Abstract

Recorded large earthquake show that different sigment may reputre at different velocities.

Abstract

The M9.3 sumitra earthquake ot 26th december 2004 is due to largest recorded seismic event along Anadama- Sunda subduction zone.

Abstract

Since many decades different ports of world's forest envirornment is getting depleted because of many other factors but major deplection due to random forest fires.

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The Doda Earthquake of 1st May 2013 at 12:27 Hrs. (IST) hit border region of two states of India (Jammu & Kashmir and Himachal Pradesh) (Mw= 5.8). This paper describes the findings of the 5-day post-earthquake reconnaissance survey undertaken in the affected areas with particular emphasis onbuilding typology, construction materials and construction practices. Post-earthquake damage assessment of the built environment suggests that recently built structures do not have adequate earthquake resistant featuresto resist severe earthquake shaking (of about IX on MSK scale) expected in the region. On the other hand, traditional constructions with good earthquake resistant features performed much better.The maximum intensity of shaking during the said event was only about VI on MSK scale, and the damage was less. But, the type of damage suggests that huge losses can be incurred in the region during a future earthquake of higher intensity, if the built environment is not retrofitted.

Abstract

Dam is one of the biggest structures built on the Earth. It is known as a life line structure, as it serves the purpose of irrigation, hydro-electric power generation, flood control, domestic and industrial water supply etc., which are important for human existence. This makes dam as a reliable structure. For this reason, dam should always be designed for highest safety, resisting worst forces of nature. India is a country with over 5,100 large dams. India is also a seismically active country with over 1,040 active faults. Earthquake events like 1988 Bihar, 1991 Uttarkashi, 1993 Killari, 1997 Jabalpur, 1999 Chamoli, 2001 Bhuj, 2002 Andaman, 2004 Sumatra, 2005 Kashmir, and 2011 Sikkim have caused enormous loss of life and property in the country. Also events like 1992 Landers, 1994 Northridge, 1995 Hyogoken-Nanbu and few other events that took place around the world proved how devastating an earthquake could be, particularly if it is near-field. Near-field ground motions could cause more damaging effects on structures, as they were observed to differ dramatically from the characteristics of their far-field counterparts. The propagation of fault rupture towards a site at very high velocity causes most of the seismic energy from the rupture to arrive in a single or multiple large long period pulse of motion, which occurs at the beginning of the record. This characteristic of near-field ground motions could cause damage to a wide range of structures including dams. Several dams that were built in India, which are in highly seismic zones are prone to near-field ground motions. In

Abstract

Pipeline generally extends over long distances traversing through wide variety of different soils, geological conditions and regions with different seismicity. Majority of the past works in the area of pipeline subjected to fault motion is restricted in several ways. There were many analytical models developed in the past for pipeline fault crossing, however, they are of limited usage, for example analytical model developed for pipeline fault crossing can be useful for strike slip fault crossing only. Likewise incorporating the large geometric changes in analytical study is a tricky task; however pipeline subjected to the fault motion itself is a phenomenon of large geometric changes. Especially when pipeline subjected to compression, where in addition to material deformation it also undergoes general as well as local buckling with bending, contradictorily past work mostly assumed that pipeline is under tension. With day by day increasing capacity of computation and advancement in numerical modeling, one can find more facts for pipeline subjected fault motions including cases of pipe under compression as well. In this paper, past work is reviewed for pipeline subjected to large fault motion. A three dimensional FE based numerical model is suggested to carry out pipeline performance of buried pipeline subjected to fault motion. A proposed model includes material nonlinearity, as well as effect of the large geometric changes. For this purpose, three dimensional FE program is developed in MATLAB. Displacement controlled Arc-length technique is implemented to solve the nonlinear behavior. To reduce the computation time of analysis here parallelization tool kit of MATLAB is utilized.

Abstract

Pounding between adjacent structures is commonly observed phenomenon during earthquakes. In metropolitan areas, due to increasing population and land values buildings have been constructed very close to each other. Although seismic pounding between adjacent structures is considered in codal provisions, the practice of construction is still a problem in developing countries resulting more vulnerable during earthquakes. To study the effect of structural pounding, a case study has been done on different setbacks and storey heights of two adjacent structures using SAP 2000. The pounding responses of two structures and collision forces are calculated. The effect of collision is more when structures are kept at extreme levels of setback. When the structures are kept at different elevation levels (setback=0), the pounding response changes significantly as the height of structure decreases.

Abstract

Abstract: Pounding between adjacent structures is commonly observed phenomenon during major earthquakes which may cause both architectural and structural damages. Generally most of the existing buildings in seismically moderate regions are built without codal provisions. In the event of earthquake, pounding may cause considerable damage and leads to collapse of the colliding structures if the separation distance is insufficient. The aim of this paper is to study the impact of first collision according to the codal provisions for five different earthquakes. For this purpose we considered two buildings and the same were idealized as linear single degree of freedom oscillators. Separation distance between buildings is provided accoding to codal provisions of various countries and the buildings are subjected to different ground motions of PGA ranging from 0.22 g to 0.88 g. Later impact force due to collision is calculation and the results were analyzed.

Abstract

It is not uncommon to find buildings in seismically active regions built adjacent to each other without following the prescribed codal separation distance. If the separation distance is insufficient, in the event of an earthquake, pounding may cause severe architectural and structural damage, and may even lead to the collapse of the structure. Seismic design codes suggest minimum separation distance between two adjacent structures; however, the spacing has to be enough to withstand earthquake excitations. To understand the effect of codal provisions on pounding, two buildings were idealised as linear single degree of freedom oscillators. The separation distance between them was provided following the codal provisions of select countries. By subjecting the buildings to five different ground motions the first impact force due to collision was calculated and the results were analysed to compare the codal provisions.

Abstract

Reinforced concrete buildings constitute the dominant type of construction in the earthquake prone countries. Many researchers have studied the performance of the RC structure in seismic environment. In this study a RC building of four storeys is considered and its performance is evaluated when subjected to five ground motions. The study is roughly divided into three parts, first part includes investigation of the dynamic characteristics of ground excitations, second part includes evaluation of the nonlinear seismic behaviour of building subjected to the given ground excitations and third part includes evaluation of damage. The present study is based on analytical investigation of seismic performance and potential seismic damage of a reinforced concrete framed building due to earthquakes in India, using nonlinear modelling and displacement-based analysis techniques. Since the seismic damage is directly correlated to the displacement (deformation) of the structure, the yield displacement of the structure is evaluated from the pushover analysis. From the displacement time history of the structure response, the peak values which exceeding yield displacement of the structure have been identified and the hysteresis energy is calculated for each cycle to calculate the damage of the structure. The estimation of structural damage is calculated as per the model of Park and Ang. At the end, authors attempted to propose a new damage scale.