ISSN: 2319-8753 International Journal of Innovative Research in Science, Engineering and Technology (An ISO 3297: 2007 Certified Organization) Vol. 2, Issue 12, December 2013 Copyright to IJIRSET www.ijirset.com 7465 Behaviour of Multistorey RCC Structure with Different Type of Bracing System (A Software Approach) Nauman Mohammed 1 , Islam Nazrul 2 Structure Engineer, Department of Civil Engineering, Faculty of Engineering and Technology, Jamia Millia Islamia, New Delhi, India 1 Professor, Civil Engineering Department, Islamic University, Medinah Munawwarah, Kingdom of Saudi Arabia 2 Abstract: Structures in high seismic risk areas may be susceptible to severe damage in a major earthquake. For the variety of structures and possible deficiencies that arise, several retrofitting techniques can be considered. Bracing system is one of the retrofitting techniques and it provides an excellent approach for strengthening and stiffening existing building for lateral forces. Also, another potential advantage of this system is the comparatively small increase in mass associated with the retrofitting scheme since this is a great problem for several retrofitting techniques. Our ability to build seismically safe structures with adequate seismic resistance has increased significantly in the past few decades. Many reinforced concrete frame structures built in seismically active areas are expected to perform inadequately in a seismic event. Braced frames are known to be efficient structural systems for buildings under high lateral loads such as seismic or wind loadings. The fact that the lateral resistance of frame can be significantly improved by the addition of a bracing system has led to the idea of retrofitting seismically inadequate reinforced concrete frames with steel bracing system. Steel bracing systems have both practical and economical advantages. The potential advantage of bracing system is the comparatively small increase in mass associated with the retrofitting scheme since this is a great problem for several retrofitting techniques. The application of steel bracings is faster to execute. The steel bracings are usually installed between existing vertical members. Furthermore, if it is used in the structure, the minimum disruption of the building is obtained. Keywords: Retrofitting, Reinforced Cement Concrete, Bracing, Lateral Loads I. INTRODUCTION During earthquake motions, deformations take place across the elements of the load-bearing system as a result of the response of buildings to the ground motion. As a consequence of these deformations, internal forces develop across the elements of the load-bearing system and displacement behaviour appears across the building. The resultant displacement demand varies depending on the stiffness and mass of the building. In general, buildings with higher stiffness and lower mass have smaller horizontal displacements demands. On the contrary, displacement demands are to increase. On the other hand, each building has a specific displacement capacity. In other words, the amount of horizontal displacement that a building can afford without collapsing is limited. The purpose of strengthening methods is to ensure that the displacement demand of a building is to be kept below its displacement capacity. This can mainly be achieved by reducing expected displacement demand of the structure during the strong motion or improving the displacement capacity of the structure. II. RELATED WORK Badoux and Jirsa investigated numerically the behaviour of RC frames retrofitted with external bracing. Researchers stated that the lateral resistance of the existing frame structures is inadequate for two reasons. First, the perimeter frames, which feature weak short columns, are likely to fail in an undesirable mode. Secondly, code provisions may have been upgraded several times since construction, so that current seismic design loads are more than the original values.
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ISSN: 2319-8753
International Journal of Innovative Research in Science,
Engineering and Technology
(An ISO 3297: 2007 Certified Organization)
Vol. 2, Issue 12, December 2013
Copyright to IJIRSET www.ijirset.com 7465
Behaviour of Multistorey RCC Structure with
Different Type of Bracing System
(A Software Approach) Nauman Mohammed
1, Islam Nazrul
2
Structure Engineer, Department of Civil Engineering, Faculty of Engineering and Technology, Jamia Millia Islamia,
New Delhi, India 1
Professor, Civil Engineering Department, Islamic University, Medinah Munawwarah, Kingdom of Saudi Arabia2
Abstract: Structures in high seismic risk areas may be susceptible to severe damage in a major earthquake. For the
variety of structures and possible deficiencies that arise, several retrofitting techniques can be considered. Bracing
system is one of the retrofitting techniques and it provides an excellent approach for strengthening and stiffening
existing building for lateral forces. Also, another potential advantage of this system is the comparatively small increase
in mass associated with the retrofitting scheme since this is a great problem for several retrofitting techniques. Our
ability to build seismically safe structures with adequate seismic resistance has increased significantly in the past few
decades. Many reinforced concrete frame structures built in seismically active areas are expected to perform
inadequately in a seismic event.
Braced frames are known to be efficient structural systems for buildings under high lateral loads such as seismic or
wind loadings. The fact that the lateral resistance of frame can be significantly improved by the addition of a bracing
system has led to the idea of retrofitting seismically inadequate reinforced concrete frames with steel bracing system.
Steel bracing systems have both practical and economical advantages. The potential advantage of bracing system is the
comparatively small increase in mass associated with the retrofitting scheme since this is a great problem for several
retrofitting techniques. The application of steel bracings is faster to execute. The steel bracings are usually installed
between existing vertical members. Furthermore, if it is used in the structure, the minimum disruption of the building
International Journal of Innovative Research in Science,
Engineering and Technology
(An ISO 3297: 2007 Certified Organization)
Vol. 2, Issue 12, December 2013
Copyright to IJIRSET www.ijirset.com 7478
load, seismic load in X and Z direction respectively. It can be seen that the bending moments for columns for dead &
live load for unbraced and different types of bracing system is almost the same. It can be seen that the maximum
bending moments for unbraced, cross braced, chevron braced, K-braced, and diagonal braced structure at base level is
63.126 kN-m, 68.364 kN-m, 59.3 kN-m, 60.304 kN-m and 79.711 kN-m respectively. It has been reduced to 16.694
kN-m, 14.334 kN-m, 14.058 kN-m, 14.684 kN-m and 14.628 kN-m for unbraced, cross braced, chevron braced, K-
braced, and diagonal braced structure at terrace level respectively.
VII. CONCLUSION
After the analysis of the structure with different types of structural systems, it has been concluded that the displacement
of the structure decreases after the application of bracing system. The maximum reduction in the lateral displacement
occurs after the application of cross bracing system. Bracing system reduces bending moments and shear forces in the
columns. The lateral load is transferred to the foundation through axial action. The performance of cross bracing
system is better than the other specified bracing systems. Steel bracings can be used to retrofit the existing structure. Total weight of the existing structure will not change significantly after the application of the bracings.
REFERENCES
[1] Marc Badoux and James O. Jirsa, “Steel bracing of RC frames for seismic retrofitting”, Journal of Structural Engineering, Vol. 116, No. 1,
January, 1990.
[2] Mahtab M. and M. Zahedi,“Seismic Retrofit of steel frames using steel plate shear walls”. Asian Journal of Applied Sciences. 1(4), pp 316-326,
2008.
[3] Bush T. D., Jones E. A. and Jirsa J. O.,“Behavior of RC frame strengthened using structural steel bracing”, Journal of Structural Engineering,
Vol. 117, No.4, April, 1991.
[4] Manish S. Takey and S.S.Vidhale,“Seismic response of steel building with linear bracing system (A software approach)”, International Journal
of Electronics, Communication and Soft Computing Science and Engineering, 2(1), pp 17-25, 2012.
[5] Desai J. P., Jain A. K. and Arya A. S., “Seismic response of R. C. braced frames”, Computers and Structures Volume 29 No.4, pp 557-568, 1988.
[6] IS 1893(part 1) – 2002, “Criteria for earthquake resistant design of structures, part 1-general provisions and buildings”, fifth revision, Bureau of
Indian Standards, New Delhi, India.
[7] Viswanath K.G, Prakash K.B and Desai Anant, “Seismic Analysis of Steel Braced Reinforced Concrete Frames”, International Journal of civil
and structural engineering volume 1, no 1,pp 114-122, , 2010.
[8] Youssef M. A., Ghaffarzadeh H. and Nehdi M. “Seismic performance of RC frames with concentric internal steel bracing”, Eng. Struct., 29, 1561-
1568, 2007.
[9] Ghobarah A. and Abou Elfath H. “Rehabilitation of a reinforced concrete frame using eccentric steel bracing”, Eng. Struct., 23, 745-755, 2001.
BIOGRAPHY
Mohammed Nauman received his B.Tech. degree in Civil Engineering from Jamia Millia Islamia, New Delhi,
India, in 2008 and the M.Tech. degree in Earthquake Engineering from Jamia Millia Islamia, New Delhi, India,
in 2013. Currently, he is a practicing structural engineer. His areas of designing are design of multistory RCC
and steel structures. His main area of interest is the retrofitting of the existing RCC and steel structures.
Nazrul Islam received her B.Sc degree in Civil Engineering from Aligarh Muslim University, Aligarh, Uttar
Pradesh, India, in 1984, the M.E.degree from University of Roorkee, Roorkee, Uttar Pradesh, India in 2004
and Ph.D. degree from Indian Institute of Technology, New Delhi, India in the year 1998. At present he is a
Professor in Civil Engineering Department, Islamic University, Madinah Munawwarah, Kingdom of Saudi
Arabia. His teaching and research areas include design of offshore structures and structural dynamics.