As in the previous edition of Seismic Design of Building Structures, considerable effort was made to present the material in both customary U.S. and SI units. All of the examples and problems continue to give you a choice of units: You can choose to work solely in SI, solely in customary U.S., or in both (for twice the practice). This edition reverses the sequence of many dual-dimensioned items, however, placing the customary U.S. values first to correspond to the unit system typically used in actual seismic design.