Deriving moments and shears for a box beam modelled as a set of plate finite elements can be very difficult, as you transform and sum all the relevant forces at a section. SAM-LEAP5's "Composite Member" feature makes this process very easy.

You could argue that modern structural analysis software has become too powerful for its own good, because you can build the most amazingly complicated models, but when you ask a simple question like "What is the total moment at a particular point?" you cannot get a straightforward answer.

Take the case of a beam and a slab where the slab is modelled as a set of finite elements, and the beam is modelled as an offset beam element: to get a bending moment at any point you have to add the moments in the slab and beam and calculate the couple caused by the axial loads in the slab and the beam. This involves wading through masses of printouts, or scrolling through screen after screen of results and in fact makes a mountain out of a molehill! And it gets worse if you are analysing a box girder where the flanges and webs are modelled with plate finite elements.

At Bestech Systems we have found a solution to this problem and we call it "Composite Results". In effect what you do is to tell SAM-LEAP5 that a "Composite Member" exists that is made up of various elements, for example, the slab elements and the beam elements of our first example. This is quick and simple to do with a few mouse clicks on one of SAM-LEAP5's graphics screens. Then, when you ask for the results for the Composite Member, SAM-LEAP5 does all the necessary resolutions, transformations and summations and presents you with a simple bending moment or shear force diagram.

If you think this sounds too simple and too easy, you may want to have us show it to you in your office, so please contact us.