SEISMIC ANALYSIS ON MEZZANINE FLOORING SYSTEM · Generally seismic analysis of structure is used to understand the structural behavior. Seismic loads are different from normal loads

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International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 4, April 2017, pp. 689–702 Article ID: IJCIET_08_04_080

Available online at http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=4

ISSN Print: 0976-6308 and ISSN Online: 0976-6316

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SEISMIC ANALYSIS ON MEZZANINE

FLOORING SYSTEM

S. Loganantham

PG Student, Division of Structural Engineering,

School of Mechanical and Building Sciences,

VIT University, Chennai – 600127, India

Dr. M. Shanmugasundaram

Asst. Professor (SG), Division of Structural Engineering,

School of Mechanical and Building Sciences,

VIT University, Chennai – 600127, 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. 689–702.

http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=4

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

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.

3.2. 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 1.



3.3. 2D 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



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.

4.1. REGULLAR STUCTURE

Figure 8 Displacement of Mezzanine at half and three-fourth height of the regular structure in X and

Y-Direction



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 three-

fourth 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



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



half storey height. Based on this mezzanine with three-fourth storey height is safer than

mezzanine at half storey height.

4.2. IRREGULLAR STUCTURE

Figure 12 Displacement of Mezzanine at half and three-fourth height of the irregular structure in X

and Y-Direction



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





structure





half storey height. Based on this mezzanine on three-fourth storey height is safer than







4.3. 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 three-

fourth is less than the displacement of mezzanine at half storey height of the structure.



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








structure on sloppy ground





on sloppy ground




mezzanine at half storey height



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



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 thee-

fourth 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.

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Documents

SEISMIC ANALYSIS ON MEZZANINE FLOORING SYSTEM · Generally seismic analysis of structure is used to understand the structural behavior. Seismic loads are different from normal loads