Abstract

The monograph is subdivided into two parts. The first part presents concepts of seismology such as intensity or magnitude, together with probabilistic concepts related to the vulnerability and the potential damage that can occur in reinforced concrete and masonry buildings. Procedures for the preliminary design of buildings are included together with conceptual design recommendations. A brief introduction to the expert systems is made, presenting the qualitative reasoning systems in more detail and giving examples for the preliminary design of structures. Finally, a summary is made of the equations that govern the dynamics of linear and non-linear structures and their solution, including numerical procedures for the modal uncoupling and the step-by-step integration of the equations of motion. In the second part of the monograph, the non-linear behavior of structures subject to earthquakes is studied. This allows to predict the response of inelastic structures without the need of performing a non-linear analysis. The relative influence of various parameters such as structural damping, global ductility and the coefficient of strength is presented in detail. Next, the seismic action necessary in the analysis of structures is defined by means of accelerograms and seismic response spectra, but the one performed in several design standards of the world is also discussed. Finally, procedures are developed for the seismic design of structural elements and systems such as reinforced concrete ductile frames, dual systems and eccentric frames. The monograph includes a brief synthesis of earthquake-resistant design codes.

Abstract

The monograph highlights the way in which, in the long term, the application of design standards can lead to a reduction of seismic risk in urban areas. The seismic design standards make recommendations regarding the seismic loads to be used, the simplified methods of structural analysis, the criteria that must be applied to ensure a good overall behavior of the same, as well as the design details that must be incorporated. The structural analysis procedures foreseen in all the world standards are based on concepts generally used in the static and dynamic calculation of structures. However, the concepts considered when using these simplified procedures of dynamic analysis and the approximate formulas for the determination of the dynamic characteristics of buildings, are not explained. For this reason, the monograph analyzes the content of the seismic-resistant design regulations in relation to the analysis methods they propose, explaining the concepts of structural analysis that are applied in each case, with special reference to the Spanish regulations in vigor, NCSE-02. Since many design codes include rules that are not justified in the text of the regulations, this monograph also deals with aspects of the so-called conceptual design that requires decisive decisions in the initial phases of the design of structures, which condition the seismic behavior of the same. To facilitate the application of the dynamic analysis of buildings, a program developed in Matlab ® has been incorporated, which can be obtained from the web page www.cimne.com/is-56/modal, together with the data files and results, which are described in the Annex to this monograph.

Abstract

The monograph begins with a review of the usual seismic analysis procedures and presents the problem of seismic-resistant projects. The required structurual analyses can be elastic or inelastic, but the latter have been used mostly during the last decade thanks to advances in numerical methods and in the area of ​​computers. It also presents a summary of the most common seismic codes prescriptions for reinforced concrete elements and examines aspects of conceptual design that often come from code recommendations. Next, an introduction to the theme of performance based design is made. A method for linear seismic dimensioning is then developed, but with displacement amplification factors obtained from research performed on the nonlinear behavior of the structures. This method allows the displacements, and not the strength, to govern the project, is simple to apply, compatible with most of the rules required by the earthquake resistant structures and is illustrated by the application to a group of reinforced concrete framed buildings. Once the buildings designed, they be subjected to seismic actions of the pseudostatic or dynamic type and will undergo a non-linear behaviour. The response of the structures is evaluated by applying a set of limit states formulated in accordance with the principles of performance based design. The non-linear response allows to calibrate some of the factors applied in the seismic project, such as the global ductility, the behavior factor and the redundancy factor and resistance reserve. From the non-linear response, damage indices are obtained, both local and global, that allow the rapid evaluation of the seismic behavior, as well as the identification of the areas in which the damage is concentrated and which must be reinforced. Finally, using a series of thresholds that allow the definition of the limit states, a mixed procedure (deterministic-probabilistic) is applied by means of which the exceedance probabilities of the mentioned states are calculated. These procedure allows calculating fragility curves and damage probability matrices that applied according to the conceptual framework of the performance based design, allow obtaining earthquake resistant buildings.

Abstract

The earthquake resistant design codes in force in the different countries are applied to the field of building structures. However, some of the standards give a certain appearance of "generality" that can give the impression that these are mandatory for any type of structure. In fact, the rules are general only in the definition of the seismic hazard of the area to which they apply, that is, in relation to the maximum ground acceleration. However, in each country, there are other specific codes for the design of non-building structures. This chapter describes the dynamic calculations foreseen in the building seismic design standards; the use of simplified, shear building models; the usual procedure of dynamic calculation of structures based on modal analysis; and, finally, the use of linear and non-linear response seismic spectra, which provides only the maximum response of the structure.

Abstract

A proposal to estimate both the hydrodynamic pressures and the maximum wave height of liquids contained in rectangular tanks subjected to earthquake ground motions is presented. The computation procedure, based on the Rayleigh-Ritz method, assumes the fluid as a continuum and it does not use concentrated masses or springs. The solution is achieved by equating the seismic input energy of the system with the total kinetic energy of the fluid assuming liquid velocity fields. The resulting design formulas are simple and they are intended to simplify the seismic design of tanks. Numerical results lead to both the liquid maximum sloshing height and hydrodynamic pressure distributions that are similar to those obtained with other simplified methods and those estimated with the finite element method. Preliminary estimations of shear forces and bending moments for a numerical example resulted 13% and 6% larger (respectively) than the corresponding values obtained with the finite element method.