Bs procedure

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STRUCTURAL

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STRUCTURAL

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INTRODUCTION

The proposed cricket stadium is located in Providence, Guyana and shall be constructed as per the ICC norms for the World Cup to be held in 2007. The stadium of 15,000 capacity is to be constructed under the Ministry of Public Works and Communications with a grant from the Govt of India. This design basis report is drawn only for the structural design of the works in the stadium complex project.

  As listed in the Architectural basis, there are various buildings in the complex, which serves the requirement for the intended capacity. The report tends to highlight the general design philosophy adopted in the structural design of the elements and also gives an overview of the basis of structural analysis and design adopted to arrive at the estimate. The report also highlights the various methods and loads assessed for the purpose of structural design of elements. It also brings out the reason for adopting various principles chosen for design and gives a comprehensive list of the codal provisions chosen. At the end the list of codes adopted for design is furnished. All materials shall be as per the Indian standards and design shall comply with BS standards as listed below. The Indian Standards are also listed for clarity.

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 DESIGN PHILOSOPHY

  The main buildings in the stadium complex are the stands, members and player's pavilion block, venue operating centre, media centre and landscaped seating stand apart from service buildings and underground structures.

The structural system adopted for the buildings are concrete/structural steel framed conventional beam slab and column structures on pile caps over bored cast-in-situ concrete piles/pre-cast concrete piles/green heart timber piles. The slabs are proposed in composite construction with concrete on profiled metal decking (serving as reinforcement). The stands are designed with pre-cast bleachers on raker beams in concrete/structural steel. The roof covering the stands are designed with structural steel elements in profiled sections to match the architectural form. The columns in cast-in-situ concrete/structural steel have insert plates/base plates to seat the roof-supporting member. The structures are analysed for dead load, live load and wind loads as per the codal provisions. Waterproofing on concrete surfaces exposed to atmosphere is done with reinforced modified bituminous membrane and is protected by cement concrete tiles. The waterproofing of sunken slabs in toilets is also achieved with the same material. All structural steel surfaces are protected from corrosion with anti-corrosive paint.

DESIGN LOADS

Dead Loads

The self weight of the various elements are computed based on the unit weight of materials as given below:

Mat er ial Unit Weight kN/ m 3

Steel 78.5

Plain Cement Concrete 24

Reinforced Cement Concrete 25

Cement Concrete Screed 24

Soil 20

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 Imposed Loads

As per BS:6399 (Part 1)-1996 the building is classified as Public Assembly building.

The superimposed loads or otherwise live load is assessed based on the occupancy classification as per BS:6399(Part 1)-1996 for assembly building. The imposed loads (in kN/m2) considered are as listed below:

Occupancy Classi f icat ion Load (kN/ m 2 )

a) Assembly areas:

1) with fixed seats 4.0

2) without fixed seats 5.0

b) Kitchens, laundries 3.0

c) Stages 7.5

d) Corridors, hallways, stairs 4.0

e) Dressing rooms 2.0

f) Areas for equipment 2.0

g) Toilets and bathrooms 2.0

On flat roofs, sloping roofs and curved roofs with slopes up to and including 10 degrees, the imposed loads due to use or occupancy of the buildings and the geometry of the roofs are given below:

As per cl 6.2, BS:6399 (Part 1)-1996

a) For roofs with access provision 1.5

b) For roofs without access provision 0.75

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On sloping roof of slope greater than 10o, as per clause 6.3 of BS:6399(Part1)-1996 the imposed loads (kN/m2 of the plan area) that are likely to act permanently are as follows:

Waterproofing* 1.5 (On roof / terrace)

Partitions 1.0 (wherever applicable)

False ceiling 0.5 wherever applicable)

Structural slab shall be sloped suitably to avoid achieving requisite slopes with screed/brick bat coba

Bleachers are designed to resist a horizontal force applied to seats of 3.0 kN per linear meter along the line of seats and 1.5 kN per linear meter perpendicular to the line of seats.

Wind Load

The wind pressure is calculated based on the data furnished below and as per the provisions laid in BS:6399 (Part 2)-1997

Basic Wind speed = 50m/sec (As assessed from UBC)

Maximum gust = 30mph (13.5m/sec) As given

Mean probable = 50 years

DESIGN LIFE OF STRUCTURE

Building Type factor Kb = 1.0

Ground roughness category = town

Built up areas with an average level of roof tops at least Ho =5m above GL

Dynamic Augmentation Factor Cr =0.03

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Static Simplified method is used for design for wind loads with the following parameters as per cl 2.2 BS:6399 (Part2)-1997

  Directional Factor Sd = 1.0

Altitude Factor Sa = 1.0

Seasonal Factor Ss = 1.0

Probability Factor Sp = 1.0

Site Wind Speed Vs = Vb x Sa x Sd x Ss x Sp = 50 x 1 x 1 x 1 x 1 x 1 = 50m/sec

Effective Wind Speed= Vs x Sb

Where Sb is the terrain and building factor obtained from cl 2.2.3.3 of BS:6399(Part2)-1997

Earthquake Load

Guyana is not within the earthquake belts and also does not figure in the places listed in the seismological active zones. It has been mentioned that Guyana experiences tremors every 5-10 years. Earthquake loads are not considered for analysis and design. With the given conditions it is assumed that the wind load on the structure would be sufficient for the lateral loads that would be generated during the tremors.

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Load Combinations

Primary loads are combined in accordance with relevant stipulations in BS:8110(Part 1)-1997. The combination that produces the most unfavourable effect in the building, foundation or structural member concerned is adopted for design.

Load Type

Dead I mposed * * Wind

Adverse Beneficial Adverse Beneficial

1 1.4 1.0 1.6 0.01.2c

1.0d —

2 1.4 1.0 - -1.2c

1.0d 1.4

3 1.2 1.2 1.2 1.21.2c

1.0d 1.2

Load Comb. St

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**Eartha and Waterb Pressure

1Dead and Imposed (and earth and water pressure)

2Dead and Wind (and earth and water pressure)

3Dead and Imposed and wind (and earth and water pressure

aThe earth pressure is that obtained from BS:8002 including an appropriate mobilisation factor. The more onerous of the two factored conditions should be taken.

bThe value of 1.2 may be used where the maximum credible level of the water can be clearly defined. If this is not feasible, a factor of 1.4 should be used.

cUnplanned excavation in accordance with BS:8002, 3.2.2.2 not included in the calculation.

dUnplanned excavation in accordance with BS:8002, 3.2.2.2 included in the calculation.

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ANALYSIS METHOD

  The analysis of the structure is carried out using the STAAAD Pro-2003. Appropriate loads and its combinations, as per relevant clauses in BS codes as described in this report are chosen for analysis and design. Precast elements are analysed manually for handling, transportation and service stresses.

DESIGN LIFE

  The design life of the structure is considered as 50 years. This requirement is not applicable for replaceable materials.

DESIGN METHODOLOGY

  All structural elements shall be designed according to the Limit State Method as specified in BS:8110 for reinforced concrete elements and BS:5950 for structural steel elements.

FOUNDATION

  As per recommendations of the soil investigation report, only piles are considered as foundations. The various types of piles considered for supporting load-bearing columns/structures are bored cast-in-situ concrete piles, pre-cast concrete piles and green heart timber piles. The vertical capacity of the pre-cast concrete piles of 20m length is 34mT and that of 23m green heart timber piles is 18mT.

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CONCRETEThe grade of concrete and type of cement adopted for the various structural

Concret e i t em Grade Max size of Type of

aggregat e (mm ) cement

Pile Concrete C35 20 OPC

Pile Caps C40 20 OPC

Column C40 20 OPC

Slabs and beams C35 20 OPC

Retaining walls C35 20 OPC

Precast Elements C50 20 OPC

REINFORCEMENT 

For all structural RC elements steel reinforcement used shall be of Fe 415 grade conforming to IS:1786-1985 or equivalent.

NOMINAL COVER TO REINFORCEMENT 

The cover to concrete shall be as per the guidelines laid in cl 3.3 of BS:8110 Part 1-1997. The cover shall also satisfy the requirements of 2h fire rating.

DESIGN STANDARDS

The relevant Standard codes, as given below, have been followed for structural design

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Codes Descr ipt ion

Br i t ish Standards

BS:648-1964 Schedule of weights of building materials

BS:4449-1997 Specification for Carbon Steel Bars for

Reinforcement of Concrete

BS:4461-1978 Specification for Cold Worked Steel Bars for the

Reinforcement of Concrete

BS:6339 Part-1-1996 Code of practice for Dead and Imposed Loads

BS:6339 Part-2-1997 Code of practice for wind loads

BS:6339 Part-3-1988 Code of practice for Imposed Roof Loads

BS:8002-1994 Code of Practice for Earth Retaining Structures

BS:8004-1986 Code of practice for Foundations

BS:8110 Part-1-1997 Structural Use of Concrete-Code of practice for

design and construction

BS:8110 Part-2-1985 Structural Use of Concrete-Code of practice for

special circumstances.

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Codes Descr ipt ion

Br i t ish Standards

BS:8110 Part-3-1985 Structural Use of Concrete-Design charts for singly

reinforced beams, doubly reinforced beams and

Rectangular columns.

BS:8102-1990 Code of Practice for Protection of Structures

against Water from the Ground

BS:5950 Part 1-2000 Structural Use of Steelwork in Building-Code of

Practice for Design in Simple and Continuous

Construction: Hot Rolled Sections

BS:5950 Part 2-1994 Structural Use of Steelwork in Building-

Specification for Materials, Fabrication and

Erection: Hot Rolled Sections.

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Codes Descr ipt ion

I ndian Standards

IS: 456-2000 Code of Practice for Plain and Reinforced Concrete

IS: 800-1984 Code of Practice for General Construction in Steel

IS: 808-1989 Dimensions for hot rolled steel beams, columns,

channels and angle sections

IS:875-1987(Part-1) Code of Practice for Design Loads (Other than

Earthquakes) for Buildings and Structures.

Dead Loads — Unit Weights of Building Materials

and Stored Materials

IS:875-1987(Part-2) Code of Practice for Design Loads (Other than

Earthquakes) for Buildings and Structures.

Imposed Loads

IS:875-1987(Part-3) Code of Practice for Design Loads (Other than

Earthquakes) for Buildings and Structures.

Wind Loads

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Codes Descr ipt ion

I ndian Standards

IS:875-1987(Part-5) Code of Practice for Design Loads (Other than

Earthquakes) for Buildings and Structures.

Special Loads and Load Combinations

IS:1786-1985 Specification for High Strength Deformed Steel

Bars and Wires for Concrete Reinforcement.