In order to assess structural safety conditions, many vibration-based damage detection methods have been developed in recent years. Among these methods, transmissibility function analysis can utilize output data only, and proves to be effective in damage detection. However, previous research mostly focused on experimental validation of using transmissibility function for damage detection. Very few studies are devoted to analytically investigating its performance for damage detection. In this paper, a spring-mass-damper model with multiple degrees-of-freedom is formulated for further analytical studies on the damage sensitivity of transmissibility functions. The sensitivity of transmissibility function against structural mass and stiffness change is analytically derived and validated by numerical examples.© (2011) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.