Structural health monitoring (SHM) is an important approach in order to evaluate the health state and so the safety and security of structures such as bridges. It also helps to maintain and to extend their servicibilities, to detect and predict their failures. This approach regroups several techniques such as vibration based inspections, acoustic, ultrasonic or magnetic field and radiographic methods. They are based on analyzing variations of some system’s characteristics and mapping them to the state of the systems and materials. For instance, in vibration based SHM, the variations of system characteristics in linear and nonlinear dynamics, e.g., frequency and damping shifts, changes of mode shapes and backbone curves, are directly related to the current state of the system.