Abstract

In this paper we propose a framework for optimum steering input determination of all-wheel steer vehicles (AWSV) on rough terrains. The framework computes the steering input which minimizes the tracking error for a given trajectory. Unlike previous methodologies of computing steering inputs of car-like vehicles, the proposed methodology depends explicitly on the vehicle dynamics and can be extended to vehicle having arbitrary number of steering inputs. A fully generic framework has been used to derive the vehicle dynamics and a non-linear programming based constrained optimization approach has been used to compute the steering input considering the instantaneous vehicle dynamics, no-slip and contact constraints of the vehicle. All Wheel steer Vehicles have a special parallel steering ability where the instantaneous centre of rotation (ICR) is at infinity. The proposed framework automatically enables the vehicle to choose between parallel steer and normal operation depending on the error with respect to the desired trajectory. The efficacy of the proposed framework is proved by extensive uneven terrain simulations, for trajectories with continuous or discontinuous velocity profile.

Abstract

Overall capacity of a structure depends on the strength and deformation capacities of the individual component of the structure. In order to determine capacities beyond the elastic limits some form of nonlinear analysis such as the pushover procedure is required. This procedure uses a series of sequential elastic analyses, superimposed to approximate a force-displacement capacity diagram of the overall structure. Usually this analysis is performed using FEM and that too with major assumption in defining hinge mechanisms and target displacement. In this paper, a new method for analysis nonlinear static large deformation analysis of bare frame subjected to lateral load is proposed. First we developed the method and later four frames were taken and they were pushed up to failure. Results clearly show the capability of the proposed method.

Abstract

Construction practices in major part of rural as well as suburban areas in India uses brick masonry type of buildings; this may be due to easy availability of material, aesthetic appeal and cost effective. Such type of construction is also found in nearby areas like Nepal and Bangladesh. In India, these buildings are most commonly found in regions where good quality clay for brick production is abundantly available (World housing encyclopaedia report, 2003). In past studies it has been found that brick quality is comparatively better in north part of India than south, this is due to good quality of soil in north India. But, such type of buildings proved to be vulnerable during past history of earthquake. Though, past experimental and analytical studies stress upon understanding behaviour of brick masonry buildings, this numerical study has advantage over others that it can show initiation of crack, gradual propagation of cracks till the total collapse of building. In this parametric study, four cases have been considered and effect of considering infill and without infill on strength, stiffness and ductility of wall has been studied.

Abstract

extensive damage Occurred in non engineered structure..Many casualities occured in stone masonary buildings

Abstract

The paper presents first-cut of the salient findings and inferences of a pilot study of housing sub-typologies practiced in seven locations in moderate to severe seismic zones in India. Field trips were conducted to understand housing approaches, methods and constraints employed in 7 locations of the moderate-to-severe seismic zones of India. Based on these field trips, the following deliverables are offered:(1) A methodology for technical documentation of housing typologies in moderate-to-severe seismic zones, through documentation of all safety-related information of an individual house; and (2) A base-level Technical Evaluation Method of earthquake safety of a house for the prevalent earthquake hazard at the location of the house. This method provides both Seismic Safety Index and Performance Rating Method for benchmarking an individual house with respect to an ideal house of the same typology built to resist earthquake shaking in the same seismic environment.

Abstract

India has been facing earthquake problems from many centuries which need no introduction. From recent earthquakes, it is very well understood that lack of awareness is one of the major factor for huge casualty losses. While still having the probability of occurrences of earthquakes in India, it becomes very important and need to increase the awareness about the effects of earthquakes among growing professionals involved in construction by making them understanding the concepts of Structural Dynamics and Earthquake Engineering. This paper will detail the use of virtual laboratory in real time environment of structural dynamics. Virtual Laboratory provides a new methodology to convey and learn concepts using the power of visualization of ideas and computations. Virtual labs rely on an active engagement of the learner in the knowledge acquisition process. This paper is aimed at promoting the new methodology and providing a glimpse into the exciting world of interactive and experimentation of structural dynamic concepts with no limitation of conductance. Using this tool, a person with little knowledge of structural engineering can enhance his fundamentals of structural dynamics. For better understanding experiments are explained with graphical diagrams seen in GUI with the support of JAVA 3D. Apart from basic understanding of dynamic behavior of structure, this tool kit also helps architects and young civil engineers in understanding the principles of structural dynamics.

Abstract

Pipeline generally extends over long distances traversing through wide variety of soil conditions with different seismicity. Majority of past work mainly restricted to pipelines exposed to strike slip fault motion or transverse permanent ground deformation that too cases of pipelines under tension. The study of buried pipeline under compression is of extreme importance, especially pipelines passing through thrusting sub-continent like India, where majority of pipelines are exposed to compression. In compression pipelines fail in material as well as in geometry. In this paper past work is reviewed and 3D finite element based model is proposed to compare pipeline performance subjected to different types of ground motion. The proposed model includes material non-linearity as well as effect of large geometric changes. In this proposed model displacement control Arc-length technique is implemented to solve the nonlinear behavior. To reduce the computational time of analysis a parallelization tool kit of MATLAB is utilized.

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.

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

Vpu is an 81-residue protein encoded by human immunodeficiency virus type I (HIV-1) that facilitates viral release from host cells. The protein has a cytoplasmic domain and a helical transmembrane (TM) domain, of which the latter oligomerizes to form cation-specific ion channels. The number of TM domains that constitute the channel is still unclear, with experimental studies indicating the existence of a variety of oligomeric states. In this study, we have examined the possibility of Vpu to exist in tetra-, penta-, and hexameric states using comprehensive molecular dynamics (MD) simulations. By modeling the TM domain as an ideal α-helix, we carried out replica-exchange MD simulations in an implicit membrane environment for obtaining suitable starting structures, which were then subjected to extensive MD simulations in a fully hydrated lipid bilayer environment. The results show that the pentameric form is the most stable oligomeric state (the tetramer and hexamer models lose their initial channel-like structure), with helices in the pentamer being held together by strong van der Waals interactions. Hydrogen bonds between lipid headgroups and basic/hydrophilic residues on the protein are stronger in the pentamer than in the tetramer or the hexamer, indicating that these interactions might play a role in adhering the pentamer to the membrane. Free energy calculations using umbrella sampling technique have been performed to examine the potassium ion permeation through the pentameric pore. The results show a high free energy barrier corresponding to ion transport indicating weak ion channel activity in agreement with previous experimental biophysical studies.