Abstract

Lighthouses are the road signs of the ocean. They guide sailors through dangerous waters. Each lighthouse design is based on the land it is built on, its purpose, and the technology available. The Geometry of the lighthouses is round, square, octagonal, or conical in shape. These lighthouses need to be in operation 24 × 7 guiding the ships coming towards the coast. However, these lighthouses got affected during past earthquakes. The main objective of this work is to perform the nonlinear time history analysis of Navadra, Kachchigadh and Dwaraka point lighthouses subjected to eight ground motions. Since most of the Gujarat state is under Zone-III, IV and V, the analysis is carried out by normalizing them to respective zone factors as suggested by Bureau of Indian Standards IS 1893 (part-1): 2002. Using energy dissipation approach, damage is quantified at every displacement level. A fragility curve has …

Abstract

In the present situation of building construction around the world, Flat slab is becoming widely popular in the multi-storied buildings due to its advantage and ease of construction over the slabs. However, during past earthquakes, many building with flats have performed poorly. This is mainly due to inadequate resistance for punching shear under the earthquake loading. Many codes that are available for the design are for the analysis of flat slab under gravity loading. Some provisions exist for punching shear resistance, however, they are inadequate. To understand the behavior of building with flat slab subjected lateral loads, a numerical study is performed. A three-dimensional finite element method is used to perform the analysis. A flat slab along with the columns is modelled. Nonlinear constitute equations are used to model material, ie, concrete. Parametric study is performed for understanding the nonlinear behavior of flat slab subjected to lateral loads.

Abstract

Urbanization is rapidly increasing in almost every city in India. Huge infrastructure developmental plans have been laid by the government and private organizations. Large advertising boards of tall buildings (ranging from 30 to 50 floors) already started attracting people to invest in these infrastructure plans. However, from the point of view of seismic hazard prevailing in the country,“Will these buildings survive during future earthquakes?” is a question to be answered before proceeding for construction. In last 2.5 decades, 7 moderate earthquakes have been witnessed: Bihar-Nepal border (M6. 4) in 1988, Uttarkashi (M6. 6) in 1991, Killari (M6. 3) in 1993, Jabalpur (M6. 0) in 1997, Chamoli (M6. 8) in 1999, Bhuj (M6. 9) in 2001, A&N Islands (M9. 3) in 2004, Muzaffarabad (M7. 2) in 2005, Sikkim (M6. 8) in 2011 and more recently Twin Earthquakes in the neighborhood Nepal. These earthquakes have clearly exposed the lack of understanding of seismic hazard of the country. Sometimes, even when the hazard is understood, the lack of knowledge is exposed on earthquake resistant design and construction practice of reinforced concrete structures. The professionals involved in building construction should be more concerned with the safety of building infrastructure during future earthquake events. Among several aspects, natural period of building is one of the crucial parameters which decide the seismic demand of the building. Present study focuses on developing an empirical expression of fundamental natural period of RC tall buildings in India with the help of ambient vibration tests. Through the study it is found that the periodheight relationship is …

Abstract

Indian standard code of practice for plain and reinforced concrete IS 456 was last revised in 2000 after 22 years of the third revision. The major revision done in the new code is shift in design philosophy from working stress method to limit state method. The new code has not shown any significant changes in the concepts of structural design, material properties for high strength of concrete and steel, material grade limitation for seismic design, design of deep beam and walls, design of infilled frames, design of beam column joint and provisions for effective length of frame members. The code does not clearly mention about mode of failures such as shear, flexure in structural members. In the present paper a comprehensive literature review on the design strength of materials, stress stain curve for concrete, steel and confined concrete, partial safety factors and limitations/recommendations for usage of concrete grade and reinforcement steel grade in design provisions of Indian Standards, American Standards, European Standards, New Zealand Standards, Japanese Standards and from the latest available literature is done.

Abstract

Strong ground motions are the most desirable for the earthquake-resistant design of structures. If the site at which a major construction is required has less ground motion records, then artificial ground motions will serve the purpose. In highly seismic areas like Kashmir and the Himalaya region, artificial ground motions are quite helpful. Artificial accelerograms can be generated either through analytical or numerical procedures. Several methods were suggested in the literature for generating artificial ground motions. However, suitability of method for the region is to be understood before application. The main objective of this paper is to generate synthetic accelerograms of May 01, 2013, Doda earthquake using modified semi-empirical approach. A MATLAB code is written to generate the ground motion records of 1991 Uttarkashi earthquake and also validate the results. Based on effectiveness of the code …

Abstract

Structures are being built very close to each other in metropolitan areas where the cost of land is very high. Due to the proximity of the structures, they often collide with each other when subjected to earthquakes. To mitigate the amount of damage from pounding, the most simplest and effective way is to provide minimum separation distance. Generally most of the existing buildings in seismically moderate regions are built without codal provisions. The main objective of the present study is to check the adequacy of provisions given in codes of various countries. For this purpose, four pairs of structures were selected. The gap between structures was estimated according to codes of different countries and the same were subjected to earthquake excitation. Some codal provisions failed to satisfy the safety requirements, whereas some were safe. Based on this study, recommendations were drawn.

Abstract

Huge damages and loss of lives due to failure of glass panels and façade structures in buildings reported during past disasters such as the 1983 Mid-Japan Sea Earthquake and glass curtain façade failures due to 1994 Typhoon in Wan Chai district of Hong Kong suggest that there is a significant difference between available research literature related to structural mechanics, codes available on glass failure behavior and that with the safe structural design, mitigation practices actually implemented by modern construction firms and industries using significant structural glass components in buildings especially in newly emerging cities of India. This study presents a web application that simulates the behavior of glass plates towards two independent loading events: wind pressure acting transversely on the plates and seismic excitations deforming the in-plane glass frames leading to stress concentration patterns around plates. The App starts by prompting the user to input site-specific, plate geometry, building type and class, terrain, location-specific parameters. The framework of the application is designed in three stages. Stage-I uses computational GPS algorithms to determine Basic wind speed of the location based on wind zone map of India, combines analytical procedures in IS 875 Part III and Indian draft codes to formulate SNT (Standard Nominal Thickness) of glass plates and net design wind pressure acting transversely on them. In stage II, Deflection and bending behavior are investigated and relevant computations are performed. Mesh-generation procedures and Finite Element Method are implemented and coded by authors to solve the …

Abstract

In the present scenario of building construction world-wide, there is a significant increase in the cost percentage of non-structural elements compared to overall building cost. However, in some cases during past earthquakes, where the main structure suffered minimal damage, it was noticed that there were severe problems in the functionality of building and also sometimes leading to injuries & life loss. It is observed that significant percentage of population is injured due to overturning of objects such as furniture. This problem is attributed mainly to the behavior of non-structural elements which are not designed taking into account their seismic performance. The aim of this study is to analyze the behavior of a rigid body ie a NSE, particularly the toppling behavior under the action of seismic forces. A linearized solution for the dynamic equation of motion of the rigid body is obtained. The results are obtained in the form of angle of rotation of body against time, providing limits of safety of the NSE against toppling under applied seismic loading. A transformer has been modelled to illustrate the same. Also a tool has been generated using python scripts to graphically simulate the behavior of nonstructural elements under earthquake loading, by placing NSEs in different floors. This tool helps us in identifying whether the NSE will slide, rock or topple when subjected to certain seismic loading and provides the limits of safety for the same.

Abstract

Many countries have their own building codes-of-practice for earthquake resistant design of structures. These codes provide conventional approach to earthquake resistant design of buildings with sufficient strength, stiffness and inelastic deformation capacity to withstand a given level of earthquake generated force. Under a given earthquake, the level of damage to a structure is greatly influenced by nonlinear capacity of its members. Even when the nonlinear capacities are same, the overall damage is critically influenced by the structure’s shape, size and geometry.This paper presents the research on the influence of aspect ratio on overall damage of the structure subjected to earthquake loading. In this paper a numerical study is carried out for 3 benchmark structures, with an aspect ratio (height to widthratio) of 3, 1 and 0.3, to define failure pattern in nonlinear state. Nonlinear static pushover analysis is performed to understand the capacity of structure and expended energy based damage assessment is used to estimate the damage. The results are compared in terms of damage, displacement and plastic hinge pattern

Abstract

n present scenario buildings with floating columns are of typical feature in the modern multistorey construction practices in urban India. Such types of constructions are highly undesirable in building built in seismically active areas. This paper studies the analysis of a G+5 storey normal building and a G+5 storey floating column building for external lateral forces. The analysis is done by the use of SAP 2000. This paper also studies the variation of the both structures by applying the intensities of the past earthquakes i.e., applying the ground motions to the both structures, from that displacement time history values are compared. This study is to find whether the structure is safe or unsafe with floating column when built in seismically active areas and also to find floating column building is economical or uneconomical.