MIST Journal of Science and Technology

INTERFACE DEPENDENCY OF REINFORCED CONCRETE JACKETING FOR COLUMN STRENGTHENING

2017-12-01T00:00:00Z

INTERFACE DEPENDENCY OF REINFORCED CONCRETE JACKETING FOR COLUMN STRENGTHENING Ahmed, K. Sakil; Mahmud, Riaz This paper investigates the structural capacity enhancement of reinforced concrete column by concrete jacketing. In view of investigating structural capacity and integrity of jacketed column, a total twelve retrofitted column samples with different jacket thickness were experimentally tested. Samples are prepared with different types of interface including no surface treatment, addition of bonding chemical, roughening of old surface, application of welded ties, and changes in clear cover to investigate the influence of interface bonding between new and old concrete. Analytical equations for jacketed columns are formulated as per elastic principle maintaining strain compatibility at the interface in addition to concrete modeling using finite element method (FEM). Column interaction diagrams as formed by analytical equations are compared and verified with existing Japanese code and available FE software packages. Experimental investigation shows that failures occur relatively earlier at the column interface than the core of the retrofitted column. Comparative study in terms of interaction diagram shows that experimental result well agrees with the computed analytical result but deviates from the FE analysis. Finally, an interface bonding reduction coefficient in the range of 0.65-0.88 is proposed for RC jacketed column subjected to different types of interface. K. Sakil Ahmed[1] and Riaz Mahmud [2] 1,2 Civil Engineering Department, Military Institute of Science & Technology, Mirpur Cantonment, Dhaka 1216, Bangladesh. 1< drksa@ce.mist.ac.bd >, 2< riazeity7239@gmail.com>

ENERGY AND EXERGY BASED ANALYSIS OF SI ENGINES USING METHANE, METHANOL AND OCTANE

2017-12-01T00:00:00Z

ENERGY AND EXERGY BASED ANALYSIS OF SI ENGINES USING METHANE, METHANOL AND OCTANE Mizanuzzaman, Md. In this study, the phenomena of air-fuel mixing and combustion of Methane, Methanol and octane has been studied numerically in order to assess the thermodynamic analysis of the system. For this purpose, a thermodynamic-based engine cycle model is developed without considering geometric features of fluid motion. Here a single cylinder four-stroke spark-ignition (SI) engine is considered as a system. Variable specific heat ratio is considered instead of constant specific heat ratio. Empirical correlations are used to predict heat loss from the engine cylinder. Developed fundamental equations and empirical relations have been used in this model with the help of FORTRAN 95. In this study, friction losses are also modeled to estimate the overall energy losses calculation. The effects of changing some design and operating parameters such as compression ratios and rpm on the variation and destruction of exergy have been investigated through the analysis. It was found that the design and operating conditions have considerable effects on the variation of energy, exergy and irreversibilities as well as the efficiency during investigated parts of the SI engine cycle. 1st law and 2nd law efficiencies were found to increase for all the (three) fuels with increasing engine speed and compression ratios. The Present study recommends the necessity of both energy and exergy analysis to identify the source of work potential losses for different fuels used in SI engine. Md. Mizanuzzaman Department of Mechanical Engineering Bangladesh Military Academy (BMA), Bhatiary, Chittagong, Bangladesh Email: mizan_zaman@yahoo.com

ASSESMENT OF EXTRACTABLE ENERGY USING OCEAN CURRENT AS RENEWABLE ENERGY SOURCE ALONG THE BAY OF BENGAL, BANGLADESH

2017-12-01T00:00:00Z

ASSESMENT OF EXTRACTABLE ENERGY USING OCEAN CURRENT AS RENEWABLE ENERGY SOURCE ALONG THE BAY OF BENGAL, BANGLADESH Ahmad, Myisha; Hasan, G. M. Jahid Electricity is the pinnacle of human civilization. At present, the growing concerns over significant climate change have intensified the importance of use of renewable energy technologies for electricity generation. The interest is primarily due to better energy security, smaller environmental impact and providing a sustainable alternative compared to the conventional energy sources. Solar, wind, biomass, tide, and wave are some of the most reliable sources of renewable energy. Ocean approximately holds 2×103 TW of energy and has the largest renewable energy resource on the planet. Ocean energy has many forms namely, encompassing tides, ocean circulation, surface waves, salinity and thermal gradients etc. Ocean tide in particular, associates both potential and kinetic energy. The study is focused on the latter concept that deals with tidal current energy conversion technologies. Tidal streams or marine currents generate kinetic energy that can be extracted by marine current energy devices and converted into transmittable energy form. The principle of technology development is very comparable to that of wind turbines. Conversion of marine tidal resources into substantial electrical power offers immense opportunities to countries endowed with such resources and this work is aimed at addressing similar prospects of Bangladesh. The study analyses the extracted current velocities from numerical model works at several locations in the Bay of Bengal. Based on current magnitudes, directions and available technologies the most fitted locations were adopted and possible annual generation capacity was estimated. The paper also examines the future prospects of tidal current energy along the Bay of Bengal and establishes a constructive approach that could be adopted in future project developments. Myisha Ahmad[1] and G. M. Jahid Hasan[2] 1,2 Department of Civil Engineering, Military Institute of Science and Technology, Mirpur Cantonment, Mirpur-12, Dhaka-1216, Bangladesh e-mail: 1myisha.ahmad@gmail.com e-mail: 2jahid@ce.mist.ac.bd

GREEN ROOF: A POSSIBLE SOLUTION FOR REVIVING URBAN GREEN IN DHAKA CITY

2017-12-01T00:00:00Z

GREEN ROOF: A POSSIBLE SOLUTION FOR REVIVING URBAN GREEN IN DHAKA CITY Momtaz, Naznia; Khan, Md. Manzur Morshed Dhaka is one of the most rapidly urbanizing cities in the world. Due to rapid urbanization, the presence of vegetation in Dhaka has been diminishing fast. Dhaka is gradually losing its portion of green day by day. Thus, the urbanization is transforming this city into a concrete jungle. World Health Organization (WHO) recommends that there should be 9 square meter green space per city dweller for ensuring better life. Moreover, according to UNEP there should be a minimum of 25% open space (plantation and water body) in a city. Whereas the open space area is only about 14.5% in Dhaka city, according to a study in 2012 [1]. RAJUK proposed management tools like FAR (Floor Area Ratio) to control the building density and urban green; however, it is not enough to effectively regenerate the lost green parts of Dhaka city. Green roof can be a possible solution for compensating urban green of this city. The objective of this paper is to analysis the possibilities of regeneration of urban green space by green roof as well as the benefits of green roof to improve the overall city environment of Dhaka. The study methodology involved to identify the problem, develop an analysis plan, collecting data from various secondary sources, analysis the data and adjust it to the identified problem and find out probable outcomes, were the methods of this research. The advantages of green roofs in urban areas are numerous. However, green roofs demand structural standards and the waterproofing system. Despite the challenges, the green roof benefits reported here suggest that green roofs can be used effectively as a solution of reviving urban green in Dhaka city. Naznia Momtaz[1] and Md. Manzur Morshed Khan[2] 1 University of Melbourne, Melbourne,Victoria, Australia, 2Faculty, Department of Architecture, Military Institute of Science and Technology (MIST), Dhaka, E-Mail: 1naznia_arc@yahoo.com E-Mail: 2morshed@arch.mist.ac.bd