Abstract

For the assessment of risk of any area three components are necessary viz., Hazard, Exposure and Vulnerability. While most of the times Exposure and Vulnerability are easy to obtain compared to Hazard. For Hazard estimation, real ground motions are required. However, in highly seismic areas with less number of recorded ground motions, artificial ground motions are quite helpful. The estimation of strong ground motion parameters for a particular region can be done either by analytical methods or by numerical methods. Present work illustrates a comparative study of real and artificial ground motion generated for Uttarkashi earthquake. Midorikawa technique is used for generating strong ground motions at different locations. Ground motions records are considered at 13 stations during Uttarkashi earthquake. The synthetic ground motions are compared with recorded accelerograms at stations. The results of the analyses with both artificial and real accelerograms were compared in terms of site-transfer function, acceleration response spectrum and several strong motion parameters.

Abstract

Analysis and design of high-rise buildings for lateral load such as wind load and earthquake are the major issues which are playing significant role in recent decades. This paper describes a recent application of the computational fluid dynamics technique for wind analysis. Conventional wind analysis suggests wind tunnel experiment for arriving at the wind forces for a given structural form. As a case study a regular 38-story high-rise building (Jamieson place, Calgary Canada1) made of concrete with shear wall, built in downtown Calgary 2010 is selected. It is assumed that the building is located in highly seismic area. The design objective was to develop most cost-effective structural system while meeting building functionality goals and adhering to code requirement. The main structural design issues considered in this building are reviewed: Static analysis, Dynamic Analysis, Wind Analysis and Stability Analysis. Initial static and dynamic analysis is conducted in SAP and later wind analysis is conducted in Ansys as opposed to wind tunnel experiments. The building model is modeled in Ansys workbench and then the mesh file is imported to Ansys CFX for CFD simulation and analysis. After CFD analysis the wind forces on the building model are extracted in Ansys CFX-Post and imported to the structural model in SAP 2000 for the structural analysis.

Abstract

Modern research in India on dams has entered a distinct phase subsequent to the damage to Koyna dam, located in hitherto considered stable continental part, due to an earthquake on 11th December, 1967 in Koyna district, India. Out of about 5,100 large dams in India, a significant number are in moderately high and high seismic zones. As such they may be prone to probable instability to the dam’s structure due to earthquake resultant impacts. Even though none of the dams other than Koyna got damaged in India due to high magnitude earthquake activity, since 1967, it is felt necessary to understand the behaviour of dams due to water load coupled with dynamics of faults that are present in the vicinity of the dam, as dam failures due to earthquake activity are reported from different parts of the world. In this paper, damage to Koyna dam due to a fault motion caused nearby has been studied. A concrete gravity dam is selected from the National Importance Dams of India. Structure-1(S1) as a concrete gravity dam with foundation and structure-2 (S2) as a concrete gravity dam with foundation and soil strata are numerically modeled using Applied Element Method (AEM). Displacement at the base of soil strata is given to generate reverse fault effect on the dam. Behavior of dam is studied by direct and sub-structure methods. In the direct method, the effect of fault motion on dam is studied in S2, by modeling dam at different locations on foot wall and hanging wall. In sub-structure method, free-field accelerations are recorded at different locations on foot wall and hanging wall while only the sub-structure is subjected to fault motion. The recorded accelerations on the surface are used as input to analyze super structure S1. Comparison on behavior of dam in models S1 and S2 is later drawn.

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

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

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

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

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.