodal support.
The foundation adopts the orientation of this local coordinate system. Direct rotation of the foundation is not supported. A prerequisite for this application is that the local Z-axis of the nodal support is parallel to the global Z-axis.

Editing Local Coordinate System of Nodal Support

The orientation of the column has no influence on the alignment of the foundation. A rotation of the column about the global Z-axis can be performed independently of the foundation and is not strictly necessary for the design of the foundation; however, the use of foundations requires that the column be aligned parallel to the global Z-axis.

Parent Chapter

Bucket Foundation