Abstract

This article aims to understand the response of soil deposits underlying bedrock fault displacement in three dimensions. When an active bedrock fault ruptures, movement along the fault propagates through the overlying soil and produces zones of intense shear. Hence, it is important to study the surface behaviour based on fault characteristics. Hence we attempted to develop application of Ap- plied Element Method by modelling the fault rupture zone. In this article, we have modelled the fault rupture problem in three dimensions. First, a simple model is used to illustrate absorption of the bedrock deformation by the overlying soil in elastic case. In the later part, nonlinear analysis is car- ried out to study the complex failure propagation in three dimensions. Influence of mechanical properties of the material is also discussed.

Abstract

The great devastating tsunamigenic earthquake of 26 December 2004 in sumatra was quickly followed by another great one on 28 march 2005 in the same region. This is for the first time in the known histroy of seismology that 2 great earthquakes have occurred in close spatial proximity in such a quick succession. In the present study we highlight the role of the multiple plate junction comprising the India, Burma, Australia and Sunda plates in in generation of such great earthquakes.

Abstract

On 26 December 2004 a devastating earthquake of magnitude 9.3 occurred in Sumatra region of Indonesia. This earthquake produced the world’s deadliest tsunami in the Indian Ocean region that claimed more than 300, 000 lives. This earthquake was quickly followed by another great one of magnitude 8.7 on 28 March 2005 in the same region. This is for the first time in the known history of Seismology that 2 great earthquakes have occurred in close spatial proximity in such a quick succession.

Abstract

India shares over 16% of world population with only 3.4% of landmass. This has resulted in the dispersion of population to disaster prone regions. Therefore even moderate earthquakes are resulting in high damage estimates. Growing opportunities, better health care and good education is holding a significant population in Indian meg a cities but almost all of these cities lie in Seismic zone III or above which is having the possibility of earthquakes up to intensity VII or more. All these factors necessitate an effective Disaster Management System in India.

Abstract

It is very well recognized that structure which is stiff interacts dynamically with soil during earthquakes. In order to carry out the investigation in dynamic way, the main problem that will arise in modeling is unbounded nature of soil medium. The real field is not surrounded by any boundary and any numerical model that we study have to be defined by using a proper boundary that takes care of radiation of dynamic energy into unbounded soil. Conventional boundaries used for studying the structural analysis may not give proper results for qualitative discussion. So, we need to model the soil similar to actual field conditions. For that we need to model an absorbing boundary condition.

Abstract

The earthquake-resistant design methodology in most existing codes of practice is based on ensuring no collapse” during the most severe event expected at the given site while most of the input energy is dissipated through inelastic deformations. Evolution of the performance-based design over the last decade has seen a few performance levels added up to this so that the structure remains functional even after a moderately strong event. This methodology however overlooks the possibility that in case of multiple earthquake events expected during the design life of the structure the structure may get gradually damaged and that it may not be feasible to carry out repairs in the structure after every damaging event. As a result, the structure may collapse earlier than expected and perhaps during an event of moderate intensity. To address such a concern a new spectrum, called as design force ratio spectrum is proposed in this paper. DFR spectrum gives the ratio by which the design yield force level of a conventionally-designed single degree of freedom structure should be raised such that the damage caused by all earthquake events expected to occur during its lifetime is limited to a specified level. A numerical study is carried out for a hypothetical seismic region by following a simple procedure based on several assumptions and DFR spectra are obtained for elastic-perfectly plastic oscillators when the return periods of earthquakes follow exponential distribution over the entire range of magnitudes.

Abstract

This article aims to understandthe response of soil deposits underlying bedrock fault displacement in three dimensions. When an active bedrock fault ruptures movement along the fault propagates through the overlying soil and produces zones of intense shear. Hence it is important to study the sruface behaviour based on fault characteristics. Hence we attempted to develop application of applied element method by modelling the fault rupure zone. In this article we have modelled the fault rupture problem in three dimensions. First a simple model is used to illustrate absorption of the bedrock deformation by the overlying soin in elastic case. In the later part nonlinear analysis is carried out to study the complex failure propogation in three dimensions. Influence of mechanical propertices of the material is also discussed.

Abstract

India has witnessed 6 earthquakes during past 15 years causing around 40,000 casualties and immense property loss. More than 90% of these casualties are due to collapse of buildings and they occurred within very short period of time after the earthquake. Hence, for reducing casualty losses and subsequent consequences due to earthquake, it is very important to study the response of structures due to seismic excitations. This paper contributes to understand the importance of concrete constructions in earthquake disaster mitigation. Paper first discusses the effects of earthquakes of past in general and gives a brief summary of 26th Jan, Bhuj earthquake. Shortcomings observed in constructions during authors visit to Bhuj are highlighted. Finally the recommendations for concrete constructions are given.

Abstract

India has witnessed 6 earthquakes during past 15 years causing around 40,000 casualties and immense property loss. More than 90% of these casualties are due to collapse of buildings and they occurred within very short period of time after the earthquake. Hence, for reducing casualty losses and subsequent consequences due to earthquake, it is very important to study the response of structures due to seismic excitations. For studying the response of the structures and consequent issues after the earthquake disaster, information technology can play a major role. This paper contributes to understand the importance of information technology in earthquake disaster mitigation.

Abstract

Natural disasters like earthquake, landslide, flood, drought, cyclone, forest fire, volcanic eruption are quite common in different parts of the globe. These natural disasters lead to the loss of life, property damage and socio-economic disruption. Earthquakes are one of the worst among the natural disasters. Seismic zonation map given in IS 1893:2002 shows that India is highly vulnerable for earthquake and over 60% of India is prone to moderate to major earthquakes. During past century, India has witnessed more than 650 earthquakes of magnitude greater than 5 and during past 15 years, 6 earthquakes of magnitude over 6. From recent earthquakes, it is very well understood that lack of awareness is one of the contributing factors for huge casualty losses. In order to increase the awareness about the effects of earthquakes among professionals involved in construction, it is necessary to make them understand the concepts of structural dynamics and earthquake engineering. For this, we have developed a software tool called Interactive Structural Dynamics Learning Kit (ISDLK) for explaining structural dynamics in a simple manner. For convenience in explaining the concepts, we divided the tool into six modules. Each module contains few experiments with good G.U.I. In these modules, user can input the value and he/she can find the desired results with explanation using graphical diagram. At the end of sixth module, user can understand the complete dynamic behavior of a structure. ISDLK aims to help students, architects and design professional in understanding structural dynamics.