Damage assessment for reinforced concrete frames subject to progressive collapse

Due to increasing threats from terrorism, progressive collapse modeling is gaining popularity with the objective of simulating the collapse process of the whole or partial structural system. In order to conduct an accurate progressive collapse modeling, one needs to identify damaged members and to trace the propagation of damage. Hence, good damage assessment criteria are vital to the modeling and analysis. Only with reliable damage assessment criteria, realistic collapse mechanisms of structures can be simulated. It can then provide useful guidance for a better and more economic structural design against progressive collapse. This paper presents a set of damage assessment criteria that can be easily implemented for progressive collapse analysis of reinforced concrete (RC) frames. Flexural, shear and axial damage criteria for RC members are separately proposed incorporating axial-shear-flexural interactions in the analysis. Three scaled moment-resisting RC frame tests were conducted to validate the proposed flexural and axial damage criteria. Three shear-dominant damaged tests were also modeled to assess the proposed shear damage criteria. The results obtained show that the proposed damage assessment criteria are effective and reliable for progressive collapse analysis of RC frames.