Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
12 results
Search Results
Item Significance of modeling techniques in pushover analysis of RC buildings(2010) Thapa, M.; BabuNarayan, K.S.; Halemane, K.P.; Venkataramana, K.; Yaragal, S.C.; Ramesh Babu, R.; Sharma, A.; Reddy, G.R.The study presented here focuses on the effectiveness of the models adopted for the nonlinear static pushover (NSP) analysis and providing the best model that can predict the nonlinear response of RC buildings with sufficient accuracy with respect to the experimentally obtained results. NSP analysis considers material nonlinearity and is an effective tool to evaluate the performance of the structure under lateral seismic loads. However, the actual test data in order to verify the results of NSP analysis are very rare for RC structures, which are analytically sensitive to the models and procedure adopted by the analyzer. Under the present work three cases of geometric models; a) Frame with beamcolumn elements, b) Frame with beam-column elements and slabs modelled as a rigid diaphragm and c) Frame with beam-column elements and slabs modelled as shell element considering concrete as confined and unconfined were analyzed. Comparision of analytical curve with the experimental pushover curve, clearly suggests that frame modelled as confined beam-column elements and slabs modelled as a rigid diaphragm gives closer results. © 2010 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Strength retention characteristics of concrete cubes subjected to elevated temperatures(2010) Yaragal, S.C.; Clarke, K.S.; Mahesh Babu, K.; Ashokumar, S.; Venkataramana, K.; Babu Narayan, K.S.; Chinnagiri Gowda, H.C.; Reddy, G.R.; Sharma, A.Concrete in structures is likely to be exposed to high temperatures during fire. The relative properties of concrete after such an exposure are of great importance in terms of the serviceability of buildings. The probability of its exposure to elevated temperatures is high due to natural hazards, accidents and sabotages. Therefore, the performance of concrete during and after exposure to elevated temperature is a subject of great interest to the designer. Physical changes like cracking, colour change, spalling and chemical changes like decomposition of Ca(OH)2 and the C-S-H gel take place when subjected to elevated temperatures. This work reports the characteristics of concrete at elevated temperatures. Popular normal strength grades (M20, M25, M30, M35, M40 and M45) produced by Ready Mix Concrete (RMC) India, Mangalore have been used in production of test specimens (150 mm cubes) to obtain more meaningful and realistic data. In the preliminary phase 150 mm cubes were cast, cured and tested by destructive method for gathering data on strength characteristics. Later these test samples were subjected to elevated temperatures ranging from 100°C to 800°C, in steps of 100°C with a retention period of 2 hours. After exposure, weight losses were determined and then again destructive tests were conducted to estimate the residual compressive strength. Test results indicated that weight and strength significantly reduces with an increase in temperature. © 2010 CAFET-INNOVA TECHNICAL SOCIETY.Item How to protect your home and neighbourhood from solar flares and solar storms(2012) Reddy, P.R.; Venkat Reddy, D.[No abstract available]Item Managing seismic risk in ancient structures: Coupled variables under numerical and experimental approaches(2013) Pineda, P.; Venkat Reddy, D.Analysis and evaluation of seismic reliability of masonry cultural heritage buildings is a difficult task, owing to a great number of uncertainties. In thesefew lines, many questions are posed, trying to learn from the wisdom of ancient times and remembering the advantages of using multidisciplinary tools when the seismic safety is the main concern. © 2013 CAFET-INNOVA TECHNICAL SOCIETY.Item Dynamic soil-structure interaction analysis of RC framed building with various positions of shear walls(CAFET INNOVA Technical Society 1-2-18/103, Mohini Mansion, Gagan Mahal Road, Domalguda, Hyderabad 500029, 2016) Chinmayi, H.K.; Jayalekshmi, B.R.In the present study, a three-dimensional dynamic soil-structure interaction analysis of symmetric buildings in time domain is performed using IS spectrum ground motion record corresponding to zone III to evaluate the dynamic response of structure-foundation-soil system. Three types of shear wall buildings of aspect ratio 1, 1.5, 2, 3 and 4 categorized based on the shear wall locations were considered in conjunction with four types of soil of shear wave velocities ranging from 150m/s to 1200 m/s, symbolizing soil classes B, C, D and E of FEMA-356: 2000. Integrated structure-foundation-soil systems were analyzed using commercial finite element software LSDYNA, based on direct method of soil-structure interaction (SSI) assuming linear elastic behavior. The study shows considerable variation in dynamic characteristics and structural seismic response of the structure due to the incorporation of the effect of flexibility of soil and position of shear walls. Tall buildings with shear walls placed at the exterior corners experience the least base shear. © 2016 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.Item Influence of ambient air relative humidity and temperature on thermal properties and unsteady thermal response characteristics of laterite wall houses(Elsevier Ltd, 2016) Saboor, S.; Ashok Babu, A.B.P.S.This paper presents the experimental investigation of the effect of ambient air humidity and temperature on thermal properties of the laterite rocks used in South-West coastal India. The experimental technique employed was transient plane source method in the saturated salt solution humidity controlled chamber. Experimental results showed an increase of thermal conductivity by 14.7% and specific heat by 9.15% with an increase in the relative humidity of ambient air in the hygroscopic range. A porous and ferruginous matrix of laterite was studied using a scanning electron microscope. The effects of relative humidity of the ambient air and temperature on the unsteady state thermal heat transfer characteristics such as transmittance, admittance, decrement factor, time lag, surface factor, surface factor time lag and heat capacity for different thicknesses of the laterite rock walls were investigated analytically. One dimensional heat flow equation under periodic convective boundary conditions was solved using matrix algebra and a computer simulation program which employs a cyclic admittance method was developed using MATLAB to compute unsteady state thermal characteristics. Results indicate that the decrement factor reduces by 8.35% and time lag increases by 2.88% with an increase in the relative humidity of ambient air compared to the dry state for the Indian standard laterite rock thickness. © 2016 Elsevier Ltd.Item Optimizing the position of insulating materials in flat roofs exposed to sunshine to gain minimum heat into buildings under periodic heat transfer conditions(Springer Verlag service@springer.de, 2016) Saboor, S.; Ashok Babu, A.B.P.S.Building roofs are responsible for the huge heat gain in buildings. In the present work, an analysis of the influence of insulation location inside a flat roof exposed directly to the sun’s radiation was performed to reduce heat gain in buildings. The unsteady thermal response parameters of the building roof such as admittance, transmittance, decrement factor, and time lags have been investigated by solving a one-dimensional diffusion equation under convective periodic boundary conditions. Theoretical results of four types of walls were compared with the experimental results available in literature. The results reveal that the roof with insulation placed at the outer side and at the center plane of the roof is the most energy efficient from the lower decrement factor point of view and the roof with insulation placed at the center plane and the inner side of the roof is the best from the highest time lag point of view among the seven studied configurations. The composite roof with expanded polystyrene insulation located at the outer side and at the center plane of the roof is found to be the best roof from the lowest decrement factor (0.130) point of view, and the composite roof with resin-bonded mineral wool insulation located at the center plane and at the inner side of the roof is found to be energy efficient from the highest time lag point (9.33 h) of view among the seven configurations with five different insulation materials studied. The optimum fabric energy storage thicknesses of reinforced cement concrete, expanded polystyrene, foam glass, rock wool, rice husk, resin-bonded mineral wool, and cement plaster were computed. From the results, it is concluded that rock wool has the least optimum fabric energy storage thickness (0.114 m) among the seven studied building roof materials. © 2015, Springer-Verlag Berlin Heidelberg.Item Response of Strata and Buildings to Blast Induced Vibrations in the Presence and Absence of a Tunnel(Springer International Publishing, 2016) Rebello, N.E.; Shivashankar, R.; Sastry, V.R.Blast induced vibrations form an inevitable and major part of modern day construction. The changes that happen to the strata or buildings surrounding the blast are evident in a fraction of a second. Effect of damage is more pronounced in the absence/presence of the tunnel. The vibration produced due to blast may be induced due to a deep underground explosion, a surface explosion or even an in-tunnel explosion. In this study the above three situations are numerically modeled by a Distinct Element software 3DEC (3.0). Soil properties are varied representing soft and stiff strata. Further, three velocity time histories of 2, 45 and 85 Hz are used as an input in the model and are applied at three different boundaries of the model. Results of the analysis reveal that the response of building in softer strata and lower frequencies led to greater magnification of velocities and displacements compared to response of buildings in stiff strata. Presence of the tunnel led to reduction of peak velocity (PV’s) and displacements at the building top due to damping effect. PV’s at the top floor were greater than the PV’s at the bottom floor and there was an upliftment of the soil mass at the ground level. However, the upliftment in the presence of the building was lower than the upliftment in the absence of the building. Stress in the tunnel lining increased in the presence of the building, however percentage reduction of stress depends on the number of building stories. © 2016, Springer International Publishing Switzerland.Item Source apportionment of PM2.5 particles: Influence of outdoor particles on indoor environment of schools using chemical mass balance(AAGR Aerosol and Air Quality Research hhyang@cyut.edu.tw, 2017) Kalaiarasan, G.; Mohan Balakrishnan, R.M.; Sethunath, N.A.; Manoharan, S.Children have higher lung function than adults and they spend most of their day time in schools. Also, children studying at schools located in the vicinity of busy roadways are vulnerable to childhood asthma and respiratory disorders. The present study is focused on estimating the sources of PM2.5 particles present in the indoor air quality in schools which are located adjacent to urban and suburban roadways. The indoor PM2.5 samples from all the four schools were collected using fine dust sampler from 8 a.m. to 4 p.m. The sampling was carried out for one complete week during various seasons including both working and non-working days. The chemical compositions of the PM2.5 samples were analyzed for certain elements like Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sr, Ti, V and Zn using Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES) and ions like F-, Cl-, NO3-, PO43-, SO42-, K+, Ca2+, Mg2+, NH4+, Na+ using Ion Chromatography (IC). Source apportionment study using Chemical Mass Balance was carried out using the species concentration of the collected samples. The major sources were found to be Paved Road Dust, Soil Dust, Gasoline Vehicle Emissions, Diesel Vehicle Emissions and Marine Source Emissions. Among these, vehicular emissions contribution was found to be higher for the schools located close to roadways rather than the school located at a considerable distance from highway. The difference in source type contribution at each school clearly depicts the difference in nature of location and type of activities in the vicinity of the sampling sites. © Taiwan Association for Aerosol Research.Item Developing a building performance score model for assessing the sustainability of buildings(Emerald Publishing, 2022) Hp, T.; C, R.; Deepak, D.Purpose: Construction industry is one of the leading causes of pollution generation in today's context. But the fact that the development of construction industry leads to the country's economic and social development cannot be unobserved. Hence, there is a need to develop a sustainable construction methodology, and while doing so, measures must be considered so as to not disturb the natural habitats. With the greater prominence shown toward the concept of green and sustainable construction developments, various tools have been developed in recent years in order to measure the performance of such sustainable and green buildings. In the Indian context, the assessment tools developed to measure the performance of the green building are found to be scanty in addressing various economic and social impacts. Design/methodology/approach: This study aims at developing a building performance score (BPS) model concerning the sustainability model built on the triple bottom priorities considering all the three vital components, viz. environmental, economic and social factors. In this study, the different phases involved in the complete life cycle of the project are recognized and then all the phases are assessed considering all the three major components mentioned in the BPS model. Findings: The outcome of this study specifies that various indicators, such as the topographical and climate change, health and safety of the construction workers, project management consultancy, risk management, security measures and solid waste management, form a chief source of a sustainable building, and these indicators are not being assessed in the existing assessment tools. Also, consideration of environmental, economic and social factors is also equally important in construction industry. Moreover, these indicators are also required to be assessed and included in the evaluation process while assessing the performance of the building. Originality/value: The BPS model developed in the study will assist to improve in assessing the building performance with respect to all indicators in the complete life cycle of the project. © 2020, Emerald Publishing Limited.