Identifying the Fixed Base Location of Building Structures under Seismic Excitation

The identification of the location of the fixed base at the bottom of a typical structure with a constant stiffness over its height in an earthquake zone is of extreme importance in the design of building structures. Few seismic design codes and investigators have suggested procedures that determine the location of the fixed base (the zero displacement position) ; these suggested methods are rather simplified and dont give the designers accurate values for the location of the base shear and maximum moment positions on the basement of a structure; this location is very important especially when using static lateral force methods for evaluating structural loads. This work provides a procedure that allows designers to locate the fixed base when subjected to seismic excitation considering the type of the soil surrounding basements. It also gives an upper and lower limit for the structure that should be chosen considering the soil-structure flexibility.