الفهرس 
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Abstract
The terrorist activities and threats have become a growing problem in Egypt and all over the world. Protection of the citizens against terrorist acts involves prediction, prevention and mitigation of such events. In the case of structures, an effective mitigation may also be thought in terms of structural resistance and physical integrity. So, there is a need to become familiar with the issue of a progressive collapse due to sudden removal of one bearing element or by blast load. This will help in proposing some guidelines for Egyptian Code of Practice for Design and Construction of Concrete Structures (ECP. 203-2007) and Egyptian Code of Practice for Calculating Loads and Forces on Structures and Buildings (ECP. 201-2012) on the verification of structures exposed to a progressive collapse due to sudden removal of one bearing element or by explosions.
Progressive collapse prevention of buildings has recently become the focus of many researchers, design engineers, and officials all over the world particularly after the failure of the twin World Trade Center towers, New York City, USA in September 2001 and the increasing terrorist acts against governmental buildings. To date, there are design guidelines which are prepared by different bodies like Department of defense (DoD) in USA, the General Service Administration (GSA) and the Federal Emergency Management Agency (FEMA).
Among the causes of the progressive collapse is the blast loads caused by explosions or terrorist attack. Generally, conventional structures are not designed for blast loads due to the reason that the magnitude of load caused by blast can be huge and therefore, the cost of design and construction is very high. Up to now, there are no code requirements for blast design. Only guidelines, for example; design guidelines for military structures for blast loads (TM-5-1300) which is periodically updated and a more functional version of it is currently, UFC 3-340-02, by DoD, USA.
While design for progressive collapse prevention is possible at the design stage, it becomes more challenging for already existing buildings. On the other hand, almost all recently designed and constructed buildings are designed for seismic resistance. Seismic design provisions allow for higher resistance to lateral reversible loads, and more ductility of structural frames and systems. Determining how much such provision adds to the building resistance to progressive collapse help when upgrading existing building for progressive collapse or when designing new ones. Furthermore, utilizing this seismic resistance and added ductility could be utilized when designing for progressive collapse. This research focuses on identifying the effect of seismic design on resisting progressive collapse due to sudden removal of one bearing element or due to blast loads.
Numerical simulation of a progressive collapse of structures using computer has a variable actual apprehension for structural engineers due to their interest in structures veracity estimation. This simulation helps engineers to develop methods for increasing or decreasing the progressive failure. In this research, first, a verification of the computer program Extreme Loading for Structures (ELS) based on Applied Element method (AEM) is conducted. Numerical modelling based on seven experimental studies available in the literature are utilized for verification. The obtained numerical results showed the capability of AEM in simulation of the progressive collapse behavior of structures. Furthermore, the results showed a better accuracy than those obtained using other software packages such as; OPENSEES, ABACUS and MSC MARC.
Second, the progressive collapse for three low rise reinforced concrete framed buildings using non-linear dynamic analysis is presented. The first building is a symmetrical regular building which is designed using ECP. 203-2007 for gravity loads but without taking lateral loads into consideration. The second building has the same dimensions of the first building but designed using ECP. 203-2007 for both gravity and lateral loads using ECP 201-2012. The third building is a unsymmetrical building which is designed for both gravity and lateral loads using ECP 201-2012. The study includes a progressive collapse by sudden removal of one of the main load bearing vertical elements according to both GSA (2003) guidelines scenarios and new suggested scenarios based on the virtual work diagrams (VMD) functionality provided in SAP2000 for the critical members. Moreover, a study for progressive collapse by blast loads with different scaled distance is presented. The obtained results showed that the vulnerability to progressive collapse becomes less in the seismic design building than the building which isn’t seismic design. This is mainly due to the increased member capacity, added ductility and the seismic requirement for reinforcement details. Also, the results showed that the new suggested scenario based on VMD is more critical than GSA (2003) scenarios. In addition, the results showed the failure of columns due to sudden column loss is less in effect than the failure of column due to blast loads. Moreover, the results showed as the blast load scaling distance increased; the behavior of building is changed from no effect, near columns failure but no collapse, partially collapse and total collapse. Finally, the results showed the new suggested scenario based on VMD technique can aid structural engineers in choosing which of the corner, edge and interior column is the most critical column for each case in the building especially, for unsymmetrical building.