1. Ph.D. Candidate, Dept. of Civil Engineering, Imperial College London, London SW7 2AZ, U.K.
2. Research Associate, Dept. of Civil Engineering, Imperial College London, London SW7 2AZ, U.K. (corresponding author).
3. Structural Dynamics Capabilities Leader, Defence Science and Technology Laboratory (DSTL), Porton Down, Salisbury, Wiltshire SP4 0JQ, U.K.
4. Reader, Dept. of Civil Engineering, Imperial College London, London SW7 2AZ, U.K.