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Literature Review:1.1. Introduction:Cement and steel being the most generally utilized and devoured material in the development of various kinds of constructions. Concrete, otherwise called the second most generally utilized material on the planet [1].Thats why there is a need to know the behavior of these two materials when used both, individually and in composite form. In recent decades, more improvements and enhancement in concrete technology is done which had a huge impact on structural systems. Structure engineer prefer to retrofit the existing structure as it would be the best solution in terms of strength, efficiency, economy and saving time [1].1.2. Beam column joint:There are considerable amount of RC structures not meeting the criteria of standard design. This is mainly due to improper design and construction techniques. Due to which most of the structures collapsed. The failure of the structures during recent earthquakes shows that most structures fails due to weak beam column joint or inappropriate transverse reinforcement in the joint causing shear failure of the beam column joint [2].Shear failures are brittle and more vulnerable to structures causing the collapse of overall structures therefore, they should be avoided. For achieving ductile design, proper reinforcement should be given to increase the shear capacity which is done mostly by providing stirrups and ties in beam and columns respectively with appropriate spacing for good bonding between concrete and reinforcement [3].The use of RSR (Rectangular Spiral Reinforcement) by testing RC beams under continuous four-point test and results shows shear capacity was increased. Yang et al. [4] studied the effectiveness of Spiral type wire ropes a shear reinforcement by testing three two span RC T- beams in four-point test under static loading condition and results show that it was highly convenient method for increasing ductility and controlling crack width. Another research by Al-Nasra in which swimmer bars used as transverse reinforcement with three type of connection (weld, bolt and U-link bolt) were tested and results shows that it is a convenient method for improving shear strength, ductility and controlling crack width[4].Structures when properly designed (prevention from brittleness instabilities due to deflections) have capacity to absorb energy when deformed beyond their plastic limits. The column axial load makes the joint stiffer as well as stresses are produced in longitudinal reinforcement of beam. From increment of stirrups ratio in joint region stress distribution becomes more uniform. Also, some tension from top is absorbed in upper part stirrups in joint. Monotonic tests show that failure of connection can be in beam (bending failure) or inside joint (shears bond failure). Shear strength of exterior joint decreases with increase of joint slenderness. Structures must be designed for monotonic loading because of failure of members are maximum. The results show that as the load increases, displacement, min max stress increases. As the stiffness of structure changes the displacement, min max stress changes nonlinearly [5].1.3.Seismic Failures: Mostly the collapse of building due to this earthquake was because of weak beam column joints. Inadequate and inappropriate reinforcement in the transverse direction in joint and weak column/strong beams design are the main causes of joint shear failure observed during recent earthquakes. In 1999 Earthquake at Kocaeli (Turkey) and Chi Chi (Taiwan), brittle shear failure was the main reason of total collapse of many buildings [6].The earthquake occurred in 1999 in Kocaeli shows exterior joint failure in RC buildings. The exterior joints are exposed, thus seismic load directly acts on it therefore more vulnerable to failure [6].1.4. Methods of strengthening Structures to seismic failures: Properand economical strengthening techniques should be applied to overcome shear failure in the joints. To counter these problems different researchers proposed different methods for increasing shear strength of beam column joint.Various methods of steel jackets, plates, prefabricated rectangular or circular tubes of different shapes have been used for improving strength and ductility of the beam column joint. Corazao and Durrani focuses on the use of external steel plates on each sides of column face by bolting it through epoxy bonding and steel angles welded to the plates and the joint region enlarged with concrete fillet in Two-way beam column slab system for providing additional strength to structure against different loadings. Since prefabricated so these methods are quite helpful in saving construction time. However, using these methods there are some problems encountered such as corrosion, heavy steel plates thus difficult to handle, in corrugated sheets it reduces aesthetics and floor space is reduced in grouted steel tubes. Thus, creating unexpected failure modes [7].For increasing shear capacity other effective method can also be incorporated like for low seismic region use of enlarged joint area is also an effective technique for increasing shear strength, stiffness, and energy dissipation of beam column joint. Experimental study consists of interior beam column joint namely Jo, J1, J2, J3 and J4. J0 was the specimen without joint enlargement, J1 was specimen in which joint enlargement is integrally cast with specimen. The other 3 specimen were strengthened with planer joints enlarged with different size and shapes. These specimens are designed to ACI-318 building codes without considering earthquake force and can be applied only for low seismic area thats why low stirrups are used and no transverse reinforcement is given in joint panel. Experimental results show that in joint J0 brittle joint failure occurs, in J1 flexural joint failure occurs. Results indicate that with too much increasing of joint area shear failure becomes more prone because it shortens the length of beams and columns [8].Because of consumption and rusting, RCC structure goes to plastic state and carries on non-homogenously. For design to be steady in any most exceedingly terrible state of stacking we need to utilize the interaction of galvanization safeguarding the regular assets and for economy we can utilize some reused total alongside quarry dust. Stream sand having a decent explicit gravity of 2.75 and quarry dust and reused total with slight reduction in their particular gravity for example 2.6 and both are similarly utilized 50%.First HYSD (High yield strength disfigured) rebar's are washed, eliminating the natural pollutions and oxidation items and afterward dunked in zinc ammonium chloride arrangement and covered support is done after this. Limited component investigation led utilizing ABAQUS programming having the capacity to recreate the harming impact of any of the three break models which might be spread break model, fragile break model or CDP model. In FE concentrate a few models were given by various creators including the solid harm models (where the plastic conduct in pressure and pressure is appeared without changing the harm qualities of a construction). The Drucker - Prager model, the all-encompassing Drucker Prager model (it tends to the some of deficiency of Drucker model that the yield surface isn't straight it is exaggerated). Diversion was estimated at center of shaft for greatest worth. The mathematical outcomes acquired for the pillar for diversion bend were near the exploratory outcomes. Failure is more defenseless at the focal point of length of pillar and in these models, it was capable that the shaft yielded at the lower part of ribs and Failure happens at the focal point of the range. The gravity of the quarry dust utilizes in this investigation was less as contrast with waterway sand however having no dampness in it hence reformist expansion in the firmness of example was seen from the underlying phase of breaking till a definitive stage. The outcomes likewise demonstrate the utilization of galvanization procedure delayed the start of erosion hence expanding the strength and toughness [9].During the 1970s, concrete having the composite strength of 50-60 MPa were indicated for segments and tall structure, since diminishing the segment cross areas will give you the additional leasing space [10].2. Finite element method:Similarly, the FDM are discretizations used for solving the differential equations by approximating them with difference equations. Although this method is not used commonly in structural engineering problems but, mostly this method is used in geotechnical engineering for simulating the effect of soil structure interaction [11].Finite Element Method being the most widely used method in numerical simulation of structures and from literature it was observed that 97% of the research paper published in journal of performance of constructed facilities (JPCF) on numerical modeling is done using FEM [12].Finite element models have the potential to solve a wide range of complex problems from elastic linear models for linear elements to highly plastic models for nonlinear and solid elements. FEM is one of the leading methods to simulate all type of structures (Timber, Steel, Concrete, masonry) [12].3. Probability of Seismic Hazards:In 475 and 2475 years have seismic hazard results are pretended to rise to peaks in acceleration in the region of Indochina. Smooth seismicity approach shows 10 by 10 km grid cell detected moderate to high earthquake risk. Three zones (Myanmar, Afghanistan Hindu Kush, and northern Thailand) are high risk areas. Some areas show 200-300 years of short period of seismic recurrence i.e. Naypyidaw and Mandalay.Chittagong-Comilla-Dhaka and Tangail are withthe possible magnitude of 6 on Richter scale Dhaka city, the soul of Bangladesh is highlyvulnerable to the earthquake disaster due to high densityof population, unplanned infrastructure and proximity with India and Myanmars active seismic area. [13,14]Bangladesh is a seismic prone area and in recent past had to go through devastating consequences of the earthquake. Most of the building collapsed due to weak beam column joint. Shear failure in beam-column joints are brittle and identied as the principal cause of collapse of many moment-resisting frame building. [15].References:[1]. C. Gagg, "Cement and concrete as an engineering material: an historic appraisal and case study analysis," Engineering Failure Analysis, 2014.[2]. Fernndez Ruiz, M., column joint with enlarged joint area. Engineering structures, 32(9), 2529-2545.[8]. Kaung, J. S., o, P. B., Krakowiak, K. J., Fernandes, F. M., nimos, Lisbon: How to learn from sophisticated numerical models. Engineering Failure Analysis, 14(2), 280-300.[13]Earthquake risks in Bangladesh: causes, Vulnerability, preparedness and trategies for mitigation by Raihanul Islam, Md. Nazrul Islam and M. Nazrul Islam, Central Womens University, Hatkhola Road, Dhaka, Bangladesh, Department of Geography and Environment, Jahangirnagar University, Savar, Dhaka,Bangladesh.www.arpnjournals.com.[14]Probabilistic seismic hazard assessment for Northern Southeast Asia: smooth seismicity approach by Earthquake spectra. journals.sagepub.com.[15] Balaji, S., Thirugnanam, G. S. (2017). Study on exterior RC beam-column joints upgrade with SIFCON in joint core under reversed cyclic loading. KSCE Journal of Civil Engineering, 21(1), 346-352.[16]Simplified design guidelines for seismic base isolation in multi-storey buildings for Bangladesh National Building Code (BNBC) A. B. M. Saiful Islam, M. Jameel1, M. A. Uddin and Syed Ishtiaq Ahmad, Department of Civil Engineering, BUET, Dhaka-1000, Bangladesh. [17]Residential Structural Design Guide, A State-of-the-Art Engineering Resource for Light-Frame Homes, Apartments, and Townhouses Second Edition Prepared for: U.S. Department of Housing and Urban Development, Office of Policy Development and Research, Prepared by:Coulbourne Consulting.
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