ANALYTICAL INVESTIGATION OF LINKED COLUMN SYSTEM FOR EARTHQUAKE RESISTANT RC STRUCTURES GUIDED BY, MS. D. DARLING HELEN LYDIA M.TECH., PRESENTED BY, S. ARUMUGAM C. JEGANATHAN T. SARAVANA KUMAR P. SIVA PANDI

ABSTRACT This project deals with the provision of the link beams and columns to improve the seismic resistance using the finite element structural engineering software SAP2000 The linked columns are designed to limit seismic forces and provide energy dissipation through yielding of links. The Non-linear push over analysis was used to investigate the performance of a three storey building. The total height of the building is 14 m.

INTRODUCTION Collapse prevention is the first priority in the seismic design of buildings. In general, buildings in modern city are often built closely to each other due to limited land availability. In order to prevent the collapse of the building, the linked column frame system is introduced.

FORCE VS DEFORMATION CURVE

SAP2000 Computers and Structures, Inc. (CSI) founded in 1975, has introduced a software known as Structural Analysis Program (SAP) In this project, SAP is used for the earthquake analysis of an RC structure. This software can also be used for design and analysis of bridges, dams, storage structures, underground tunnels, pipes,etc…

LITERATURE REVIEW According to A. Srinivasu Dr. B. Panduranga Rao (2013) : The nonlinear analysis of a structure is an iterative procedure. It depends on the final displacement. Difficulty in the solution is faced near the ultimate load. Since the displacement at the top level is maximum. Structural Analysis Program that works with complex geometry and monitors deformation at all hinges to determine ultimate deformation.

According to M. Malakoutian J.W. Berman P. Dusicka A. Lopes (2012): In this research, a new seismic load resisting system, called the Linked Column Frame system (LCF) is investigated. The LCF consists of two components: a primary lateral system denoted the linked column, consisting of dual columns interconnected with replaceable link beams. a secondary lateral/gravity system, which is an exible moment resisting frame with beams having fully restrained connections at one end and simple Connections at the other.

This LCF system utilizes replaceable link beams that provide initial stiffness and then act as yielding energy dissipators. It provide nonlinear softening behavior, ductility, and energy dissipation. They limits the inelastic deformation and related damage to the structural members of the adjacent moment resisting frame. The LCF links behave similarly to links in eccentrically braced frames, depending on their lengths.

Conclusions From Literature The link beam and column concept has been introduced in steel structures. Normally Active Mass dampers or Hybrid Mass Dampers are used to resist the seismic forces. But these methods are highly cost effective. . Hence the link beam and columns are provided to resist the seismic forces which are less cost and economical in usage. The storey drift value is taken at the node where the deflection is maximum. Based on the storey drift values, the link beams are provided at the desired columns.

METHODOLOGY Number of Links Size of Links Effective Span Location of columns Number of Links Effective Span

BUILDING DESCRIPTION Number of Storey: G+3 Bay length in X direction: 5m Bay length in Y direction: 5m Bay length in Z direction: 3.5m Size of the Main Beam: 0.3m x 0.6m Size of the Link beam: 0.3m x 0.3m Size of the Main Column: 0.5m x 0.5m Size of the Linked Column: 0.4m x 0.4m Spacing between the Linked Columns: 1.1m

MATERIAL PROPERTIES Modulus of Elasticity of Steel, Es = 210,000 MPa Modulus of Elasticity of Concrete, Ec = 22,360.68 MPa Characteristic Strength of Concrete, fck = 25 MPa Yield Stress for Steel, fy = 415 MPa Poisson’s Ration = 0.2 Co-efficient of Thermal Expansion = 9.9 x 10-6 /°C Concrete Cube Compressive Strength = 27.579 MPa Bending Yield Stress of Reinforcement = 413.685 MPa

LOADING DETAILS Self Weight of the Structure : Self Weight of the Beam, Column and Slab Dead Load : 4.25 kN/m Floor Finish : 1.00 kN/m Live Load : 5.00 kN/m

ANALYSIS DATA FOR BUILDING Zone V Seismic Intensity Very Severe (0.36) Response Reduction Factor 5 Importance Factor 1.0 Soil Condition Hard Height of the Building 14

MODEL OF G+3 FLOOR BUILDING Model Frame of the Structure

PLACEMENT OF THE LINKED COLUMN AT ENDS AT INTERMEDIATES

HINGE FORMATIONS IN 1st Mode

IN 2nd Mode

IN 3rd Mode

DISPLACEMENT VALUES JOINTS AT ENDS 29 0.03883 112 0.10571 147 0.16459 182 0.20531 JOINTS AT INTERMEDIATE 109 0.04486 108 0.12523 107 0.19833 106 0.25117

LINKED COLUMN AT INTERMEDIATE STOREY DRIFT VALUES LINKED COLUMN AT ENDS LINKED COLUMN AT INTERMEDIATE 0.01163 0.05284 RESULT: The Storey Drift value for the structures with linked column at ends is lesser than the linked column at intermediate. Hence, the provision of the linked column at ends is safe.

MODEL OF THE STRUCTURE WITH ONE LINK

HINGE FORMATIONS 1st MODE 2nd MODE

MODEL OF THE STRUCTURE WITH TWO LINKS

HINGE FORMATIONS 1st MODE 2nd MODE

MODEL OF THE STRUCTURE WITH THREE LINKS

HINGE FORMATIONS 1st MODE 2nd MODE

PROVISION OF LINKED COLUMN AT ENDS COMPARISION RESULTS STOREY DRIFT VALUES PROVISION OF LINKED COLUMN AT ENDS ONE LINK TWO LINKS THREE LINKS 0.01234 0.00519 0.00484

CONCLUSION Since, the drift values goes on reducing with the increase in the number of links, thus the provision of the three link beams are much safer. It can also be effectively used as a rehabilitation of the existing structure. Cost of construction is reduced.

REFERENCES ATC 40-“Seismic Evaluation and Retrofit of Concrete Buildings”, Applied Technology Council, November 1996 V. Kapur and Ashok K. Jain, Seismic response of shear wall frames versus braced concrete frames. Indian Concrete Journal, 57,1983,107 Peter Dusicka, Steel Frame Lateral System Concept Utilizing Replaceable Links, NZSEE Conference.2009 Maheri MR, Sahebi A, Use of Steel Bracing in Reinforced Concrete Frames, Engineering Structures, 19(12),1997, 1018-1024.

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