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

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

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

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

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

Reinforced concrete structures with open ground storey have shown very poor earthquake performance during past events. Despite of considering the design recommendations provided in the various international codes of practices for structural elements of open ground storey, the damage in the building has not reduced significantly. Literature shows damage to structural members in the soft storey depends on their relative stiffness with respect to adjacent storeys and eventually affects the deformation characteristics. Hence the problem of soft storey cannot be addressed independently without considering the relative effects of adjacent storeys. In this paper, the seismic response of open ground storey structure with openings in the upper storeys is studied and amplification factor for designing and strengthening of open ground storey members is determined. Static Nonlinear pushover analysis is used to carry out the study. The main parameters investigated are stiffness, strength, inter-storey drift and fundamental period. It is found that the presence of wall opening in upper storey will decrease its stiffness and strength significantly compared to full infill, which directly leads to reduction in the deformation and decrease in amplification factors for design and strengthening of ground storey members.

Abstract

This paper presents a parametric study on behavior of a shallow foundation resting on pond ash deposit with and without reinforcement. The behavior of foundation resting on the reinforced ash deposit is examined and studied by considering the parameters like effective depth of reinforcement; width of reinforcement; number of reinforcing layers. The parametric study has been performed using three dimensional finite element software, PLAXIS 3D. With the provision of reinforcement, the displacement is reduced as compared to unreinforced case. Also, with the increase in number of reinforcement layers, the bearing capacity of reinforced pond ash foundation is increased. Based on the results obtained, it is concluded that effective placement of reinforcement is observed at a depth of 2.67 B below the foundation for a width of 2B. Also, with the increase in number of layers, the bearing capacity is increased and the optimum provision of number of reinforcing layers is found to be two. Hence, it can be concluded that the performance of shallow foundation is better when pond ash underlying the shallow foundation is reinforced with geosynthetics material.

Abstract

It is well known that loss of life during an earthquake event is mainly due to collapse of buildings that are not designed, executed or maintained properly. Therefore there is an urge for pre-earthquake vulnerability assessment of buildings in moderate-to-severe earthquake prone areas world-wide. Vulnerability assessment of a building is a challenging task and it has to be dealt very carefully. However, for large number of buildings in a city or town, some simple methods have to be employed. Rapid Visual Survey (RVS) is one such method which is widely used all over the world. It uses many parameters like presence of soft storey, plan irregularities, stiffness irregularities, short-column effect, etc., for evaluating the score. This score has a limitation because the forms that are developed at one place cannot be used in different region, due to large variation in design guidelines and construction technology and hence it is important to develop forms which are specific to an area and also building technology used. In addition, it is also important to calibrate RVS scores to possible damage indicators. Hence it is important to know the effect of individual parameter (ie, vulnerability score modifier) on the overall score. This paper describes the numerical procedure for defining the value of vulnerability score modifiers for parameters that affect RVS score.

Abstract

ndia and nearby countries in Asia witness major earthquake in recent days and in past. Although after witnessing many earthquakes in past, for aesthetic purpose big window openings in wall and even whole brick wall replaced by glass can be seen in metro cities and suburban areas in cities of India. Opening and aspect ratio in wall plays great role in strength and stiffness of wall and overall behavior of building. Without understanding effect of openings and aspect ratio on strength, stiffness and behavior of wall it can be dangerous to use such practices in construction of building. In this research study, effect of opening and aspect ratio on overall behavior of building has been studied. This numerical study has been done by considering a RC framed brick infill wall using Applied Element method. Applied element method is capable of showing crack initiation, crack propagation till total collapse of building. This research study will focus on importance of placement of opening and consideration of aspect ratio for RC infilled brick masonry building.

Abstract

Methods capable of assessing the vulnerability of houses for future earthquakes are of fundamental importance for the safety and development of an area. As the detailed assessment is limited to number of houses and cost, one of the appraising methods currently used for seismic vulnerability assessment is rapid visual screening (RVS). This methodology has led to determination of risk of an area subjected to an earthquake event. Many codes have limited rapid visual screening to housing typologies like reinforced concrete and Brick masonry structures. This paper delivers an approach on how to perform RVS for five varieties of buildings in Himachal Pradesh state. The RVS scores have been calculated for 9099 buildings and normal distribution curves are plotted for each typology of building to understand the distribution of buildings in Himachal Pradesh. Finally, a new modified format for performing rapid …