In 'Sap2000 Analysis Reference', there says 'Influence lines are available after any analysis for which traffic lanes were define. It is not necessary to define Vehicles, Classes, Moving load cases, or response control in order to get influence lines'. However, I don't understand what this paragraph means. In what kind of analysis except bridge analysis we need traffic lanes? I had a try in an example. I defined the traffic lanes and run a static analysis case. After analysis, I find 'show influence line' in display menu. But in fact all the values of influence lines are ZERO!!! So I maybe misunderstood the paragraph listed above.
Can somebody give me some help. I just want to use sap2000 to get influence lines of a beam or a truss. Thank you very much!