Methodology

Analysis Methods

You can choose whether to use the Advanced Yield Line Method or the older Panel Method.

Panel Method

In the panel method (Use AYLA not highlighted) the vertical loads are taken down through the wall along with the self-weight. Openings are dealt with by splitting the overall panel into sub-panels for both vertical and lateral (wind) loads. Note that the Panel Method can only handle 2 isolated openings.

You must select an appropriate design method for the openings – you can choose between the span horizontally, vertically, or reduced partial fixity methods.

If you choose to select span vertically, then you have the option to use Partial Fixity to main sub-panels. This will increase the size of the secondary panel above and below the openings. It will also take a partial fixity equal to 50% of the solid height to increase the support on the vertical edges of the main sub-panels from fully free to partially simply supported.

You can use the View Options in the Openings tab to display or hide support conditions, and the dead and live load calculation from each sub-panel design. You can also select to summarise the sub-panel design output and show the sub-panel division on the graphics.

You can use the General Settings icon to select the Output you wish to produce for the design of the openings.

Advanced Yield Line Method

To turn on the Advanced Yield Line Analysis method click on the Use AYLA icon. Using the down arrow next to the Analyse button, you can choose which node density to employ. Normally the Medium density will suffice for a first analysis. Then click on the Analyse button to activate the analysis of the wall.

In the advanced yield line analysis method, the vertical loads are taken down through the wall with localised additional compressive stresses being taken into account where there are lintels over openings or point loads bearing on the top of the wall.

Openings are dealt with using a sophisticated yield line analysis method when lateral loading is applied. This method analyses the wall including any openings and displays the locations of yield lines that will form in the plane of the wall. The heavier the line, the earlier that yield line will form. Blue lines will show where part of the wall is yielding in one direction with the green lines showing yielding in the opposite direction, for example, close to supports. The stiffness of the walls leafs, piers, wind posts and edge restraints are taken into account when calculating the yield line pattern and the wall’s capacity to resist the lateral forces.

You can choose to have the program update the calcs with every change of the input data (‘Auto-solve' icon) or wait until all the data changes have been made and then press the ‘Analyse’ button to update.

The source for the Advanced Yield Line Method is:- Munro J, Da Fonseca A, 1978. Yield line method by finite elements and linear programming. Structural. Engineer. 56B, pp37–44.

A technical document explaining the Advanced Yield Line Analysis method is available here.