international journal of pure and applied …€¦ · · 2015-04-05the seismic analysis and...

Research Article Impact Factor: 4.226 ISSN: 2319-507X Wayal G. S., IJPRET, 2015; Volume 3 (8): 159-167 IJPRET

Organized by C.O.E.T, Akola & IWWA, Amravati Center. Available Online at www.ijpret.com

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INTERNATIONAL JOURNAL OF PURE AND APPLIED RESEARCH IN ENGINEERING AND

TECHNOLOGY A PATH FOR HORIZING YOUR INNOVATIVE WORK

SPECIAL ISSUE FOR NATIONAL LEVEL CONFERENCE

"SUSTAINABLE TECHNOLOGIES IN CIVIL ENGINEERING"

RESPONSE MODIFICATION FACTOR FOR LOW RISE CONFINED MASONRY

BUILDING

WAYAL G. S.1, WATILE R. K.2

1. Assistant. Professor, Department of Civil Engineering, Navsahyadri Engineering College, Pune (MS) Indian - 412206

2. Assistant. Professor, Department of Civil Engineering College of Engineering & Technology, Akola (MS) Indian - 444104

Accepted Date: 13/03/2015; Published Date: 01/04/2015

Abstract: The purpose of this paper is to study the behavior of low rise confined masonry (CM) building during the earthquake. In this study (G+ 2) CM model analyzed with help of SAP 2000 (V14) Software. The building model proposed accordingly Euro code 6 and analyzed using Euro Code 8-2004 and IS 1893-2002. The analytical data on the basis of Pushover analysis which propose R-factor value evaluated. In the particular study it has been found that the behavior factor for confined masonry R = 2.2 to 3.2 as per European Standard and R = 2.6 to 3.4 as per Indian standard.

Keywords: Seismic Behavior; Confined Masonry, Pushover Analysis, Base Shear, R-Factor.

Corresponding Author: MR. WAYAL G. S.

Co Author: MR. WATILE R. K.

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How to Cite This Article:

Wayal G. S., IJPRET, 2015; Volume 3 (8): 159-167 PAPER-QR CODE



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INTRODUCTION

Confined masonry is knows as masonry with vertical tie columns, represents one of the most

widely used masonry construction systems in Europe, Asia, and Latin America. The basic feature

of confined masonry structures are the vertical, reinforced-concrete or reinforced-masonry

bonding elements tie-columns, which confine the walls at all corners and wall intersections, as

well as along the vertical borders of door and window openings. In order to be effective, tie-

columns are well connected with the bond-beams along the walls at floor levels. It is generally

believed that tie-columns prevent disintegration and improve the ductility of masonry when

subjected to severe seismic loading [1].

The seismic analysis and design of masonry buildings require parameters of dynamic behavior.

Modern seismic building codes like Euro code and Uniform Building Code (UBC) gives these

provisions. Immediately after the Kashmir earthquake many countries was modifying modern

international seismic building codes for example the Uniform Building Code (UBC 97), American

Concrete Institute (ACI) and American National Standard Institute (ANSI).[2]

During 1935 Quetta earthquake more than 60, 000 people were killed, in1974 earthquake

about 5,300 people lost their lives and more than 17,000 people were injured. During October

8, 2005 Kashmir earthquake about 73,000 people lost their lives, more than 80,000were

injured, and 3.5 million people were left homeless. This was the most dangerous earthquake in

the history of Pakistan. About 400,000 buildings were fully or partially damaged [3]. However,

earthquakes of moderate magnitudes (i.e., Mw = 5.0 to 5.5) have struck the region very

frequently, the Himalayan region has the capacity of producing earthquakes of magnitude 8.0

and greater once every 100 years [4]. The main cause of the huge losses due to Kashmir

earthquake in Northern Pakistan and Kashmir was the absence of a seismic building code; all

the buildings were either non-engineered or designed for gravity loads only. The initial survey

reports demonstrated that the performance of confined brick masonry buildings was quite

good if compared to unreinforced stone and brick masonry buildings. [2-5].

In this analytical study the model prepared accordingly Euro code 6 and analyzed using Euro

Code 8-2004 and IS 1893-2002 [6, 7, 8]. The analytical data on the basis of Pushover analysis

which propose R-factor value evaluated.

2. RESPONSE MODIFICATION FACTOR

The R factors in many developing countries are often adopted from the well developed seismic

design codes used in the United States or Europe. These developing countries sometimes have



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more severe nature of seismic hazard, but lack technology to construct structures according to

any seismic guidelines. One example of such developing country is Pakistan, which faces high

seismic hazard because of its proximity to a major fault zone. [9]

2.1 Definition of R-factor and Components

R factors are essential seismic design tools, which defines the level of inelasticity expected in

structural systems during an earthquake event and it is defines as “…factor intended to account

for both damping and ductility inherent in structural systems at the displacements great

enough to approach the maximum displacement of the systems.” R factor is used to reduce the

design forces in earthquake resistant design and accounts for damping, energy dissipation

capacity and for over-strength of the structure. The philosophy of earthquake resistant design is

that a structure should resist earthquake ground motion without collapse, but with some

damage. Consistent with this philosophy, the structure is designed for much less base shear

forces than would be required if the building is to remain elastic during severe shaking at a site.

Such large reductions are mainly due to two factors(Fig. No.1): (1) the ductility reduction factor

(Rμ ), which reduces the elastic demand force to the level of the maximum yield strength of the

structure, and (2) the over strength factor, which accounts for the over strength introduced in

code-designed structures. Thus, the response reduction factor (R) is simply Ω times Rμ.

R = Rμ x Ω

Figure 1: Relationship between force reduction factor (R), structural over strength, and

ductility reduction factor (Rμ)

Therefore for the calculation of R factor following factor are necessary. [9]



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2.1.1 Ductility Reduction Factor (Rμ)

The ductility reduction factor (Rμ) is a factor which reduces the elastic force demand to the

level of idealized yield strength of the structure and, hence, it may be represented as the

following equation:

Rμ = Ve / Vy …. (i)

Where Ve is the max base shear coefficient if the structure remains elastic.

2.1.2 Structural Over strength (Ω)

Structural over strength plays an important role in collapse prevention of the buildings. The

over strength factor (Ω) may be defined as the ratio of actual to the design lateral strength:

Ω = Vy / Vd …..(ii)

Where Vy is the base shear coefficient corresponding to the actual yielding of the structure;

From Equation 1 & 2 Cleared that

R = Ve / Vd …..(iii)

3. MODEL DESCRIPTION FOR CONFINED MASONRY BUILDING

Confined masonry Building and RCC frame considered for pushover analysis consist of one

symmetrical plan shown in fig. 2 and SAP model shown in fig. 3 & 4. Building having 450 mm x

240 mm RC members (bond-beams and tie–columns). Here, a confined masonry wall is

considered panel with and without opening of thickness 240mm with 200mm x 20mm x 20mm

bricks, The RC members are assumed to be of the concrete with a compressive strength equal

to 20 MPa and 4 longitudinal reinforcement bars with 10mm diameter yielded at equal to 250

Mpa. Also the RC members have closed stirrups with diameter 6 mm @ 200 mm c/c and other

detail shown in table 1.



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Fig. 2 Building Plan

Table 1 detail of material used in CM building model

Material Weight per unit

Volume (KN/m3)

Modules of elasticity

(KN /m2)

Poisons ratio

M20 25 2 x 108 0.3

Fe250 78.5 2 x 108 0.15

Brick 20 5.5 x 105 0.15

Fig. 3 Confined Masonry Fig. 4 RCC frame



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4. ANALYSIS RESULTS

R-Factor of CM and RCC are found by using equation (iii), for the calculation of R-factor first

find Design base shear as per IS 1893:2002 [8] shown in table 2 and secondly find maximum

base shear from push over analysis [10] shown in table 3. After finding these two values then

find R-Factor shown in table 4.

4.1 Design Base shear (Vd)

Design base shear is calculate from the IS 1893: 2002 and results as per given below

Table 2. Design Base Shear

Design Base Shear (KN)

CM RCC

Open 362 KN 301.66 KN

Without open 385.32 KN 321.11 KN

4.2 Maximum Base Shear

Maximum Base shear is finding from Force vs. Deformation graph shown in fig. 5 and this graph

is obtained from Push-over analysis. [10]

Fig. 5 Force vs. Deformation curve

Point A is the origin.

Point B represents yielding. No deformation occurs in the hinge A to B called as Elasticity

region.



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Point C represents fail deformation. Hinge B to C called plastic region. In that three tyoe

deformation is occurs i.e. IO (immediate occupancy), LS (life safety), and CP (collapse

prevention)

From point D to E deformation is subtracted and results collapse the member.

The analysis results of CM Building model and RCC frame model in SAP Software for maximum

base shear is shown in table 3.

Table 3 Maximum Base Shear

Max. Base Shear (KN)

EC IS 1893

CM RCC CM RCC

Open 807.43 772.10 820.88 900.11

Without open 1266.6 1014.5 1193.7 1087.9

From Table 2 and table 3 Response modification factor is as follows shown in table 4

Table 4 Response modification Factor

Response Modification Factor

EC IS 1893

CM RCC CM RCC

Open 2.2 2.6 2.3 3

Without open 3.2 3.2 3 3.4

5. CONCLUSION

This Paper study shows analytically the response modification factor (R factor) of Confined

Masonry Building In this work four models of RCC frame are taken, from which two models are

analyzed by using IS 1893 with and without open and two models are analyzed by using Euro

code 8 with and without open. Similarly four models of CM building are taken and analyzed as



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per mention. This paper study involved inelastic static pushover analysis by SAP 2000 (V14)

software. It was found from analysis that the R factor for both RCC and CM by varying code is

nearly same and satisfied the code standard. From the investigation and calculation the

response modification factor for CM found between 2.2 to 3.2 for all models which are nearly

as per the European standard range i.e. 2-3; for RCC found 2.6 to 3.4 which are also nearly for

reinforced masonry as per Indian standard i.e. 3.

6. REFERENCES

1. Moha Tomazevic and iztok Klemenc, Prediction Seismic behaviour of confined Masonry

Walls, EEAD, vol. 26, 1997, 1059-1079.

2. Naseer, A., Khan, A, to Observed Seismic Behaviour of Buildings in Northern Pakistan during

Kashmir Earthquake, Advanced Materials Research (2011) pp 689-693 www.scientific.net.

3. Jawed ali, Prediction Preliminary Damage and Needs Assessment-Pakistan 2005 Earthquake,

from Asian Development Bank and World Bank (ADB WB), Pakistan.

4. W.F.Chin & Charles Scawthorn,, Earthquake Engineering Hand Book”, CRC 2003, pp 2-5.

5. Javed M., Khan A.N. and Magenes G.: prediction Performance of masonry structures during

earthquake -2005 in Kashmir, RJET2 008, Vol. 27, No. 3, pp. 271-282..

6. Eurocode 6: Design of masonry structures, Part 1-1: Common rules for reinforced and

unreinforced masonry structures. ENV 1996-1-1: 2004:E (CEN, Brussels).

7. Eurocode 8: Design provisions for earthquake resistance of structures, Part 1-2: General

rules, seismic actions and rules for buildings. ENV 1996-1-1: 2004:E (CEN, Brussels).

8. IS 1893:2002 (I) for finding Design Base Shear and study of R factor of different building.

9. Adeel Zafar, study the, Response Modification Factor of Reinforced Concrete Moment

resisting frames in Developing Countries, Illinois at Urbana-Champaign, 2009.

10. G.E. Manoukas, A.M. Athanatopoulou and I.E. Avramidis. Prediction is Static Pushover

analysis based on an Energy–Equivalent SDOF System. The 14th World Conference on

Earthquake Engineering October 2008, PN 12-17.

11. Saiidi, M, Sozen, MA. Prediction Simple nonlinear seismic analysis of R/C structures. Journal

of the Structural Division, ASCE 1981; 107(ST5): 937-52.

http://www.scientific.net/



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SNAPSHOTS

CM without opening (Euro code) RCC without opening (Euro code)

international journal of pure and applied …€¦ · · 2015-04-05the seismic analysis and...

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