Piezoelectric active structural elements with built-in sensing and actuation function and feedback control are used to suppress vibration in adaptive truss structures. The problems of optimal placement and feedback gain of these active members are two important issues, which should be addressed in the design of adaptive truss structures. An efficient optimal placement strategy has been developed using minimum control energy dissipating over an infinite time interval. The nearly optimal placement of active members is consistently treated through the use of the control energy dissipating over an infinite time interval within the framework of the simulated annealing algorithm. Moreover, considering the material characteristics (modulus of elasticity and density of material), the geometric characteristics (the length and cross-sectional area of truss members), and external force such as the random variables, a mathematical model with reliability constraints on stress and displacement has been developed and using a probabilistic optimization technique the optimal velocity feedback gain of active members has been obtained. Illustrative examples are used to demonstrate the effectiveness of this methodology. It has been shown that the deterministic approach cannot provide reliable optimum design values.