The Effect of Non-implementation of the Beam Roof of the Last Floor Block on the Irregularity of the Analysis and Design of the Structure

Abstract

Knowledge about the earthquake phenomenon is increasing day by day, and building regulations are evolving due to these developments. Previously, all the structures were designed in the elastic range and depending on the intensity of seismicity of the region and the importance of the structure, but now the regulations consider the structures to withstand significant inelastic deformations under the forces resulting from earthquake movements. In general, in earthquake-prone areas, it is not economically appropriate to design common buildings in such a way that these structures remain in the elastic range during severe earthquakes. The development and progress of the knowledge of the dynamics of structures, on the one hand, and the increase of information obtained from recorded earthquakes, on the other hand, show that various factors are effective in the amount of earthquake force. Some of these factors are related to the dynamic properties of structures, such as periodicity, damping, mode shape, structure malleability, etc. In addition, other factors, such as the type of soil and the level of seismicity of the place, are also effective in determining the strength of the earthquake. In fact, the building is not rigid, and it changes shape and vibrates during an earthquake so that the displacement and acceleration created in it gradually increase from the first floor upwards. Also, the natural period of its vibration will be longer, and the acceleration caused by the earthquake will be smaller. In other words, the taller the building, the smaller the acceleration of the earthquake.