1. Fire Research Center, Korea Institute of Civil Engineering and Building Technology, 64, Mado-ro 182 beon-gil, Mado-myeon Hwaseong-si, Gyeonggi-do 18544, South Korea (corresponding author).
2. Dept. of Civil and Environmental Engineering, Univ. of Illinois at Urbana–Champaign, 205 N Mathews Ave., Urbana, IL 61801.