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LONG SPAN ROOF

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zafikha aida

on 26 September 2010

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Transcript of LONG SPAN ROOF

fig. 1 fig. 2 Long Span Roof Introduction The design and construction of long-span roof structures requires a blend of skills from the structural engineer not normally required in more normal building types.

Forces come into play, including material shrinkage, support settlement, temperature effects and sequence of erection that can normally be ignored in many building types but can have a dramatic effect on long-span structures.

Long span roof structures can be defined as those exceeding 12.0m in span

Fabricated in steel, aluminium alloy, timber, reinforced concrete and pre-stressed concrete Functions? Covering on the uppermost part of a building

Protects the building and its contents from the effects of weather

Most countries a roof protects primarily against rain

May also protect against heat, sunlight cold and wind Concept & Principles Designing long-span structures requires an obsession with stability

The structure has to hold up its own weight; just to span the required distance a structure has to support significant dead load

The complexity of long-span design increases exponentially when snow load, wind load, seismic load, deflection, serviceability, and the dead weight of roof system are all factored in Materials Timber Steel Both structural timber and steel are graded with special designations depending on the region of the production

This grading system is necessary for a uniform construction, to simplify calculations and site applications

Manufacturers produce the raw material according to these specifications, so that faults are decreased during application period. Roof Structures The selection of the basic roof structure and the general roof structure and the general roof construction must respond to various issues including: The materials and basic construction for the rest of the building

The dimension of required horizontal clear span

Special needs for particular geometric form

The form and the layout of the supports

Penetrations of the roof for vents, elevators, skylights, and so on

Acceptable range for deformations

General architectural impact of the roof in terms of its form, visibility of the top surface, and the possible exposure of the underside structure. Classification of structural forms
Form active systems Is a systems of flexible and non-rigid matter in which the redirection of forces is effected by particular form design and characteristic form stabilization. Example of structures:
Cable structures
Tent structures
Pneumatic structures
Arch structures Parallel cable Radial cable Biaxial cable cable structures formed by arch tent structures pneumatic structures Vector active systems
Systems of short, solid, straight lineal members, in which redirection of forces is effected by vector partition, i.e. by multi-directional splitting of single force simply to tension or compressive elements Example of structures:
Flat trusses
Curved trusses
Space trusses Curved trusses structures
Hinged trusses structures
flat trusses structures Section active systems
Systems of rigid, solid, linear elements, in which redirection of forces is effected by mobilization of sectional forces
Example of structures:
Beam structures
Frame structures
Slab structures Surface active systems Systems of flexible or rigid planes able to resist tension, compression or shear, in which the redirection of forces is effected by mobilization of sectional forces Example of structures:
Plate structures
Folded structures
Shell structures Contemporary Roof Structures
Beams
Beams may be classified under four main topics: straight, simply supported, shaped and cantilever. a) Straight beams: Simply supported straight beams are widely used for purlins, lintels, flat roof joists and similar applications.

b) Simply supported beams: Simply supported beams are usually deflection governed in design. It follows that beams which are continuous over multiple supports are more efficient with consequent cost savings.

c) Shaped beams: For roofs that are nominally flat a generous fall is strongly recommend. Timber beams can be tapered from one end or both ways from centre.

d) Cantilever beams: It is easy to taper Glulam & LVL. Balconies, canopies and larger roofs will look better trimmed to a structurally efficient profile. Trusses
Roof trusses may be constructed in steel, timber, aluminium alloy, in spans up to 60m, even more when required.

In case of very large spans, the pitch is designed in low height; to prevent the excessive internal volume, to reduce the area of roof to be covered and the weight of the structure (Foster, 1983). Arches
Arch form is a suitable system for laminated sections, spans up to 40 m can be designed with arches. When the hinge is introduced to arch form, span distance increases, more than 70 m can be passed by hinged arches.

Steel arches can be used up to 70 m, longer spans can be achieved by trussed arches, that the truss form increase span distance due to secondary members, and three dimensional stability of the truss form. Frames
In a truss design the connections are accepted as hinged joint theoretically however is constructed as fixed joint because of practical reasons, which increases the stress about 15% on the truss. Introducing a hinge connection needs extra labor and detailing.

Over large spans, deep trusses may result in excessive volume within the roof space of the building, furthermore an increase in the span cause the need of extra material to provide strength where the own dead weight increase.
can be designed as?
1) 2) Rigid frames with fixed connections; Hinge frames with pin connections. Space Frames
Space frame is a form mainly suitable to steel. In timber construction due to the amount of connections, span sizes are less than steel

Although all structures apart from single layer flat grids are in fact space frames, the term space frame is usually used as a hollow section or three dimensional lattice beam (Foster, 1983).

A space frame is composed of nodes that the members intersect, and linear elements.

Toydemir, classified the space frames as: a) Flat; b) Arch; c) Dome.

Structurally space frames are divided into two basic types: four faced and diagonal triangular space frames. Folded roofs are suitable for timber, but not for steel; because folded form defines a plate and steel are used in sections but not in plates.

Folded plate is another form of stressed skin that the stiffness of the skin is used to distribute the loading to the supports.

As the span increases, the depth of the folded section rise, that it is not appropriate for long spans due to increase in the depth of the structure
Shells are 3 dimensional designs and every design has its unique form.

Design may include both concave and convax forms, every part should be specially calculated.

Concave and convax parts do not have the same span and depth according to different response of timber and steel to compression and tension. Enhanced Roof Structures Roof structure of the Hanover Expo CanopyHanover, Germany
FOLDED ROOF SHELLS Dome forms are appropriate for timber, but not for steel in long span; due to increasing height in steel, amount of connections and heat expansion of steel

Timber based dome forms may have a span more than 150 m, which is very suitable for long span roof structures.

Steel is not preferred in long span dome design, especially over 60 m span, due to increase in height, amount of dead weight and connections of linear pieces. DOME Long-span roof structural members/components
Structural members that span the distance between main elements, hold insulation, cladding, lighting and ventilation, moreover they constitute three dimensional stiffness. Basic structural elements that compose a roof structure are:

Rafter
Purlin
Strut
Diagonal
Collar
Siding
Tension beam
Cladding board
Connection Connection
CASE STUDIES ERICSSON REGIONAL HQ, CYBERJAYA
1.BACKGROUND OF THE PROJECT

2.DESIGN CONCEPT OF LONG SPAN ROOF

3.ROOF FEATURES AND COMPONENTS

4.METHOD OF INSTALLATION 1.BACKGROUND OF THE PROJECT Ericsson Regional HQ is an office building hosts a regional expertise and competence development hub to support the company's operations in Asia Pacific, including Network Design & Implementation, Systems Integration, Training & Education, and Hardware Repair & Services.
The Grand Opening was officiated by former Prime Minister of Malaysia, Tun Seri Dr Mahadhir Mohamad in 2002. The new Ericsson office should contribute to building an environment that enhances the productivity of the people they house
BUILDING NAME : CORPORATE HEADQUARTERS AND REGIONAL TRAINING CENTRE - ERICSSON REGIONAL HQ

LOCATION: CYBERJAYA, SELANGOR

FUNCTION : HEAD OFFICE AND TRAINING CENTRE

CLIENT : ERICSSON MALAYSIA

LAND OWNER : CYBERVIEW SDN BHD

DEVELOPER : SETIA HARUMAN SDN BHD

ARCHITECT : HIJJAS KASTURI ASSOCIATES SDN BHD

PROJECT
MANAGER : PENGURUSAN LEBUHRAYA BHD

COST OF THE
PROJECT : RM 110 M

CONSTRUCTION
SYSTEM : POST AND BEAM CONSTRUCTION (ROOF)
ARCH TRUSS SYSTEM

GROSS FLOOR
AREA: 9000 m2
PROJECT DETAILS AND LOCATION ARCHITECTURE DRAWING 2.0 Design Concept
The style relate to the technical and professional nature of Ericsson’s interest, tempered by a humanistic scale and environmental landscape design that expresses its tropical location. The main architectural statement expressed by the roof’s rhythm of waves, arcing over the buildings and dipping towards the landscapes spaces between the fingers of office module accommodation. An environment can be global, regional, local or immediate. The covering is environment friendly which not contribute to the greenhouse effect.
3.0 Roof Components and Features
The main roof is using developable shell which cylindrical shape and it is single curvature shell. The plane truss used for the truss system which is arched truss. It has both curved (top and bottom). It is to achieve lightweight.
3.1 ROOF FEATURES 3.2 ROOF COMPONENTS
3.3 ROOF JOINTING

The connections between the members of a truss were traditionally bolted but welded connections are preferred for this structure. Nevertheless it necessary to use splices in the chord members if the complete trusses especially the roof span are too long.

these splices provide for bolting individual lengths of trusses on site and should be located and detailed carefully if they are architecturally important. The existing of L-plate is to make a jointing between roof trusses and wall and to strengthen the connection. 4.0 Method of Installation
There are two techniques of roof truss erection which are Pre-Fabricated and Semi Pre-Fabricated. For the speedily purpose, client hope the truss erection can be done quicker. Top chord, bottom chord, web and node had been weld off-site which is done in the factory as a pre-fabricated. Bracing and purlin will be done on-site. Unfortunately, there are some truss that need to make jointing on-site because the chord is too long. Truss erection have done as follows :-


Steel post will erected at its position. It is not dismantle for all ends of roof trusses. Some of end truss will connect with steel post.
STEP 01 –Erection of steel post A few labour prepare to receive
truss that hoist upward STEP 02 –Truss lifting

The truss installer should always follow any special instructions by the manufacturer. Trusses should never be modified or cut without first seeking engineering advice. If the truss was damaged during shipment, the installer should contact the truss engineer for a workable repair scheme.
STEP 03 – Connection between steel post and roof trusses T-Bracing - a common web strengthening technique - is best applied on the job site. Failure to install the bracing can drastically alter the strength of the truss system STEP 04 –Install bracing
Coverings will rest on the purlin. Besides that, purlin is to stable the trusses.
STEP 05 – Connection of purlin
STEP 06 –Lay up the coverings
Before covering is to be laid, other components such as aluminium foils, insulation material and so on will be laid first.
TTDI PLAZA, TAMAN TUN DR. ISMAIL
LOCAL Malaysia 1.BACKGROUND OF THE PROJECT

2.DESIGN CONCEPT OF LONG SPAN ROOF

3.ROOF FEATURES AND COMPONENTS

4.METHOD OF INSTALLATION 1.0 BACKGROUND OF THE PROJECT
Located at Taman Tun Dr. Ismail
- It is a mix construction comprises of low rise shop office, 29-storey condominium, 3 storey basement car park and multi use plaza.
PROJECT DETAILS & MAPS Building : The plaza, Phase 6D3

Function : Multi –use Plaza

Client : TTDI Harta Sdn Bhd

C&S Engineer : Zaidun Leeng Sdn Bhd

M&E Engineer : KTA Tenaga

Main contractor : Bina Goodyear

Completion period : 26months

Construction cost : 96.4 million
2.0 DESIGN CONCEPT
Design concept of this construction is based on the principle of ecological design.

Main design for roof is flying roof which is supported by the mild steel column.

The roof shields the building from sun, reducing the glare and air-conditioning load whilst

Roof canopy is naturally ventilated and assisted by mixed-mode extraction fans.

The exhaust fan will help to remove excessive heat
Component and connection of trusses
Bottom chord (100x50x3mm) Purlin
Connection with bolt and nut and welding
Web members (bracing)
(50x50x3mm) Top chord
(100x50x3mm) 3.0 ROOF FEATURES & COMPONENTS
Pictures of steel roof structure and connection 4.0 Method of Installation STEP 01 Firstly, curvilinear steel pipe column with 12.50m high are erect.

It is connect with concrete stump with 1.00m high. This column will support
STEP 02 Then, circular hollow steel post is been assemble to support flat truss that next to be lift.
Purlin is been install along the steel post to hold steel trusses.
STEP 03 Flat truss is assemble at the top of steel post.

Before assembles, it is been erect at the ground and connect with bolt and nut
STEP 04 The triangle in shape of trusses is then lift .

It is supported by the curvilinear steel pipe column
STEP 05 The next step is installation of purlins of the top flat truss and at top of triangle in shape of trusses to support the glass frame.
STEP 06 Glass frame (tinted laminated E-float glass) is been fix and the jack roof structure is used to naturally ventilated the area and it is assisted by mixed mode extraction fans
STEP 07 & 08 RELIANT STADIUM, HOUSTON TEXAS, USA
ABROAD 1.BACKGROUND OF THE PROJECT

2.DESIGN CONCEPT OF LONG SPAN ROOF

3.ROOF FEATURES AND COMPONENTS

4.METHOD OF INSTALLATION 1.0 BACKGROUND OF THE PROJECT
PROJECT DETAILS 1. Completed : 2010
2. Location :Houston, Harris Country, Texas, USA
3. Structural Type :Truss Roof, Retractable
4. Owner :Harris Country, Texas
5. Architect :HOK sports+Veneu+Events Group, and HSC (Houston Stadium Consultants)- Hermes Reed 6. Architects and Lockwood, Andrews, Newman
6. Construction Manager : Manhattan Beers, a joint venture of Manhattan Construction Co. and Beers Skanska.
7.Structural Engineer : Walter P.Moore and Associates
8.Co-contractor : Beers Manhattan Construction Co.
9.Steel Construction : Derr Steel Erection Co.
10.Roof Machanization : Uni – Systems, LLC
Supplier
Cost of Construction : US$ 417 000 000 2.0 DESIGN CONCEPT
Design Concepts for roof structure this building is square and this roof is retractable roof.
The retractable roof structure solves a challenging tenant program by offering the flexibility to play football games in either an open-air environment or in air-conditioned comfort.
Electric motors connected to roof carriers housing standard steel wheels drive the operable roof on a single 175-lb crane rail to open and close in as quickly as 10 minutes.
3.0 ROOF FEATURES/COMPONENTS
The main components in reliant stadium roof structure consists 3 main structures :

Supertruss:
Trichod Struss
Box Truss Supertruss is to support and track structure for the two retractable roof panels. The supertruss is located both side of stadium.
Trichord Trusses is to support the roof surface.
Box struss is to support the massive stadium scoreboard.
4.0 Method of installation STEP 01 Roof Steel structure made from factory
STEP 02 Delivery to construction site
STEP 03 Erection by using tower crane/ mobile crane
CONCLUSION THANK YOU... COMPARISON BETWEEN LOCAL AND ABROAD LOCAL ABROAD PREPARED BY:
MOHD SHAHIZAD BIN SAMAD (2009791507)
KHAIRUNNISA BINTI OTHMAN (2009992665)
PHIL MARVIN AK NISEH (2009730691)
RUSYDIA AIFAA BINTI SAINI (2009490308)
SHAHIDATUL IZZATI BINTI MOHD ALI KHAN (2009163841)
SITI HAJAR BINTI ROHHIZAT (2009705495)
SYARIFAH EDA ADLINA BINTI SYED MOHD MAHZAN (2009550209)
ZAFIKHA AIDA BT BIDIN (2009147765)
The basic long span roof component, it is mostly similar to short span roof component but with an extra care because of the wider and larger load to be supported.

Long span roof is needed to covering a very large area.

Few factors need to be consider to make sure that the roof construction suit it purposes as a long span roof such as material, design and features, element of the roof, Method of construction, connection and jointing and load to be carry.

Material chosen, mostly steel is preferable to be use compare to timber because of it flexibility for construction of long span roof.

Few design and features for a long span roof depending to the uses and type of the building.

Roof members are pre-made or prefabricated in the factory before being erected at site.

Erection on site needed skilled labour and lifting up plant and machinery.

Members of trusses can be joined by riveting, bolting or welding.

Design of the roof structure must be able to carry loads that are imposed to it to prevent failure to its function.

Every project must demonstrate that the roof system is cost effective, aesthetically pleasing, readily construct able and able to meet all of the structural requirements of long span roof structures.
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