5.1 structural design basis

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5.1 STRUCTURAL DESIGN BASISREPORT

Proposal Number 1103133; Date: 19 Nov 2010 Page 1 of 12


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5.1.1 Introduction :

The purpose of the report is to outline the Structural design as intended to be carried

out in a step by step fashion like modeling, loading , detailing and codes of practice for

the proposed Solar Cell Factory of Surana Ventures at Hyderabad (India).

5.1.2 Project Description :

The proposed project consists of the following facilities as per Architectural drawings.

Production Cell

Fire Pump House

WTTP/D/W/WTP

Chemical

Chillers CDA

UPS Electrical Room

Toilets & Lockers

Offices & Security

Raw Material Storage

Loading Dock etc.

5.1.3 Structural System

CONSIDERING THIS AS A STANDARD FACTORY WE HAVE PROPOSEDPREENGINEERED BUILDING (PEB) FOR THE ENTIRE SHED. DETAIL DESIGN

SHALL BE SUBMITTED DURING ENGINEERING STAGE. HOWEVER GENERALCONCEPTS ARE AS DESCRIBED BELOW AND MAY GET REVISED AS PERDETAIL DESIGN WORKS.

Foundation: In the absence of soil report, isolated pad footings shall be designed withan SBC of 200 kN/Sqm at 2.5m depth from natural ground level, as per the soil datanear by the proposed site.

Super Structure: The super structure will be a framed steel structure with regularcolumns and rafter beams. RCC Plinth beams are connected at ground level (level-1)i.e pedestal level.The roof will be a light weight structure consisting of built up steelrafters at 7.5m c/c and purlins are provided at every 1500mm intervals. GI Galvalumeroof sheet will be provided for roofing of this building. Slope of roof will be 5 deg withhorizontal. Necessary roof, wall and flange bracings will be provided as per structuralrequirement.



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5.1.4 Design Philosophy

A. Robustness

Structures are planned and designed so that they are not unreasonably susceptibleto effects of accident wherein damage to small area of failure of single element maylead to collapse of major portions of the structure. This is catered to by taking thefollowing precautions:

Designing buildings to withstand horizontal loads from Wind & Seismic Loads also.Providing effective horizontal ties, around the periphery, internally and to columnsand walls.

B. Serviceability

The design properties of materials and the design loads comply with design codesspecified in later part of this report and would typically include,

C. Deflection Criteria:

Final deflection below level of supports should not be greater than l/250 where l is

the span of the member or the length of the cantilever. Deflection after installationof elements such as cladding and partitions not greater than l/350 or 20mmwhichever is lesser.

D. Cracking of concrete :

Design surface crack width due to applied loads or thermal or shrinkage effects notgreater than 0.3 mm for general structures and 0.1mm in case of importantstructures. However no crack is allowed for water retaining structures.

E. 1.2.3 Durability

Durability is achieved by integration of all aspects of design material andconstruction. The environmental effect to which the concrete or steel is exposed towill taken into account during the design by providing adequate cover toreinforcement and use of protective coatings to structural steel works.

The nominal cover to main reinforcement for mild environmental conditions wouldbe as give below.

STRUCTURAL ELEMENT COVER

Foundation and walls 50mmColumn/pedestals below groundColumns/pedestals above ground

50mm40mm



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Beams 25mm

F. Fire Resistance

The design of structural elements is to be based on fire resistance levels to satisfyCode of design for fire protection and prevention requirements as advised in NBC.

5.1.5 DESIGN DATA

The following service loads are expected to act on the structure during its intended lifeand they are considered as follows with reference to relevant codes.

A. Dead Loads:

Roof loads (As per relevant Codes of practice)

Floor finishes : 1.5 kN/m2

Partitions if any : 1.0 kN/m2

Self weight of RCC : 25 kN/m

3

Brick Masonry and plastering : 20 kN/m3

External finishes :As per actuals Equipment loads : As Furnished by respective service

consultants.

B. Imposed loads:

Floor Loads (as per Centrotherm Specifications)

Production area : 15 kN/m2 Technical Rooms : 15 kN/m2

Ceiling System : 0.25 kN/m2 +0.90 kN (point load)

Ceiling Support System : 0.25 kN/m2 +0.90 kN (point load)

Floor loads (As per relevant Codes of practice)

Offices : 2.5 kN/m2

Corridors : 4.0 kN/m2

Staircases : 4.0 kN/m2

AHU areas : 7.50 kN/m2

Metal Roof : 0.75 kN/m2



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C. Wind load: (As per relevant Codes of practice)

Basic Wind speed Vb=44 m/s from Appendix-A of Code

Risk Coefficient k1=1.0 from Table-1 of Code

Terrain/Height Coefficient k2=Varies as per Height (Table-2 of Code)

Topography factor k3=1.0 from Clause 5.3.3 of Code

The external and internal pressure co-efficient shall be as per respective clauses of the abovecode. Refer the following map for basic wind speeds of the adjoining locations.



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INDIA MAP SHOWING BASIC WIND SPEED ZONES


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D. Seismic Load: (As per relevant Codes of practice)

Zone : II from ANNEXE-E of Code

Zone factor (Z) : 0.10

Importance factor (I) : 1.0 Table 6 of Code

Response reduction Factor (RF) : 4.0 Table 7 of Code (concentric bracings)

Average response acceleration coefficient (sa/g) : As per soil conditions.Damping : 5%

Detailing as per IS:456 & SP34 : OMRF (Ordinary Moment Resisting Frame)

Refer the following map for different seismic zones of India.



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E. Temperature:

Temperature loads are generally considered to account for expansion and

contraction of structural members. Alternatively, expansion joints to be provided at

appropriate locations within 228m as per IS 800-1984. Since the proposed building

length is less than 228m no expansion joints are needed.

F. Application of the loads on the model

The dead loads of all reinforced concrete members will be given as self weights ofthe members, all the floor/roof loads expressed as load per square area will be

applied as distributed floor loads onto the supporting beams as per IS 456: 2000, all



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wall loads will be applied as uniformly distributed load per unit length onto thesupporting beams. Wind Loads are applied as member loads and Seismic are

applied as nodal loads which are generated from the inbuilt program of STAD Pro

(8i).

5.1.6 MATERIAL DATA

5.1.6.1 Concrete

Grad of Concrete (for all RCC elements) =M25 (i.e fck=25 N/sqmm)

Static Modulus of Elasticity Ec =5000fck

Poissons ratio =0.17

5.1.6.2 Reinforcement steel

Specification = All reinforcement shall confirm to IS 1786 1985.

Yield Strength fy =500 N/mm2.

Modulus of Elasticity Es=2x105 N/mm2.

Poissons ratio =0.3

5.1.6.3 Structural steel

Yield Strength fy =240 N/mm2 / 345 N/mm2

Modulus of Elasticity Es=2x105 N/mm2.

Poissons ratio =0.3

5.1.6.4 STRUCTURAL MODELING, ANALYSIS & DESIGN

The superstructure will be modeled using standards software STAAD-Pro (8i) as aspace frame with a grid of columns in the vertical direction, interconnected with beamsin the orthogonal directions at each floor level. The nodes (the meeting points of beamsand columns) will be treated as rigid joints due to monolithic construction. All supportingnodes at foundation/pedestal level will modeled as fixed/pinned supports based on

limiting sway conditons. The pedestals will also be interconnected at the plinth level byplinth beams to increase the stability of the structure wherever necessary.



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The 3D space frame analysis will be carried out using the modeling software, whichutilize finite element technique to carry out the analysis. The in-built solver processesthe number and element properties, load combinations and support conditions to arriveat the stiffness and load matrices. The solver further uses the matrix method todetermine the nodal displacements, member forces/stresses, element forces/stressesand support reactions, which will be further utilized in the design of the structuralmembers.

The member forces and support reactions as arrived through the analysis are utilized inthe design of structural members as per IS:456-2000 and IS:800-1984 using standarddesign software and manual calculations in MS-Excel. As per this method, the structureshall be designed for all possible limit states of collapse and serviceability.

5.1.6.5 DESIGN STANDARDS

The design of the above structure is in accordance with the following latest design

codes.

IS : 875 Part 1 Code of Practice for design loads for buildings and structures

(Dead Loads).

IS : 875 Part 2 Code of Practice for design loads for buildings and structures

(Imposed loads).IS : 875 Part 3 Code of Practice for design loads for buildings and

structures

(Wind Loads).

iS : 875 Part5 Code of Practice for design loads for buildings and structures

(Special loads & combinations).

IS : 1893 2002 Criteria for Earthquake Resistant Design of Structures Part-1

IS : 456 2000 Plain and Reinforced Concrete Code of Practice.

IS : 800 1984 Code of practice for General Construction in Steel.

IS : 1080 -1985 Code of practice for Design and construction of shallow

foundations.

IS : 1904-1986 Code of practice for structural safety of building foundations.

SP: 16 Design aid for reinforced concrete to IS 456.

SP: 34 Hand Book on Concrete, reinforcement and Detailing.


5.1 structural design basis

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