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 …

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.