Abstract

Ask a common man about past earthquakes in india. Most people would answer Latur earthquake of 1993 and Bhuj earthquake of 2001 in addition to tsunami devastation of Dec 2004. However if we look at the figure we can see many events have occurred in last two decades. But why we remember only few events. The reason being obvious i.e life loss during these events. From the figure we can easily understand that during during last decades we have witnessed 6 moderate earthquake.

Abstract

Bamboo was used as construction material for housing since times immemorial. However, with the advent of materials like concrete and steel, its use has been signicantly reduced in last 50-100 years. On the other hand concrete and steel has large carbon footprints before even they are born. Use of wood has already banned by Central Public Works Department (CPWD). Similarly, State PWD's are also trying to follow the same. In this scenario, there is a great need to demonstrate cost eective housing with alternate technologies, especially like bamboo. However, for promoting bamboo as natural building material for housing, several dificulties are involved. This paper discusses the dificulties involved in promoting bamboo as sustainable construction material.

Abstract

Transmission tower lines are one of most important life-line structures. It is necessary that these structures are designed for seismicity. The dynamic behavior of a single transmission tower and transmission tower system that are linked by conductors has been studied in this research work. The dynamic analysis is performed on both the single transmission tower and the tower line system. The wind force acting on the tower is considered as an equivalent static force. The seismic analysis of the tower has been performed in SAP2000 Nonlinear computer program (SAP2000, Computers and Structures). The tower elements are modeled using 3 D frame elements. The tower has been subjected to North-ridge strong ground motion (1994) and the Koyna strong ground motion (1967) to study the dynamic behavior as described in the present work. Parametric study has been carried out by studying the influence of cable on the tower when the force in the cable is applied at different angles to the cross arms. The non-linear material behavior of the leg members of the tower has been studied when it is subjected to the two strong ground motions considered. To understand the non-linear behavior of the material bi-linear model has been considered and it is analyzed in the present work.

Abstract

Bhuj earthquake of 26 January 2001 caused 14,000 casualties. Main reason for such huge casualties is low earthquake awareness and poor construction practices. Based on the technology advancement and knowledge gained after earthquake occurrences, the seismic code is usually revised. Last revision of IS 1893 (Criteria for earthquake resistant design of structures) was done in 2002 after a long gap of about 18 years. Some new clauses were included and some old provisions were updated. Assuming that concerned authorities will take enough steps for code compliance and the structures that are being constructed are earthquake resistant. In this light, what will happen to the safety of pre-code revision structures? These structures carry major percentage of vulnerable structure stock. Even if we have a very good disaster response system, it is impossible to reduce earthquake damage without considering the safety of pre-code revision structures. In this regard, a comprehensive study of seismic risk assessment of Gujarat is necessary. As a pilot study, government of Gujarat selected Gandhidham and Adipur cities. Rapid Visual Screening (RVS) was conducted on 16000 buildings in Gandhidham and Adipur cities. Initial results reveal that there are large variety of construction practices, however, predominantly RCC and masonry structure were found. RVS score of these structures reveal that in general buildings are of low quality and further evaluation and strengthening of buildings is recommended. Keywords: RVS, performance score, preliminary assessment and detailed assessment Earthquake Vulnerability Assessment of Existing Buildings in Gandhidham and Adipur Cities Kachchh, Gujarat (India)

Abstract

In the proximity of an active fault, spatial variation of peak ground motion is significantly affected by the faulting mechanism. It has been observed that near fault ground motions consists of different characteristics compared to the far fault ground motions. Near fault records, in the distance range of less than 100 m from the faults are not available except for few cases. Therefore numerical simulation of ground motions for such near-fault situations is necessary. There is a need to enhance our understanding of the possible potential hazard that can be caused due to the future rupture activity by understanding the phenomenon of surface faulting. In this paper we propose numerical simulation based on discrete modeling to investigate the fault rupture propagation. Initially a two dimensional study is done for understanding the crack propagation due to various types of bedrock movement. A model of size 1000x150 m is selected for this purpose. It is observed as the stiffness of the media is decreasing, the affected surface is decreasing and also width of the shear crack zone is decreasing. However in the dynamic analysis we can observe the significant increase in amplification in soft media. Secondly, we attempted to study the presence of boulders. Surface faulting has been examined by keeping the boulder at different positions. We find that there is an increase in the shear zone as well as the PGA on the surface when the boulder is present on the foot wall. Finally, we performed the analysis using layered media and studied the affect of crack propagation and also the variation of peak accelerations Findings from the study can be utilized to assess the …

Abstract

Experiences from past earthquake disasters clearly shows that the ground motion was responsible for majority of property and life loss. Among the collapsed structures during the 1964 Niigata earthquake, the 1995 Kobe earthquake, the 1999 Koceli earthquake, the 2001 Bhuj earthquake and the 2004 Sumatra earthquake, excessive damage was occurred to pile supported bridges, towers, chimneys, high rise structures, etc. In view of this there is a need to study the complex behavior of soil-pile-structure interaction problems using numerical methods. In this research paper, a numerical study is carried out to understand the dynamic soil structure interaction of a high rise structure in a visco elastic half space in the presence of near by pile supported structures. The structure soil structure interaction is modelled by considering the direct methodology using a Finite element method based code ANSYS 10. Initially a two dimensional study is carried out for understanding the seismic response of group of high rise structures supported on pile foundations. The linear super structures are considered as framed structures of different dynamic characteristics suported on group of piles. Different case studies are made one in which the group effect of structures supported on piles are considered like group of two identical structures, group of three identical structures and group of three different structures, second one in which the effect of variability in structure height is considered like 5 storey structure, 10 storey structure and 15 storey structure and the third one in which the effect of variability in structure shape is considered. For each case the effect of structure …

Abstract

Pipelines are common transportation means for oil and natural gas, which act as an important lifeline facility for any nation. Often the design of these pipelines is a difficult task because they commonly are installed underground passing through different types of soil media. Many of these existing pipelines run through the faulted area, which continuously exposed to considerable risk of failure due to movement along the fault. In this paper, a numerical study is carried out to understand stress development in buried pipeline subjected to fault motion with Mundra-Delhi pipeline as a case study. For this purpose, a 3D finite element program is developed and the same is used to study stress development in the pipe subjected to fault motion. Also here study has been done to find out the effect of different soil media and effect of fault-pipeline angle for both strike slip and dip slip fault motion.

Abstract

In the case of foundations of bridges, transmission towers, offshore structures and for other type of huge structures, piles are also subjected to lateral loads. This lateral load resistance of pile foundations is critically important in the design of structures under dynamic loading. Load carrying capacity and load deformation behavior of a single pile and group of piles subjected to lateral load is obtained using nonlinear finite element method of analysis. According to Poulos and Davis (1980) the maximum deflection of the pile is the major criterion in its design and made the initial attempts to study the lateral behavior of piles included twodimensional finite element models in the horizontal plane. Several investigations have attempted to study the behavior of pile under lateral load using 3D finite element analysis. In this paper a detailed study on the piles subjected to lateral loads are investigated.

Abstract

The amplification of ground motion is being observed during major earthquake events all over the world and is highly dependent on the local geological, topography and geotechnical conditions. In view of this there is a great need to study the local site effects in a seismically active region. In this paper, the numerical modeling of infinite media is carried out by using transmitting boundary condition. Wave interaction with different kinds of boundaries like fixed and viscous boundary is discussed. The heterogeneities in the soil media are taken into account by considering the soft clay and the rock inside the half-space. Peak ground acceleration at the surface is plotted and local amplification of soils is studied by giving Elcentro ground motion as input at the bed rock for both the cases. In the half-space where clay is present, PGA is amplified by a factor of 2.5 with respect to input. More energy is concentrated in the half-space where clay is present. In the half-space where rock is present the area adjacent to the rock is getting amplified as energy is concentrated around the rock.

Abstract

Many countries have become victims of terrorism on a large scale. Bombs have exploded in and around buildings in many countries causing civilian causalities and structural damage. A bomb explosion with in or around a building can have catastrophic effects, damaging and destroying internal or external portions of the building. Bomb damage to buildings depends on the type and layout of the structure, material used, range of the located explosive device and the charge weight. The impact from the blast causes debris, fire and smoke and hence can result in injury and death of occupants. Escape of the occupants and protection of the valuable documents, equipments, property is possible only when there is minimum damage to structures. This may be achieved by designing the building structures for blast loading. This attempt gives basic idea to all the consultants in estimating the blast loads over the building structures.