Seismic Response of Cylindrical Elevated
Steel Water Tank
-- Keerti M Telsang, Raikar R V and Kiran M Malipatil
Elevated water tanks are most commonly used to store water and to supply at certain height for pressurizing the water distribution system. A major irregularity along the height of the structure is due to large water mass on the top and complex phenomenon of dynamic interface between the fluid and the walls of the tank with the horizontal acceleration causing the sloshing, which determines the need for specific conditions. These issues pose significant problems in terms of design and modeling of such structure, making it particularly inspiring from a structural analysis point of view. The seismic performances of these storage tanks are a matter of special importance extending beyond the economic value of the tanks. The seismic behavior of the elevated water tanks is different from that of a ground supported tank or underground water tank. Therefore, in the present paper, a seismic analysis using response spectrum method is carried out for steel elevated water tanks. The study is made on cylindrical elevated water tank with and without the bracing configurations (2-storey, 3-storey and 4-storey) considering different earthquake zones (zone 2 to 5) and soil conditions. The analysis is carried out using STAAD-PRO V8i (SELECT series 4) software. The results for bare and braced frame tanks, which are in terms of base shear, time period and displacement for different seismic zones and soil conditions, are compared. The water tanks with 3-storey and 4-storey showed better performance than 2-storey in terms of displacement. The braced frame steel elevated tank showed an increased overall stiffness than the unbraced one.
© 2015 IUP. All Rights Reserved.
Experimental Investigation of Waste Glass Powder as Partial Replacement of Cement and Sand in Concrete
-- S Sai Tejaswi, R Chinna Rao, B Vidya and J Renuka
Concrete is one of the most widely used construction materials in the world. However, the production of Portland cement, an essential constituent of concrete, leads to release of significant amount of CO2, a greenhouse gas. Environmental issues are playing an important role in the sustainable development of the cement and concrete industry. There is a need to replace a part of cement with some pozzolonic material to reduce the consumption of cement. Extensive research is going into the use of cement replacement using many waste materials and industrial by-products. Efforts have been made in concrete industry to use waste glass as partial replacement of coarse or fine aggregate and cement. Glass is used in many forms in day-to-day life. It has limited span, and after use it is either stockpiled or sent to landfills. Since glass is non-biodegradable, landfills do not provide an environment-friendly solution. Hence, there is a strong need to utilize waste glass. In this study, finely powdered waste glass is used as a partial replacement of cement and fine aggregate in concrete and the same is compared with conventional concrete. This paper examines the possibility of using glass powder as a partial replacement of cement and fine aggregate. Glass powder is partially replaced at 10%, 20%, 30%, 40% and 50% and tested for its compressive strength. The cubes are put to oven heating at 100 °C for different exposures to heat and the residual compressive strength is determined. But after heating, it is found that the residual compressive strength of 20% replacement of glass powder concrete is almost equal to concrete without replacement and hence it can be used as a fire-resistant concrete.
© 2015 IUP. All Rights Reserved.
Factors Affecting the Compressive Strength
of Heat-Cured Geopolymer Concrete
with Fly Ash and Slag
-- Sonal Thakkar and Darpan Bhorwani
Sustainable development and preservation of environment for future generation are the need of the hour. It is very much essential to have an alternative to cement due to its disadvantage of large emission of carbon dioxide into atmosphere and highly energy-intensive process. Geopolymer concrete is an alternative to conventional concrete. This paper presents a study carried out on the combination of industrial waste fly ash and slag as source materials and the factors affecting the compressive strength of oven cured specimen. The ratio of alkaline liquid to source material was kept at 0.4, the rest period at 1 day and temperature at 90 °C. The density of geopolymer concrete was kept approximately equal to 2400 kg/m3 equivalent to conventional Ordinary Portland Cement (OPC) concrete. It was found that compressive strength of geopolymer concrete increased with increase in curing duration. Increase in strength was also observed with increase in molarity and increase in alkaline solution ratio. Also, if dosage of superplasticizer increased, workability also increased, and it led to increase in compressive strength.
© 2015 IUP. All Rights Reserved.
An Experimental Study on the Exterior
Behavior of Beam-Column Joint
Reinforced with GFRP Rebars
-- A Sofi and J Saravannan
FRP materials are currently used as reinforcement for concrete structures in which corrosion protection is a primary concern. FRP materials are corrosion-resistant and exhibit several properties that make them suitable for structural reinforcement. In a conventional structural system, joints are important part of the system, which transfer forces to the nearest members. Therefore, the present study is aimed at assessing the behavior of exterior RC beam-column joint reinforced with fiber reinforced polymer (the type of reinforcement) used, under static loading conditions. In this work, totally four exterior RC beam column joint specimens are casted. Two of them are reinforced with conventional steel and the remaining two are reinforced with GFRP rebars. These specimens are casted with no additional reinforcement at the joints. These specimens are tested under static loading conditions by keeping a constant load on the column and incremental load given on the beam. It is found that the load and moment carrying capacity of GFRP specimens are reduced by 20-30%. Cracks are initially developed at the beam-column joint interface and then further cracks are developed between the joint interface and loading point on the beam. The deflection of the beam is also higher for GFRP specimen compared to the control specimen.
© 2015 IUP. All Rights Reserved.
Thermal Buckling and Post-Buckling
of Columns of Variable Cross-Section
--N Venkateshwarlu, Suresh Akella, T Kishen Kumar Reddy
and G Venkateswara Rao
The paper investigates thermal buckling and post-buckling of columns of variable cross-section along the length. Two types of variable cross-section columns, namely, sinusoidally and linearly varying cross-sections, are considered. The geometry of the cross-section is taken as symmetric about the midpoint of the length of the columns. The thermal buckling and post-buckling loads, which are the mechanical equivalent of the uniform compressive load developed when the column is subjected to high temperature, are evaluated by applying the classical Rayleigh-Ritz (RR) method. The variable cross-section of the columns is quantified through an easy-to-recognize taper ratio. The numerical results in the form of the thermal buckling loads and the thermal post-buckling loads are obtained for different taper ratios and the reference central deflection parameters. The numerical results are found to be reliable when compared with similar results of the limiting cases and from the logical physical trends in the absence of the corresponding results for the definition of the taper ratios used in this study.
© 2015 IUP. All Rights Reserved.
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