Investigating the impact of structural systems on the potential for progressive collapse in reinforced concrete buildings due to column removal

Progressive collapse is a particular phenomenon in structures in which all or a part of the structure is collapsed due to a local damage or fracture in a limited part of the structure. This phenomenon is often triggered by an accident such as an explosion in the structure and then progresses for reasons other than the proper redistribution of forces between other members of the structure. In this phenomenon, failure is often triggered by an accident such as an explosion in the structure and then progressed to other parts of the structure due to some reasons such as inappropriate redistribution of forces between the other structural members. In recent years, study on progressive collapse in structures has been increasingly taken into account and a number of different researches have been conducted on this topic. One of the issues discussed in this regard is the impact of structural systems on the potential for progressive collapse in buildings. One of the most common types of building structures is reinforced concrete buildings that are also widely used in Iran. In these buildings, various types of structural systems such as “moment-resisting frames systems”, “bearing wall systems”, “dual systems include moment-resisting frames and shear wall”, etc. are used. Choosing an appropriate system to have more safety against a premature failure requires knowledge of the behavior of these systems against this phenomenon. Proposing and choosing an appropriate structural system to have more safety against the progressive collapse, taking account economic considerations, requires having sufficient knowledge of the behavior of these systems against this phenomenon. In this paper, an attempt has been made to compare the behavior of various structural systems of reinforced concrete structures against the progressive collapse. In this regard, after literature review on the researches and existing standards/codes provisions related to this issue, nine reinforced concrete frames different in structural systems or number of stories have been modeled and the behavior of these frames has been investigated. These frames consist of 3, 7, and 10-story frames, as well as three structural systems: “Intermediate reinforced concrete moment frame”, “special reinforced concrete moment frame” and “Intermediate reinforced concrete moment frame + Intermediate reinforced concrete shear walls”. The loading and design of these frames is done in two ways: taking into account the criteria for progressive collapse, without taking into account these criteria. In the design of the structures with the aim of preventing a progressive collapse, the UFC-4-023-03 regulations have been used and these structures have been evaluated under different column removal scenarios. Finally, the provisions for linear and nonlinear analysis presented in this code are also compared. The results show that in terms of the ability to withstand the loads on the structure after column removal and also economic considerations, “Intermediate reinforced concrete moment frame” have better behavior than other structural systems studied in this paper. Moreover, in the studied structures, it is determined that the UFC-4-023-03 regulations, in the nonlinear analysis method, has been provided more conservative criteria compared with linear analysis.