## Example 83 Propped Cantilever

A propped cantilever is L m long and supports a collapse load of w kN/m as shown in Figure 8.7. Determine the position of the plastic hinges and the required plastic moment of resistance Mp. Solution:

The number of hinges required to induce collapse=(ID+1)=2 (see Figure 8.1)

The possible hinge positions are at the support A and within the region of a distributed load since these are the positions where the maximum bending moments occur. In this case the maximum moment under the distributed load does not occur at mid-span since the bending moment diagram is not symmetrical. Consider the final bending moment diagram:

Figure 8.8

The maximum bending moment (i.e. Mp) occurs at a distance 'x' from the roller support and can be determined as follows;

Since the moment is a maximum at position 'x' the shear force at 'x' is equal to zero. Equate the Mp values to determine x: This is a standard value, i.e. for a propped cantilever the plastic hinge in the span occurs at a distance x=0.414L from the simply supported end and the value of the plastic moment Mp=0.0858wL2

This is a standard value, i.e. for a propped cantilever the plastic hinge in the span occurs at a distance x=0.414L from the simply supported end and the value of the plastic moment Mp=0.0858wL2

+8 -3

### Responses

• andrea
How to calculate moment of propped contilever with example?
2 years ago
• isto
How to determine moment of propped?
2 years ago
• Lidya
What is collapse load for propped beam?
1 year ago
• uffo
How can we calculate collapse load in propped cantilever?
5 months ago