Abstract It was noted that a fully (symmetrically) distributed piezoelectric sensor/actuator could lead to minimum, or zero, sensing/control effects for antisymmetrical modes of structures, especially with symmetrical boundary conditions. One method to improve the performance is to segment the symmetrically distributed sensor/actuator layers into a number of colocated subsegments. In this paper, distributed vibration sensing and control of continua using segmented distributed piezoelectric sensors and actuators is studied. Sensing and control effectiveness of the segmented sensors and actuators are discussed. In Part I, mathematical models of a plate with a single-piece symmetrically distributed and quarterly segmented-distributed sensors/actuators are formulated and analytical solutions are derived. Modal sensitivities and modal feedback factors for the two sensor/actuator configurations are defined, and modal displacement and velocity feedbacks are formulated. Based on analytical solutions, this proves that the single-piece symmetrically distributed sensor/actuator layers are deficient for antisymmetrical modes (all even modes) of the plate. The quarterly segmented distributed sensors/actuators can sense/control most of the natural modes, except for all quadruple modes.