EARTHQUAKES RESISTANT STRUCTURES & MORE !

CONTENTS

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GENERAL  INTRODUCTION

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Homogeneous composites have been with us for quite some time in the form of alloys (mixtures) and matrix composites in the form of Concrete. In the construction industry, we have extensively been using 'Reinforced' concrete; a composite material, and constructing Composite Structures (combination of rolled Steel sections and Reinforced Concrete Construction, etc.).  Most of these are non-homogeneous and heterogeneous arrangements. There are new materials being developed which have structures within structures, i.e. the building blocks are themselves becoming fairly complicated structures. Post-tensioning and pre-stressing have become more prevalent.

Materials have inherent and quite different properties. Interfaces of non-homogeneous materials are locations of (boundary conditions) stresses and strain incompatibility or separation.

'Soil' is a rather complicated heterogeneous structure in itself. Unlike air it is a medium with largely varying properties, having high density and the ability to behave smoothly like a fluid. Unlike fluid it also has the inertial ability to pull you in. Habitation structures normally lie in two mediums (exception: in space).

If the soil underlying the structure were to really behave awkwardly there is really nothing much that can be done. It would be difficult to design a structure to be able to remain afloat and stable in the most varying conditions of the soil (across the structures layout and in 'magnitude').

So essentially a good arrangement of the foundation system is a must. As is the non-disintegrating or non 'sequentially collapsing' (like a pack of cards) arrangement of the superstructure for providing safety and extended stability of the structure under severe earthquake or such loadings.

Here a collection of information and ideas is presented to make the reader aware of some important points that should be kept in mind while designing a structure or  assessing its safety and suggesting remedial measures.

Important to say that very tall and flexible structures are only susceptible to earthquakes if the entire foundation soil system comes apart. Very tall structures are more affected by the effects of large displacements, mainly due to severe wind loads. Sometimes earthquakes can be dangerous for the tall structures when the construction methodology and the elements put together create problems.