SEISMIC ANALYSIS ON MEZZANINE FLOORING SYSTEM

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1 International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 4, April 2017, pp Article ID: IJCIET_08_04_080 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed SEISMIC ANALYSIS ON MEZZANINE FLOORING SYSTEM S. Loganantham PG Student, Division of Structural Engineering, School of Mechanical and Building Sciences, VIT University, Chennai , India Dr. M. Shanmugasundaram Asst. Professor (SG), Division of Structural Engineering, School of Mechanical and Building Sciences, VIT University, Chennai , India ABSTRACT In this study the seismic performance of mezzanine flooring system is compared to various storey heights of the structure. For this purpose, seven storey structure was modelled using E-tabs. In this study three type model was taken they were regular structure, irregular structure and irregular structure on sloppy ground. In this three model mezzanine floors are located first at half storey height of the structure and then mezzanine floors are located at three-fourth height of the structure and its assumed that the building were located in the seismic zone V. In this study linear dynamic and nonlinear dynamic analysis is carried out using E-tabs. This method is used to study the response of the building under seismic loadings in terms of storey displacement, storey drift and as well as response spectrum analysis, time history analysis. The response for each type of building are studied and compared. Introducing mezzanine floors in the structure, its creates short column effects so this study also concentrated on how to overcome the short column effect economically. Key words: Mezzanine Flooring; Response Spectrum; Short Column Effects; Time History Analysis Cite this Article: S. Loganantham and Dr. M. Shanmugasundaram, Seismic Analysis On Mezzanine Flooring System. International Journal of Civil Engineering and Technology, 8(4), 2017, pp

2 Seismic Analysis On Mezzanine Flooring System 1. INTRODUCTION The primary concern of structural engineer is protected structure from seismic forces and design will be economical. Generally seismic analysis of structure is used to understand the structural behavior. Seismic loads are different from normal loads like wind and gravity loads. Based on this type load analysis, we will expect damage level of structure and we will redesign before construction stage [15]. Mezzanine floors are like temporary floors it is used to increase a space of existing areas. It can be easily removable and reusable. This type of mezzanine floors is used in industrial purpose, educational institute and storage yards. It also called semi-percent structure, it s generally placed in the half of the storey height of the building. It s didn't consider as a floor of the building, its normally consider as a temporary structure of the building. Based on the international codes mezzanine to have as much as one-third of the floor space compare to floor below. This type of mezzanine floors is used in modern architecture. In industrial mezzanine floors are used for storage purpose in industrial mezzanine floors are free standing using steel columns and joist it can be easily removable and relocatable. But no one defining the perfect height to locate mezzanine in storey of the building [11]. For Mezzanine floorings slabs and beams are made of fiber reinforced aerated light weight concrete (FALC). This type of concrete is made for improving thermal conductivity, fire resistance and energy absorption. In this study, about carbon and polypropylene fibers were investigated0 to 4 percentage volume ratio and self-compacting agent also used for reducing the water cement ratio. In this study, they investigated based on uni-axial compression test, modulus of elasticity and toughness index. In this research, 4 percent of polypropylene fiber aerated concrete gives better result compared to carbon fiber based on this Mezzanine floor and beams are considered polypropylene fiber reinforced aerated concrete [19]. In seismic force all of the structural components act similar in regular structure, but in irregular structure, each and every component act differently but in real-time structures are irregular type only. So a study of irregular structure is very important. Irregularity is classified based on two classifications In this project we took vertical and horizontal irregularity. In vertical irregularity, we have taken Mass, stiffness and strength irregularity and in horizontal irregularity Asymmetrical plan shape irregularity are taken [17]. Mass irregularity means if the mass of the any storey is more than 150 percentage of the any adjacent storey it s called mass irregularity, but in this type of irregularity isn't affecting structure safety that much [13]. Stiffness irregularity means when the lateral stiffness of the storey is less than 70 percentage of the stiffness any adjacent storey or 80 percentage of average stiffness of three storeys above or below in the structure. Strength irregularity means the shear strength of the building is less than 90percentage that in the storey above. For strength and stiffness irregularity creates storey displacement and storey drift due to seismic loads [18]. So we want to take consider seismic storey displacement and storey drifts. Storey displacement is the total displacement of its storey of with respect to the ground for high rise buildings (H/350) and for low rise building (H/250) in here H is total height of the building. Storey drift is the ratio of displacement of two consecutive floors in height of the floor. This type of irregularities creates severe damage in structure so we want to give importance to this type irregularity for generally irregular structures and structure located in high seismic zones are tested by dynamic analysis. Dynamic analysis is classified in two types they are linear dynamic and Non-linear dynamic analysis. In linear dynamic response spectrum analysis are carried out and for Non-linear dynamic Time History analysis are carried out. In response spectrum analysis, seismic response of structures based on range of periods is shown in a single graph. For an earth quake motion and percentage of critical damping response spectrum plot given earthquake response related to acceleration, displacement for a complete range of building period. For Time History analysis specified loadings and specified time periods are editor@iaeme.com

3 S. Loganantham and Dr. M. Shanmugasundaram given directly and it shows the response of the building. In this research response spectrum analysis is compared to time history analysis. [12] Due to the introduction of mezzanine floors at existing structure is create a short column effect. Short columns create severe damage due to seismic force. Short column is stiffer than long column, so it attracts large seismic forces [10]. To rectify this type of effect we want to give shear reinforcement, but it increases the required reinforcement of the building so we want to find an economical solution for this problem. 2. OBJECTIVE To find the effect of Mezzanine floors in structure under seismic loadings To design an economical mezzanine floor incubated in structures in the high seismic zone for regular and irregular structures. To overcome the short column effects due to introducing mezzanine in structures without increase shear reinforcement. To find better height of Mezzanine floor to locate in storey height. Dynamic analysis of mezzanine floors incubated structures using response spectrum and time history analysis. 3. STRUCTURAL MODELLING AND ANALYSIS 3.1. General The structural analysis and design of the building software E-tabs 2016 is used to design a model based on this software we can analysis linear and Non-linear analysis. This software is used to predict the geometrical linear and Non-linear behavior of structure under static and dynamic loadings taking into account Non-linearity and material inelasticity. This software accepts static (either force or displacement) and dynamic (acceleration) action Detail of Model The models which have been adopted for the study are three types A regular structure Irregular structure Irregular structure at sloppy ground Each structure is seven storey (G+6). The building is considered rectangular column (450X300 mm) and square beam (300X300mm). The floor slabs are taken as 125mm thickness and for Mezzanine floor beams are (230X230mm) and floor slabs are taken as 100mm thickness and type of concrete is fiber aerated polymer reinforced concrete and for normal structure M30 and Fe415 steel and each storey are 3meter height for Mezzanine first located at half of the storey height and another one is three-fourth of the storey height of the building and shear walls are used for lift pit thickness of 230mm. A structure located in high seismic zones (V- zone). Loads are given based on IS codes like Live load and floor finish loads are taken from IS 875- part 2 and wind load is taken from IS 875-part-3. Seismic loadings are taken from IS 1893-part 1 and Dead load directly calculated from E-tabs. In E-tabs all code books are already in build so we want to assign codes based on type of loads. A response reduction factor taken has 3 because of general building based on IS 1893-part 1 and Importance factor taken has 1.5 for R.C buildings based on IS 1893-part 1. Zone factor is 0.36 for zone 5 as per IS 1893-part editor@iaeme.com

4 Seismic Analysis On Mezzanine Flooring System D AND 3D PLAN OF Figure 1 Regular structure Figure 2 Irregular structure Fig 3 Section view of Irregular on structure on sloppy ground Fig 4 Plan view of irregular structure on sloppy ground Figure 5 Mezzanine at half and three-fourth height of the regular structure editor@iaeme.com

5 S. Loganantham and Dr. M. Shanmugasundaram Figure 6 Mezzanine at half and three-fourth height of the irregular structure Figure 7 Mezzanine at half and three-fourth height of the irregular structure on sloppy ground 4. RESULTS AND DISCUSSION Dynamic analysis of three types of structure carried out. Due to introducing of Mezzanine floors its creates Mass, strength and stiffness irregularity so we want to consider storey displacement and storey drift results in both X and Y directions. Response spectrum analysis and Time history analysis results also compared. Introducing of mezzanine its create short column, so we want to take shear force and bending moment of the column. In this results structure is mentioned in two types. They are type 1 is a mezzanine at half storey height of structure and type 2 is mezzanine at three-foot height of the structure REGULLAR STUCTURE Figure 8 Displacement of Mezzanine at half and three-fourth height of the regular structure in X and Y-Direction editor@iaeme.com

6 Seismic Analysis On Mezzanine Flooring System Above fig8 shows the displacement results of mezzanine at half and three-half storey height of the building. In this result shows displacement in X and Y Direction of mezzanine at threefourth is less than the displacement of mezzanine at half storey height of the structure. Figure 9 Drift of Mezzanine at half and three-fourth height of the regular structure in X and Y Direction Above fig9 shows the drift results of mezzanine at half and three-half storey height of the building. In this result shows drift in X and Y Direction of mezzanine at three-fourth is less than the drift of the mezzanine at half storey height of the structure. Figure 10 Response spectrum analysis of Mezzanine at half and three-fourth height of the regular structure Table 1 Maximum and minimum acceleration of mezzanine at half and three-fourth storey height editor@iaeme.com

7 S. Loganantham and Dr. M. Shanmugasundaram From table1. Maximum acceleration of mezzanine at three-fourth is less than mezzanine at half storey height. Based on this mezzanine with three-fourth storey height is safer than mezzanine at half storey height Figure 11 Time history analysis of Mezzanine at half and three-fourth height of the regular structure Table 2 Maximum and minimum acceleration of mezzanine at half and three-fourth storey height From table2. Maximum acceleration of mezzanine at three-fourth is less than mezzanine at half storey height. Based on this mezzanine with three-fourth storey height is safer than mezzanine at half storey height IRREGULLAR STUCTURE Figure 12 Displacement of Mezzanine at half and three-fourth height of the irregular structure in X and Y-Direction editor@iaeme.com

8 Seismic Analysis On Mezzanine Flooring System Above fig12 shows the displacement results of mezzanine at half and three-half storey height of the building. In this result shows displacement in X and Y Direction of mezzanine at three-fourth is less than the displacement of mezzanine at half storey height of the structure. Figure 13 Drift of Mezzanine at half and three-fourth height of the irregular structure in X and Y Direction Above fig13 shows the drift results of mezzanine at half and three-half storey height of the building. In this result shows drift in X and Y Direction of mezzanine at three-fourth is less than the drift of the mezzanine at half storey height of the structure. Figure 14 Response spectrum analysis of Mezzanine at half and three-fourth height of the regular structure Table 3 Maximum and minimum acceleration of mezzanine at half and three-fourth storey height editor@iaeme.com

9 S. Loganantham and Dr. M. Shanmugasundaram From table3. Maximum acceleration of mezzanine at three-fourth is less than mezzanine at half storey height. Based on this mezzanine on three-fourth storey height is safer than mezzanine at half storey height. Figure 15 Time history analysis of Mezzanine at half and three-fourth height of the regular structure Table 4 Maximum and minimum acceleration of mezzanine at half and three-fourth storey height From table4. Maximum acceleration of mezzanine at three-fourth is less than mezzanine at half storey height. Based on this mezzanine on three-fourth storey height is safer than mezzanine at half storey height Irregullar Stucture on Sloppy Ground Below fig16 shows the displacement results of mezzanine at half and three-half storey height of the building. In this result shows displacement in X and Y Direction of mezzanine at threefourth is less than the displacement of mezzanine at half storey height of the structure editor@iaeme.com

10 Seismic Analysis On Mezzanine Flooring System Figure 16 Displacement of Mezzanine at half and three-fourth height of the irregular structure on sloppy ground in X and Y-Direction Figure 17 Drift of Mezzanine at half and three-fourth height of the irregular structure of sloppy ground in X and Y Direction Above fig17 shows the drift results of mezzanine at half and three-half storey height of the building. In this result shows drift in X and Y Direction of mezzanine at three-fourth is less than the drift of the mezzanine at half storey height of the structure. From table5. Maximum acceleration of mezzanine at three-fourth is less than mezzanine at half storey height. Based on this mezzanine on three-fourth storey height is safer than mezzanine at half storey height. Figure 18 Response spectrum analysis of Mezzanine at half and three-fourth height of the regular structure on sloppy ground editor@iaeme.com

11 S. Loganantham and Dr. M. Shanmugasundaram Table 5 Maximum and minimum acceleration of mezzanine at half and three-fourth storey height Figure 19 Time history analysis of Mezzanine at half and three-fourth height of the regular structure on sloppy ground Table 6 Maximum and minimum acceleration of mezzanine at half and three-fourth storey height From table6. Maximum acceleration of mezzanine at three-fourth is less than mezzanine at half storey height. Based on this mezzanine on three-fourth storey height is safer than mezzanine at half storey height editor@iaeme.com

12 Seismic Analysis On Mezzanine Flooring System Due to introducing of Mezzanine floors in existing structures so its create short column effects. So based on this critical section of structure is taken and its bending moment and shear forces are compared. Table 7 Maximum and minimum bending moment and shear force for regular structure Table 8 Maximum and minimum bending moment and shear force for irregular structure Table 9 Maximum and minimum bending moment and shear force for irregular structure on sloppy ground Based on the critical section bending moment and shear force mezzanine at three-fourth is create less than compared to mezzanine at half storey height editor@iaeme.com

13 S. Loganantham and Dr. M. Shanmugasundaram 5. CONCLUSION From the above results it can be can be concluded 1. Based on storey displacement and storey drift mezzanine at three-fourth height is less than mezzanine at half of the storey height so if mezzanine at three-fourth is safer in regular and irregular structure 2. Based on response spectrum analysis and Time history analysis maximum acceleration for theefourth height of mezzanine is less than half storey height of mezzanine. So three-fourth mezzanine is safer than mezzanine at half storey height. 3. Based on bending moment and shear force in critical section mezzanine at three-fourth gives less value compared to mezzanine at half of the storey height. So we can reduce the shear force and bending moment without increasing a shear reinforcement. 4. Due to introducing mezzanine its create mass, stiffness and strength irregularity. Based on this storey displacement and storey drift result show structure is safe in both mezzanines at half and three-fourth height of the structure, but mezzanine at three-fourth gives better results than mezzanine at half of the storey height. 5. Mezzanine at three-fourth height gives better results without increasing shear reinforcement so we don t need to give additional reinforcement. So it's economically better than introducing shear reinforcement methods. REFERENCE [1] Al-Ali AAK, Krawinkler H. Effects of vertical irregularities on seismic behaviour of building structures, Stanford University, San Francisco, [2] Alper Kanyilmaz, Giovanni Brambilla, Gian Paolo Chiarelli, Carlo Andrea Castiglioni. Assessment of the seismic behaviour of braced steel storage racking systems by means of full scale Push over analysis, Journal of Thin wlled Structures, 2016 [3] Bureau of Indian Standards, IS: 1893 part , Criteria for Earthquake resistant design of general provisons and buildings. [4] Bureau of Indian Standards, IS: , Indian standard code of practice for plain and reinforced concrete. [5] Bureau of Indian Standards, IS: part , Indian standards code of practice for Imposed loads. [6] Bureau of Indian Standards, IS: part , Indian standards code of practice for wind loads. [7] Chambers J and Kelly T, Non-linear dynamic analysis the only option for irregular structure,13th world conference on Earthquake engineering, paper No.1389, issue 2004 [8] Chambers J and Kelly T. Non-linear dynamic analysis the only option for irregular structure, 13th world conferenceon Earthquake engineering, 2004, pp [9] Fabio Mazza. Nonlinear sesmic analysis of R.C framed buildings with setbacks retrofitted by damped braces, Engineering Structures, [10] IITK BMTPC. Why are short columns are more damaged during Earthquke, [11] Mezzanine floors from [12] Patil A S and P D Kumbhar. Time history analysis of multistoried RCC buildings for different seismic intensities, internation journal of structural and civil engineering research, 2, [13] Poncent.L and Tremblay.R. Influence of Mass irregularity on the seismic design and performance of multi-storey and braced steel frames, 13th world conference on Earthquak engineering, 2004, pp editor@iaeme.com

14 Seismic Analysis On Mezzanine Flooring System [14] Ramin k and Mehrabpour F. Study of short column behaviour originated from the level difference on sloping lots during Earthquake, open journal of civil engineering, [15] Romy mohan and chem. Prabha. Dynamic analysis of R.C.C buildings with shear wall, International journals of Earth sciences and Engineering, 04, [16] Valmundsson EV, Nau JM. Seismic response of building frames with vertical structural irregularities, Journal of Structural Engineering, [17] Varadharajan S,V.K.Shegal and B.Sanini. Review of different structural irregularities in building, journal of structural engineering, 39, [18] Vinod K shadhasiva, Gregory A macrae and Bruce L Deam. Effects of coupled vertical stiffness-strength irregularity due to modified interstorey height, The Newzland society for Earthquake engineering, 44, 2011 [19] Yoo-jae kim, Jiong hoe, Soon-jae lee and Byung-hee you. Mechanical properties of fiber reinforced lightweight concrete containing surfactant, Advances in civil Engineering, editor@iaeme.com