Analysis Procedure for Earthquake Resistant Structures

In the recent two decades, the number of high intensity earthquake occurrence is incredibly increased which resulted many building damages and human lost. Inappropriate design of structures and construction process are the main reasons of buildings damage and collapse due to seismic load. The main challenge of structure design is determining the imposed earthquake load to the building and also the distribution of seismic load to the different structural components. Therefore, the main focus of this chapter is about calculation of earthquake load and process of seismic load distribution between structural members in various type of buildings such as steel and concrete structures. However, the same procedure can be implemented for distribution of any lateral load effect on structural elements such as wind load. In this chapter, the moment-resistance frame system is considered which is one of the most conventional earthquake resistant systems for buildings. This chapter is divided into 5 main sections: In the first section of this chapter, behavior of the moment-resistance frame system subjected to gravity and the lateral load is demonstrated. The approximate methods are implemented for analysis of the framed structure, and slope-deflection method is explained to calculate the displacement of moment resistant frame subjected to lateral load after determining of lateral stiffness of the frame. In order to clear understanding the highlighted concepts in this book, it is tried to demonstrate the application of explained theories and methods in real buildings in each section and describe all calculations and computations process for real structure details. For this purpose, a 6 story building is considered, and in the second section of this chapter, the all architectural plans and structure detail are presented. The third section of the first chapter is devoted to defining the gravity load and seismic force based on IBC Code and EURO CODE and determining of the center of mass, stiffness, shear rigidity and the eccentricity of each floor level of building by proposing the calculation charts. Furthermore, the distribution of the earthquake force in the structural members using the Portal and Cantilever methods are explained in details. The fourth section illustrates the calculation procedure for determining displacements in the different frames in two perpendicular directions of the moment-resistance structure subjected to earthquake force. Finally, the fifth section of this chapter presents the proposed charts and detail calculation of weight, stiffness, and displacement of the floor levels and frames of the considered structure.

In this chapter, the braced frame system and its effects on building systems is demonstrated. The first section of this chapter focus on the behavior of the braced frame system subjected to gravity and lateral load. The structure is analyzed by approximate methods and the virtual work method is used to explain and calculate the frame’s displacement under lateral load. Different types of bracing system are demonstrated and the lateral stiffness is determined. In order to better demonstration of bracing design concept, a 6 story building is considered and its architectural and structural detail plans are given in the second section of this chapter and the applied theories and methods, along with all calculations and computations processes related to the real considered building are explained.

In this chapter, the concrete shear wall system and its effects on building systems is discussed. The first part presents the concept of shear walls and its characteristic. Approximate and virtual work are implemented to determine the displacement of concrete shear wall frame with considering the lateral stiffness of frame as well when subjected to a lateral load. The next section presents the architectural and structural detail of considered 6 story real building and all described calculations and computations processes are applied on this structure.

Chapter four focused on demonstration the basics of structural dynamic and explain the fundamental process to determine structural seismic response. In order to have a clear comprehending of the highlighted concepts within this book, it is tried to present the application of theories and calculation processes in a real buildings in all sections. Therefore, a 6 story building is considered and in the second section of this chapter the architectural plans and structure details are demonstrated. The third part of this chapter describes the response spectrum analysis and the analytical model for the multi degree-of-freedom (MDOF) structure. The shear force for every mode is computed from the natural frequency and eigenvalue analysis of the structure. The square root of the sum of squares (SRSS) technique and complete quadratic combination (CQC) technique are employed to determine the critical seismic responses for considered structures using maximum modal responses. In the last section, the procedure for nonlinear static analysis is demonstrated after describing the concept for plastic hinge occurring in the structural member. The nonlinear static analysis technique is considered as one of the mainly applicable techniques for nonlinear analysis of the structures subjected to lateral load.