Sensitivity analysis of focal depth in seismic hazard assessment

Khan Mohammad Muzzaffar, Teja Munaga and Kumar Gonavaram Kalyan

Page No. 1-7

The general way of representing the seismic hazard at a particular site is by estimating the Peak Ground Acceleration (PGA) using the probabilistic or deterministic approach. The PGA and Spectral Acceleration (SA) values at different time periods also known as Response spectra are usually provided by the seismic code of a particular country which prescribes the minimum requirements for designing of infrastructure. However, a sensitivity analysis generally provides the increased information associated to the result or procedure. In this study, we carried out the sensitivity analysis to understand the effect of focal depth in probabilistic seismic hazard analysis (PSHA) of Warangal region. CRISIS2015 code was utilized in the estimation of PGA and SA values for 475 years and 2475 years return period by varying the focal depth from 5 to 25 km.

The results indicated that the sensitivity analysis of focal depth has prominent influence on the obtained values of PGA. The PGA varies from 0.117 for focal depth 5 km to 0.057 for focal depth of 20 km for 475 years return period whereas for 2475 years return period, PGA varies from 0.254 for focal depth 5 km to 0.102 for focal of 20 km. Later, PGA values are calculated using logic tree approach by assigning normalized weight to each focal depth. The estimated PGA value was later compared with Indian Standard code (IS 1893).

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Seismic strengthening of overhead water tanks (OHWT) using tuned mass curved sliding roof

Titiksh Abhyuday

Page No. 8-16

This experimental study involved constructing the roofs of elevated tanks as tuned mass dampers. Moreover, they were cast in a curved form which provided the much-needed reentering capability to such sliding roofs. The concept of modeling the roofs of structures as tuned mass has already been established but these flat sliding roofs are required to be pushed back into their original position after a seismic event, which meant they needed external restoring forces which are very costly. Tuned mass curved sliding roofs can overcome this problem as the curvature of the roof lying over the sliders will automatically re-center the roof thereby negating the need of external restoring forces. A prototype of the said tank was thus constructed and its performance was compared to that of a conventional tank. Two parameters namely storey acceleration and top storey displacement were measured using an array of accelerometers and ultrasonic sensors attached to the models.

The data acquisition was done using ARDUINO and LABVIEW used to synthesize the final output so as to present the results in a graphical format. The results revealed that constructing the roofs of overhead water tanks as tuned massed curved sliding roofs with a roof to body mass ratio of 0.3 can effectively reduce maximum top storey displacement by almost 50%.

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Impact of El Niño-Southern Oscillation and Sunspot Activity on India’s Climate

Mishra Ashutosh

Page No. 17-23

Among several factors of climate, the El Niño-Southern Oscillation (ENSO) and Sunspot cycles work on interannual to interdecadal scales and it is believed that while the El Niño–La Niña pressure seesaw of Pacific Ocean affects climate by altering global wind and rainfall patterns, the 11 years periodic variability of sunspot appearance bring changes in insolation and cloud formation. Thus, the role of these two climate forcings seems critical in pushing short term climatic variabilities. This study attempts to know the impact of these two climatic phenomena on temperature and rainfall patterns at regional scale and for the purpose the study considers India as the case.

Analysis reveals that temperature show a good correlation with sunspot activities, while the effect of ENSO cycle on country`s rainfall is not very clear. However, India’s coastal states record a notable rise in temperatures during El-Niño phase of ENSO phenomenon and this may be the cause behind fragmented and uneven rainfall over the country during El-Niño years.

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A Comparative Study on the Floods of 1924 and 2018 in Kerala

Aiswarya Jyothi K.G. and Meera B.

Page No. 24-29

The flood is the most recurrent natural disaster in India which in turn had resulted in huge loss of life, infrastructure and financial crisis. It has played a prominent role in Kerala civilization, culture and economy. This study is a comparative study of the floods that had happened in the years 1924 and 2018 in Kerala. These two disasters which happened in two different eras have altered man’s perception of life and the traumatic experience they have encountered stays within them forever.

The flood taught Malayalis the importance of nature and its influence in the lives. Thus, it is requisite to take into consideration the areas affected in the flood in both the years so as to get to know the disaster-prone areas and the necessary measures to be implemented to reduce the impact of the catastrophe in the coming years.

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Disaster Mitigation of RCC Buildings using Sacrificial Surface Anode Cathodic Protection

Sharma Jaiprakash B. and Patil Yogesh D.

Page No. 30-40

The recent collapse of buildings or part of the buildings has increased the need for economical and reliable protection system to mitigate such disasters in which several lives are lost. The major cause is corrosion of reinforcement and further loss of strength of structural elements. The present technology of cathodic protection of steel is one of the well proven and widely adopted means for corrosion protection of steel. The application of this technology is not common for RCC buildings; the reason may be cost and lack of awareness about structural health.

The present study deals with various methods and devices used for cathodic protection of steel and the development of Sacrificial Surface Anode CP (SSACP) technique along with CP device which is tested in laboratory as well as in building and proved to be a success. Apart from the success of the Sacrificial Surface Anode CP technique, it is external, can be installed on surface of column, beam or slab, can be easily replaced and monitoring by measurement of potential difference and current flow between anode and cathode is possible. The application for patent of Sacrificial Surface Anode technique and device is submitted to Indian Patent Office, Mumbai. It was published on 10th August 2018 as application no. 201821023741.

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From Surviving to Thriving? Evaluating the Resilience of Rural Tourism Businesses in Disaster-Prone Area of Sabah, Malaysia

Kamarudin K.H., Razak K.A., Omar Chong N., Abd Wahid S.N.A. and Wan Mohd Rani W.N.M.

Page No. 41-48

It is always fascinating to learn how tourism businesses can persist in rural areas that are prone to disasters. This study examines the enabling factors for rural tourism resilience in a changing environment. Mesilou Village in Kundasang, Sabah was selected as a case study and 20 respondents i.e. homestays owners and operators participated in the questionnaire-guided interview conducted in October 2018. Results from this study indicated that there is a combination of factors that influence the survivability of rural tourism businesses in Mesilou Village, particularly after the 6.0 Richter scale earthquakes struck the Ranau-Kundasang area in June 2015.

These factors included; (1) strong self-belief among tourism operators that they will recover from the disaster; (2) strong kinship and family support for business recovery; (3) respondents’ possession of suitable skills to carry out own maintenance and recovery works; (4) diversification of household income to fund recovery works and (5) the low severity of damages suffered by the business/premise i.e. minor to no damage. The case of Mesilou Village demonstrates resilience from highly motivated respondents to rebuild their lives and businesses, pushing for business recovery and growth with an important goal in mind which is to improve the quality of life while coping with adversity.

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Spatial Analysis on Landslide Disaster Risk in the Semarang City, Central Java, Indonesia

Heri Tjahjono, Suripin and Kismartini

Page No. 49-58

Historically, the city of Semarang in Central Java Province, Indonesia has often experienced landslides due to a number of factors. This study aims to develop a landslide risk map and analysis of disperse level in that city to support risk reduction efforts. This research is an observational type whose data is analyzed quantitatively. Population is the physical condition of the community and those who have experienced landslides or those who live in disaster-prone areas. The variables of this study are the danger, vulnerability and capacity of the community in the face of landslides.

Data analysis was done by scoring and spatial analysis using GIS techniques. In the end, the results show that the level of disparity in landslide risk is spread across 8 sub-districts in the city ranging from low, medium and high. The highest risk areas are widespread in Gunungpati sub-district, Semarang. Overlay analysis with GIS technology resulted in 563 landslide risk concepts, which were simplified into 16 concepts and were successfully generalized to the new theory of landslide risk.

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Changes in Soil Physical Structures due to Variations in Land Use Patterns in North East India: Disaster to Soil Health

Bhuyan Shafiqul Islam and Laskar Imrana

Page No. 59-63

Present study was conducted in Meghalaya, north east India which lies between 25°41′21′′ North latitude and 91°55′25 ′′ East longitude to investigate the effect of land use patterns on the changes of soil physical properties. Five Major lands use pattern such as Home garden, Grassland, Agro forestry, Pine plantation and Forest were selected for the detailed study. Soil samples were collected by using a steel corer i.e. 5 cm inner diameter from five different locations of the respective study sites at approximately 100 m intervals at each site from two depths (0-15 cm an 15-30 cm).

Laboratory experiments were carried out with the standard methods. Land use systems have great impact on the soil physics in the study area. Different land use patterns such as agro forestry, home garden etc. practiced by the farmers and large patches of cultivable land are openly exploited through unscientific and age-old practice of farming which is detrimental not only to crop production but also to the immediate environment and biodiversity.

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Avalanche forecasting model based on Independent Component Analysis

Kushe Neha Ajit and Magar Ganesh M.

Page No. 64-68

Mitigation of the danger posed by snow avalanches is important for the protection of the human settlements residing in the alpine regions. Many methods have been put forth that deal with prediction of the avalanches. The methods involving nearest neighbour algorithm make use of the snow and meteorological data of the particular region to obtain the avalanche occurrence situation. Extraction of important parameters plays a vital role in forecasting.

Current work suggests the use of independent components analysis to extract the features present in the dataset without losing any important information conveyed by the dataset. These independent components are then applied to cosine similarity based nearest neighbour model for snow avalanche prediction to find avalanche occurrence situation for the given day. The results of this model depict an improvement from the basic avalanche forecasting model using cosine similarity after the use of independent component analysis on the data. This research has been undertaken for the Bahang region of Himachal Pradesh, India.

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Diagrid building model: Design, fabrication and 1:75 scale testing for experimental seismic analysis

Naik Swaral R. and Desai Satish N.

Page No. 69-80

This study presents a systematic methodology for testing a small-scale steel DiaGrid building model. Instead of vertical columns in conventional tall structures, DiaGrid building consists of inclined columns that convert all the forces into axial forces, resulting in higher lateral stiffness to resist heavy winds and severe earthquakes. Earthquake being a major disastrous force for high-rise structures, engineers are accepting the challenge to deal with disaster and secure life of the habitants as well as the life of the structure. This study aims to discuss design and construction of a low-cost scaled DiaGrid building model and the procedure for the shake table test. The scaling factor of 1:75 is finalized according to the similitude requirements and availability of testing resources.

The analytical model is tested and verified using finite element software SAP2000. The main physical measurement for validating the test is lateral displacement. All the experimental displacement values for different earthquakes fall very close to the analytical values. With small scale DiaGrid building models, the actual behavior of the full-scale DiaGrid structure can be predicted and it can be tested with all the probable, non-predictable, or even unrealistic earthquakes which may or may not be occurring during the life span of the full-scale DiaGrid structure.

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