Diagrid Structure

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International Journal of Recent Advances in Engineering & Technology (IJRAET)

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ISSN (Online): 2347 - 2812, Volume-5, Issue -2, 2017 9

1Dipesh Joshi, ²Arpan Khatadia, ³Sujit Tare, ⁴Sandesh Mane, ⁵Dixita Sawant, ⁶Nilesh Gaikwad

1,2,3,4,5,6Dept. of Civil Universal College of Engineering Vasai, India Abstract – In today’s world new construction technique as

well as design aspect are coming to forefront as conventional method of designing have failed to give the desired result. The scope of this paper is related to study of DIAGRID STRUCTURE and its significance in today’s age. Diagrid Structure is new trending concept in field of Structural Engineering taking into account factors of structural stability, aesthetic appearance and economic consideration

Keywords: Diagrid, High rise buildings, TABS, story displacement, story shear, story drift, pushover analysis

I. INTRODUCTION

A Diagonal Grid or Diagrid Structure is a framework of diagonally intersecting section (steel section used in this paper) that is used in the construction of skyscrapers buildings and rooftops. These structures offer unique supremacy to high risers because of structural efficiency and pleasant aesthetics. It conveniently eliminates the dependence on column of a structure and also requires comparatively lesser structural steel and thus optimize the cost. The Steel Diagrid Structure are more popular than other conventional materials such as wooden beams and concrete as they are quickly erected. These buildings are energy efficient, environmentally sensitive and a clear winner in the run for what future sustainable buildings may look like

II. OBJECTIVE OF STUDY

As Diagrid Structure are efficient in providing solution both in terms of strength and stiffness. Therefore nowadays widespread application of Diagrid is used in high rise building and skyscrapers, particularly when complex geometries and curved shapes are involved. As height of building rises, not only D.L and L.L are predominant forces but along with it W.L and Seismic forces equally hold a share with it. In order to provide resistance against these forces, conventional design approach might be sufficient to counteract these loads but may lead to uneconomical design, lesser F.O.S, greater stability requirement and aesthetics part may not be up to the mark. Diagrid takes into account above mentioned limitation which conventional building faces and proves to be one of the solution for getting optimum structure skyscrapers, particularly when complex geometries and curved shapes are involved.

III. METHODOLOGIES

The innovative and revolutionary new ETABS is the ultimate integrated software package for the structural analysis and design of buildings. Incorporating 40 years of continuous research and development, this latest ETABS offers unmatched 3D object based modelling and visualization tools, blazingly fast linear and nonlinear analytical power, sophisticated and comprehensive design capabilities for a wide-range of materials, and insightful graphic displays, reports, and schematic drawings that allow users to quickly and easily decipher and understand analysis and design results.

A. Plan and Elevation View

Fig.1: Plan

Fig.2: Elevation B. Geometric Parameters

Table 1 Geometric Parameters Sr. No. Description Values

I. No. of Story 40

II. Plan Size 36m*36m

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III. Story Height 4m

IV. Dead Load 3 kN/m2

V. Live Load 4 kN/m2

VI. Seismic Zone II

VII. Structure Type Steel Frame VIII. Diagrid Angle 69.44 IX. Diagrid Module 4 X. Diagonal Members Pipe

Section

XI. Beams

1.Periphery 2.Internal

ISMB600 ISMB500

XII. Columns ISHB450

XIII. Module Geometry Triangle

IV. ANALYSIS

The nonlinear behavior of the elements is modelled using plastic hinges based on moment–curvature relationship as described in FEMA 356 guidelines.

Seismic response of structure in terms of base shear and roof displacement corresponding to performance point were evaluated using nonlinear static analysis and the results are compared. The performance of the structure is influenced by brace angle and aspect ratio. Some of the results are as follows:

V. RESULTS

Table 2: Brace Forces Story Range Load Cases/

Load Combination

Item Drift

Story 31-40 Seismic Max Max Drift X 0.001996 Story 21-30 Seismic Max Max Drift X 0.001943 Story 11-20 Seismic Max Max Drift X 0.001779 Story 1-10 Seismic Max Max Drift X 0.001395

Story Brace Load

Case/Load Combination

P (KN) Story 31-40 D1 Comb 2 Max -204.626 Story 21-30 D1 Comb 2 Max -2590.440 Story 11-20 D1 Comb 2 Max -4101.665 Story 1-10 D1 Comb 2 Max -5210.658

Table 2 Continued Table 3: Storey Drift V2

(KN)

V3 (KN)

T (KN- m)

M2 (KN- m)

M3 (KN- m) -9.784 28.121 16.159 178.561 40.478 10.119 20.041 11.750 130.611 40.136 11.787 18.006 11.746 -116.40 23.014 19.600 -6.314 10.710 -22.137 -67.726

Fig 3: Storey vs Displacement Graph

VI. ADVANTAGES

Recent advancement in construction technology, analytical methods for design and analysis, materials and structural systems have facilitated the growth of skyscrapers. Some of the most prominent benefits that make Diagrid Structures stand on a pedestal are:

i. Diagrid Structure are Cost Effective. They utilize around 20% lesser structural steel without compromising on structural efficiency of the building. In fact, full exploitation of the structural material used is achieved.

ii. Free and clear, unique floor plans are possible due to lesser area utilized by structural components of a conventional structure (for e.g., large size columns).

iii. Diagrid Structure are aesthetically dominating and far more expressive when compared to conventional building systems.

iv. Generous amount of day lighting, natural air and improved cross air ventilation can be achieved due to minimum provision of interior columns in the plan of structure and thus the optimum usage of natural resources could be achieved.

v. These structures have a similar conduct in design and satisfy various construction tolerances when compared to a typical moment frame structure.

VII. WORK DONE SO FAR

Work done so far is mentioned below:

i. By date, analysis of 40 story Diagrid building has been completed.

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ii. Optimum section for diagonal braces was achieved.

iii. Design of same was carried out then and beam forces (internal, periphery), diagonal member forces, columns forces, story shear, story drift result were observed.

VIII. FUTURE WORK

Further work need to be done are as follows:

i. Design of conventional building with same specification, no. of stories and design parameters as that of Diagrid Structure earlier done.

ii. Comparing Design Parameters iii. Parameters to be compared:

o Story Shear / Story Drift o Shear Force / Bending moment

Result expected: Diagrid results better than conventional building.

IX. CONCLUSION

In this paper, analysis of Diagrid Structural Building and its comparison with conventional building is presented.

A 36m*36m size regular floor plan is considered.

Modelling and analysis of structure is done by ETABS software. All structural members are as design code IS 800:2007 considering all load combinations. The inspiration for this study arises from the impact that the construction industry has on the environment, in terms of use of resources and production of waste, and the social need that calls for investigating sustainable solutions, such as the considered sustainable Diagrid high rise buildings. Among the finding, the way in which Diagrid structure lead to a considerable reduction of material (steel) compared to more conventional structural system such as outrigger structure is quantified. Furthermore, the performance of Diagrid structure has been assessed, not only in terms of structural steel reduction, but also in terms of safety, serviceability and structural robustness. The configurations allows a considerable reduction of

weight, provide a better performance in terms of strength, stiffness and ductility.

Nevertheless, there are certain limitation to this study.

Additional loading scenarios should be accounted for, in order to have a broader insight on the structural behavior.

REFERENCES

[1] “A New System of Construction: the “Diagrid Method” Explained.”

[2] Architect and Building News.

[3] Kim J., Jun Y. and Lee Y.H.”Seismic Performance Evaluation of Diagrid Buildings”, 2nd Specially Conference on Disaster Mitigation, Manitiba, June 2010.

[4] Genduso, Brian. “Structural Redesign of a Perimeter Diagrid Lateral System University of Cincinnati Athletic Centre.” Senior Thesis. Penn State University. Spring 2004.

[5] Willis C. 1995. Form Follows Finance:

Skyscrapers and Skylines in New York and Chicago. Princeton Architectural Press: New York.

[6] Design and Construction of Steel Diagrid Structures. K. Moon School of Architecture, Yale University, New Haven, USA.

[7] Diagrid: Structural Efficiency & Increasing Popularity. Ian McCain.

[8] Sustainability Concepts in the Design of High- Rise Buildings: The Case of Diagrid Systems [9] Giulia Milana, Konstantinos Gkoumas* and

Franco Bontempi.

[10] Diagrid Structures: Innovation and Detailing T.

M. Boake School of Architecture, University of Waterloo, Canada

[11] Numerical Modelling and Evaluation of Hybrid Diagrid Structures.

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