ABSTRACT
In this chapter, the author deals with the methods of obtaining influence lines for statically indeterminate structures but, by way of introduction and review, influence lines for statically determinate structures. An influence line shows the value of any action due to a unit point load moving across the structure. For example, the influence line for the bending moment at a section of a continuous beam shows the variation in the bending moment at this section as a unit transverse load traverses the beam. One of the most effective methods of obtaining influence lines is by the use of Muller-Breslau's principle, which states that the ordinates of the influence line for any action in a structure are equal to those of the deflection curve obtained by releasing the restraint corresponding to this action and introducing a corresponding unit displacement in the remaining structure.
