Abstract

Structures are being built very close to each other in metropolitan areas where the cost of land is very high. Due to closeness of the structures, they often collide with each other when subjected to earthquakes. Many studies have been carried out on separation distance between adjacent structures to mitigate pounding. Although some modern codes included seismic separation requirement for adjacent structures, some of them have failed in providing the appropriate minimum separation distance. In this paper, two linear single degree of freedom oscillators are used to study the impact force for five different ground motions ranging from 0.2 g to 0.8 g. The separation distance is calculated from the codal provisions of different countries. The separation distance between the two structures decreases, the amount of impact increases which is applicable when the impact time is same. It may also decreases when separation distance decreases. For structures having same period, no need to provide separation distance. The amount of impact depends on response of the structures at particular time, minimum space between the structures and velocity of the structures.

Abstract

Pipeline generally extends over long distances traversing through wide variety of soil conditions with different seismicity. Majority of past work mainly restricted to pipelines exposed to strike slip fault motion or transverse permanent ground deformation that too cases of pipelines under tension. The study of buried pipeline under compression is of extreme importance, especially pipelines passing through thrusting sub-continent like India, where majority of pipelines are exposed to compression. In compression pipelines fail in material as well as in geometry. In this paper past work is reviewed and 3D finite element based model is proposed to compare pipeline performance subjected to different types of ground motion. The proposed model includes material non-linearity as well as effect of large geometric changes. In this proposed model displacement control Arc-length technique is implemented to solve the nonlinear behavior. To reduce the computational time of analysis a parallelization tool kit of MATLAB is utilized.

Abstract

Brick masonry type of construction is found all over India and neighbouring countries like Nepal and Bangladesh. In India, these buildings are commonly found in North, extending from Punjab to West Bengal and Central India, from Haryana to Madhya Pradesh. These buildings are most commonly found in regions where good quality clay for brick production is abundantly available (World housing encyclopaedia report, 2003). But, past earthquakes witness major loss to brick masonry type of buildings. Many analytical and experimental studies have been done in past to understand the behaviour of brick masonry buildings during earthquake. Analytical study mainly includes, numerical modelling of the brick masonry buildings of type URM and Reinforced concrete Infill wall. In this work, primary focus is given to numerical modelling and nonlinear behaviour of brick masonry buildings subjected to lateral loads and understanding crack propagation in wall and calculation of quantitative damage to the building in terms of stiffness, ductility in load displacement curve.

Abstract

Reinforced concrete buildings constitute the dominant type of construction in the earthquake prone countries. Many researchers have studied the performance of the RC structure in seismic environment. In this study a RC building of four storeys is considered and its performance is evaluated when subjected to five ground motions. The study is roughly divided into three parts, first part includes investigation of the dynamic characteristics of ground excitations, second part includes evaluation of the nonlinear seismic behaviour of building subjected to the given ground excitations and third part includes evaluation of damage. The present study is based on analytical investigation of seismic performance and potential seismic damage of a reinforced concrete framed building due to earthquakes in India, using nonlinear modelling and displacement-based analysis techniques. Since the seismic damage is directly correlated to the displacement (deformation) of the structure, the yield displacement of the structure is evaluated from the pushover analysis. From the displacement time history of the structure response, the peak values which exceeding yield displacement of the structure have been identified and the hysteresis energy is calculated for each cycle to calculate the damage of the structure. The estimation of structural damage is calculated as per the model of Park and Ang. At the end, authors attempted to propose a new damage scale.

Abstract

It is not uncommon to find buildings in seismically active regions built adjacent to each other without following the prescribed codal separation distance. If the separation distance is insufficient, in the event of an earthquake, pounding may cause severe architectural and structural damage, and may even lead to the collapse of the structure. Seismic design codes suggest minimum separation distance between two adjacent structures; however, the spacing has to be enough to withstand earthquake excitations. To understand the effect of codal provisions on pounding, two buildings were idealised as linear single degree of freedom oscillators. The separation distance between them was provided following the codal provisions of select countries. By subjecting the buildings to five different ground motions the first impact force due to collision was calculated and the results were analysed to compare the codal provisions.

Abstract

Abstract: Pounding between adjacent structures is commonly observed phenomenon during major earthquakes which may cause both architectural and structural damages. Generally most of the existing buildings in seismically moderate regions are built without codal provisions. In the event of earthquake, pounding may cause considerable damage and leads to collapse of the colliding structures if the separation distance is insufficient. The aim of this paper is to study the impact of first collision according to the codal provisions for five different earthquakes. For this purpose we considered two buildings and the same were idealized as linear single degree of freedom oscillators. Separation distance between buildings is provided accoding to codal provisions of various countries and the buildings are subjected to different ground motions of PGA ranging from 0.22 g to 0.88 g. Later impact force due to collision is calculation and the results were analyzed.

Abstract

Pounding between adjacent structures is commonly observed phenomenon during earthquakes. In metropolitan areas, due to increasing population and land values buildings have been constructed very close to each other. Although seismic pounding between adjacent structures is considered in codal provisions, the practice of construction is still a problem in developing countries resulting more vulnerable during earthquakes. To study the effect of structural pounding, a case study has been done on different setbacks and storey heights of two adjacent structures using SAP 2000. The pounding responses of two structures and collision forces are calculated. The effect of collision is more when structures are kept at extreme levels of setback. When the structures are kept at different elevation levels (setback=0), the pounding response changes significantly as the height of structure decreases.

Abstract

Pipeline generally extends over long distances traversing through wide variety of different soils, geological conditions and regions with different seismicity. Majority of the past works in the area of pipeline subjected to fault motion is restricted in several ways. There were many analytical models developed in the past for pipeline fault crossing, however, they are of limited usage, for example analytical model developed for pipeline fault crossing can be useful for strike slip fault crossing only. Likewise incorporating the large geometric changes in analytical study is a tricky task; however pipeline subjected to the fault motion itself is a phenomenon of large geometric changes. Especially when pipeline subjected to compression, where in addition to material deformation it also undergoes general as well as local buckling with bending, contradictorily past work mostly assumed that pipeline is under tension. With day by day increasing capacity of computation and advancement in numerical modeling, one can find more facts for pipeline subjected fault motions including cases of pipe under compression as well. In this paper, past work is reviewed for pipeline subjected to large fault motion. A three dimensional FE based numerical model is suggested to carry out pipeline performance of buried pipeline subjected to fault motion. A proposed model includes material nonlinearity, as well as effect of the large geometric changes. For this purpose, three dimensional FE program is developed in MATLAB. Displacement controlled Arc-length technique is implemented to solve the nonlinear behavior. To reduce the computation time of analysis here parallelization tool kit of MATLAB is utilized.

Abstract

Pipeline generally extends over long distances traversing through wide variety of different soils, geological conditions and regions with different seismicity. Majority of the past works in the area of pipeline subjected to fault motion is restricted in several ways. There were many analytical models developed in the past for pipeline fault crossing, however, they are of limited usage, for example analytical model developed for pipeline fault crossing can be useful for strike slip fault crossing only. Likewise incorporating the large geometric changes in analytical study is a tricky task; however pipeline subjected to the fault motion itself is a phenomenon of large geometric changes. Especially when pipeline subjected to compression, where in addition to material deformation it also undergoes general as well as local buckling with bending, contradictorily past work mostly assumed that pipeline is under tension. With day by day increasing capacity of computation and advancement in numerical modeling, one can find more facts for pipeline subjected fault motions including cases of pipe under compression as well. In this paper, past work is reviewed for pipeline subjected to large fault motion. A three dimensional FE based numerical model is suggested to carry out pipeline performance of buried pipeline subjected to fault motion. A proposed model includes material nonlinearity, as well as effect of the large geometric changes. For this purpose, three dimensional FE program is developed in MATLAB. Displacement controlled Arc-length technique is implemented to solve the nonlinear behavior. To reduce the computation time of analysis here parallelization tool kit of MATLAB is utilized.

Abstract

Building construction in India has been on rise since last two decades. More recently construction of tall buildings ranging from 30 to 50 stories have been proposed in many cities. For these buildings, wind analysis is as important as earthquake analysis, since in taller buildings, wind loads are dominant than earthquake loads at greater heights. In India, wind analysis is done according to IS 875 (Part III)-1987 (here after IS 875). But this code doesn’t provide sufficient information analysis of different structural forms. Quite often, engineers generally rely wind tunnel experiments to understand the behaviour. However, for arriving at the best orientation several tests have to be conducted which is tedious job. In the paper a necessity to adopt a different approach such as wind tunnel experiments and CFD simulation is proposed. Case study on wind analysis of Y-shaped tall building is illustrated using Ansys CFX and SAP 2000.