The effectiveness of Tiger Conservation Landscapes in decreasing deforestation in South Asia: a remote sensing-based study

Sabu Minu Merin,Pasha S. Vazeed,Reddy C. Sudhakar,Singh Randeep,Jaishanker R. 대한공간정보학회 2022 Spatial Information Research Vol.30 No.2

The alarming loss of tiger (Panthera tigris) populations due to degrading habitat called for an international commitment to double the wild tiger population by 2022 (‘‘Tx2’’ goal). In the present study, eighteen Priority Tiger Conservation Landscapes (PTCLs) distributed in India, Bangladesh, Bhutan, Nepal and Myanmar were identified to investigate the trends in deforestation and fragmentation in core forest area. We used multi-decadal remote sensingbased maps to assess the rate of deforestation from 1975 to 2016. The time-series analysis revealed that there is a low to moderate level of deforestation reported in PTCLs from1975 to 2016. The Northern Forest Complex-Namdapha-Royal Manas and Tenasserims are the geographically larger landscapes of the eighteen PTCLs that show the relatively high annual rate of deforestation from 2005 to 2016 due to the practice of shifting cultivation. The Mann Kendall trend test has indicated a statistically significant decreasing trend in deforestation across the 18 PTCLs. Overall, a low level of forest fragmentation was found in core forest habitat in the landscapes from 1995 to 2016. The results indicate management has been effective in minimizing habitat loss. The study outcomes would lead to a holistic understanding at the landscape level for long-term conservation planning in PTCLs.

The effectiveness of Tiger Conservation Landscapes in decreasing deforestation in South Asia: a remote sensing-based study

Sabu Minu Merin,Pasha S. Vazeed,Reddy C. Sudhakar,Singh Randeep,Jaishanker R. 대한공간정보학회 2022 Spatial Information Research Vol.30 No.1

The alarming loss of tiger (Panthera tigris) populations due to degrading habitat called for an international commitment to double the wild tiger population by 2022 (‘‘Tx2’’ goal). In the present study, eighteen Priority Tiger Conservation Landscapes (PTCLs) distributed in India, Bangladesh, Bhutan, Nepal and Myanmar were identified to investigate the trends in deforestation and fragmentation in core forest area. We used multi-decadal remote sensingbased maps to assess the rate of deforestation from 1975 to 2016. The time-series analysis revealed that there is a low to moderate level of deforestation reported in PTCLs from1975 to 2016. The Northern Forest Complex-Namdapha-Royal Manas and Tenasserims are the geographically larger landscapes of the eighteen PTCLs that show the relatively high annual rate of deforestation from 2005 to 2016 due to the practice of shifting cultivation. The Mann Kendall trend test has indicated a statistically significant decreasing trend in deforestation across the 18 PTCLs. Overall, a low level of forest fragmentation was found in core forest habitat in the landscapes from 1995 to 2016. The results indicate management has been effective in minimizing habitat loss. The study outcomes would lead to a holistic understanding at the landscape level for long-term conservation planning in PTCLs.

Experimental and analytical investigation on seismic behavior of RC framed structure by pushover method

Sharma, Akanshu,Reddy, G.R.,Eligehausen, R.,Vaze, K.K. Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.1

Pushover analysis has gained significant popularity as an analytical tool for realistic determination of the inelastic behaviour of RC structures. Though significant work has been done to evaluate the demands realistically, the evaluation of capacity and realistic failure modes has taken a back seat. In order to throw light on the inelastic behaviour and capacity evaluation for the RC framed structures, a 3D Reinforced concrete frame structure was tested under monotonically increasing lateral pushover loads, in a parabolic pattern, till failure. The structure consisted of three storeys and had 2 bays along the two orthogonal directions. The structure was gradually pushed in small increments of load and the corresponding displacements were monitored continuously, leading to a pushover curve for the structure as a result of the test along with other relevant information such as strains on reinforcement bars at critical locations, failure modes etc. The major failure modes were observed as flexural failure of beams and columns, torsional failure of transverse beams and joint shear failure. The analysis of the structure was by considering all these failure modes. In order to have a comparison, the analysis was performed as three different cases. In one case, only the flexural hinges were modelled for critical locations in beams and columns; in second the torsional hinges for transverse beams were included in the analysis and in the third case, joint shear hinges were also included in the analysis. It is shown that modelling and capturing all the failure modes is practically possible and such an analysis can provide the realistic insight into the behaviour of the structure.

Experiments on reinforced concrete beam-column joints under cyclic loads and evaluating their response by nonlinear static pushover analysis

Sharma, Akanshu,Reddy, G.R.,Eligehausen, Rolf,Vaze, K.K.,Ghosh, A.K.,Kushwaha, H.S. Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.1

Beam-column joints are the key structural elements, which dictate the behavior of structures subjected to earthquake loading. Though large experimental work has been conducted in the past, still various issues regarding the post-yield behavior, ductility and failure modes of the joints make it a highly important research topic. This paper presents experimental results obtained for eight beam-column joints of different sizes and configuration under cyclic loads along with the analytical evaluation of their response using a simple and effective analytical procedure based on nonlinear static pushover analysis. It is shown that even the simplified analysis can predict, to a good extent, the behavior of the joints by giving the important information on both strength and ductility of the joints and can even be used for prediction of failure modes. The results for four interior and four exterior joints are presented. One confined and one unconfined joint for each configuration were tested and analyzed. The experimental and analytical results are presented in the form of load-deflection. Analytical plots are compared with envelope of experimentally obtained hysteretic loops for the joints. The behavior of various joints under cyclic loads is carefully examined and presented. It is also shown that the procedure described can be effectively utilized to analytically gather the information on behavior of joints.

Shake table tests on a non-seismically detailed RC frame structure

Akanshu Sharma,G.R. Reddy,K.K. Vaze 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.41 No.1

A reinforced concrete (RC) framed structure detailed according to non-seismic detailing provisions as per Indian Standard was tested on shake table under dynamic loads. The structure had 3 main storeys and an additional storey to simulate the footing to plinth level. In plan the structure was symmetric with 2 bays in each direction. In order to optimize the information obtained from the tests, tests were planned in three different stages. In the first stage, tests were done with masonry infill panels in one direction to obtain information on the stiffness increase due to addition of infill panels. In second stage, the infills were removed and tests were conducted on the structure without and with tuned liquid dampers (TLD) on the roof of the structure to investigate the effect of TLD on seismic response of the structure. In the third stage, tests were conducted on bare frame structure under biaxial time histories with gradually increasing peak ground acceleration (PGA) till failure. The simulated earthquakes represented low, moderate and severe seismic ground motions. The effects of masonry infill panels on dynamic characteristics of the structure, effectiveness of TLD in reducing the seismic response of structure and the failure patterns of non-seismically detailed structures, are clearly brought out. Details of design and similitude are also discussed.

Shake table tests on a non-seismically detailed RC frame structure

Sharma, Akanshu,Reddy, G.R.,Vaze, K.K. Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.41 No.1

A reinforced concrete (RC) framed structure detailed according to non-seismic detailing provisions as per Indian Standard was tested on shake table under dynamic loads. The structure had 3 main storeys and an additional storey to simulate the footing to plinth level. In plan the structure was symmetric with 2 bays in each direction. In order to optimize the information obtained from the tests, tests were planned in three different stages. In the first stage, tests were done with masonry infill panels in one direction to obtain information on the stiffness increase due to addition of infill panels. In second stage, the infills were removed and tests were conducted on the structure without and with tuned liquid dampers (TLD) on the roof of the structure to investigate the effect of TLD on seismic response of the structure. In the third stage, tests were conducted on bare frame structure under biaxial time histories with gradually increasing peak ground acceleration (PGA) till failure. The simulated earthquakes represented low, moderate and severe seismic ground motions. The effects of masonry infill panels on dynamic characteristics of the structure, effectiveness of TLD in reducing the seismic response of structure and the failure patterns of non-seismically detailed structures, are clearly brought out. Details of design and similitude are also discussed.

Managing a Prolonged Station Blackout Condition in AHWR by Passive Means

Mukesh Kumar,A. K. Nayak,V. Jain,P. K. Vijayan,K.K. Vaze 한국원자력학회 2013 Nuclear Engineering and Technology Vol.45 No.5

Removal of decay heat from an operating reactor during a prolonged station blackout condition is a big concern for reactor designers, especially after the recent Fukushima accident. In the case of a prolonged station blackout condition, heat removal is possible only by passive means since no pumps or active systems are available. Keeping this in mind, the AHWR has been designed with many passive safety features. One of them is a passive means of removing decay heat with the help of Isolation Condensers (ICs) which are submerged in a big water pool called the Gravity Driven Water Pool (GDWP). The ICs have many tubes in which the steam, generated by the reactor core due to the decay heat, flows and condenses by rejecting the heat into the water pool. After condensation, the condensate falls back into the steam drum of the reactor. The GDWP tank holds a large amount of water, about 8000 m3, which is located at a higher elevation than the steam drum of the reactor in order to promote natural circulation. Due to the recent Fukushima type accidents, it has been a concern to understand and evaluate the capability of the ICs to remove decay heat for a prolonged period without escalating fuel sheath temperature. In view of this, an analysis has been performed for decay heat removal characteristics over several days of an AHWR by ICs. The computer code RELAP5/MOD3.2 was used for this purpose. Results indicate that the ICs can remove the decay heat for more than 10 days without causing any bulk boiling in the GDWP. After that, decay heat can be removed for more than 40days by boiling off the pool inventory. The pressure inside the containment does not exceed the design pressure even after 10days by condensation of steam generated from the GDWP on the walls of containment and on the Passive Containment Cooling System (PCCS) tubes. If venting is carried out after this period, the decay heat can be removed for more than 50 days without exceeding the design limits.

Experimental and analytical investigation on seismic behavior of RC framed structure by pushover method

Akanshu Sharma,G.R. Reddy,R. Eligehausen,K.K. Vaze 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.1

Pushover analysis has gained significant popularity as an analytical tool for realistic determination of the inelastic behaviour of RC structures. Though significant work has been done to evaluate the demands realistically, the evaluation of capacity and realistic failure modes has taken a back seat. In order to throw light on the inelastic behaviour and capacity evaluation for the RC framed structures, a 3D Reinforced concrete frame structure was tested under monotonically increasing lateral pushover loads, in a parabolic pattern, till failure. The structure consisted of three storeys and had 2 bays along the two orthogonal directions. The structure was gradually pushed in small increments of load and the corresponding displacements were monitored continuously, leading to a pushover curve for the structure as a result of the test along with other relevant information such as strains on reinforcement bars at critical locations, failure modes etc. The major failure modes were observed as flexural failure of beams and columns, torsional failure of transverse beams and joint shear failure. The analysis of the structure was by considering all these failure modes. In order to have a comparison, the analysis was performed as three different cases. In one case, only the flexural hinges were modelled for critical locations in beams and columns; in second the torsional hinges for transverse beams were included in the analysis and in the third case, joint shear hinges were also included in the analysis. It is shown that modelling and capturing all the failure modes is practically possible and such an analysis can provide the realistic insight into the behaviour of the structure.

MANAGING A PROLONGED STATION BLACKOUT CONDITION IN AHWR BY PASSIVE MEANS

Kumar, Mukesh,Nayak, A.K.,Jain, V,Vijayan, P.K.,Vaze, K.K. Korean Nuclear Society 2013 Nuclear Engineering and Technology Vol.45 No.5

Removal of decay heat from an operating reactor during a prolonged station blackout condition is a big concern for reactor designers, especially after the recent Fukushima accident. In the case of a prolonged station blackout condition, heat removal is possible only by passive means since no pumps or active systems are available. Keeping this in mind, the AHWR has been designed with many passive safety features. One of them is a passive means of removing decay heat with the help of Isolation Condensers (ICs) which are submerged in a big water pool called the Gravity Driven Water Pool (GDWP). The ICs have many tubes in which the steam, generated by the reactor core due to the decay heat, flows and condenses by rejecting the heat into the water pool. After condensation, the condensate falls back into the steam drum of the reactor. The GDWP tank holds a large amount of water, about 8000 $m^3$, which is located at a higher elevation than the steam drum of the reactor in order to promote natural circulation. Due to the recent Fukushima type accidents, it has been a concern to understand and evaluate the capability of the ICs to remove decay heat for a prolonged period without escalating fuel sheath temperature. In view of this, an analysis has been performed for decay heat removal characteristics over several days of an AHWR by ICs. The computer code RELAP5/MOD3.2 was used for this purpose. Results indicate that the ICs can remove the decay heat for more than 10 days without causing any bulk boiling in the GDWP. After that, decay heat can be removed for more than 40 days by boiling off the pool inventory. The pressure inside the containment does not exceed the design pressure even after 10 days by condensation of steam generated from the GDWP on the walls of containment and on the Passive Containment Cooling System (PCCS) tubes. If venting is carried out after this period, the decay heat can be removed for more than 50 days without exceeding the design limits.

Experiments on reinforced concrete beam-column joints under cyclic loads and evaluating their response by nonlinear static pushover analysis

Akanshu Sharma,G.R. Reddy,Rolf Eligehausen,K.K. Vaze,A.K. Ghosh,H.S. Kushwaha 국제구조공학회 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.35 No.1

Beam-column joints are the key structural elements, which dictate the behavior of structures subjected to earthquake loading. Though large experimental work has been conducted in the past, still various issues regarding the post-yield behavior, ductility and failure modes of the joints make it a highly important research topic. This paper presents experimental results obtained for eight beam-column joints of different sizes and configuration under cyclic loads along with the analytical evaluation of their response using a simple and effective analytical procedure based on nonlinear static pushover analysis. It is shown that even the simplified analysis can predict, to a good extent, the behavior of the joints by giving the important information on both strength and ductility of the joints and can even be used for prediction of failure modes. The results for four interior and four exterior joints are presented. One confined and one unconfined joint for each configuration were tested and analyzed. The experimental and analytical results are presented in the form of load-deflection. Analytical plots are compared with envelope of experimentally obtained hysteretic loops for the joints. The behavior of various joints under cyclic loads is carefully examined and presented. It is also shown that the procedure described can be effectively utilized to analytically gather the information on behavior of joints.