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.

Abstract

Heritage structures bears a valuable testimony of ancient cultural heritage of any country. Among these structures statues, iconic emblems plays significant role. In the proposed to study the vulnerability of monolithic statues to earthquake ground motions. Initially we used the equations developed by Housner for studying the dynamics of rigid blocks. Parametric study was conducted to study the inuence of size of the block and input parameters such as amplitude and frequency on the behaviour of the block. The study was extended to generate safe surface for the block of given dimensions. This surface gives the information that with any combination of parameters such as amplitude of vibration, frequency of vibration and duration of vibration, if the point lies outside the surface then block overturns otherwise it is safe. To verify the above formulation we selected four statues, viz, Gomateswara statue, Christ the Redeemer, Statue of Liberty, Guinyin Statue for case study. Initially all the statues were idealized like rigid blocks and later safe surfaces were developed for each statue. Since each statue is having different dimensions, surfaces were are also of different nature. Later, eighteen earthquake records were selected and strong ground motion parameters were estimated. Finally every statue was tested for the safety during the earthquake events. It was found that as the height of the statue is increasing its vulnerability is increasing. However, for all the given ground motions, none of the statue overturned.

Abstract

Graphics processing units provide a large computational power at a very low price which position them as an ubiquitous accelerator. Efficient primitives that can expand the r ange of operations performed on the GPU are thus important. Discrete Range Searching(DRS) is one such primitive with direct applications to string processing, document and text retrieval systems, and least common ancestor queries. In this work, we present a GPU specific implementation of DRS with an optimal space-time trade off. Toward this end, we also present GPU amenable succinct representations and discuss limitations on the GPU. Our method uses 7.5 bits of additional space per element. The speedup achieved by our method is in the range of 20-25 for preprocessing, and 25-35 for batch querying over a sequential implementation. Compared to an 8-threaded implementation, our methods obtain a speedup of 6-8. We study applications of the DRS on the GPU. Also, we suggest that most graph algorithms which focus on using least common ancestor, can easily be enabled on the GPU based on range minima primitive. Beyond this, we show applications of DRS in string querying and tree queries, and suggest how DRS can be helpful in implementing tree based graph algorithms on the GPU.

Abstract

Graphics Processing Units (GPU) are application specific accelerators which provide high performance to cost ratio and are widely available and used, hence places them as a ubiquitous accelerator. A computing paradigm based on the same is the general purpose computing on the GPU (GPGPU) model. The GPU due to its graphics lineage is better suited for the data-parallel, data-regular algorithms. The hardware architecture of the GPU is not suitable for the data parallel but data irregular algorithms such as graph connected components and list ranking. In this paper, we present results that show how to use GPUs efficiently for graph algorithms which are known to have irregular data access patterns. We consider two fundamental graph problems: finding the connected components and finding a spanning tree. These two problems find applications in several graph theoretical problems. In this paper we arrive at efficient GPU implementations for the above two problems. The algorithms focus on minimising irregularity at both algorithmic and implementation level. Our implementation achieves a speedup of 11-16 times over a corresponding best sequential implementation.

Abstract

Symmetry breaking is a fundamental operation in distributed computing. It has applications to important problems such as graph vertex and edge coloring, maximal independent sets, and the like. Deterministic algorithms for symmetry breaking that run in a polylogarithmic number of rounds are not known. However, randomized algorithms that run in poly-logarithmic number of rounds are known starting from Luby's algorithm. Recently, orientation on edges was considered and it was shown that an O(Δ) coloring of the vertices of a given oriented graph can be arrived at using essentially O(log Δ + √log n) bits of communication. In this paper we further demonstrate the power of orientation on edges in symmetry-breaking. We present efficient algorithms to construct fractional independent sets in constant degree graphs using very low order communication between the vertices. For instance, we show that in bounded degree graphs and planar graphs, it is possible to construct a fractional independent set by exchanging O(1) bits. Further, we present algorithms to construct maximal independent sets in bounded degree graphs and oriented trees. Our algorithm for constructing an MIS of an oriented tree uses only O(log n) bits of communication.