The development of damage identification methods that enable rapid implementation holds great promise for assessing structural integrity to avoid further damage or catastrophic failure. Here, an on-line model updating approach is proposed to rapidly and simultaneously identify the mass, stiffness, and damping properties of a structural model. The proposed approach facilitates identification of these unknown parameters using two steps: first, energy equilibrium equations are used to establish a relationship between structural energy and unknown parameters; second, the Kalman filter is adopted to obtain the unknown parameters in a short period of time. Numerical verification is conducted on a 158-degree-of-freedom truss model with 324 unknown parameters based on a real-world structure. The results indicate that the proposed approach can simultaneously identify the model parameters for the mass, stiffness, and damping of both the damaged and undamaged structures online, and also can effectively identify the stiffness damage and mass change, even in an environment with noise. Copyright (c) 2016 John Wiley & Sons, Ltd.