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 behaviour of soil-pile-structure interaction problems. In this research paper, a numerical study is carried out to understand the dynamic soil Foundation structure interaction (SFSI) of a framed structure supported on a pile foundation. For that purpose a 5 storey pile supported framed structure is modeled and the behaviour under strong earthquake excitations associated with nonlinear material behaviour is studied. A peculiar behaviour in the stress state of pile in the SFSI system is observed. This behaviour is because of Soil resistance acting downward along the pile shaft because of an applied transient load. Also, the comparison of linear and nonlinear stress states and the effect/significance of soil plasticity on the stress states are commented.

Abstract

With the announcement of smart cities, construction of tall buildings is booming in India. There are quite a few codes for tall buildings and many of them have shortcomings in addressing the parameters for seismic design. One such parameter is the fundamental natural period of tall buildings. The expression of the fundamental period is originally developed based on Californian earthquakes and adopted by many seismic codes around the world; including current, Indian seismic code IS 1893: 2002. This paper aims to study the reliability of empirical expression of the fundamental period for tall buildings in India. For this purpose, ambient vibration tests have been carried out for 21 RC buildings, located in Mumbai and Hyderabad cities, by placing vibration sensor on topmost accessible floor. The measured periods have been compared with the code provisions. It is found in the study that as the height of the building increases, natural period is not linearly proportional to height; rather it is becoming flexible. Hence there is an urgent need for revision of the empirical expression.

Abstract

Earthquake resistant design of structures requires the knowledge of quantified seismic hazard. To quantify the seismic hazard, Peak Ground Acceleration (PGA) is used for design procedures. The maximum possible PGA of a particular region depends on seismic parameters like magnitude, hypocentral distance, type of soil etc. Though it can be obtained by observing the past seismic events, it is more realistic to relate it with the parameters that influence it. Due to high seismic activity at the Himalayan region, this paper is aimed at developing a Ground Motion Prediction Equation (GMPE) for this region. For this purpose, two sets of 168 earthquakes (2.5-7.2 Mw) have been selected that are recorded at different stations within 500 km radius along the Himalayan belt. A statistical analysis is carried out on both sets separately based on the relation of PGA with magnitude, hypocentral distance and the type of soil. New GMPE equations have been proposed. The same are compared with the existing GMPE for the same region and seismically similar regions.

Abstract

In recent past due to rapid growth of Indian cities, there is a tremendous increase on housing industry, especially in seismic Zone IV & V. As most of these constructions are without earthquake resistant measures, the built environment in these zones has been found seismically vulnerable. Detailed seismic vulnerability evaluation is a technically complex and expensive procedure and can only be performed on a limited number of buildings. The present paper highlights the use of Rapid visual screening (RVS) method for seismic assessment of reinforced concrete (RC) buildings in Himachal Pradesh state. A RVS survey has been carried out on 1540 RC buildings, out of which 6 buildings are selected for detailed analysis. The selected buildings are modeled and analyzed through numerical approach. A correlation graph has been constructed between peak ground acceleration (PGA) and, RVS, indicating different damage states of a building. Around 80% of RC buildings located in Zone V of Himachal Pradesh will suffer moderate damage and around 73% of RC buildings located in Zone IV will suffer slight damage in the event of earthquake with PGA prescribed as per IS 1893.

Abstract

etties are one of the most important structures in the coastal area, which can be used for transporting large quantities of goods and raw materials from one place to the other. Their functionality is very much essential because they are lifeline structures of the country. It is observed during the past earthquakes that jetties have been damaged even under mild shaking. Damaged and unserviceable jetties cause delay of export and import business. It directly affects the economy of particular region in terms of business, employment and growth. This clearly indicates the need to design these facilities so that they can withstand natural disasters particularly earthquakes and tsunamis. In this paper, a study has been carried out to find out the damage (D) to the Jetty. The Jetty is modeled using 2D Applied Element Method (AEM) to perform damage analysis of structure. Pushover analysis is done to get base shear vs roof displacement of building using displacement control method. Using the dissipated energy approach, damage is quantified at every displacement level and normalized to 1. A fragility curve has been developed to quantify the damage of Jetty with respect to different peak ground accelerations. The damage values were calculated for the PGA values of KHF Mandvi, NKF Jodiya and KMF Jhangi and found that the Jetty got light damage (D= 0.2), and moderate damage (D= 0.38 and 0.42) respectively.

Abstract

Strong earthquakes cause a great damage to buildings and other infrastructure. It is difficult to get an overview of the situation immediately after an earthquake, to facilitate the initiation of appropriate emergency and rescue measures. Shake map provides early information on the intensity of ground shaking in a location. This data will be useful to help authorities and rescue workers for planning their work. For the purpose of study, Vijayawada city, India has been selected to generate shake map. Peak ground accelerations (PGA) are generated using ground motion prediction equations (GMPE) and the shaking intensities are also estimated for Vijayawada city. A tool for shake map has been generated using php applications. Map generation is automatically triggered by any earthquake in the vicinity of Vijayawada region and the map will be available for the public and government for post-earthquake decision making.

Abstract

Current methods of building segmentation from LiDAR depends on extraction of roof planes to segment the buildings. In our work, we propose a new method to extract buildings using the wall facades. The motivation of using wall facades is based on the rise of terrestrial LiDAR compared to aerial LiDAR. The shape property is the most important information obtained from a LiDAR file. We try to use this shape property from the LiDAR file to segment buildings from the given scene. In the algorithm, the non-ground return points parallel to a facade of the potential building are combined to form multiple slices. These slices are parallel to the facade of a potential building. These slices are then merged based on the shape similarity and proximity to generate the footprint of the building. After generating the footprint of the building, we can also reconstruct the 3D model of the given building. The algorithm was tested both on simulated synthetic data containing different buildings and real world benchmark datasets. The results show complete segmentation of buildings from the synthetic datasets and promissory results from the real world datasets. The algorithm proposed is versatile in nature and can be easily adapted to different datasets with minimal modifications and tweaking. Existing works involve the use of secondary datasets like satellite images, orthophotos etc in order to aid in segmentation. Our work uses only the LiDAR data and no other secondary data to identify the buildings from the scene. Demonstration have been shown to segment partial buildings in a given scene as well. Thus, the novelty of the proposed work is non-dependence on any other form of data required except LiDAR. The applications of segmenting buildings from a given LiDAR scene can be used in urban planning, resource management and monitoring tasks.

Abstract

In the aftermath of 2015 Gorkha Earthquake in Nepal the challenging task was to classify structural damage; for further consideration of the building for living purposes. Manual classification of such a large number of building stock is tedious job in terms of collecting and maintaining data, particularly from the point of view of using the same for further planning purposes. Hence a web based application will make the job simple and easy for the surveyor as they will fill the details from the application and get the damage state of the building and know whether or not the building is safe for living and maintain the record of their decision. The other important feature of this application is it also does the pre-earthquake assessment of the building; thus it evaluates the state of the building before an earthquake through which occupants will know whether it safe or not to live in a particular building and also the improvements required from overall safety point of view. In this paper, description of the web application is given with some case studies. Post-earthquake assessment is done for two types of buildings which is quite common i.e., Reinforced Concrete Building and Brick Masonry Building. Pre-earthquake assessment is done in three parts, first part is Detail Visual Assessment of building based on BMTPC form and second part is Simplified Quantitative Assessment and third one is Detail Qualitative Assessment

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

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 …