Abstract

Structures are being built very close to each other in metropolitan areas where the cost of land is very high. Due to closeness of the structures, they often collide with each other when subjected to earthquakes. Many studies have been carried out on separation distance between adjacent structures to mitigate pounding. Although some modern codes included seismic separation requirement for adjacent structures, some of them have failed in providing the appropriate minimum separation distance. In this paper, two linear single degree of freedom oscillators are used to study the impact force for five different ground motions ranging from 0.2 g to 0.8 g. The separation distance is calculated from the codal provisions of different countries. The separation distance between the two structures decreases, the amount of impact increases which is applicable when the impact time is same. It may also decreases when separation distance decreases. For structures having same period, no need to provide separation distance. The amount of impact depends on response of the structures at particular time, minimum space between the structures and velocity of the structures.

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

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

This paper presents a methodology to understand the interface behavior of soil and pile under transient loading. Previous works by Trochanis (1991), Bently and Naggar (2000) and others gave an insight to the problem. But this paper illustrates the research methodology developed to understand the dynamic behavior of pile and soil by taking the soil yielding effects and also the interface effects. A detailed parametric study has been done to understand the behavior of the same by varying the length of the pile for various soil conditions. For the purpose of comparison, soil model size was taken as 15m x 10m x 11m with pile cross section as 0.5 X 0.5 m and length of pile as 10m. For this we have developed a program for modeling the soil pile structure interaction using three dimensional Finite Element Method in MATLAB R2009a, the details of the same have been given in this paper along with the validity of it with benchmark problems in the literature.

Abstract

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

Abstract

The objective of this paper is to compare pushover response of ductile and non-ductile frames using AEM (Applied Element Method). Pushover analysis is non linear static analysis, a tool for seismic evaluation of existing structures. Unlike FEM, AEM is a discrete method in which the elements are connected by pair of normal and shear springs which are distributed around the elements edges and each pair of springs totally represents stresses and deformation and plastic hinges location are formed automatically. In the present case study a 1 x 1 bay four storied building is modeled using AEM. Gravity loads and laterals loads as per IS 1893-2002 are applied on the structure and designed using IS 456 and IS 13920. Displacement control pushover analysis is carried out. The effect of ductile detailing, change in grade of concrete and bar sizes in columns is also compared.

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

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

Motion segmentation is an inevitable component for mobile robotic systems such as the case with robots performing SLAM and collision avoidance in dynamic worlds. This paper proposes an incremental motion segmentation system that efficiently segments multiple moving objects and simultaneously build the map of the environment using visual SLAM modules. Multiple cues based on optical flow and two view geometry are integrated to achieve this segmentation. A dense optical flow algorithm is used for dense tracking of features. Motion potentials based on geometry are computed for each of these dense tracks. These geometric potentials along with the optical flow potentials are used to form a graph like structure. A graph based segmentation algorithm then clusters together nodes of similar potentials to form the eventual motion segments. Experimental results of high quality segmentation on different publicly available datasets demonstrate the effectiveness of our method.

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.