The goal of seismic design is to determine the proportions of structural elements and their detailing so that the code requirements are fulfilled as well as the optimal configuration from the point of view of building function, easy construction and maintenance, labor and material economy, minimizing the need of post-seismic intervention. In respect with these requirements, so different in their nature, the structural design
is similar to the process of creation of an artwork object, mobilizing powerful professional knowledge and skill, capacity of imagination and specific technical sense. Selection of appropriate analysis methods, good communication with the architect and capacity to accept rational compromises from both parts (architect and structural designer) without altering the general conception, implementation of lessons drawn from design, construction and behavior of existing buildings are premises for obtaining an optimal solution. The purpose of the present book is to examine and to present essential aspects of
behavior, analysis, design and detailing of reinforced structures for buildings subjected to strong seismic actions. It tries to show how the up-to-date principles and methods of Earthquake Engineering can be applied to seismic analysis and design of reinforced concrete structures for buildings. The traditional way of presenting the fundamentals of reinforced concrete structures, based mainly on hand-made elastic analysis, evolved nowadays towards advanced approach based on the extensive use of powerful software packages able to simulating accurately the reinforced concrete seismic behavior. Topics like post-elastic, dynamic and hysteretic behavior and corresponding analysis methods, design procedures meant to ensure a controlled, predictable seismic response of structures can be nowadays implemented into advanced seismic analysis and design. The authors of present book believe that only a thorough understanding of the basic notions, concepts and assumptions of up-to-date methods of seismic analysis and design enable the structural designer to select appropriate strategy in searching optimal solution for each specific structural system. Following this conception, the present book starts with the examination of fundamental aspects of reinforced concrete behavior quantified through constitutive laws for monotonic as well as for hysteretic loading. Basic concepts of post-elastic analysis like plastic hinge, plastic length, fiber models, stable and unstable hysteretic behavior, etc. are, accordingly, defined and commented. Based on this theoretical background the seismic behavior, analysis, design and
dual systems – are examined and presented. Recommendations have been formulated for optimal usage of each of these systems. Principles and rules for conceptual design have been synthesized for each basic structural system of earthquake prone buildings. Several case studies are presented trying to illustrate the design process steps. Trying to synthesize the most relevant aspects of seismic design of buildings, as
developed within present book, following recommendations can be highlighted:
1. In contrast with gravity-dominated buildings, those subjected to high intensity seismic actions behave under lateral forces similar to a cantilever. The cantilever behavior ofmultistory building subjected to high-intensity seismic actions suggests advantageous (recommended) shape and proportions of the building. It is advantageous to avoid excessive building slenderness (recommendable total height/total width less than 3-5); this is an efficient way to ease the fulfillment of basic requirements of good seismic conformation. Try to obtain as far as possible symmetrical plan shape and similar (close) stiffness of the whole system according to principal axes. Potential pounding between building sections or between adjacent buildings have to be prevented. Similar danger occurs when two neighboring buildings are connected through pedestrian bridges inappropriately treated. Cantilever effect justifies also the need of appropriate foundation system for the whole structure rather than for isolated elements. Optimal recommended solution is to provide medium-and high-rise buildings with rigid and strong infrastructure, located at the basement level, consisting of a system of walls, horizontal diaphragms and a raft.