Active structural flow control has emerged as an effective way to suppress the vibration of large structures by controlling in the vicinity of the disturbances with a limited number of sensors and actuators. This is in contrast with other active structural control strategies which employ distributed sensors and actuators to provide a global control of the modes of the structure. This paper presents theoretical and experimental structural intensity control results, where the instantaneous intensity is completely taken into account in the control algorithm, i.e. all the terms are considered in the real-time control process and, in particular, the evanescent waves are considered in this approach. Moreover, both the flexural and extensional waves are taken into account in the control algorithm. As they are especially well-suited for integration into structures in order to create smart materials, piezoelectric strain sensors (PVDF) are used in the sensing approach. The structural intensity is estimated from the discrete strain measurements using a finite difference scheme. A feedforward filtered-X LMS algorithm is adapted to this energy-based control problem, involving a non-positive definite quadratic form in general. In this respect, the approach is limited to cases where the geometry is such that the intensity component will have the same sign for the control source and the primary disturbance. Experimental validation of the approach is conducted on a structure made of a beam connected to a plate, where the beam is covered with viscoelastic material. A comparison of the proposed approach is made with classical acceleration control and these results show that intensity control using strain sensors allows the error sensors to be placed closer to the control source and the primary disturbance, while preserving a good control performance.