Long Paper - Peb Hangar

LONG PAPER ON “CONSTRUCTION OF PEB HANGAR (70 METER CLEAR SPAN)

WITH ANNEXE AND SERVICES AS PART OF MODERNISATION OF

AIRPORT INFRASTRUCTURE AT BANGALORE

By

AJAY KUMAR JAIN

PGPIDM-M-54

REGN NO. 27-08-32-4210-291

NATIONAL INSTITUTE OF CONSTRUCTION MANAGEMENT AND RESEARCH

Pune Campus

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DECLARATION

I declare that the long paper entitled “Construction of PEB hangar (70 meter clear span) with annexe and services as part of modernisation of airport infrastructure at Bangalore” is the bonafied work carried out by me, under the guidance of Prof. P. Nagarguna, further I declare that this paper has not been previously formed the basis of award of any degree, diploma, associate-ship or other similar degrees or diplomas, and has not been submitted anywhere else

Date: AJAY KUMAR JAIN PGPIDM-M-54REGN NO. 27-08-32-4210-291NICMAR, Pune

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CERTIFICATE

This is to certify that the long Paper entitled “Construction of PEB hangar (70 meter clear span) with annexe and services as part of modernisation of airport infrastructure at Bangalore” is the bonafied work carried out by Mr. Ajay Kumar Jain, in partial fulfilment of the academic requirements for the award of Post Graduate programme on Ifrastructural development and Management(PGPIDM). This work has been carried out by him under my guidance and supervision.

Date: Prof. P. Nagarguna NICMAR, Pune

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ACKNOWLEDGEMENT

I express my sincere and heartfelt thanks to Dr. M.G. Koregaonkar, Director general, NICMAR, Pune ,Prof. Ajit Patwardhan, Dean, NICMAR, Pune for giving me an opportunity to undertake this research subject for preparing long paper.

I also express a deep sense of gratitude to Prof. P.Nagarjuna, faculty, NICMAR, Pune for his constructive support, constant encouragement, guidance and channelizing my efforts in the right direction without which this long paper would not have attained its present form.

I also thank librarians of NICMAR, Pune, for giving us access to the facility whenever required.

I would also like to thank my family and friends who encouraged us constantly throughout the research period.

(Ajay Kumar Jain)

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ABSTARCT

Hangars are always considered as prestigious projects due to their operational use, constructional aspects and structural complexity. Due to recent advancement in concepts, materials and construction techniques a revolutionary change could be seen world over in conceiving industrial structures like Hangars, Garages, Workshops etc not merely as covered shed for housing aircrafts, specialist vehicles, equipments etc but as Architectural Marvels as well. This conceptual change could be seen in almost all ports, workshops and factory projects. Modern hangars are large sized with respect to span and height and require most modern facilities to suit the modern days aircrafts. A Hangar project at Bangalore constructed during modernisation of airport infrastructure project was also conceived with state-of-the-art concept of Pre Engineered Building using all modern materials and techniques which no doubt makes this an ideal project in the category of A Complex Architectural and Engineering Marvel. The project demanded use of modern techniques and materials with high degree of construction precision, excellent quality control, constant supervision through experienced executives and regular monitoring up to the highest level. The paper cover the case study of this hangar constructed as a large span Pre-Engineered Rigid Frame Structure. .

The paper shall depict the evolution of Steel Hangar Structures through a Gallery of hangar constructed in India over last five decades. Due to revolutionary change in concept of design, construction techniques and materials it is now possible to provide large span hangars at considerably faster rate and lighter in weight. Requirement of Hangar users have also changed over the years from simple, small sized hangar for housing small aircrafts usually conceived as industrial sheds to considerably large sized hangars with all modern facilities like repair shops, office accommodations for the technical staff, testing labs etc in the form of side annexe. The executives involved in the execution of the project had varied and unique experiences and challenges during execution of the work which shall be presented in this paper.

The use of steel structures in various types of buildings/accommodation is not uncommon, e.g. aircraft hangars, covered garages, storage accommodation, auditoriums, towers etc. Most of these structures commonly consist of elements such as beams, columns, trusses & portal frames which are basically two dimensional from the point of view of analysis as well as design. Interconnecting members in the third dimension ( for example purlins) are usually of secondary character, present merely for the purpose of transferring load and not contributing to the rigidity of the structure. A structural arrangement in which there is integrated load sharing in all the three directions will obviously have more advantage, since every part of the structure makes an effective contribution. Such structures are known as Space Structures and are gaining importance in its use all over the world due to various advantages over traditional structures. The study shall present some insight in the advantages of use of PEB system for hangar construction as part of any major airport modernisation project.

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TABLE OF CONTENTS

Title page i

Certificate ii

Declaration iii

Acknowledgment iv

Abstract v

Contents vi-

List of tables

List of figures

Chapter Page No.

1.0 INTRODUCTION 1-

2.0 LITERATURE REVIEW

3.0 PRESENT SCENARIO IN THE FIELD OF STEEL

HANGARS

4.0 SPECIFICS ABOUT PEB AND ITS ADVANTAGES

5.0 CASE STUDY OF A 70 METER CLEAR SPAN

HANGAR CONSTRUCTED AT BANGALORE UNDER

MODERNISATION OF AIRPORT

INFRASTRUCTURE PROJECT

6.0 SUMMARY, FINDINGS, CONCLUSIONS AND

RECOMMENDATIONS

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PAGE INTENTIONALLY KEPT BLANK FOR NOTES ETC..

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CHAPTER 1INTRODUCTION

1.1 GENERAL

The use of steel structures in various types of buildings/accommodation is not uncommon, e.g. aircraft hangars, covered garages, storage accommodation, auditoriums, towers etc. Most of these structures commonly consist of elements such as beams, columns, trusses & portal frames which are basically two dimensional from the point of view of analysis as well as design. Interconnecting members in the third dimension ( for example purlins) are usually of secondary character, present merely for the purpose of transferring load and not contributing to the rigidity of the structure. A structural arrangement in which there is integrated load sharing in all the three directions will obviously have more advantage, since every part of the structure makes an effective contribution. Such structures are known as Space Structures and are gaining importance in its use all over the world due to various advantages over traditional structures. The study shall present some insight in the advantages of use of PEB system for hangar construction as part of any major airport modernisation project.

Hangars are always considered as prestigious projects due to their operational use,

constructional aspects and structural complexity. Due to recent advancement in concepts,

materials and construction techniques a revolutionary change could be seen world over

in conceiving industrial structures like Hangars, Garages, Workshops etc not merely as

covered shed for housing aircrafts, specialist vehicles, equipments etc but as

Architectural Marvels as well. This conceptual change could be seen in almost all ports,

workshops and factory projects. Modern hangars are large sized with respect to span and

height and require most modern facilities to suit the modern days aircrafts. A Hangar

project at Bangalore constructed during modernisation of airport infrastructure project

was also conceived with state-of-the-art concept of Pre Engineered Building using all

modern materials and techniques which no doubt makes this an ideal project in the

category of A Complex Architectural and Engineering Marvel. The project demanded

use of modern techniques and materials with high degree of construction precision,

excellent quality control, constant supervision through experienced executives and

regular monitoring up to the highest level. The paper cover the case study of this hangar

constructed as a large span Pre-Engineered Rigid Frame Structure.

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1.2 OBJECTIVES OF STUDY

The paper shall depicts the evolution of Steel Hangar Structures through a Gallery

of hangar constructed in India over last five decades. Due to revolutionary change in

concept of design, construction techniques and materials it is now possible to provide

large span hangars at considerably faster rate and lighter in weight. Requirement of

Hangar users have also changed over the years from simple, small sized hangar for

housing small aircrafts usually conceived as industrial sheds to considerably large sized

hangars with all modern facilities like repair shops, office accommodations for the

technical staff, testing labs etc in the form of side annexe. The executives involved in the

execution of the project had varied and unique experiences and challenges during

execution of the work which shall be presented in this paper. So the objectives of the

study can be summarised as:

(a) To understand Evolution of technologies in construction of large

hangars over past 05 decades.

(b) To analyse Latest technology i.e PEB system being used in Hangar

construction, and its advantages over conventional system.

(c) To Prepare a case study of a Large span Hangar covering all relevant

aspects of planning, material and construction management etc..

1.3 LITERATURE REVIEW

There is a lot of literature available on steel structure as the steel is the main

construction material world over. However in India we have mostly concrete intensive

construction instead of steel intensive construction due to cheap availability of labour.

PEB system being new concept to India not many books are available on the subject,

however a lot of material and data is available on internet and write-up available in

structural journals and relevant IS cades like BIS-800 etc. has been used.

1.4 METHODOLOGY OF STUDY

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The study requires detailed study of conventional system of Hangar Construction

and the PEB system and their applicability. The following method of study has been

adopted for conducting the study:

a) Literature review regarding conventional and PEB system of Hangar construction from various published material.

b) Interviews with experts in the field of PEB steel construction

c) Websites related to the PEB construction

d) Case study after discussion and collection of data for a already completed project.

1.5 SCOPE AND LIMITATION OF STUDY

The study shall present some insight in evolution of technologies in construction

of large hangars over past 05 decades and the advantages of use of PEB system for

hangar construction as part of any major airport modernisation project. The project

demanded use of modern techniques and materials with high degree of construction

precision, excellent quality control, constant supervision through experienced executives

and regular monitoring up to the highest level. The study shall cover the case study of

this hangar constructed as a large span Pre-Engineered Rigid Frame Structure.

Although the scope of the subject is enormous, the study shall have following limitation:

a) Application of the proposed study is mainly suitable to steel intensive construction

b) Time and monetary constraints may limit the depth of penetration of the study.

c) The data required for case studies are many times confidential which limits the study to certain extent.

1.6 SCHEME OF STUDY/CHAPTERIZATION

The study shall consist of following 06 Chapters:

i. In Chapter 1 I have discussed the objectives of the study stating scope and

limitation of study with methodology of the study.

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ii. In Chapter 2 the literature review is done to understand evolution of technologies

in construction of large hangars over past 05 decades and highlighting the need

and importance of PEB structural steel system for aircraft hangars.

iii. In Chapter 3 I have covered present scenario in the field of hangar construction

in India

iv. In Chapter 4 I have covered specifics about PEB system for Steel structure, its

advantages over conventional system etc.

v. In Chapter 5 I have covered the case study of a 70 meter clear span hangar

constructed at Bangalore under modernisation of airport infrastructure project

covering following issues:

(a) Project definition concept and scope and cost

(b) Project institutional framework with role and responsibility matrix.

(c) Project planning and phasing

(d) Project execution and related issues

vi. In Chapter 6 I have given summary findings, conclusions and recommendations.

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CHAPTER 2LITERATURE REVIEW

2.1 Pre-Engineered Steel Buildings use a combination of built-up sections, hot rolled sections, cold formed elements and profiled steel sheets which provide the basic steel frame work with a choice of single skin sheeting with added insulation or insulated sandwich panels for roofing and wall cladding or brick wall. The concept is designed to provide a complete building envelope system which is air tight, energy efficient, optimum in weight and cost and, above all, designed to fit user requirement like a well fitted glove.

2.2 These Pre-Engineered Steel Buildings can be fitted with different structural accessories including mezzanine floors, canopies, fascias, interior partitions etc. The building is made water-tight by use of special mastic beads, filler strips and trims. This is a very versatile building system and can be finished internally to serve any required function and accessorized externally to achieve attractive and distinctive architectural styles. It is most suitable for any low-rise building and offers numerous benefits over conventional buildings.

2.3 Pre-engineered buildings are generally low rise buildings, however the maximum eave heights can go upto 25 to 30 metres. Low rise buildings are ideal for offices, houses, showrooms, shop fronts etc. The application of pre-engineered concept to low rise buildings is very economical and speedy. Buildings can be constructed in less than half the normal time especially when complimented with other engineered sub-systems.

The most common and economical type of low-rise building is a building with ground floor and two intermediate floors plus roof. The roof of a low rise building may be flat or sloped. Intermediate floors of low rise buildings are made of mezzanine systems. Single storeyed houses for living take minimum time for construction and can be built in any type of geographic location like extreme cold hilly areas, high rain prone areas, plain land, extreme hot climatic zones etc.

2.4 There are basically eight major components in a pre-engineered residential building such as :

Main framing or vertical columns Purlins, girts and eave struts Sheeting and insulation or prefab panels Brick & Cement Board Walls

Flooring Paints and finishes False Ceiling Miscellaneous services

2.4..1 MAIN FRAMING

Main framing basically includes the rigid steel frames of the building. The PEB rigid frame comprises of tapered columns and tapered rafters (the fabricated tapered sections are referred to as built-up members). The tapered sections are fabricated using the state of art technology wherein the flanges are welded to the web. Splice plates are welded to the ends of

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the tapered sections. The frame is erected by bolting the splice plates of connecting sections together.2.4.2 PURLINS, GIRTS AND EAVE STRUTS

Purlins, girts and eave struts are also known as secondary cold-formed members. There is no welding involved in their preparation. They are prepared by just bending the steel coil giving it the desired shape (Z-shape for purlins and girts, and C-shape for eave struts).

Purlins : Purlins are the secondary members are for supporting the roof panels & wall cladding.

2.4.3 PANELS AND INSULATION

Single skin profile or ribbed steel sheets are used as roof and wall sheeting, roof and wall liners, partition and soffit sheeting. The steel sheets are generally made from steel coils. Minimum thickness of steel coils used is 0.5mm high tensile steel.

The steel sheets are normally of zincalume or galvanized bare and permanently colour coated or plain which can be coated at site after installation.

These buildings can be properly insulated by providing fibrous insulation slabs / rolls of non- combustible Rockwool, Aluminium foil laminated, placed over a metal mesh bed created between the purlins, and then the roofing steel sheet fixed over it. The siding walls can also be insulated by providing a double skin profile or ribbed steel sheet or cement board sheets on inner side wall cladding having Rockwool Insulation slab sandwiched in between and held in position with the help of ‘Z’ spacers in between the two steel sheets. In similar pattern a double skin insulated roofing system can also be erected. The cement boards will give a conventional white finish after paining.

Another alternative is to provide pre-fabricated insulated panels, which comprises of two single skin panels (plain steel sheets galvanized / zincalume colour coated) with polyurethane foam insulation in between. These panels are intended for use as thermally efficient roof and wall claddings for buildings e.g. in high altitude areas and hilly terrains.

Roof is of profile steel sheet with or without insulation fixed underneath. False Ceiling of particle / rigid board is fixed to a steel frame work hung from the trusses. Insulation can also placed over the false ceiling packed in polythene. Here a 2 ft. high brick wall is required to be given on the outside for protection.For walls a second alternative can be by way of normal brick work.

The latest trend developed for construction of pre-fab single storeyed residential houses does not involve any steel structure (columns & purlins). The walls are constructed with profiled GI sheet of high crest height and faced with cement particle boards and the crest depths filled with either high density Rockwool or Rigid insulation material like Polyurethane Foam or Expanded Polystyrene.

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The roof is erected with trusses placed over the walls and profile sheet fixed to purlins and bolted to the trusses.

The corners of the walls are provided with steel flashings fixed to the profiled GI sheet on both sides before fixing of the cement particle boards.

2.4.4 PAINTS AND FINISHES

Normally the primary and secondary steel are coated with one coat (35 microns) of redoxide paint without any special treatment to steel. However, if some special paint has to be applied to steel in order to give better anti-corrosion properties etc. then the steel members have to be shot-blasted and then coated with the special paints.

For houses inside & outside painting on walls & false ceiling is to be provided.

2.4.5 DOORS AND WINDOWS

Steel or aluminium framed doors and windows are fixed to the purlins or the supporting profiled steel either by welding or bolted to the flanges already fixed to the purlins. Proper flashings are applied wherever necessary.

2.4.6 FALSE CEILING

This is usually required for residential building or offices. A metal frame work is hung from the ceiling and false ceiling of rigid boards are either bolted or placed over the frame work.

2.4.7 PARTITION WALLS

This is usually required for residential building or offices. Partition wall comprises of two rigid boards having insulation sandwiched in between and fixed to the steel columns or supporting profiled steel and purlins. Alternatively prefab sandwich panels can also be fixed to the columns and purlins.

2.4.8 FLOORING

Flooring is usually of conventional nature consisting of cement concrete. For intermediate floors metal decking sheet is fixed to purlins and concrete poured over it.

2.4.9 DESIGN CODES

Design codes that govern the design procedures and calculations are as follows :-

Frame members (hot rolled or built-up) are in accordance with AISC (American Institute of Steel Construction) Specifications for the design, fabrication and erection of structural steel.

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Light gauge cold-formed members are designed in accordance with AISI (American Iron and Steel Institute) Specification for the design of light gauge cold formed steel structural members.

IS : 8750 - 1987 : Code of practice for design loads of buildings & structures.

IS : 800 -1984 : Code of practice for general construction in steel.

IS : 801- 1975 : Code of practice for use of Cold formed light gauge Steel Structural Members in general building Construction

3. ERECTION

Steel framing members are delivered at site in pre-cut sizes, which eliminates cutting and welding at site. Being lighter in weight, the small members can be very easily assembled, bolted and raised with the help of cranes. This system allows very fast construction and reduces wastage and labour requirement. These buildings can then be provided with roof decking and wall cladding with metal profile sheets and proper insulation. The framing are so designed that electrical and plumbing services are part of it and can be very easily concealed.

For the latest developed technology on pre-fab residential house construction without steel columns & purlins, the construction method begins with grouting of ‘C’ channels to the floor on the periphery of the building. Thereafter placing 1.2mm GI profiled sheets (of high depth crest) over the ‘C’ channel and fixed with screws. Fixing of high density Rockwool or Polyurethane Foam or Expanded Polystyrene with adhesive on the crests on both sides. Then providing and fixing 8mm cement particle boards on inner side and 10mm cement particle boards on outer side of the profiled GI sheet, with screws, followed by fixing of a ‘C’ channel on top of the GI profiled sheet. Then trusses are placed over the top ‘C’ channel and purlins fixed to it at 1500mm distance. Colour coated profile steel sheets are fixed to the purlins. GI ‘T’ frame work making a grid of 600 x 600mm hung from the trusses with GI rods for false ceiling frame work and 6-8mm E boards are placed over it.

Floors are constructed of cement concrete at a raised level for special requirements tiles can be fixed as the final finish. For kitchen and toilets, the floor and walls up to 2-3 feet is constructed or in tradition houses or normal cement finish or with tiles.

For fixing of electrical accessories, grills, shelves and other miscellaneous services wooden supports are pre-fixed to the GI profiled sheet ceiling fan support is taken from the trusses.

Doors & windows frames are made of steel and fixed to the profiled GI sheet with proper flashings.

Rain guard covers over windows made of steel are fixed to the profiled GI sheet of walls.

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The gaps between the cement particle boards are filled with a putty and finally painting is done on both sides of the walls.

4. MAINTENANCE

In Pre-engineered Pre-fabricated steel houses the maintenance area is the roofing & cladding.

Steel roofing & side wall cladding requires minimum maintenance. The roof should be inspected immediately after installation to check if cleaning of the roof has been carried out fully. It is very often seen that the drilled out metal and debris are not swept away. These can act as initiators of corrosion and lead to premature failures.

In case of cement particle board walls painting required every 3-4 years.

Installed roofing must be inspected atleast once a year. Any exposed metal that can rust or has rusted should be painted. Leaves, branches, and trash should be removed from gutters, at ridge caps and in corners. Also watch out for discharge from industrial stacks, and particulate matter and high sulphur exhaust from space heaters which could get piled up.

Roof top ancillaries and air conditoner supports, drains and housing should be checked. Particular attention should be paid to add-on roof ancillaries that create new roof penetrations. Roof-top air conditioners should be installed on curbs designed to avoid ponding water. Condensate from air – conditioning and refrigeration equipment should never be allowed to drain directly on to the roof panels. The drainage contains ions from condenser coils that accelerate corrosion.

In the event of a roof leak, do not indiscriminately plaster the suspected leak area with tar or asphalt or use repair tape. Water can collect under the repair material causing corrosion. Instead, have an experienced roofing foreman locate the leak, identify its cause and properly repair the roof.

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CHAPTER 3

PRESENT SCENARIO IN THE FIELD OF STEEL HANGARS

3.1 Hangars are always considered as prestigious projects due to their operational use and constructional and structural complexity. Due to recent advancement in the concepts, materials and construction techniques a revolutionary change could be seen world over in conceiving industrial structures like Hangars, Garages, Workshops etc not merely as covered shed for housing aircrafts, specialist vehicles, equipments etc but as Architectural Marvels as well. This conceptual change could be seen in almost all the air ports, workshops and factory projects. Modern hangars are large sized with respect to span and height and require most modern facilities to suit the modern days aircrafts. Hangar project at Bangalore was also conceived with state-of-the-art concept of Pre Engineered Building using all modern materials and techniques which no doubt makes this an idle project standing in the category of A Complex Architectural and Engineering Marvel. The project demanded use of modern techniques and materials with high degree of construction precision, excellent quality control, constant supervision through experienced executives and regular monitoring up to the highest level. In this project executives have had varied and unique experiences and challenges during execution of work which have been documented in this report.

3.2 Pre-engineered buildings are the state-of-the-art steel solution to developing an efficient and cost-effective infrastructure. PEB’s offer ultimate design flexibility and an extremely short construction time (right from initial design to completion). They are supplied as a fully finished product along with steel structure, building accessories and roof cladding. They require no on-site fabrication or welding – they can simply be bolted together as per specifications. PEBs are best suited for warehouses, sports halls, factories, workshops, distribution centers, cold storages, supermarkets, aircraft hangars or any ground + two-storey construction.

3.3 EVOLUTION OF STEEL STRUCTURE AND HANGARS IN INDIA

3.3.1 In India, the use of steel structures in various types of buildings/accommodation is not uncommon, e.g. aircraft hangars, covered garages, storage accn, auditoriums, towers etc. Most of these structures commonly consist of elements such as beams, columns, trusses & portal frames which are basically two dimensional from the point of view of analysis as well as design. Interconnecting members in the third dimension ( for example purlins ) are usually of secondary character, present merely for the purpose of transferring load and not contributing to the rigidity of the structure. A structural arrangement

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http://www.mpil.in/steel_roofing_manufacturers_cladding.htm

http://www.mpil.in/prefabricated_steel_houses_costsavings.htm

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in which there is integrated load sharing in all the three directions will obviously have more advantage, since every part of the structure makes an effective contribution. Such structures are known as Space Structures and are gaining importance in its use all over the world due to various advantages over traditional structures.

3.3.2 Among various structures developed by Civil engineers in, aircraft hangars are considered important from operational point of view. These hangars are of span varying from 30m to 70m and cover large spaces. Traditional arrangement for covering such structures with trusses and purlins was being adopted in MES till recent years. The requirement of steel in such structures was as high as 100kg/m2 to 150kg/m2 depending upon the span and spacing of trusses. The modern trends for covering large spaces with much reduced requirement of steel are Pre-Engineered Rigid Frame Structures, Space Structures and Tensile Structures.

3.3.3 A Gallery of hangar structures constructed at Bangalore since inception of the base can be seen in Photographs P-(1) to P- (8) for understanding the evolution of Steel Hangar Structures over last five decades. Due to revolutionary change in concept of design, construction techniques and materials it could be possible now to provide large span hangars at considerably faster rate and lighter in weight. Requirement of users have also changed during this period from simple, small sized hangar for housing small aircrafts usually conceived as industrial sheds to considerably large sized hangars with all modern facilities like repair shops, office accommodations for the technical staff, testing labs etc in the form of side annexe.

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P-1 : SW TYPE HANGAR(1965) P-2: LETTICE FRAME TYPE HANGAR (1965)

SPAN – 49.9m, HEIGHT – 9m SPAN – 28.25m, HEIGHT – 8.5m

P-3, P-4 : BOWSTRING – GIRDER TYPE HANGAR (1993) SPAN – 60m HEIGHT- 11m

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P-5 : TRADITIONAL TRUSS TYPE P-6 : LIGHT WEIGHT TWIN HANGAR

HANGAR (1998) USING TUBE SECTIONS (1996)

SPAN 70m, HEIGHT -11m SPAN 35m HEIGHT -6m

P-7 : PRE ENGINEERED BLDG HANGAR (2003) P-8 : PRE ENGINEERED BLDG HANGAR (2003)

SPAN 40m x 3, HEIGHT – 8m SPAN 60m HEIGHT - 10m

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CHAPTER 4SPECIFICS ABOUT PEB AND ITS ADVANTAGES

4.1 In pre-engineered building concept the complete designing is done at the factory and the building components are brought to the site in knock down condition. These components are then fixed / jointed at the site and raised with the help of cranes. The pre-engineered building calls for very fast construction of buildings and with good aesthetic looks and quality construction. Pre-engineered Buildings can be used extensively for construction of industrial and residential buildings. The buildings can be multi storeyed (4-6 floors). These buildings are suitable to various environmental hazards. PEB concept has been very successful and well established in North America, Australia and is presently expanding in U.K and European countries. PEB construction is 30 to 40% faster than masonary construction. PEB buildings provides good insulation effect and would be highly suitable for a tropical country like India. PEB is ideal for construction in remote & hilly areas.

4.2 Strengths of PEBs are :

Clear spans up to 100m without internal columns

Flexibility in building dimensions

ISO 9001 quality accreditation

Easy expansion

Fixed deadlines and costs

Weather-tight roof and wall coverings with accessories for long maintenance free exteriors

4.3 Advantages of PEBs are :

Single source responsibility

Low initial cost

Engineering flexibility

Faster overall project completion

Low maintenance

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Fast modular expandability

4.4 PEBs also include :

4.4.1 Primary structures: H/I BeamsH/I Beams in the PEB industry often refer to primary built-up members. Primary members consists of columns, rafters, beams etc. These are fabricated from high strength Gr. 50 HR plates. Plates are cut to size and shape. Built up sections a re-made form these plates in Automatic Beam Welding Line by submerged arc welding.

4.4.2 Secondary members :Secondary Members in the PEB industry refer mostly to longitudinal roof and wall members that are roll formed from galvanized coils. Secondary members used in a PEB include steel purlins, side runners, fascia channels, door posts, window posts, rafter stays, column stays base angles and other miscellaneous structural parts.

”Z” sections acting as longitudinal roof purlins and longitudinal wall girts that connect to columns & rafters and support exterior roof and wall panels.

"C” sections used primarily in framed openings and as a transition member between partial block walls and wall panels.

Steel Deck used to support concrete slabs in second level flooring.

Base angles, gable angles, and mezzanine edge angles.

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4.5 Roofing & Cladding SystemsMPIL PEBs offer you choice of 5 different types of roofing and cladding systems that enhance the aesthetic appeal of the building and are ideally suited for rapid and low cost construction.

4.6 Exterior Facades

4.6.1 Single Skin Panels are trapezoidal ribbed sheets roll formed from thin mill finish or prepainted aluzinc coated steel and aluminum coils and cut-to-length to meet the requirements of a specific building4.6.2 Sandwich Panels have a polyurethane foam core sandwiched between two single skin metal panels (or an exterior single skin metal panel and an interior aluminum faced laminate).

4.7 PEB Accessories

Trims and Flashing include eave trim, eave gutters, downspouts, gable trim, curved eave panels, flashing around building accessories, etc. which are produced from prepainted aluzinc coated steel or aluminum sheets that are bent to the required shape.Building Accessories include sliding doors, rollup doors, personnel doors, fiberglass insulation, sandtrap louvers, windows, ridges ventilators.

Typical Girt Joint

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Typical Purlin Butt Joint

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4.8 PEB BUILDINGS VS CONVENTIONAL BUILDINGS

PEB Buildings

Conventional Building

Aesthetically appealing appearance Special aesthetic design required

Aesthetically appealing appearance Special aesthetic design required

Reduced time because of international design standards & codes using standard sections and connections

Increased design time due to scratch and availability of less design aids

Higher resistance to seismic forces due to low weight flexible frames

Rigid heavy weight structures not suitable for seismic zones

30% less PEB steel structures weight through efficient use of steel

High weight due to excessive safety factor and the usage of heavier steel sections

Factory controlled quality Every project to be fabricated at site

Lower initial cost of peb steel buildings(cost per square meter about 30% less than the conventional) and faster delivery

Special design and features developed for each project at higher costs

Simple Foundation, easy to construct and light weight of PEB structures

Extensive heavy foundation

Average delivery time 6-8 weeks Average delivery time 22-28 weeks

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CHAPTER 5

CASE STUDY OF A 70 METER CLEAR SPAN HANGAR CONSTRUCTED AT BANGALORE UNDER MODERNISATION

OF AIRPORT INFRASTRUCTURE PROJECT

5.1. A large number of technical accommodations including hangars of varying sizes have been constructed at different air ports and air force bases since the invention of Air Craft. The oldest of these hangars were constructed during 1955 to1965 for small sized aircrafts operating from this air strips at that time. Over a period of time the type and size of hangars have grown from simple steel trussed structure to complex 70m span bowstring girder type and light weight steel tubular section structure to the modern trend of PEB structure. Requirement of hangars as covered exhibition space for aviation companies in aero shows being held at different locations near airports has also increased many fold since 1996 when first Aero India Exposition was held in India at Bangalore. The participation level of national and international companies has also increased from 10 numbers to 24 numbers during this period. A work initiated by authorities “Construction of Hangars with Annexe at Bangalore” for parking of aircrafts and facilitating additional covered space for exhibition and other allied facilities.

5.2. Approval to go ahead with the work was issued under fast track procedure wherein tender action was completed based on go-ahead sanction The work commenced on 30 Mar 06 and was successfully completed on 18 Jan 2007.

5.2.1 BRIEF SCOPE OF WORK

The scope of the work broadly consisted of construction of 60m x 70m x 10m clear size Hangar with no intermediate supports, flanked with Annexes on three sides and a electrically operated gate on the fourth side along with associated services. The annexes on two sides

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were to be in Double Storey and the third side to house two auditoriums of 200 and 50 seats capacity each with Air conditioning, complete furniture and PA system besides a VIP lounge, a large Dining Hall and acoustically treated Class Room etc. The plinth area of the Hangar and annexes put together was about 9000 Sqm.

State-of-the-art Hangar with Rigid Frame construction and maintenance free Galvalume colour coated steel profiled sheets along with FRP sheets having minimum light transmission of 60% for receiving the natural light was planned. The work being of specialised nature and keeping in view the availability of reputed manufacturers in the field, the design and fabrication was assigned to the tenders. The design check and certificate for structural stability with respect to the Indian Standards was specified to be obtained from any IIT or IISc Bangalore or SERC Chennai.

Steel PEB structure for the Hangar and rear side annexe has been designed by one of the leading manufacturers of pre-engineered, pre -fabricated Buildings in the country. The two side annexes, foundation for pre-engineered structure including steel gate are designed by private consultant (Structural Designers) Bangalore. Both the designs were checked at Indian Institute of Science, Bangalore and certified correct. Detailed scope of work for the Project was as given below:-

(a) Hangar

(i) A single span hangar was proposed to be constructed north of existing hangar. The dimensions of the proposed hangar were 60m x 70m with a clear height of 10m inside the hangar to cater for servicing and maintenance of aircrafts. The physical dimensions of an aircraft were taken into consideration while planning the clear height required. It was decided that the new hangar would be pre-engineered pre-fabricated structure. The floor of the hangar was planned for PCN 36 with Pavement Quality Concrete(PQC).

(ii) The hangar was planned to be provided with sliding doors at the front. The hangar doors were proposed to be provided with motor mechanism for opening and closing of the doors.

(b) Annexes to the Hangar

Two double storey annexes were proposed to be constructed on the Northern and southern sides of the hangar.

(c) Media Centre

(i) It was proposed to provide PEB Media Centre in the Eastern side annexe catering for two air conditioned briefing halls with a seating capacity of 200 and 50 seats respectively along with communication centre, cafeteria, VIP Lounge, class room and sanitary annexe etc.

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(ii) The briefing halls was planned to be acoustically treated. PA system was catered in both the halls. Provision of control room out side the briefing rooms was catered for controlling the light and sound systems.

(iii) Communication Centre being the nodal communication point during Air Show, it was proposed to house facilities for Computers, Internet facilities, Telephones, Fax, Photocopying machines, etc.

(iv) The cafeteria was required to meet the catering requirement of ground crew during the intervening period between air shows. The cafeteria could also be used by the organisers and personnel during the preparatory and conduct phases of the air show.

(v) Class room of 50 seating capacity was planned with sound proofing of noise level within 60 db.

(vi) All toilets in Media Centre and Officers toilets were planned to be equipped with Hand Dryers, soap dispensers, wash hand basins with Granite top and designer tiles with borders and motifs. The urinals in Media Centre were to have sensors. All the toilets were to have stainless steel doors. These special requirements were worked out keeping in view the fact that these toilets would be used during the actual conduct of the air show.

(vii) The roof of annexe on the Northern side was proposed to be viewing area for the air show. The terrace was therefore planned with PCC tiles.

(viii) The flooring in verandahs, Officers rooms, Tech Library, Computer room, Dining Hall, Communication Centre, Class room and toilets were proposed to be of granite slabs, vitrified tiles and rectified ceramic tiles. The flooring of entrance foyer, lobbies, stage and Media centre were proposed to be of granite slabs.

(d) External Services

Roads, Hard Standings, Water Supply, Electric supply, Stand by Power Supply DG set with AMF panel of 250 KVA capacity etc were planned as external services.

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5.3 An architectural plan and four side elevations of the Hangar are shown in Fig(1)

and Fig( 2) below:

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Fig(1) : Ground Floor Plan of the Hangar

Fig(2):All Four Side Elevations of Hangar

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5.4 PROJECT PLANNING SCHEDULE

Based on the recommendations of board of officers a go ahead sanction was accorded by MOD on 28 Oct 2003. Total time available for detail planning, preparation of architectural drawings, structural design, tendering, processing of all documents for issue of A/A and execution of work till completion was only 16 months. Based on the available crashed time, a schedule drawn for above activities is shown in Table (1)

Table(1): Time Schedule for Engineering Activities

SL No

STAGE DATE REMARKS

01 GO AHEAD 28 OCT 2005 PLANNING,DESIGNING 45 DAYS.

03. DIT 11 DEC 2005 TENDER ACTION 47 DAYS04. DRT 27 JAN 200502. ISSUE OF A/A 23 MAR 2005 ADMIN APPROVAL 55 DAYS05. COMMENCEMENT 30 MAR 2006 EXECUTION 290 DAYS 06. COMPLETION 20 JAN 2007

5.5 It was decided to provide “Pre-engineered Building” structure for main hangars similar to that provided during AI-03 for Hangar –D. Since the time available for all the above activities was not enough for in house preparation of drawings and carry out design, it was decided to outsource this activity through the tenderers to the manufacturers of PEB structure and other consultant with an explicit requirement of getting the design verified from premier institutions like IIT’s or IISc Bangalore. Apart from design and drawings of PEB structure, design and drawings of RCC structure, acoustics in Auditorium and Air-conditioning works were also outsourced though the tenderers. This approach could certainly reduce 2 – 3 months time in over all planning and Tender action. With an aim to reduce the execution time entire structure was sub divided into five independent buildings/structures so that execution of these five buildings could be undertaken concurrently. These five buildings are as under:-

(i) PEB Hangar.

(ii) Double storey Northern Annexe in two parts with a crumple joint in between.

(iii) Double storey Southern Annexe in two parts with a crumple joint in between.

(iv) Rear annexe housing Media Centre, Communication Centre, Cafeteria.

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(v) Hangar Gate & Gate structure.

5.6 In the above planning, it was important to design the interface of two buildings keeping in view the requirement of movement joints and over lapping of roof projections so that water ingress could be prevented. Details of such interface have been discussed subsequently. All specifications with respect to finishes were frozen to the micro level by specifying even catalogue numbers for avoiding delay in decision/changes during execution. Important items where such detailed specifications were given in the tender are:-

(a) Flooring tiles.

(b) External finishes

(c) Furniture items of Featherlite & Design.

(d) Acoustic Boards & wall & ceiling.

(e) PA Equipments.

5.7 In order to materialise the above innovative ideas of planning, tender document was also framed suitably with relevant clauses to cater for out-sourcing of design of various structures / items and their verification. It was decided to conclude only one tender for all activities including PEB structure, RCC Buildings, Gate structure, Air conditioning, Acoustics, Furniture and PA equipment. This was considered necessary for avoiding non co-ordination among contractors, at the time of execution which usually causes delay in such type of multidiscipline projects. A typical execution schedule in the form of bar chart is shown in Figure (3).

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PEB

PEB

A TYPICAL BAR CHART OF PROJECTDEC 04

RCC ANNEXE -1

RCC ANNEXE - 3

ACAUSTICS

AIR CONDITIONING

FINISHES

GATE STRUCTURE

NOV 04SEP 04AUG 04 OCT 04 JAN 05JUL 04JUN 04MAY 04APR 04DESCRIPTION OF ACTIVITIES

RCC ANNEXE - 4

RCC ANNEXE - 2

PEB STRUCTURE

FOUNDATION

DESIGN MIX FOR M-25 CONCRETE.

LAYOUT, DEMOLITION OF BLDGS, EXCAVATION FOR FOUNDATION

FIG (3): Bar Chart of Project Showing Concurrent Activities of Five Parts

5.8 DESIGN CONCEPTS OF PEB STRUCTURE

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5.8.1 “Pre-engineered Building” Structure used in this project is comparatively a new concept in India. In this type of structure, all structural elements like Columns, Beams, Purlins, Bracings, Base plates etc. are prefabricated in modular forms at modern workshops equipped with fully computerised machineries required for precision fabrication. Advantages of such structure over traditional steel structure are:-

(a) Quality control is par-excellence since fabrication work is through computerised plants. All members are cut to shape and tailor made as per structural requirement thus works out to be lighter and economical.

(b) Elements are in modular forms where each module is of length not exceeding 10 M which can be transported easily.

(c) Construction in faster and erection is easier.

(d) Structure is maintenance free and aesthetically elegant

5.8.2. General Parameters: General design and architectural parameters like dimensions, type of structure, spacing of frames / portals roof slope etc. are given in Table (2).

Table ( 2) : General Design and Architectural Parameters

BUILDING A B C

Type Rigid Frame (RF) Lean – To Lean–to & Unsym RFWidth 60.00m I/I of Steel Columns 164.00m O/O 8.60m Lean-To + 1.90m

O/O Unsym RFLength 70.00m C/I Of Steel

Columns71.70m O/O 35.0m O/O

Bay Spacing 1 @ 7.777 + 7 @ 7.78 + 1 @7.777m C/I

1 @ 6.895 + 2 @ 6.890 + 1 @ 8.65 + 5 @ 8.475m

1 @ 8.20 + 1 @ 7.90 + 2 @ 6.20+1 @ 6.30m

Eave Height 10.0m Clear 5.50m Clear 3.20m ClearNo of Main Ends

2 With Half Bay Loading 2 With Half Bay Loading

2 With Half Bay Loading

Roof Slope 1 : 10 1:10 1:20Roof Covering

Kr 26 Ga Colour (Kirbi Galvalume Roof Sheets)

Kr 26 Ga Colour Kr 26 Ga

Wall Covering

Kw 26 Ga Coloured (Kirbi Galvalume Wall Sheets)

Kw 26 Ga Colour Brick work incl Gables

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5.8.3. Design Criteria

(a) Code of Practice for General construction in steel (IS:800-1984)

(b) Code of Practice for design loads (IS:875-1987)

(c) Cold form light Gauge steel (IS:801-1975)

(d) Welding Design (AWS-D1.1)

(e) Criteria for Earthquake resistance (IS:1893-2002)

5.8.4. Material Specifications

(a) Built-up Sections - ASTM A 570/A572 Gr 50 (Fy = 50 Ksi)

(b) Hot-Rolled Sections - ASTM A 36 (Fy = 36 Ksi)

(c) Angle-Bracings - ASTM A 36 (Fy = 36 Ksi)

(d) Tubes - ASTM A 500 Gr C (Fy = 50 Ksi)

(e) Cold-Formed Sections- ASTM A 570 Gr 50 (Fy = 50 Ksi)

(f) High Strength Bolts - ASTM A 325 (Fy = 92 Ksi)

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(g) Anchor Bolts - ASTM A 36 (Fy = 36 Ksi)

5.8.5 Loading

Dead Load : 0.10 KN/m2 + Self Weight of Structure for Frame.

(Sheeting–0.0427 KN/m2 & Purlins–0.0482 KN/m2)

Live Load : 0.75 KN/m2 on Purlin & Sheeting

Wind Speed : 120 KMPH Applied on Main Frame Rafters as per IS: 875 (Part 3) – 1987

Seismic Load : Zone II (IS:1893 Part -I : 2002)

The design was carried out for all possible combinations of Dead Load + Live Load,

Dead Load + Wind Load and Dead Load + EQ Load

5.8.6 Design Assumptions

(a) The main frame rafters and columns are moment connected to each other.

(b) The lateral stability of the building is provided through the frame action of the main frame.

(c) The longitudinal stability of the building is provided through the braced action in the braced bays of the building.

(d) The roof purlins are continuously supported beams supported at rafter location and span the bay spacing of the building.

(e) The roof sheeting provides lateral support for purlins.

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(f) The Main frame column base is pinned for building A & C. For building B, base is assumed to be fixed.

(g) The Main frame rafter of lean-to frames are pin connected to wind columns.

5.8.7. Purlin Design: All purlins were designed as per IS:801 using Cold Form light weight Z Sections. Purlins of size 200 Z 2.0 with two 12 mm dia sag rods for buildings A & C and of size 200 Z 2.5 with two 12mm Dia sag rods for buildings B were used with a Lap of 706 mm. All purlins were considered continuous over rafters.

5.8.8 It is worth mentioning here that with the use of cold form section purlins and Galvalume sheets dead load over frame got reduced considerably as compared to traditional angle or channel sections of mild steel. In the instance case a channel section ISMC 250 (weight 15KN/m2 ) would have been required for the span of 7.2m.

5.8.9 Eave Struts & End Wall Girts: Similar to purlins eave struts of Cold form section of size 200 Es 2.5 with two sag rods with Lap of 706 mm, Girt on side walls of size 200 Z 2.0 with two sag rod all for building ‘A’ and Girt of size 200 Z 2.0 for building ‘B’ on grid Q & 200 Z 2.5 on grid Z with two sag rods were found adequate as per design.

5.8.10. Important structural details of PEB structure viz Portal frames at different grid lines, purlins, girts, moment flange joints, gutter fixing with brackets, lean-to porch, etc are as shown in fig(4) to Fig().

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Fig (7)

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5.9 Photograph No P(1) TO P(04) shows few elements of PEB structure.

P-1 : PEB ELEMENTS: RAFTERS P-2 : ERECTION OF RAFTERS

P-3: PEB ELEMENTS: RAFTERS P-4: ERECTION OF STANCHIONS

5.10 SPECIAL ARCHITECTURAL FEATURES AND NEW MATERIALS INTRODUCED IN THE PROJECT

5.10.1 . Specifications of large span steel structures have seen advancements from heavy weight mild steel two dimensional traditional truss type structures over pylons or RCC columns to third generation Rigid Frame Pre Engineered Buildings of profile commensurate to bending moment diagram to fourth generation three dimensional space, transigrity and tensile structures. It has been possible to develop such structures due to advancement in construction materials and techniques like High Strength Steel (Fe-510), large length Galvalume sheets as roofing and cladding materials etc. State-of-the-art building materials recently introduced in our

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country were effectively used in this work to their advantages. Description of some of the important materials is given as follows;

(a) High Strength Steel PEB Structure: As already brought out in preceding paragraphs, Pre Engineered Building Structure fabricated from high strength steel plates were used for the hangar. All the materials used in PEB structures viz steel plates , cold formed sections, High tension bolts etc. were tested in the quality control laboratory at the manufacturers end before fabrication. Quality assurance tests were also got carried out at IISc Bangalore as confirmatory tests for these materials.

(b) Galvalume Roofing System: A significant advancement in the field of metallic roofing system could be seen in the market from CGI sheets of maximum length 3.0m to GALVALUME and ZINCALUME Sheets of 10m to 12m length. In this project GALVALUME high tensile cold rolled steel sheets conforming to AS 1397, coated with min 150 gms/m2 of Zinc-aluminium alloy coating mass (class AZ150),and colour coating with oven baked paint applied to substrate manufactured by M/S Kirbi Building System India Ltd was used in this project. The profile of sheets used are shown in Fig(26) and Fig(27).

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5.10.2 . Other new materials and important architectural features used in this work are;

(a) Alu-K-Bond Lining for Wall and Columns for improving aesthetics of the structure

(b) Cold Formed Section for Purlins, Girts as light weight secondary members in lieu of traditional open structural steel sections. Weight of CFS purlins of size 200Z2.0 used in this work is 4.8 Kg/m2 as compared to ISMC 250 structural steel section of weight 15.6Kg/m2.

(c) Vitrified and Rectified tiles have been provided in various rooms and corridors in lieu normal ceramic tiles as has been discussed subsequently.

(d) Structural Glass Façade in staircase mumty has been provided in lieu of PCC block masonry panel wall with an aim to improve side elevations and increase lighting level in staircase hall.

(e) Polycarbonate Double Walled Sheet Dome

5.11 METHOD OF PHYSICAL EXECUTION

5.11.1 Survey and Investigation: Prior to commencement of work, proper and accurate survey and investigation of existing soil and area of the plot was of paramount importance. Soil investigation was carried out by Karnataka Test House Pvt Ltd, Bangalore. Five bore holes were explored for this purpose and SBC reported was 13 T/m2. North-eastern edge of the rectangular plot as shown in Fig(1) was appx 3.5m higher than the south-western corner. Total Station survey equipment was used to take the initial and final levels.

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5.11.2 . The architectural drawings and specification were prepared by CE (AF) Bangalore and the design drawings were supplied by the contractor. The Pre Engineered Building was designed by M/S Kirby India, Hyderabad and other works by M/S Civil World, Bangalore.

5.11.3 Site Clearance and Foundation Work: Before commencement of excavation of earth all the existing buildings were demolished. The ground was made level as hangar floor was required to be in level. Existing water pipes and cables passing in the area were diverted. Cutting of appx 20,000 Cum earth was involved.

5.11.4 Foundation of the annexe was designed as raft foundation. The Main Hangar was designed as Pre-Engineered structure with stanchions erected over RCC pedestals and fixed with anchor bolts. The foundation for the pedestals was designed as strip footing. SBC of soil being low, the soil was stabilized with sand cement (10:1) cushion 500mm thick. M 25 concrete was used for all RCC works and Ready Mix Concrete(RMC) with cement content of 340 kg/cum, was supplied by M/S ACC Ltd.. Photographs P(13) to P-(16) depict site clearance and foundation activities in the project.

5.12 PEB Structure: Primary members called stanchions and rafters were fabricated in the factory of M/s Kirby India Ltd in Hyderabad and were transported to site by road. The stanchions were single piece and rafters were in six pieces assembled with nut and bolts at site. These members were erected within a short span of 30 days. The erection was done with the help of derricks & cranes. All stanchions were erected first on the top of pedestals. The gap in pedestals and stanchions was filled with non shrinkable grouts. Thereafter rafters were put on stanchions. The erection manual of manufacturer was followed for safe erection. After erection of all members the roofing and cladding was done with Galvalume sheet 0.5mm thick. The sheet was fixed to purlins etc with the help of self driven screws. The roof of rear bay of the hangar was provided with polycarbonate sheet dome of 10 m span and 12 m height for better elevation and natural lighting. The polycarbonate sheet used was 6mm thick Multi wall marketed by M/S GE Corpn. Various activities of PEB structures viz individual members, erection work, connection and junction details, completed frames, fixing of Galvalume roof and wall sheeting could be seen in Photograph P-(05) to P-(31).

5.13 Pavement Quality Concrete Floor: Pavement Quality concrete designed for Flexural strength of 45 Kg/Cm2 with cement content 395 Kg/Cum and water cement ratio of 0.38 with slump 25 to 30 mm considering compaction factor 0.82 was designed by ACC (RMC).

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5.13.1 The concrete was manufactured under strict quality control from ACC Ready Mix Concrete plant brought in Transit Mixers to the site and discharged over WMM & Polythene sheet. The concrete was initially leveled manually and vibrated with the help of needle vibrators subsequently concrete was paved. Compacted and leveled with “Mechanical Paver” (MULTI EQUIP)

5.13.2 The compacted and leveled concrete was allowed for its initial setting when concrete is still green (Approximately after 20 to 35 minutes) the non metallic monolithic surface hardening compound NITOFLOR Hard top of M/s FOSROC Chemicals was spread over the concrete surface at the rate of 3 Kg per SM. If the concrete is designed with higher water cement ratio for easy pouring of Ready Mix concrete from Transit Mixer it is recommended to go for “Vacuum-De-Watering”.

5.13.3 Vacuum-De-Watering was not required and not done at Yelahanka since W/C ration was too low to perform this activity. If higher W/C ratio is adopted in mix design for improving workability this activity can be performed prior to Floating and Trowelling.

5.13.4 After uniform spreading of hardner, the concrete surface was “Floated” with tremix skim Floater for top layer. Subsequent two passes of floating was carried out with floater at a interval of 1 to 11/2 hours.

5.13.5 Once the Floating was completed, the surface was “Troweled with power trowel for three times at a interval of 2 to 2 to hours depending upon the weather condition. The smooth finished surface was achieved in 10 hours of operation.

5.14 Electrically Operated Door Shutters: The main hangar has been provided with electrically operated door shutters, twelve numbers, each of size 10mx5m. These twelve doors were placed over guide rails at the bottom and supported on guide channels fixed to steel wind girder at the top. The girder & doors structures were designed by M/S Madhu Industries, Bangalore. The total steel used was approx 45 MT. The gantry was fabricated at site in three parts. These three parts were then shifted at location and assembled with welded joints. The gantry was lifted en-block with two cranes of 100 Ton capacity and placed in position. The speed of movement of doors is adjusted for 10m per minute.

5.15 Double Story RCC Annexe: The conventional annexes on South and North were designed as framed structure with isolated footings. The panel walls were constructed with PCC

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Solid / hollow blocks. The floor finishes were with rectified ceramic, vitrified tiles and granite slabs in stairs. The railings on verandah were of stainless steel matt finish.

5.16 Media Center and Auditorium: The rear annexe was designed as Pre-Engineered Building structure of approx plinth area 2100Sqm to house two auditoriums of capacity 200 & 50, VIP lounge, class room, communication room, dining hall with Kitchen, store and toilets. Auditoriums are provided with Air conditioning, acoustically treated and provided with state-of-the-art Public Address system centrally controlled from control room. The media centres were provided with modern furniture manufactured by M/S Featherlite Industries and M/S Durian Ltd. Air conditioning was designed and erected by M/S Blue Star Ltd. The acoustic treatment was designed by a renowned consultant, Prof B Ramakrishna. All toilets were provided with designer tiles, stainless steel doors and urinals with sensors. The PEB stanchions and Columns are clad with ALUCOBOND cladding material for aesthetics.

P-5 : FOUNDATION OF PORTALS: P-6 : EARTH WORK IN PROGRESS

PEDESTALS CAN BE SEEN

P-7: STRIP FOOTING BEING CASTED P-8 : STRIP FOOTING REINFORCEMENT

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P-9 : ELEMENTS OF PEB STRUCTURE P-10 : FIXING OF STANCHIONS OVER

BASE PEDASTALS

P-11 : ERECTION OF END TWO PORTALS P-12 : PRECISE SETTING OF RAFTER OVER

IN PROGRESS STANCHIONS

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P-13 : SETTING OF RAFTER OVER P-14 : ERECTION OF STANCHIONS AND

STANCHIONS RAFTER IN PROGRESS

P-15 : FIXING OF ELEMENTS OF RAFTER P-16 : PORTAL BRACING IS SEEN DULY

WITH BOLTS BEFORE ERECTION ERECTED

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P-17 : RAFTER BRACING IN SECOND SPAN P-18 : A VIEW OF PEB STRUCTURE

WITH ROOF SHEETING IN PROGRESS

P-19 : ERECTED PEB PORTALS P-20 : AERIAL VIEW OF PEB STRUCTURE

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P-21 : READY MIX CONCRETE BEING PUMPED TO FIRST FLOOR

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P-22 : ROOF SLAB OF ANNEXE BEING CAST WITH PUMPED READY MIX CONCRETE

P-23: WMM IN HANGAR FLOOR BEING P-24 : WMM IN RAMP PORTION BEING LAID

LAID WITH PAVER WITH PAVER & VOBROMAX

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P-25 : STAINLESS STEEL DOORS IN TOILET P-26 : ENTRANCE HALL OF MEDIA CENTER

DESIGNER TILES IN GENTS TOILET

P-27: ACOUSTIC BOARDS IN AUDITORIUM P-28 : INTERLOCKING PAVEMENT TILES AND ALUCOBOND LINING AROUND COLUMN

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P-29 :ALUCOBOND LINING AROUND P-30 : STRUCTURAL GLASS CLADDING OVER

PEB COLUMNS STAIR CASE HALL

P-31 : COMPLETED GATE STRUCTURES

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5.17. Important technical parameters of the completed hangar are given in Table (3)

Table: ( 3 ) Parameter of the Hangar

PEB RCC TOTAL

PLINTH AREA 7061 SqM 3250 SqM 8992 SqM

COST 820 LAKHS 180 LAKHS 900 LAKH

PA RATE Rs 11613/SqM 5540/SqM 10008/SqM

TOTAL WEIGHT OF PEB MATERIALS : 910 MTWEIGHT PER SM : 129 KG/SM

DETAILS OF PEB MEMBERS

PRIMARY MEMBERS COLUMNS/RAFTERS : 310 MT

SECONDARY MEMBERS: PURLINS, STRUTS, : 57 MTWIND BRACING ETC

ROOF SHEETING 6717SMX0.005MX7850 : 264 MT

WALL CLADDING 6200SMX0.005X7850 : 244 MT

GUTTER, DOWN SPOUTS, BOLTS ETC : 10 MT

BIRD PROOFING : 55 MT

DOORS : 138 MT

TOTAL : 1098 MT

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CHAPTER 6

SUMMARY, FINDINGS, CONCLUSIONS AND RECOMMENDATIONS

SUMMARY/FINDINGS/DISCUSSION ON IMPORTANT TECHNICAL ISSUES

6.1. Smooth Concrete Floor: As per specifications given in the specifications, hangar floor was to be of Pavement Quality Concrete designed for Flexural strength of 45 Kg/cm2 with rough broomed surface finish. This practice has been followed in almost all the hangars constructed in the past. During visit to the project, Pilots/Aircraft maintenance engineers pointed out that the rough surfaces in hangar floors cause maintenance problems with reference to cleaning of floor off grease / oil etc. They brought out that all over the world, hangar floors are now being provided with smooth floor which attract less dust and are easy to clean. It was desired by them that hangar floor in this project should also be finished smooth for avoiding such problems. A detailed survey was carried out for ascertaining suitable techniques and material which could provide smooth finished floor without causing any shrinkage cracks. Subsequently trials were carried out over floor of existing hangars by M/S Fosroc Chemicals, M/S Sika chemicals and M/S Berger Paints for self levelling epoxy floor coatings. All these products were appearing technically suitable but economically unviable. It was finally decided to obtain smooth surface by using power floats and trowels in combination with floor hardener NITOFLOR STANDARD of M/S Fosroc Chemicals Ltd. applied @ 2.5 kg/sqm. This technique was found effective in achieving an excellent, smooth, high wear resistance floor finish without any shrinkage cracks. Photographs P-(32) to P(35) show various activities of hangar floor.

P-P-32 : CONCRETE PAVER (M/S MULTIQUIP) P-33 : PQC FLOOR CASTED IN PANELS

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P-34 : POWER TROWELLING IN PROGRESS P-35 : JOINT CUTTING IN PROGRESS

6.2. Erection of Gate Structure: The gate structure was designed as an independent structure for the entire wind load over a large area of 60mX10m. This has necessitated the wind girder depth and weight as high as 4.5m and 45 Tonnes respectively. The girder was fabricated at site in three parts. The erection of Girder as one unit after connecting three parts was done carefully by using three cranes of 100Ton capacity with one crane as stand by. Erection of the gate supporting girder is seen in Photographs P-(36) to P-(39).

P-36 : WIND GIRDER LYING ON GROUND P-37 : WIND GIRDER BEING ERECTED

FOR ERECTION

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P-38 : ERECTION OF WIND GIRDER USING P-39 : ERECTION OF WIND GIRDER USING

100 T CRANES 100 T CRANES

6.3. Polycarbonate Roof Panels and Dome: Use of polycarbonate roof panels and dome has been found very effective in improving lighting level inside the hangar apart from improving the front elevation and overall aesthetic of the structure. These panels and dome can be seen in Photographs P- (40) and P-(41)

P-40 : COMPLETED DOME AND FRONT VIEW P-41 : A CLOSE UP OF DOME OF HANGAR

MADE OF POLY CARBONATE

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6.4. Bird proofing panels fixed directly to flange of Portal Beam: As specified in the CA bird proofing panels made out of square tube section frame and weld mesh were to be fixed with suspenders at suitable intervals. This technique was used in Hangar ‘D’ constructed for 2003 aero show. It was observed that bird proofing in this hangar has developed sag at many places and got de-shaped over short span of time. Photographs P-( ) and P-( ) indicate such sagged panels. Similar type of problems have been experienced at other places as well in bird proofing work with different specifications viz. Angle or Tee section frame with weld mesh or wire mesh fixed to frame with FI sections using suspenders or directly fixed to tie member of trusses. It was thus decided to fix these panels directly to bottom flange. This practice apart from imparting greater stability to bird proofing frame has rendered additional working height inside hangar. Photographs P-(42) and P- (43) indicate the modified arrangement of bird proofing in this project.

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P-42 : BIRD PROOFING IN

HANGAR “D” WITH SUSPENDERS

6.5. Interface of Steel and RCC structure: As already brought out in this report the main hangar is made of steel portal structure whereas the double story side annexes are of RCC framed structure. Structural and architectural detailing at the interface of two type of structures has been of paramount importance from structural, and functional point of view. It was important to keep all elements of the two type of structures at their interface separated adequately with movement / separation joints and at the same time it was desirable to take adequate care in detailing at such interface like overlaps and projection at roof level to avoid in-grace of rain water. These details can be seen in Photographs P- (44) and P -(45).

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P-43: FIXING OF BIRD PROOFING PANEL DIRECTLY TO FLANGE OF RAFTER IN HANGAR ‘E’

P-44 : FIRST FLOOR CORRIDOR WITH P-45 : INTERFACE OF PEB STEEL AND RCC

STAINLESS STEEL RAILING STRUCTURE

6.6. Gate structure and Gate panel Design: Design of gate panels and gate structure including fabrication was done by M/S Madhu Industries Pvt. Ltd. Bnaglore. The gate supporting structure ie wind girder was fabricated out of Tube sections RH 100 to RH 50 size and ISMC 250 sections with total weight of 45Ton. Similarly twelve number gate panels of size 10mx5m were fabricated out of ISMC 250 main frame with ISA 75756 diagonal bracing, each panel weighing to 2.5Ton. Since the wind girder was designed as structure independent of main hangar due to time constraints as already clarified in para( ), its size w.r.t depth, height and size of member has been on higher side. The same could have been reduced if this structure was connected to the adjacent braced rigid frame. Similarly weight of gate panels could have been reduced if fabricated out of built-up section made out of 4 Nos ISA placed at 300mm C/C laced on all faces with 16mm MS rods. Due to time constraint the revision of design was not considered appropriate.

P-46: GATE PANELS BEING ERECTED

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6.7 MONITORING OF WORK and QUALITY CONTROL

6.7.1 The progress of work was being monitored right up to top management level. Regular meetings were being held at different levels so as to monitor the progress. Apart from many other progress reports, a daily report up to CE’s Office and a fortnightly progress report up to departmental head was being initiated, intimating the latest progress of the work. Project was visited by several senior officials during the progress of work .

6.7.2. A well equipped laboratory was set up by contractor at the site of work immediately after issue of work order. One officer specifically for Lab assisted by one JE was made in charge of the laboratory under direct control of Chief Engineer. Most of the quality control tests were conducted in this laboratory in presence of Engineer and contractors representatives. All field tests were also being carried out by Field lab incharge, contractor and executives jointly. One senior officer from head office was also deputed verify the correctness of test results periodically for ensuring strict quality control.

6.8 CONCLUSION

6.8.1 The time was in true sense an essence of this project since dates for Aero India-2005 exhibition were fixed. In-spite of excessive rains and tight schedule the work could be completed in record time with excellent quality control to the entire satisfaction of users. This was possible due to judicious planning, timely decisions, close interaction between users and engineers and, of course, round the clock close supervision by executives.

6.8.2. Technical knowledge and innovative approach applied in the work were quite effective in overcoming day to day problems encountered at site and in improving quality of work. User’s interaction in technical accommodation like hangar is of paramount importance. In this work also a close liaison with users has given important inputs in achieving finished product to their entire satisfaction.

6.8.3. The technical issues discussed in this report will prove to be useful in planning and execution of similar projects in future.

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Long Paper - Peb Hangar

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