Structural Design of Data Centre Building
Md. Jaweed Jilani Khan1*, Prof Dr. Seshadri Sekhar Tirumala2
1Ph.D. Scholar, GITAM University, Department of Civil Engineering, Hyderabad, India
2Dean, NICMAR, Hyderabad, India
*Corresponding Author Email:
ABSTRACT:
The focus of the study is the Structural design of "Data Centre Building". Data Centre buildings are the one which houses the complete systems such as computer systems, telecommunication systems and storage systems along with its components. It also contains the redundant power supplies, redundant data communication systems in a controlled environment which provides air conditioning, electrical equipments, fire protection and functional use at desired levels.
Architecture layout and space planning of Data centre depends upon various factors such as location of the site, local bye laws, electrical systems, mechanical systems, number of racks, Tier level, modularity and future expansion [1]. Tier levels are defined by Uptime and TIA 942 guidelines [2].
Structural design of Data centre Building should be such that it has lager columns bays such as 25ft x25ft, Minimum height clearance of 4 m from structural slab to lowest structural member, loading considerations depending upon tier level and raised floors, Seismic design requirement, Building lateral force resisting system [3].
In this study, 3D analytical model of the Data Centre Building of G+3 storied have been modeled and analyzed using the structural design and analysis tool "Etabs 2015"[4]. To study the structural characteristics of the Data centre building analytical model includes all important structural elements that includes strength, stiffness, mass and structural deformability. From the studies it has been ascertained that the storey drifts are found within the limit as specified by code (IS: 1893-2002, Part-1).
KEYWORDS: Server rooms, Data centre, Static and Dynamic analysis, Storey shear, Drifts.
INTRODUCTION:
A data Centre is the equipment and IT layout of the room (or rooms). Layout of the data centre room is critical for performance of these precision equipments. A data centre can be fit out in existing buildings or housed in buildings specially constructed for these purposes. Structural layout of the new buildings which are to be constructed as data centers are planned from day one at structural concept stage to avoid the columns in server areas. Columns should be placed at larger spans to facilitate the placement of equipments. Structural layout and position of columns have huge impact on the no. of racks that can be provided in data centers. Large span columns placed strategically will help in placing optimal no. of racks in a data centre servers. No columns are allowed to form hindrance to the equipment placements. Columns are to be avoided in passages, access, aisle it is better to lose one or two rack rather than providing columns in the aisle. Columns in aisle will be of huge hindrance in performance of data centre, it is always recommended to have align the columns with the racks and/or equipments. Final Structural layout should be as such which locates the columns carefully in relation with the equipment rows and it is the primary concern in the structural design of data centre buildings. Keeping columns out of the access areas and aisles will decide the final count of no. of racks/equipment that can be placed in data centre and it is the critical constrain in maximizing the equipment count and locations. Structural form consumes the equipment count and is to be arrived at optimized solution in order to build and effective data centre buildings. Thus combine structural and Architectural layout will have dramatic effect on number of racks in data centers. In most of the data centers Ceilings and Floors are used as air distributions systems necessitating the raised floors. When data centers are with raised floors the salient points such as the drop of levels and access ways are a part of integral structural system.
This study seeks to understand the insight into the structural aspects of a data centre buildings. In this study 3D analytical model of G+3 storied data centre building is modeled and analyzed using structural analysis and design tool Etabs 2015. Analytical model included all the structural characteristics such as strength stiffness and mass. From the studies it has been established that the storey drifts are within the limits' specified by the code [5].
ANALYTICAL MODELLING
Building houses equipment rooms such as electrical, ups and transformer rooms at ground floor and data centre server rooms in first and second floor. Outer walls of equipment areas are considered as 300mm RCC walls and internal partitions of block wall of 200mm is considered.
The stiffness and mass of the walls are included. The Ground floor height is 5.6 m and upper floor height is 4.25 m.
Figure 1: Plan Plinth Level
Figure 2: Three dimensional view.
Figure 3: Plan First Floor.
Figure 4: Plan Second Floor.
Figure 5: Plan Terrace.
Figure 5: Plan Third Floor.
ETABS is a general purpose finite element analysis program for static and dynamic analysis of two and three-dimensional linear and nonlinear structures with a particular emphasis on dynamic loading and earthquake loading. The program used for this study, ETABS Nonlinear, is a general purpose finite element software for static and dynamic analysis of two and three dimensional linear and non linear analysis. For an existing building which houses the data centre, it should be first checked for its capability to resists earthquake from structural design point of view and ascertained thoroughly if the building needs to be retrofitted as per standard procedures [6].
Utmost importance to be given for the design of buildings which houses data centre and it should be design for the loads subjected to earthquake apart from the other natural disasters. In first place the site selected should be in low risk zone of earthquake and other natural calamities [7]. Buildings should be design to resist the gravity and earthquake loads [8]. And as per the guide lines provided in TIA 942 according to the Tier level.
Table1: Building Dimensions.
Design variable |
Value |
Reference |
Dead loads(a)Masonry(b) Concrete |
20 kN/m325 kN/m3 |
IS 875:1987(part 1) |
Live loads(a) Floor load(b) Roof load(c) Floor Finishes |
3kN/m22.0kN/m21.0kN/m2 |
IS 875:1987(part 2) |
Importance factor |
1.0 |
IS 1893:2002 |
Response Reduction Factor |
5 |
IS 1893:2002 |
The results from analysis can be displayed in a variety of formats including the displacements, drifts, storey shears and overturning moment.
Table2: Building Dimensions.
|
Slab thickness |
175 mm in server areas and 150mm in other general areas. |
|
Beam dimensions |
Main beams sever areas 530 mm x 600 mm. Seondary beams server areas 530x430 |
|
Column dimensions |
600mm x 900mm (Data Centre pheripheri). 530mm x 900mm (Data Centre interior). |
|
Grade of Concete and Steel |
M30 concrete, Fe 500 steel |
RESULTS:
NATURAL PERIODS:
Analytical Periods differ from the Codal periods.
Table 3: Codal and Analytical Periods.
|
S.no. |
Natural Periods (sec) |
||
|
Codal |
Analysis |
||
|
Static |
Dynamic |
||
|
1 |
0.23 |
1.465 |
2.59 |
DISPLACEMENTS (mm):
Table 4: Displacements along longitudinal and Transverse direction.
|
Displacement. |
||||
|
EQ Static |
EQ DYN |
|||
|
Story |
X-Dir |
Y-Dir |
X-Dir |
Y-Dir |
|
5 |
21.8 |
21.3 |
23.9 |
19.5 |
|
4 |
19 |
19 |
20.6 |
17.2 |
|
3 |
14.5 |
15.4 |
15.6 |
14.1 |
|
2 |
9.1 |
10.6 |
9.8 |
9.8 |
|
1 |
2.3 |
2.9 |
2.5 |
2.7 |
|
0 |
0 |
0 |
0 |
0 |
DRIFT (Unit less):
Table 5: Drift ratio along longitudinal and Transverse direction.
|
Drift |
||||
|
|
EQ Static |
EQ DYN |
||
|
Story |
X-Dir |
Y-Dir |
X-Dir |
Y-Dir |
|
5 |
0.00038 |
0.00022 |
0.00096 |
0.00089 |
|
4 |
0.00072 |
0.00055 |
0.00077 |
0.00072 |
|
3 |
0.0011 |
0.00085 |
0.00118 |
0.00101 |
|
2 |
0.00129 |
0.00113 |
0.00137 |
0.00109 |
|
1 |
0.00127 |
0.00145 |
0.00136 |
0.00135 |
|
0 |
0.00058 |
0.00072 |
0.00062 |
0.00068 |
STOREY AND BASE SHEAR (Kn):
Table 6: Storey Shear and Base Shear (Kn) along longitudinal and Transverse direction.
|
Shear |
||||
|
|
EQ Static |
EQ DYN |
||
|
Story |
X-Dir |
Y-Dir |
X-Dir |
Y-Dir |
|
5 |
3101.58 |
3298.84 |
3456.77 |
3676.62 |
|
4 |
5714.58 |
6078.03 |
5969.81 |
6349.49 |
|
3 |
7195.74 |
7653.39 |
7394.3 |
7864.58 |
|
2 |
8140.73 |
8658.48 |
8303.14 |
8831.22 |
|
1 |
8229.68 |
8753.09 |
8388.7 |
8922.22 |
|
0 |
8229.68 |
8753.09 |
8388.7 |
8922.22 |
OVERTURNING MOMENT (Kn-m):
Table 6: Overturning Moment (Kn-m) along longitudinal Transverse direction.
|
Overturning moment. |
||||
|
EQ Static |
EQ DYN |
|||
|
Story |
X-Dir |
Y-Dir |
X-Dir |
Y-Dir |
|
5 |
0.0 |
0.0 |
0.0 |
0.0 |
|
4 |
13181.7 |
14020.1 |
16420.8 |
17465.2 |
|
3 |
37468.7 |
39851.7 |
41792.5 |
44450.5 |
|
2 |
68050.6 |
72378.6 |
73218.3 |
77875.0 |
|
1 |
113639.0 |
120866.1 |
119716.0 |
127329.8 |
|
0 |
146557.0 |
155878.4 |
153271.0 |
163018.7 |
CONCLUSIONS:
1) Fundamental natural period is not matching with the empirical formula given in code.
2) Storey drifts are found within the limit as specified by code (IS: 1893-2002, part-1) in both static and dynamic analysis.
3) Drop beams at the junction of the structural drop to accommodate the raised floor are safe in deflection and strength.
4) The presence of expansion joints influences the overall behavior of structures when subjected to lateral forces.
5) Beam deflection of the data centre area beams are all safe within the limits.
6) Proper Structural design of data centre is necessary without which architectural and space planning is technically ambiguous and incomplete.
7) Data centre equipment space can be effectively utilized provided proper Structural planning is done for column orientation and position.
ACKNOWLEDGMENT:
The authors wish to acknowledge to the management and faculty of GITAM University, Hyderabad and NICMAR, Hyderabad for continuous encouragement.
REFERENCES:
1. Yee Keen Seng., et al. "Planning and Designing Data Centres", DSTA horizons.
2. TIA-942, "Telecommunications Infrastructure Standards for Data Centers" Telecommunications Industry Association.
3. Neil Rasmussen & Wendy Torell., "Data Center Projects establishing a Floor Plan", American power conversion.
4. ETABS nonlinear version 2015. Computers and Structures, Inc, CA.
5. IS: 1893 (Part 1) 2002- Indian standard- “Criteria for earthquake resistant design of structures”, Bureau of Indian Standards, New Delhi.
6. ATC-40. “Seismic evaluation and retrofit of concrete buildings.” Volume 1 and 2. Applied Technology Council, California, 1996.
7. Michael A. Bell,. “Use Best Practices to Design Data Center Facilities.” Gartner 2005.
8. Agarwal.P. and Shrikhande. M., 2006 “Earthquake Resistant Design of Structures” Prentice- Hall of India Private Limited, New Delhi, India.
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Received on 14.11.2015 Accepted on 20.12.2015 © EnggResearch.net All Right Reserved Int. J. Tech. 5(2): July-Dec., 2015; Page 173-176 DOI: 10.5958/2231-3915.2015.00016.4 |
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