2. MODELING

CHAPTER 2 "MODELLING" 97 Enter the serial number of the member " A/A " and the start nodes " i " and end nodes " j ", the Rigid Offsets and the geometric and inertial characteristics, or let the program calculate them automatically. In this case select "OK" and point mouse to the start and end nodes on the screen in either 2D or 3D view. In detail: ❖ " Press , B-3d : The type of rod used in most cases. There are intensive quantities from all kinds of works and forces (tension, compression, bending, shearing, etc.) depending on the degrees of freedom of the member. Truss : The type of rod which is stressed only by axial forces. CAUTION not to be used when at least one of its two nodes belongs to a diaphragm. B-3def (Beam 3d on elastic foundation) : The type of beam used in the foot beams. In this case there are no works from axial forces. The start and end nodes are buttressed in x and z displacements and for y bending. ❖ " Cross-sectional Performance ", You can enter the physical cross-section you want so that the program can calculate the cross-section automatically its inert elements. First select from the list whether the cross-section you enter will be a beam or column. Pressing the key "Cross-section." appears respectively, the beam or column input mask where you enter the data, based on what was mentioned in the corresponding paragraph, where you select the material, cross-section and layer: By selecting the "OK" button in the cross-section input mask, you return again to the bar input mask where you can now see in the corresponding fields the inertial elements of the cross-section as well as the type and dimensions of the cross-section. The checkbox next to the " Cross section button is checked which means that the rod you will enter has a "physical" representative which will be displayed and dimensioned normally. If you wish the rod you insert to participate only in the mathematical model as a take-up of intensive quantities you should uncheck this checkbox. OBSERVATIONS: Under the "Cross-section" command, there is a list that only applies to metallic cross-sections and requires the selection of the corresponding group each time you assign a metallic cross-section to the member.