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THE SINGAPORE ENGINEER Jun 2010 1

Published ByTh e Institution of Engineers, Singapore

Director, MarketingRoland Ang

Marketing & Publications ExecutiveJeremy Chia

Chief EditorT Bhaskaran

Editorial BoardEr. Dr Adhityan AppanMr Lee Siew WeiEr. Siow Keng ChengMr Wong Chung Wan

Manager, External RelationsValerie Neo

Cover designed by Jeremy Chia

Cover image by HDB

Th e Singapore Engineer, Th e Magazine of the Institution of

Engineers, Singapore (IES) is published on a monthly basis,

by the Institution of Engineers, Singapore.

Th e title Th e Singapore Engineer is the property of the

Institution of Engineers, Singapore (IES).

Th e Institution of Engineers, Singapore. Th e copyright

of the contents of Th e Singapore Engineer is held by the

Publisher. All rights reserved. Reproduction of information

contained within the magazine, in its entirety, or in part, in

any format, requires written permission from the Publisher.

Contents

Th e contents within the magazine, unless explicitly stated otherwise, do not re ect the opinions of the Institution of Engineers,

Singapore (IES), and therefore have not received any endorsement from IES. Th e Editor reserves the right to amend, add to,

condense, or rewrite, any editorial release or submission.

Although all e orts will be made to ensure that information is accurate at the time of going to print, the Publisher and Editor,

as well as the Institution of Engineers, Singapore (IES), will not accept any liability for errors within the magazine.

Th e publication is distributed free-of-charge. For enquiries on Editorial and Advertising, please contact the Institution of

Engineers, Singapore, 70 Bukit Tinggi Road, Singapore 289758. Tel: (65) 6469 5000 Fax: (65) 64671108.

Printed in Singapore by SUN RISE Printing & Supplies Pte Ltd.

Section 1: Engineering (General)

2 IES Update

Section 2: Engineering (Civil & Structural Infrastructural Environmental Focus)

10 Cover Story: Th e Pinnacle@Duxton

22 Structural Engineering: Burj Khalifa Tower

30 Interview: Engineering urban transformation

32 Products & Services

38 Section 3: News & Events

2 THE SINGAPORE ENGINEER Jun 2010

IES Update

Message from the President

IES COUNCIL MEMBERS 2010/2011

PresidentEr. Ho Siong Hin

Vice PresidentsEr. Chong Kee SenEr. Prof Chou Siaw KiangEr. Edwin KhewEr. Lum Chong ChuenEr. Ong See HoProf Yeoh Lean Weng

Honorary SecretaryEr. Ng Say Cheong

Honorary TreasurerAssoc Prof Daniel Lim

Assistant Honorary SecretaryEr. Jee Yi Yng

Assistant Honorary TreasurerMr Je rey Chua

Immediate Past PresidentEr. Lee Bee Wah

Past PresidentsEr. Tan Seng ChuanEr. A/Prof Foo Say WeiEr. Ong Ser Huan

Council MembersDr Boh Jaw WoeiProf Er Meng JooEr. Koh Beng Th ongMr Lim ShiyiEr. Low Wong FookMr Neo Kok BengEr. Ong Geok SooEr. Prof Ong Say LeongEr. Pak Yew Hock, LawrenceProf Seeram RamakrishnaMr Tan Kai HongEr. Toh Siaw Hui, JosephMr Alfred Wong

Er. Ho Siong HinPresidentTh e Institution of Engineers, Singapore (IES)

Dear Friends

As the new President of IES, I welcome the opportunity to communicate with the readers of Th e Singapore Engineer on a regular basis.

In the last few weeks, we have seen how the blow-out of the oil well on the seabed in the Gulf of Mexico has played out for BP. Th e incident caused an explosion on the o shore oil drilling platform, killing 11 workers and injuring 17 others. It also resulted in a massive oil spill that continues to threaten the east coast of the US, on an unprecedented scale. E orts to cap the oil are ongoing but a lot of damage has already been done.

Th is man-made disaster is an example of the consequences to human life, assets, and the environment (in this instance directly a ecting the livelihoods of people), when production operations go wrong. A myriad of questions strike our minds: Why did the explosion happen? Were all the safety measures including those relating to materials, equipment, instrumentation, personnel and procedures etc, in place, that could have prevented it? Were scenarios for di erent kinds of abnormal situations visualised, and response measures developed, prioritised, and simulated?

What we can say is that, as far as possible, such a situation should never be allowed to happen. Th e subject of safety should be given top priority, so that human beings, property, and the environment, are protected at all times.

Engineers have a major role to play in the achievement of this objective. Backed by their technical knowledge and experience, they can take the lead in the development and implementation of safety measures and post-accident response programmes.

Th is is why we place paramount importance on workplace safety in IES. Th e IES Academy has been organising training courses with an emphasis on safety to inculcate the safety rst mindset in our engineers. Lessons to be learnt from accidents in our recent memory, such as the Nicoll Highway collapse and the Marina Bay Sands fatality, are imparted to our engineers through relevant seminars and courses. Th rough education we hope that the safety mindset will be prevalent among our engineers.

E H Si Hi


IES Update

From left to right: Dr Low Eicher, Acting Executive Director, IES; Er. Dr Chew Soon Hoe; Er. Ong Ser Huan; Dr Lueny Morell; Dr John Lamancusa; Er. Ng Say Cheong; and A/Prof Daniel Lim.

Courtesy visit by IFEESOn 17 May 2010, Dr Lueny Morell, President, International Federation of Engineering Education Societies (IFEES), paid a courtesy visit to IES. Accompanying her was Dr John Lamancusa, Professor, Department of Mechanical and Nuclear Engineering, Th e Pennsylvania State University, USA.

Th e IFEES representatives were received by Er. Ng Say Cheong, IES Honorary Secretary; Er. Ong Ser Huan, IES Past President; A/Prof Daniel Lim, IES Honorary Treasurer; and Er. Dr Chew Soon Hoe, Past Chairman of the National Committee of Engineering Organisations (NCEO).

Th e parties exchanged updates on their respective institutions and how IES can play a role in the upcoming World

Engineering Education Forum (WEEF) in October 2010. Th e meeting ended with

a presentation of tokens and a dinner hosted by IES.

EAB workshop on Developing Sustainable

Program Assessment ProcessesTh e workshop on Developing Sustainable Program Assessment Processes by Dr Gloria Rogers, Managing Director, Professional Services, ABET Inc, was organised by the Engineering Accreditation Board (EAB) of IES from 10 May to 12 May 2010 at Furama Riverfront Hotel.

Th e intention of the workshop was to prepare all local universities for the outcome-based accreditation which will be in place in Year 2012.

Th e three-day workshop saw a total of 60 participants hailing from Nanyang Technological University (NTU), National University of Singapore (NUS), and SIM University (UniSIM). All participants were actively involved in the programme lined up by Dr Rogers.

At the end of the workshop, a majority of the participants (85%) gave the feedback that rubrics writing and designing good surveys are the most useful and meaningful lessons they have learnt.

Many also commented that they enjoyed the activities i.e the table discussion and silent brainstorming, and the toys provided by Dr Rogers.

EAB workshop participants.

Prof Fung Tat Ching (NTU) explaining the written performance indicators to fellow group members.

Dr Rogers examines the performance indicators written by A/Prof Chen Zhongs (NTU) group.


IES Update

H.K.U. Engineering Alumni Associations

(HKUEAA) Sustainable Development Study

Tour to Singapore

Er. Ho Siong Hin (on right) receiving a token of appreciation from Dr Francis Lung, Immediate Past President of HKUEAA.

On 2 June 2010, 17 delegates from the H.K.U. Engineering Alumni Association (HKUEAA) paid a courtesy visit to IES. Th e HKUEAA delegates were in Singapore for a three-day study tour with the theme Sustainable City. HKUEAA, founded to promote friendship amongst Engineering graduates from the University of Hong Kong (HKU) and to initiate and assist the professional furtherance within and outside the campus, has been aggressively promoting sustainable development (SD) by having experiential projects for HKU engineering alumni and students to appreciate the examples of SD outside Hong Kong. Th e delegation has identi ed Singapore as a good example demonstrating the sustainable city development concepts.

Th e HKUEAA delegation was received by Er. Ho Siong Hin, IES President; Er. Lawrence Pak, Chairman, Civil and Structural Technical Committee; Ms Titis Primita, Vice Chairman, Young Members Committee; Er. Dr Lim Ewe Chye, Chairman, IES Clean Energy Interest Group; and Dr Low Eicher, Acting Executive Director.

Besides visiting IES, the delegation also visited the Urban Redevelopment Authority (URA) Gallery; ARUP Singapores o ce; Building and Construction Authoritys (BCA) Zero Energy Building; Solar Technology Centre

at Ngee Ann Polytechnic; Gardens by the Bay Visitor Centre; NEWater Visitor Centre; Changi Water Reclamation Plant, and the Marina Barrage.

Th roughout the three-day study tour, the HKUEAA delegation were committed to the sharing of information and thoughts on the subjects / venues they visited. Th ey were vocal and did not hesitate to make comments or seek additional information from the guides in the various places they visited. Th ere was strong bonding between the students and alumni, where

mentoring was not limited to sharing of technical information but to general life aspects as well.

Dr Lung commented that the trip was indeed inspirational to the students and praised the foresight of Singapore and its Governments commitment on sustainable development. During the meeting, both sides exchanged information on the latest developments in their respective institutions and countries. Th e meeting ended with an exchange of tokens and a networking dinner.

Visit to Solar Technology Centre @ Ngee Ann Polytechnic. Students admiring the barrage simulation at the Marina Barrage Gallery.

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The challengeEstablished in 1995, Singapore based CS Consulting Engineers Pte Ltd provides structural engineering, industrial architecture and project management services.

Providing innovative, design-led schemes was top of CS Consulting Engineers Pte Ltds list when it came to offering their clients best value. To do this they needed to invest

in reliable, fast and flexible steel building design software to help them engineer schemes quickly, while at the same time conform to complex design standards.

A busy design office meant it was vital that changing design software created minimal disruption. The new software had to be easy to adopt and backed up by a competent technical team. With this in mind, CS Consulting Engineers Pte Ltd turned to CSC.

The solutionAfter reviewing the market, CS Consulting Engineers Pte Ltd opted for CSCs Fastrak Building Designer, aware that this was the steel equivalent of Orion, CSCs market leading concrete building design software used by 1000s of engineers worldwide.

Nigel Watts, Asia Pacific Regional Director for CSC, says, Choosing a software solution can be challenging. We eased the transition by providing a one-stop solution, offering the software, the training and the technical support.

CSC was confident that Fastrak Building Designer was the right solution as it would enable CS Consulting Engineers Pte Ltd to design factories, commercial buildings, industrial facilities and even complex steel roofs with ease. Plus it would help them to quickly manage those inevitable variations that occur on every project.

Fastrak has saved us time and money and allows us to Value Engineer each scheme to find the best option for our clients.Er Soo Chee Sern, Managing Director - CS Consulting Engineers Pte Ltd

All our structural engineers use Fastrak Building Designer; its integral to our business, says Er Soo Chee Sern, Managing Director of CS Consulting Engineers Pte Ltd. It has saved us money, increased our productivity and improved the service we can provide to our clients. I am convinced that this has generated us more business.

CSC was confident that Fastrak Building Designer was the right solution as it would enable CS Consulting Engineers Pte Ltd to design factories, commercial buildings, industrial facilities and even complex steel roofs with ease.

Fastrak Building Designer integrates with leading BIM and steel detailing software such as Revit Structure and Tekla Structures

Er Soo comments, It was essential that Fastrak could automatically design buildings quickly and in one go; we were delighted with the level of automation provided.

Fastrak Building Designer also integrates with leading BIM and steel detailing software such as Revit Structure and Tekla Structures, comments Watts. This gives ultimate flexibility as engineers and technicians can share and synchronise models during the complete design process.

Getting started with Fastrak Building Designer was easy. Er Soo explains,

We invested in training in-house so that all our engineers could benefit from the same level of understanding. CSCs training was real value for money.

Whats more, CSCs technical support team are all structural engineers, so they understand our business and the technical issues we face. Theyre proactive and are always able to offer us a practical solution to our query.

The resultFastrak has saved us time and money and allows us to Value Engineer each scheme to find the best option for our clients, concludes Er Soo. It is a market leading and well considered product that is going from strength to strength. I highly recommend Fastrak Building Designer to any forward thinking business that wants to offer their clients the best service.

Discover the benefits of Fastrak for yourselfCall 6258 3700 or visit www.cscworld.com/fastrak/asia

Fastrak Building Designer is the steel equivalent of Orion, CSCs market leading concrete building design software, used by 1000s of engineers worldwide.

Fact fileName: CS Consulting Engineers Pte Ltd

Area of operation: Structural Engineering , Industrial Architecture and Project Management

Location: Singapore

Founded: 1995

Number of employees: 15

CSC products:X Fastrak Building DesignerX TEDDSX OrionX S-Frame

Key benefits of Fastrak:X Increased productivityX Time and cost savingsX Improved customer service


Cover Story

The Pinnacle@Duxton

Fig 2: Overall view of the completed Th e Pinnacle@Duxton.

Over the last 50 years since its establishment in 1960, the Housing & Development Board (HDB) has chalked up an impressive array of achievements. Extending the track-record further is the rst 50-storey public housing project in Singapore, which is also, at 168 m, the tallest.

Introduction Th e Pinnacle@Duxton comprises 1848 residential units spread over seven blocks, and one multi-storey carpark. It is located on a site (Fig 1) on which, in 1963, Blocks 1 and 2 Cantonment Road, the rst two HDB blocks in the area, were built.

An international architectural competition was organised by Singapores Urban Redevelopment Authority to obtain the best design ideas for high-rise living in the city, that would also take into account the historical signi cance of the site. Th e competition was won by architect Mr Khoo Peng Beng from ARC Studio Architecture + Urbanism, a Singapore-based rm.

Important features of the project include sky bridges and sky gardens at the 26th and 50th storeys, linking all the seven blocks, as well as a variety of faade elements. Th e circuit board-like arrangement of bay windows, planters, and balconies, helps to di erentiate Th e Pinnacle@Duxton from other regular HDB projects (Fig 2).

Fig1: Site layout plan.

Project information

Number of blocks and storey

7 blocks, each 50 storeys high

Total number of units

1,848

Type of unit S1 1,232 units (93 m2 - 97 m2)

Type of unit S2 616 units (105 m2 - 108 m2)

Facilities

Basement Carpark below blocks 1A to 1E

1st Storey 1 food court, 4 shops, and 1 convenience store and carpark

2nd Storey Carpark at Blk 1A, 1B and 1D

3rd Storey (Environmental deck)

1 childcare centre, 1 education centre, playground, event plaza, basketball court, and pavilion

26th Storey (Active Zone)

jogging track, 840 m long

50th Storey (Contemplative Zone)

Viewing decks and themed garden


Cover Story


Cover Story

Fig 3: Typical work ow using SE CAD.

Design of super-structure and sub-structureAs Th e Pinnacle@Duxton was HDBs rst super high-rise development, rigorous design analyses were conducted to ensure structural stability. Th e structural system adopted is reinforced concrete construction coupled with a beam-column-slab rigid frame for the building. All column loads are transferred directly, oor to oor, down to the foundation. No transfer beams have been used. Th e design also responded to the need for robustness, with the provision of peripheral ties and internal ties, to ensure that the building is not vulnerable to progressive collapse.

HDB collaborated with the National University of Singapore in the study of lightning protection and for wind tunnel analysis, during the design stage of the project. Numerous wind tunnel simulations were also conducted in the laboratory to analyse the e ect of wind currents on the seven tall buildings and also their environmental impact on the neighbourhood. In addition, tra c impact modelling and analysis were also performed to ensure optimal travelling times along the two abutting major roads.

HDBs own in-house design and detailing software, SE CAD, was used to model and design the tower blocks. SE CAD has been developed for high-rise building analysis and design. Key performance parameters required for high-rise, reinforced concrete buildings, were computed automatically by the software.

Powered by a robust, nite element engine with a built-in precast components database, and incorporating a user-friendly interface, SE CAD provided solutions for tasks ranging from 3D structural analysis, computation, design, and detailing, to the production of drawings (Fig 3).

As the modelling and analysis process was fully integrated, feasibility studies were carried out on various possible structural con gurations, to identify the most suitable design proposal.

Once the shapes and layouts for the tall structures were established, their structural behaviour was simulated e ortlessly. Th e design and analysis results

(eg for bending moments and shear forces), structural drawings, and material quantities, were obtained instantly, once a buildings super-structure was modelled. Additional contributions from the SE CAD software included auto-generation of the loading plan, 3D model rendering, and production of shop drawings for precast components and prefabricated reinforcements.

For the sub-structure design, thorough investigations were conducted around the site, to ascertain the

properties of the soil. Th e Duxton site consists primarily of hard silty sandstone, and concrete bored piles have been used to support the foundation. A total of 1330 bored piles was designed with an average pile penetration length of 19 m. Each tower block was designed to sit on a 2.7 m thick raft foundation supported by 140 equally spaced bored piles of 1.5 m diameter. Th e raft foundation system provides structural stability and rigidity for the high-rise tower block and prevents di erential settlement.


Cover Story

Fig 4: Typical oor layout showing the construction joint which divides the oor into two segments.

Precast technologyFor Th e Pinnacle@Duxton, conscientious e orts were made by the architects and engineers to make the project buildable, through the adoption of modularisation and standardisation concepts. Th e various options for the standard layouts (S1 and S2) of the units in the residential blocks, were obtained by con guring units as mirror images of one another and by rotation of these unit plans. Th e modularisation of the units was replicated to obtain the block design. Th e oor plans for a typical storey were also repeated for better e ciency in precast construction. Th e adoption of modularisation and standardisation also enabled prefabrication to be cost-e ective due to the high repetition of the precast components and prefabricated reinforcement.

As a result, it was possible to incorporate a high proportion (about 85% of the total volume of concrete) of precast technology in the construction of the tower blocks. Precast components were utilised for various elements including prestressed plank, column, lift wall, household shelter wall, gable end wall, faade wall with bay window, faade wall with planters, faade wall with balcony, screen wall, refuse chute, staircase, and parapet.

Th e use of large volumes of precast concrete in the project increased productivity by about 15%. In addition, it facilitated construction works in a tight, built-up, working environment, and reduced environmental impact on the existing area. In addition, precast concrete elements are of better quality as they are produced in a factory-controlled environment.

To expedite construction works, a typical oor was divided into two segments (part A and part B) by a construction joint (Fig 4). Th e construction work was staggered, that is, a team of workers from a construction trade would work on part A and then move on to part B without having to stop for workers from the other trades to complete their tasks. With this, it was possible to achieve the anticipated 6-day construction cycle for each segment of a typical oor.

Th e project team adopted the use of large precast facade panels, measuring

Fig 5: Large precast faade panels.

Fig 6: Precast, volumetric hollow-cored wall.

about 7 m in length (Fig 5) compared to the usual length of 3 m to 4 m. Th is enhanced tower crane utilisation and improved site productivity. Th e faades of planter boxes, sun-shaded louvred windows, and balconies, are arranged in di erent combinations, creating a series of vertical, zigzag lines that resemble

owing water. In addition, the window frames were xed to the facades before delivery to site. Th is will eliminate water seepage through the windows. Th e wall panels were designed to be hollow-cored (Fig 6) so as to reduce the weight of the components and minimise risk during hoisting and erection.


Cover Story

Design and installation of sky bridgesTh e 12 sky bridges, connecting the seven blocks, at the 26th and 50th storeys, form part of outdoor sky gardens which are equipped with amenities for recreational purposes. Th e bridges are made of steel with concrete slabs on top. Th e lengths of the bridges vary, with the longest spanning 48 m and weighing 327 t. Th e widths and heights of the bridges are 20 m and 3.9 m, respectively.

Th e design of the sky bridges was carried out by T.Y.Lin International Pte Ltd, HDBs consultant. Th e design adopted a 3-dimensional triangular truss layout which is stable without lateral support and could be erected independently. Th e bridges are designed to withstand wind forces in all directions. Th e side faces are tapered to reduce the obstruction to wind ow, thus minimising the wind pressure on the face. One end of each bridge was designed to be xed to the building, to improve the natural frequency of the bridge and reduce vibrations from walking and jogging, thus enhancing comfort levels for people.

Owing to the tight site conditions, there were many challenges in the erection of the bridges, relating to the installation method and procedures, availability of space at site, and duration of the installation. Owing to the sizes, the bridges were fabricated in segments o -site, at a factory (Fig 7), transported to the site, and assembled onto the complete structure. To overcome the space constraints, the 50th and 26th storey bridges were stacked on top of each other (Fig 8). Th is also facilitated the subsequent lifting operation.

In the factory, as well as during the on-site assembly of the sky bridge members, the tting up, welding, testing, and trial assembly of the sky bridge trusses were supervised by an independent checker. Th e progress of the work was closely supervised by the Resident Engineers and Resident Technical O cers who were stationed on-site and at the fabrication yard.

After fabrication, the sky bridges were lifted to their respective heights using the strand jack system which was used instead of cranes, due to the height of the buildings. In addition, this system

Fig. 7: Welding, testing, and trial assembly, of sky bridge steel trusses at the factory.

Fig 8: Assembly of the sky bridge steel trusses on site. Th e 50th and 26th sky bridges are stacked on top of each other.

allowed the bridges to be assembled at a lower level before hoisting the whole assembly, thus enhancing safety on site. Four strand jacks were required for each lifting. Th e jacks were installed and positioned at four corners between the two buildings at the 50th storey roof top position (Fig 9). Prior to the lifting, a trial jacking was done, that raised the skybridge 300 mm o the ground, to ensure that the jacks were functioning properly.

Th e bridges are xed to the core

walls of the residential buildings. To x the bridges safely and securely to the core walls, base plates and sleeves for tension bars were cast together with the core walls. Great care was taken to ensure that the cast-in items aligned accurately with the tower blocks. When the bridges were lifted to their nal positions at the 50th and 26th storeys, and adjusted, the main trusses were connected to the building by high strength bars and locked in-place by casting the concrete slab which forms the oor of the bridge.


Cover Story

PROJECT CREDITS

ClientHousing & Development Board

Project ManagementSIPM Consultants

Design ArchitectARC Studio Architecture + Urbanism

Project ArchitectRSP Architects Planners & Engineers

C&S ConsultantSurbana International

Sky Bridge ConsultantT.Y.Lin International

M & E ConsultantSurbana International

Cost ManagementSurbana International

Main ContractorChip Eng Seng Contractors (1988) Pte Ltd.

All images by HDB. Fig 9: Lifting of sky bridges to the 50th storey using the strand jack system.

Th e sky bridge structural system

Main structure

Th ree-dimensional steel truss.

Diaphragm Concrete topping 125 mm thick.

Connecting member to member

Full penetration butt weld.

Connection to building core wall

Using Macalloy post-tensioned bars.

Main truss Consists of 1 top chord and 2 bottom chords. Th e top chord has a 125 mm thick concrete topping. Th e combination acts as a composite.

Th e concrete topping at the top deck level and mezzanine level ties with the building oor slab and, together with the tie beam between two core walls, acts as a diaphragm to resist the lateral and vertical loads.


Cover Story

Panoramic view of the skyline from the viewing deck.

Th e Pinnacle@Duxton is the tallest public housing development in Singapore.

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Making energy together

Refreshing the GeoFEAs Users Interface By S.H. Hong, GeoSoft Pte Ltd

In this article, we are offering a glimpse at the user interface in the next version of GeoFEA. We had consolidated some feedbacks from users and prioritised the wish-list for our prototype.

Introduction It had been two years since we started this column in 2008. A sneak into our new graphical users interface will conclude our series of articles in The Singapore Engineer. Much effort was put in to raise awareness of some key issues in geotechnical finite element modelling. It is also time for us to take a break and concentrate our effort on raising the bar in terms of users experience. We had made revamping the Graphical User Interface (GUI) our priority.

(a)

(b)

Figure 1: GeoFEAs user interface. (a) Prototype new look. (b) Old look.

We're considering revamping the GUI to a

Windows application that was written with Windows Presentation Foundation (WPF), Figure 1(a) instead of Windows Forms, Figure 1(b). WPF is a graphical subsystem for rendering user interfaces in Windows-based applications. The core of pre- and post- processor will have to be build from the ground up, allowing easier development. GUI things that were previously not possible are now a possibility.

Figure 2: Buttons for various stages of modelling.

The user will be guided by the visible buttons (Figure 2) on what options are made available at each stage of modelling.

Workspace and tool panels Frequently used tool panels are opened by default. The users will have the freedom to move these panels from their default positions to a location that the users are comfortable with (Figure 3). Alternative placeholders are highlighted as shown in Figure 3 as arrow in a box ( ).

Figure 3: Placeholders for docking panels.

Another obvious change is the axes orientation indicator which is now coloured differently for each axis and resides on the workspace itself.

GUI buttons The buttons are made larger with superfluous buttons removed for a clearer line of operation (Figure 4). For example, in a two-dimensional (2-D) project, buttons relating to 2-D work space are shown. The 3-D options are left out to give a cleaner look. This is a marked improvement from the previous GUI where the 3-D buttons are simply deactivated.

You talk, we listen and respond. This change arises from feedbacks by our current user that the current interface has too many buttons to start with. Without proper hints and guidance, the old interface workflow is perplexing for beginners.

(a)

(b)

Figure 4: Work space buttons. (a) 2D project. (b) 3D project.

View controls We had also included easy 3D view change and intuitive 3 Button Mouse support. The trackball was modified to give user a better control over the view angles. Mouse over the view controls will bring them into focus and dimmed when not in use. This allows a larger screen estate to be tenanted by other essential controls.

Maintaining an in-plane view rotation was quite a task in the old pre- and post-processors. The in-plane rotation is decoupled from the out-of-plane rotation by the implementation of a circumferential ring control (Figure 5). The out-of-plane rotation can be realised by holding down the left mouse button in the preferred direction within the inner circular control (Figure 6).

Figure 5: Modified trackball control.

Figure 6: Inner circular control for out-of-plane rotation.

View rotation using the centre mouse button is still available other than a minor tweak to the sensitivity level.

A new zoom control was added for users without a scroll wheel mouse control.

The panning operation, which was well tested by other computer aided design software, was left largely unchanged by dragging the mouse keeping its right button depressed.

Attributes of a model We had placed the attributes to a model as the default dock panel on screen to allow users access to various parameters defining geometry, analysis data and construction sequence as shown in (Figure 7). The properties for each parameter will be reflected in another dock panel below the model attributes docking panel in the default layout.

Figure 7: Dock panel for model attributes.

Stepping through the construction stages We have also made it easier to cycle through various construction stages by setting the stage view control as one of the default panels docked at the bottom right screen estate (Figure 8).

Figure 8: Construction stage controls

Dimensions indication feature One new feature that has successfully made its way into our prototype is the on-screen dimensioning function. The length and width of the rectangle is displayed on the screen to help user determine its size for the example shown in Figure 9.

Figure 9: Dimensions during basic shape creation.

The coordinates of the cursor is also shown if the user is more comfortable with the old versions way of input.

Figure 10: Dimensions during extrusion operation.

In Figure 10, the extrusion dimension from the basic shape is displayed so that the user can easily determine the third dimension in a 3-D view.

Reporting functions We hear you! In the pipeline, we are adding a report generation feature (Figures 11). The report wizard allows the user to quickly create a new text report. It includes features for filtering parameters to output, and also allows the user to easily create title box containing various information such as the date, time and page number (Figure 12). We aim to turn the tedious chore of drafting technical reports into something close to playing a video game.

Figure 11: Tree view of report generation user interface.

Figure 12: Sample layout of image with title block.

Going online Looking forward, GeoSoft is poised to take a giant leap forward with an exciting project - a dream of an internet-based engineering platform on which a collaborative culture can be developed (Figure 13). The power of the Internet in the Blue Ocean is there for all to tap. This platform will be designed to facilitate communication, collaboration and content sharing across networks of contacts.

The evolution of personal computer technologies will no doubt opens up exciting possibilities in the way engineers conduct finite element analyses. With the Internet no longer constrained by slow connections and computer processors and high costs for storage, it is time to rethink and revamp the way construction industry embraces these new technologies in terms of engineering services.

Figure 13: Login page prototype for online engineering portal.

Conclusion The graphical user interfaces revealed in this article is a prototype. This prototype will be used as part of the software design process to allow our engineers and designers the ability to explore design alternatives, test theories and confirm performance prior to our up-coming alpha test version release.

Software should routinely be designed to make it easy for people to do what works and difficult to do what doesnt. One important and powerful way that software products can do this is through well-designed defaults. Given the power of defaults, our designers could use them to nudge people in a direction that will enhance their work efficiency.

According to Porter 2001, the greatest impact of the Internet is to enable the reconfiguration of existing industries that had been constrained by high cost for communicating, gathering information and accomplishing transactions. By integrating the internet into our overall strategy, GeoFEA will realise its potential as a powerful engineering tool.

Reference Michael E. Porter. "Strategy and the Internet, Harvard Business Review, Vol. 79, No. 3, March 2001.

About GeoSoft Pte Ltd GeoSoft Pte Ltd is registered in Singapore. GeoSoft focuses singularly on geotechnical products with unparalleled developments. We are the leader in the FEM mesh generation and solver technologies implemented on desktop PC platform.


Structural Engineering

The design of Burj Khalifa Tower the worlds

tallest structure

Fig 1: Th e Burj Khalifa Tower.

Th e objective in creating this building, besides setting a record, is to embody the highest aspirations of mankind.

Such a project goal, by necessity, requires pushing current analysis, as well as materials and construction technologies, to literally new heights. However, as building to such a height had never been attempted before, it was also necessary to ensure that all technologies and methods utilised are of sound development and practice.

Mr William F Baker, Partner, Mr James J Pawlikowski, Associate Director, and Mr Bradley S Young, Associate, from Skidmore, Owings & Merrill LLP (SOM), Chicago, Ilinois, USA, explain how the designers sought to use conventional systems, materials, and construction methods, modi ed and utilised in new capacities, to achieve this lofty goal.

IntroductionTh e tower (Fig 1) opened to much fanfare on 4 January 2010 and was re-christened Burj Khalifa (it was previously known as Burj Dubai). Rising to a height of 828 m and with over 160 storeys, it is the worlds tallest building and the tallest man-made structure ever built.

Th e Burj Khalifa Tower is the centrepiece of a US$ 20 billion development located just outside of downtown Dubai. Th e project consists of the tower itself, as well as an adjacent podium structure, a separate 12-storey o ce annexe, a two-storey pool annexe, and four levels of sub-grade parking under the site. Th e 280,000 m2 reinforced concrete multi-use tower comprises predominantly residential and o ce units, and it also houses retail establishments and a Giorgio Armani Hotel. Together, the tower and podium structures have a combined area of 465,000 m2.

From the outset, the intention was to make Burj Khalifa the worlds tallest building (Fig 2 presents the worlds 10 tallest buildings). Th e o cial arbiter on heights is the Council on Tall Buildings and Urban Habitat (CTBUH). Th e CTBUH



Fig 2: Lineup of the worlds 10 tallest buildings.

Fig 3: Typical oor plan.

measures the heights of buildings using three criteria. Table 1 compares the values for Burj Khalifa with the corresponding values for the previous record holders.

Architectural designTh e primary design concept for the tower took the form of an indigenous desert ower. Th e organic form, with tri-axial geometry and spiralling growth, can be easily seen in the nal design.

Additionally, traditional Islamic forms were utilised to enrich the towers design, and to incorporate visual references to the culture and history of the surrounding region. Th e oor plan has a tri-axial, Y-shaped con guration, formed by three separate wings connected to a central core (Fig 3). As the tower rises, one wing at each tier sets back in a spiralling pattern, further emphasising its height (Fig 4). Th e Y-shaped plan is ideal for residential and hotel usage, in that it allows the maximum views outward, without overlooking a neighbouring unit. Th e wings contain the residential units and hotel guest rooms, with the central core housing all of the elevatoring and mechanical closets.

Additionally, the tower is serviced by ve separate mechanical zones, located approximately 30 oors apart, over the height of the building. Located above the occupied reinforced concrete portion of the building is the structural steel spire,

Height to Architectural Top 828 m (Burj Khalifa) 508 m (Taipei 101)Highest Occupied Floor 535 m (Burj Khalifa) 474 m (Shanghai

World Financial Center)Height to Tip 830 m (Burj Khalifa) 527 m (Sears Tower)

Table 1: Comparison of height values for Burj Khalifa and those for previous record holders.

housing communication and mechanical oors, completing the architectural form of the tower. Th e architects and engineers worked closely together from the beginning of the project to determine the shape of the tower, in order to provide an e cient building in terms of its structural system and in its response to wind, while still maintaining the integrity of the initial design concept.

Structural system descriptionIn addition to its aesthetic and functional advantages, the spiralling Y-shaped plan was also utilised to shape the building, to reduce the wind forces on the tower, as well as to keep the structure simple, and foster constructability. Th e structural system can be described as a buttressed core, and consists of high-performance concrete wall construction.

Each of the wings buttresses the others via a 6-sided central core or hexagonal hub. Th is central core provides the torsional resistance of the structure, similar to that

for a closed pipe or axle. Corridor walls extend from the central core to near the end of each wing, terminating in thickened hammer-head walls. Th ese corridor walls and hammer-head walls are similar to the webs and anges of a beam in the way they resist wind shears and moments. Perimeter columns and at plate oor construction complete the system. At mechanical



Fig 4: Tower perspective.

oors, outrigger walls are provided to link the perimeter columns to the interior wall system, allowing the perimeter columns to participate in the lateral load resistance of the structure. Hence, all of the vertical concrete is utilised to support both gravity and lateral loads. Th e result is a tower that is extremely sti laterally and torsionally. It is also a very e cient structure in that the gravity load resisting system has been utilised so as to maximise its use in resisting lateral loads.

As the building spirals in height, the wings set back to provide many di erent oor plates. Th e setbacks are organised with the towers grid, such that the building stepping is accomplished by aligning columns above with walls below, to provide a smooth load path. As such, the tower does not contain any structural transfers. Th ese setbacks also have the advantage of providing a di erent width to the tower for each di ering oor plate. Th is stepping and shaping of the tower has the e ect of confusing the wind - wind vortices never get organised over the height of the building because at each new tier, the wind encounters a di erent building shape.

Structural analysis and superstructure designTh e reinforced concrete structure was designed in accordance with the requirements of ACI 318-02 Building Code Requirements for Structural Concrete. Wall and column concrete strengths range from C80 to C60 cube strength, and utilise Portland cement, y ash, and local aggregates. Th e C80 concrete has a maximum speci ed Youngs Elastic Modulus of 43,800 N/mm2 at 90 days. Wall and column sizes were optimised using virtual work / LaGrange multiplier methods, resulting in a very e cient structure. Wall thickness and column sizes were also ne-tuned to reduce the e ects of creep and shrinkage on the structure. To reduce the e ects of di erential column shortening due to creep between the perimeter columns and interior walls, the perimeter columns were sized such that the self-weight gravity stress on the perimeter columns was equal to the stress on the interior corridor walls. Th e outriggers at the ve mechanical oors tie all the vertical load carrying elements



together, further ensuring uniform gravity stress by essentially allowing the structure to redistribute gravity loads at ve locations along the buildings height, thereby reducing di erential creep movements. Additionally, the perimeter columns and corridor walls were given matching thicknesses, providing them with similar volume to surface ratios, to minimise di erential shortening due to concrete shrinkage.

Th e majority of the tower is a reinforced concrete structure. However, the top of the tower consists of a structural steel spire utilising a diagonally braced lateral system. Th e spire, which houses several mechanical and communication oors, and open void space, culminates in a pinnacle element. Th e structural steel spire was designed for gravity, wind, seismic loads, and fatigue, in accordance with the requirements of AISC Load and Resistance Factor Design Speci cation for Structural Steel Buildings (1999).

Th e entire building structure was analysed for gravity (this included the performance of P-Delta analysis), wind, and seismic loadings, utilising ETABS version 8.4 (Fig 5). Th e three-dimensional analysis model consisted of the reinforced concrete walls, link beams, slabs, raft, piles, and the spires structural steel system. Th e full analysis model consisted of over 73,500 shells and 75,000 nodes. Under lateral wind loading, the building de ections were well below commonly used criteria. Th e dynamic analysis indicated that the rst mode is lateral side-sway with a period of 11.3 seconds. Th e second mode is a perpendicular lateral side-sway with a period of 10.2 seconds. Torsion is the fth mode with a period of 4.3 seconds.

Th e Dubai Municipality speci es Dubai as a UBC97 Zone 2a seismic region (with a seismic zone factor Z = 0.15 and soil pro le Sc). Th e seismic analysis consisted of a site-speci c response spectra analysis. Seismic loading typically did not govern the design of the reinforced concrete tower structure. However, seismic loading did govern the design of the reinforced concrete podium buildings and the towers structural steel spire. Site-speci c seismic reports were developed for the project, including a seismic hazard analysis. Th e potential for liquefaction

Fig 5: Th ree-dimensional analysis model dynamic mode shapes.

Fig 6: Construction sequence analysis.

was investigated, based on several accepted methods. It was determined that liquefaction is not considered to have any structural implications for the deep-seated tower foundations.

A comprehensive construction sequence analysis incorporating the e ects of creep and shrinkage was performed to study the time-dependent behaviour of the structure (Fig 6).

Since the vertical concrete elements tend to have similar compression stress, the building performs well under the e ects of creep and shrinkage. Th e results of this analysis were utilised to determine the horizontal and vertical compensation programmes. For horizontal compensation, the building is re-centred with each successive centre core jump, correcting for gravity-induced side-sway e ects which occur up to the casting of each storey. For vertical compensation, additional

height was added by increasing oor-to- oor height, o setting the predicted vertical shortening of the column and wall elements.

Wind engineering approachAn extensive programme of wind tunnel tests and other studies was undertaken in RWDIs 2.4 m x 1.9 m, and 4.9 m x 2.4 m boundary layer wind tunnels in Guelph, Ontario, Canada. Th e wind tunnel testing programme included rigid-model force balance tests, a full aeroelastic model study, cladding pressure studies, and pedestrian wind environment studies (Figs 7 and 8). Th ese studies used models mostly at 1:500 scale. However, the pedestrian wind studies utilised a larger scale of 1:250 for the development of aerodynamic solutions aimed at reducing wind speeds. Wind statistics played an important role in relating the predicted



levels of response to return period. Extensive use was made of ground-based wind data, balloon data, and computer simulations employing regional atmospheric modelling techniques, in order to establish the wind regime at the upper levels.

To determine the wind loading on the main structure, wind tunnel tests were undertaken early in the design, using the high-frequency-force-balance technique. Th e wind tunnel data were then combined with the dynamic properties of the tower, in order to compute the towers dynamic response and the overall e ective wind force distributions at full scale. For Burj Khalifa, the results of the force balance tests were used as early input for the structural design and allowed parametric studies to be undertaken on the e ects of varying the towers sti ness and mass distribution.

Th e building has essentially six important wind directions (Fig 9). Th ree of the directions are de ned by the wind blowing directly into a wing. Th e wind blows into the nose of each wing (Nose A, Nose B, and Nose C), creating the cut-water e ect. Th e other three directions are de ned by the wind blowing in between two wings, in the tail directions (Tail A, Tail B, and Tail C). It was noticed that the force spectra for di erent wind directions showed less excitation in the important

Fig 10: Tower wind behaviour.

Fig 7: Aeroelastic wind tunnel model.

Fig 8: Cladding wind tunnel model.

Fig 9: Plan view of tower.

frequency range for winds impacting the pointed or nose end of a wing than from the opposite direction (tail). Th is was kept in mind when selecting the orientation of the tower relative to the most frequent, strong wind directions for Dubai northwest, south, and east.

Several rounds of force balance tests were undertaken as the geometry of the tower evolved, and as the tower was re ned architecturally. Th e three wings are set back in a clockwise sequence with the A wing setting back rst. After each

round of wind tunnel testing, the data was analysed and the building was reshaped to minimise wind e ects and accommodate unrelated changes in the clients programme. In general, the number and spacing of the setbacks changed as did the shape of wings. Th is process resulted in a substantial reduction in wind forces on the tower by confusing the wind, by encouraging disorganised vortex shedding over the height of the tower (Fig 10).

Towards the end of design, more accurate aeroelastic model tests were



initiated. An aeroelastic model is exible in the same manner as the real building, with properly scaled sti ness, mass, and damping. Th e aeroelastic tests were able to model several of the higher translational modes of vibration. Th ese higher modes dominated the structural response and design of the tower except at the very base where the fundamental modes controlled. Based on these results, the predicted building motions are within the ISO standard recommended values there is no need for auxiliary damping.

Tower foundationsTh e tower is founded on a pile-supported raft foundation (Fig 11). Th e solid reinforced concrete raft is 3.7 m thick and was poured utilising 12,500 m3 of C50 (cube strength) self-consolidating concrete (SCC). Th e raft was constructed in four separate pours (for the three wings and the centre core). Each raft pour occurred over at least a 24-hour period. Reinforcement

Fig 11: Tower raft under construction.

Fig 12: Tower pile load test. Fig 13: Cathodic protection below raft.

was typically spaced at 300 mm in the raft, and arranged such that every 10th bar in each direction was omitted, resulting in a series of pour enhancement strips throughout the raft. Th e intersections of these strips created 600 mm x 600 mm openings at regular intervals, facilitating access and concrete placement.

Owing to the thickness of the tower raft, limiting the peak and di erential temperatures due to the heat of hydration was an important consideration in determining the raft concrete mix design and placement methods. Th e 50 MPa raft mix incorporated 40% y ash and a water-cement ratio of 0.34. Th e concrete mix was poured into large-scale test cubes with 3.7 m side dimensions, prior to the raft construction, so as to verify the concrete placement procedures and monitor the concrete temperature performance.

Th e tower raft is supported by 194 bored, cast-in-place piles. Th e piles are 1.5 m in diameter and approximately 43

m long, with a capacity of 3,000 t each (the pile load is tested to 6000 tonnes). Th e diameter and length of the piles represent the largest and longest piles conventionally available in the region. Additionally, the 6000 tonne pile load test represented the largest magnitude pile load test performed to date within the region (Fig 12). Th e C60 (cube strength) SCC concrete was placed by the tremie method utilising polymer slurry. When the rebar cage was placed in the piles, special attention was paid to orient the rebar cage such that the raft bottom rebar could be threaded through the numerous pile rebar cages without interruption, which greatly simpli ed the raft construction.

Another design challenge in the project arose from the existing site conditions. Th e ground water, which is quite high at approximately 2 m below the surface, is extremely corrosive, containing approximately three times the sulphates and chlorides present in sea water. As such, a rigorous programme of anti-corrosion measures was followed to ensure the long-term integrity of the towers foundation system. Measures instituted included the implementation of specialised waterproo ng systems and increased concrete cover for the reinforcement, addition of corrosion inhibitors to the concrete mix, applying stringent crack control raft design criteria, and the implementation of an impressed current cathodic protection system utilising titanium mesh (Fig13). Additionally, a controlled permeability formwork liner was utilised for the tower raft, which resulted in a higher strength / lower permeability concrete cover for the rebar. Th e concrete mix for the piles was also enhanced. It was designed as a fully self-consolidating concrete to limit the possibility of defects during construction.



Fig 14: Tower construction sequence.

Tower construction methodsTh e Burj Khalifa Tower utilised the latest advancements in construction techniques and materials technology. Th e walls were formed using Dokas SKE 100 automatic self-climbing formwork system.

Th e circular nose columns were formed with circular steel forms, and the oor slabs were poured on MevaDec panel formwork.

Wall reinforcement was prefabricated on the ground in 8 m sections to allow for fast placement. Th ree primary tower cranes were located adjacent to the central core, with each continuing to various heights as required. High-speed, high-capacity construction hoists were utilised to transport workers and materials to the required heights. A specialised GPS monitoring system was developed to monitor the verticality of the structure, due to the limitations of conventional surveying techniques.

Th e construction sequence for the structure had the central core and slabs being cast rst, in three sections. Th e wing walls and slabs followed behind, and the wing nose columns and slabs followed behind these (Fig 14). Concrete was distributed to each wing utilising concrete booms which were attached to the jump form system.

One of the most challenging construction issues was ensuring the pumpability of the tower concrete to reach the world record heights of the tower, which necessitated that concrete be pumped well over 600 m in a single stage. High performance concrete is utilised for the tower, with high modullus concrete speci ed for the columns and walls. Th e concrete mix was designed to provide low permeability / high durability concrete.

A horizontal pumping trial was conducted prior to the start of the superstructure construction in order to ensure the pumpability of the concrete mixes (Fig 15). Th is trial involved the use of a long pipe with several 1800 bends to simulate the pressure loss in pumping to heights over 600 m in a single stage.

Th e nal pumping system utilised on-site Putzmeister pumps, including two of the largest in the world, capable of reaching concrete pumping pressures up to 350 bars through a high pressure 150 mm pipeline.



PROJECT CREDITS

OwnerEmaar Properties PJSC, Dubai

Project Manager Turner Construction International

Architect / Structural Engineers / MEP Engineers Skidmore, Owings & Merrill LLP

Adopting Architect & Engineer / Field SupervisionHyder Consulting Ltd

General ContractorSamsung / BeSix / Arabtec

Foundation ContractorNASA Multiplex

Fig 15: Concrete pumping system test.

All images by SOM.

ConclusionTh e Burj Khalifa Tower has claimed the title of the worlds tallest structure. It is an example of a successful collaboration between the requirements of structural systems, wind engineering, and architectural aesthetics and function. Th e tower represents a signi cant achievement in terms of utilising the latest design, materials and construction technology, and methods, in order to provide an e cient, rational structure, that rises to heights never seen before.

REFERENCES

Baker W F, Pawlikowski J J, & Young B S: Th e Challenges in Designing the Worlds Tallest Structure: Th e Burj Dubai Tower. Proceedings of the SEI/ASCE Structures Congress, 2009.


Interview

Engineering urban transformation

Th e iconic Singapore Flyer. Image by Singapore Flyer Pte Ltd.

Arup brings t o g e t h e r individuals from a wide range of disciplines and encourages them to look beyond the constraints of their own specialisations, so that the

engineering consultancy can in uence the future of the built environment in a distinctive manner.

Mr Andr Lovatt, Principal and O ce Leader, Singapore, Arup Singapore Pte Ltd, highlights the factors underpinning the rms impressive track record in the republic, in this interview with Th e Singapore Engineer.

Q: What makes Arup di erent from other rms?

A: One of the things that makes us di erent is how Arup is owned. Th e rm is owned in trust on behalf of its

Arup Singapore: overview of skills

Acoustics, Audiovisual and Th eatre ConsultingBuilding Services / M&E Building Structures Environmentally Sustainable Design (ESD)Facade Fire Geotechnics Green Mark / LEED Consulting Infrastructure IT and Communications Maritime Programme and Project ManagementRisk and Security Specialist Lighting Tra c and Transport Planning Tunnelling Urban Design Vertical Transportation

Mr Andr Lovatt.

sta . Th e result is an independence of spirit that enables us to take long-term decisions and chart unconventional routes. Th is is re ected in the rms work, and in its dedicated pursuit of technical excellence.

One good way to think of Arup is as an idea factory. Our ability to generate great ideas is entirely vested within our people. As a result, we take a great deal of care to select the best possible people and to give them the freedom to do the sort of work they like and are good at.

Q: How is Arup responding to developments in the construction industry in Singapore?

A: In terms of growth, Asia will continue to have huge prospects and opportunities and Arup has o ces in key Asian cities such as Hong Kong, Shanghai, Beijing, Tokyo and Singapore to meet these demands.

In Singapore, with over 200 local sta , Arup is well-placed within the booming professional services sector and we work on a wide range of commercial and

residential building, and infrastructure projects.

Q: What are some of the landmark projects in Singapore that Arup has been involved in recently?

A: Arup has made signi cant contributions to three major developments that have shaped Marina Bay, Singapores premier waterfront destination. Th ey are the Singapore Flyer which, at a height of 165 m, is the worlds largest Giant Observation Wheel; Marina Bay Sands Integrated Resort which o ers a 2560-room luxury hotel, advanced convention and exhibition facilities, shopping mall, restaurants, and theatres; and Th e Helix, a 280 m bridge, inspired by the shape of a DNA molecule.

Arup provided consultancy for the Downtown Mass Rapid Transit (MRT) line that connects Marina Bay with the city centre and we are also a member of the team that will be responsible for delivering a second footbridge that will complete the pedestrian route around the bay.


Interview

Arup Singapore Pte LtdArup opened its Singapore o ce in 1968. Over the years, the rm has made signi cant contributions to landmark projects such as OCBC Centre, UOB Plaza, Temasek Towers, Expo MRT station, Singapore Expo, and the National Library Building.

Th e companys other projects in Singapore include the Singapore Flyer, Fusionopolis, ION Orchard, Marina Bay Sands Integrated Resort, Th e Helix bridge, Gardens by the Bay, Singapore Sports Hub, School of the Arts, and the renovation of Victoria Th eatre and Victoria Concert Hall.

ArupFounded by Sir Ove Arup in 1946,

Arups rail engineering capability is allowing us to assist Singapore in meeting its vision of developing a world-class transportation system, particularly the Downtown MRT Line project where we have provided a range of services from alignment and routing studies to detailed engineering design.

Q: How is Arup approaching the issue of sustainability?

A: In the early 1970s, Sir Ove Arup, our founder, was one of the rst people to talk of sustainability. So, sustainability is not new to Arup.

Our design teams are working together to investigate ways to reduce energy demands. Th rough careful design of the facades for projects like the National Library, One George Street and 20 Anson, solar thermal loads on the building are minimised by reducing the cooling needed from airconditioning systems. Carefully positioned sunshades project natural daylight into the spaces within the building, thus saving electricity to run arti cial lights.

However, the greatest energy savings would come from avoiding airconditioning altogether. Th is is cleverly

with an initial focus on structural engineering, Arup has become a global design, engineering, and business consultancy, with a sta of over 10,000 spread over 92 o ces in 37 countries.

Th e rm rst came into prominence with the structural design for the Sydney Opera House in Australia, followed by its work on the Centre Pompidou in Paris, France. Arup has since grown into a multidisciplinary organisation. Most recently, the rms contributions to the 2008 Olympics facilities in Beijing, China, particularly the National Aquatics Center (Water Cube) and the Beijing National Stadium (Birds Nest), have served to rea rm its reputation.

achieved by permitting the passage of natural breezes for the integrated civic, cultural, retail and entertainment hub (CCRC) and by providing assisted ventilation and heat-re ecting canopies for Clarke Quays streetscape.

As the Singapore and other Asian property markets become more mature and sophisticated, increasingly the life of commercial buildings is being extended

by retro tting and refurbishment. Th e Green Building agenda, along with a tighter nancial environment will increase this trend.

Arup has studied the factors that in uence client decisions, and have recently worked with the BCA to prepare a guide book targetted at owners existing buildings as part of their Green Building Guide Platinum Series.

On the right of the picture, Th e Helix is set against the backdrop of the Marina Bay Sands Integrated Resort. Image by Darren Soh.


Products & Services

Paving ahead for growing population down

under In 1970, Perth in Western Australia had a population of just 700,000 and a footprint of approximately 500 km2. Today the population has increased to 1.9 million and the metropolitan area is more than twice the size.

Developers are lling in the few remaining plots of land, stretching along a north to south coastal corridor, to provide housing for the ever increasing population, led by todays new immigrants.

Predictions are that the population will double to 3.8 million over the next 40 years, meaning that the city will stretch from Lancelin in the north, to a point between Mandurah and Bunbury in the south covering more than 10 times the surface area it covered in 1970.

Western Australia asphalt specialist BGC Asphalt, is fully utilising a Dynapac F6-4W paver, laying roads in the last few remaining sub-divisions of Ridge Wood in Brighton, the latest northern suburb of Perth.

BGCs latest contract, sub-contracted by earthmoving specialist R J Vincent, features the laying of 6000 m2 of asphalt over three days. A 40 mm base coarse with 14 mm aggregate will be topped by a 25 mm wearing coarse both sitting on a 200 mm limestone sub-base.

Backing up the Dynapac paver is a CP142 pneumatic tyred roller and a CC142 twin drum compaction roller. Across the sub-division, roads are generally 5.5 m wide, often with 2.2 m wide parking bays. Outside the sub-division, the main roads can be 6 m or 7.4 m.

By tting extensions, the paver can o er a 3.8 m width, making it versatile for any road work in the suburbs.

With a Deutz diesel engine, rated at 52 kW at 2300 rpm, the paver o ers high power for a machine of this size and it can easily push 47 t gross.

Th e paver is rear-driven and incorporates a 4-wheel drive and integrated anti-spin system. It provides a maximum placement thickness of 270 mm and o ers a capacity of up to 250 t/h.

On the sub-division contract, the paver is followed by two vibratory passes

by the CC142 and multi-passes with the CP142 until the surface is rm. Th e CC142 then makes two nal vibratory passes to remove the possibility of any tyre marks made by the CP unit.

Depending on the paving speed, pass lengths of around 20 m are made,

although this can be increased to 80 m, subject to the ambient temperature and weather conditions.

Th e slide plates are suitable for laying up to the ush kerbs and are easy to set.

Although delivered only last year, the paver has clocked more than 410 hours.

Th e paver o ers high power for a machine of this size.

BGC Asphalt is utilising a Dynapac F6-4W paver to lay roads in the northern suburb of Perth.


Products & Services

Taking the drudge out of planning repetitive

on-site tasks Balfour Beatty, a leading construction and civil engineering company in the UK, now holds a number of licences of the award-winning MethoCAD software package developed by Paris-headquartered Creative Business Solutions.

According to Balfour Beatty, it is proving to be an invaluable organisational tool in the pre-planning and maintenance of a wide range of the companys construction sites, currently including major works in London.

In planning projects, MethoCAD is helpful in drawing up site plans right from the excavation stage, which includes the positioning of tower cranes. Balfour Beatty has been using MethoCAD for about a year now and it has been facilitating quick overviews of the site, since all the dimensions for the plant machinery that will be required, are stored in the system. It cuts out a lot of the drudgery in drawing up these plans.

For one of the projects, for example, there is an existing old road running underneath the site, and Balfour Beatty is currently working on how long it will take to excavate it in sections, whilst keeping the tra c owing.

With MethoCAD, the company has been able to rapidly determine, for instance, what excavation is required, how many excavators are needed (visualising their rotational paths throughout), and how long the excavation will take before it can move in to start doing the piling for the new structure.

By eliminating much of the repetitive and routine planning elements, it is estimated that man-hours in the planning procedures can be reduced by 30%.

MethoCAD is supplied with a library of hundreds of accurate, dimensional drawings of virtually all plant equipment employed in construction projects worldwide. In addition to excavators, this includes top and front drawings of all major machinery, including concrete batching plants, delivery vehicles, and cranes.

Turning curves of the delivery and removal trucks, through to those of cranes,

are essential parameters which can all be quickly visualised with MethoCAD.

Th e positioning of tower cranes can be checked both in plan and elevations, to ensure safe distances between jibs, counter jibs, anchor cables, and masts. Th is can be particularly useful for checking the minimum clearance when not working.

MethoCAD allows Balfour Beatty to see exactly what is required and ensure that the site will be both e ciently and safely operated.

Other features such as protective walkways, fences, and service networks, can all be quickly put in place. It allows the company to visualise the entire site, and prove that it can operate at full capacity in the time-frame provided.

It is useful not only as a space planning tool, but also for presenting projections of the work, and if required, it can be turned into a dynamic 3D model for video presentations.

Meanwhile, Creative Business Solutions introduced two new MethoCAD modules for construction site management and safety, at bauma 2010.

Th ey are an audio-visual module that depicts, in 3D format, the safety aspects of construction sites and equipment, together with the simulation of accidents, and the Eco-friendly sites (ESM) module.

According to Creative Business Solutions, the new 3D format module is aimed primarily at site sta training in construction companies.

By using the latest virtual reality software in three dimensions, together with sound, the user will recognise the environment of the construction site, and be more conscious of the risks.

Th e MethoCAD module, available on a USB key, can be used anywhere, and is designed to complement the existing training materials of construction companies.

Th e user visualises the various sequences by means of a menu under Windows.

Th e ESM module is intended to assist contractors meet todays high on-site environmental quality standards, by incorporating aspects relating to tra c disturbance, waste management, ground pollution, visual impact, and site safety.

MethoCAD assists in the pre-planning and maintenance of construction sites.


Products & Services

Plastic formwork offers advantages Plastic forming panels developed by Vietnamese company FUVI Mechanical Technology Company, are marketed under the brand name FUVI Coppha. Th e panels were developed a decade ago, and were rst exported in 2003.

According to the company, there has been a great deal of interest in the system during the past two or three years, because contractors have begun to appreciate just how wasteful the use of plywood is, in terms of environmental impact, durability, cost, and time. Plywood formwork requires the destruction of trees and it can be used only a few times.

Th e original FUVI HDPE panel system is available in sizes from 100 mm to 2,000 mm and features a 50 mm thick pro le.

Accessories include push-pull props, sca olds, U-heads and jack bases, slipform hydraulic jacks, and slipform surface and corners.

FUVI is particularly appropriate for use in mass building projects following slum clearance programmes, for example.

In India, the FUVI system has been written into the speci cations for building high-rise apartments that are

replacing slums in cities such as Chennai, Mumbai, and Delhi, and other countries with similar building programmes are considering doing likewise.

Th e company is currently talking to government housing departments in South and Central American countries, where slum clearance has become a priority.

FUVI is becoming the formwork of choice also for large and prestigious projects, such as the Saigon M&C Tower which is currently being built in Ho Chi Minh City, Vietnam, by French contractor Bouygues Construction.

Th e project has two 45-storey towers, making it one of the tallest buildings in Vietnam. With its Grade A o ce and residential accommodation, and its riverside setting, Saigon M&C Tower is expected to be one of the smartest addresses in the city.

FUVI has designed and manufactured, and is operating, two independent FUVI slipform units on the building cores.

Th e plastic panels are lighter than other slipform panelling, weighing 7 kg/m as opposed to an approximate 10 kg/m for wood, 20 kg/m for aluminium, and 31 kg/m for steel. Consequently, a

medium-range tower crane can be used.According to FUVI, whereas plywood

can be used only ve to 10 times, the FUVI plastic panels can be used 100 times without any deterioration in quality.

For high-rise construction, this is particularly e ective. Moving up to the next oor is fast and easy, because the assembly is simple. Also, unlike wood, the plastic does not adhere to the concrete, releasing itself when the curing is complete. Chemical release agents or oils are not required. As the plastic does not absorb water, a smooth nish is ensured. And usually, there is no need to wash the forms before starting on the next oor, as they are already clean.

With no timber waste to be disposed of, no hammering and nailing, and no washing of the formwork, the site is clean and tidy.

Th e FUVI system is exible enough to be used on infrastructural projects such as bridges and harbours. FUVI recently supplied a large number of jumpform units to CC1, one of Vietnams largest infrastructure contractors, for the construction of Phu My Bridge in Ho Chi Minh City.

FUVI Coppha formwork is said to o er advantages such as environment-friendliness, durability, low costs, and shorter construction times.


Products & Services

First Liebherr LTR 1100 crawler crane

delivered in Hong Kong Hong Kongs rst Liebherr LTR 1100 crawler crane has been delivered to rental specialist Chim Kee for its rst application on a government housing project in Hung Hom.

In its rst rental, the crane has been specially down-rated for a 50 t maximum lift at the boom length of 54 m, in order to meet the loadings of a steel platform, erected over the excavated 10 m deep basement of the project.

Th e Liebherr crawler crane is being used to lift and place steel girders and 40 mm dia rebar at the basement levels of the projects 30-storey twin-towers.

Th e main contractor for the project, Shun Tak Yee Fai Joint Venture, started work on the project in October last year, under a 30 month contract.

With a 40 m x 90 m frontage, the project will include a four-storey retail and recreation podium above the two basement levels. Two 30-storey towers will rise from the podium.

With foundations completed by Gammon in an earlier contract, the joint

venture contractor excavated more than 36,000 m3 to clear the basement area.

By opting to install the steel deck over approximately 75% of the site, the contractor has been able to speed erection of the basements steel girders and concrete deliveries. It also allows temporary parking for delivery trucks, preventing congestion in the busy narrow roads around the site.

Th e LTR 1100 is proving to be ideal for the Hung Hom project because of its small footprint and mobility.

Th e telescopic crane provides a high lift capacity for its 50 m boom and o ers a maximum lifting capacity of 100 t at 2.5 m.

In ordering the new crane, Chim Kee also incorporated a 7 m folding jib and 19 m boom extension, to o er a variety of con gurations including a maximum extended 78 m boom.

Further, the cranes advanced control system provides smooth motion and precise lifting.

Chim Kees rental eet features 11

Liebherr crawler cranes. Th e company was formed in 1962 as a small crane rental company and contractor. Growth continued throughout the 1970s, with Chim Kee introducing a eet of trucks for heavy transportation and heavy lift contracting.

By the early 1990s, the company ceased operating its contracting business, concentrating on rentals, particularly throughout construction of Chek Lap Kok International Airport, in which area it enjoyed signi cant growth with piling rigs, drives, jacking cranes, and transportation.

Today, as a heavy lift contractor, Chim Kee has successfully participated in several projects such as Container Port Number 9 and Stonecutters Bridge, with heavy lifts up to 400 t.

Th e new LTR 1100 is suitable for Hong Kongs congested sites and o ers fast erection. It combines the advantages of crawler and telescopic mobile cranes. Th e LTR 1100s ability to pick and carry loads, eliminates the need for outriggers.

Th e Liebherr LTR 1100 crawler crane has been specially down-rated for a 50 t maximum lift at the boom length of 54 m, in order to meet the loadings of a steel platform, erected over the excavated 10 m deep basement of the project.


Products & Services

Cost and CO2 savings from in-situ road

recycling

Th e WR 2500 S is granulating the existing pavement while mixing in pre-spread cement and PFA at the same time. Water is directly injected into the recycler's mixing chamber from tanker trucks.

Bath and North East Somerset (B&NES) Council, in the UK, has saved nearly 220,000 on the cost of repairing a 400 m long section of the B3110 Midford Road at Odd Down, on the southern outskirts of Bath. Th is vast saving has been achieved by the councils Design Group, in partnership with the councils term maintenance contractor Atkins, by choosing to recycle and strengthen in-situ, existing tar-bound hazardous carriageway materials, instead of using conventional full depth pavement reconstruction techniques with new bituminous materials. Th e existing layers throughout the depth of the road pavement were disintegrating and required strengthening.

In addition to the estimated 220,000 construction cost savings, the Design Groups rst-time use of in-situ recycling has also provided substantial environmental bene ts.

Th e bulk of the construction cost saving was achieved by not having to extract and dispose of the roads existing

hazardous tar bound material o -site at a special licensed waste tip. Instead, the existing road materials were used as a kind of linear quarry for aggregates which were recycled and strengthened in-situ.

Cold in-situ recycling considerably reduces CO2 emissions, as the technique vastly reduces the need for extraction and transportation of existing in-situ materials to land ll sites, as well as the production and transportation to site of virgin materials extracted from natural sources. An estimated 12 t of savings in CO2 emissions, has been achieved for the site.

Th is stretch of Midford Road was in urgent need of strengthening and we found from site investigations and subsequent material testing that the road pavement contained a high proportion of tar material. In conjunction with the councils term maintenance contractor Atkins, we considered the road repair options available and concluded that in-situ recycling o ered the most cost-e ective and environmentally bene cial

solution, said Mr Konrad Lansdown, B&NES Project Manager and Scheme Designer.

Th ere was approximately 1,800 t of hazardous tar material in the road pavement, which would otherwise have been extracted and disposed o -site at a special waste licensed tip at Cheltenham, about 50 miles away. Tar material disposal costs alone would have been approximately 180,000 and some of this material was classed as special hazardous waste, which meant that it probably needed incineration, costing around 1,000/t, he added.

Th e Atkins project engineer had previous experience of in-situ recycling and with the added complication of the tar, the process proved to be the best option to reconstruct this particular section of Midford Road. In-situ recycling has shown to be less disruptive to local tra c than conventional reconstruction as about 180 to 200 movements of 20 t wagons have been saved.

Th e construction work would have


Products & Services

cost around 550,000 using conventional pavement reconstruction methods and would have taken longer and been more disruptive to road users and local residents, said Mr Lansdown.

Th e in-situ repair has proved to be operationally quicker on-site and can be tra cked almost straight away as a temporary running surface prior to applying the surface course. Th is has been my rst experience of using the in-situ repair technique and would anticipate using it on similar road strengthening schemes in future, he added.

The in-situ recycling process, as practised by the specialist road recycling and stabilisation contractor, Stabilised Pavements, involves rotovating and pulverising damaged road pavements to depths of up to 320 mm. This is performed with a special purpose-built 500 kW machine, while simultaneously mixing in specific predetermined quantities of either lime, cement, pulverised fuel ash (PFA), bitumen emulsion, or foamed bitumen, and water, or combinations of these ingredients.

Th e revitalised mixture is then rolled, repro led, re-rolled, and overlaid with an appropriate nal surfacing for a fast return to tra c. Th e process is performed in accordance with the Transport Research Laboratory TRL Report 386: Design guide and speci cation for structural maintenance of highway pavements by cold in-situ recycling.

For Midford Road, Stabilised Pavements used a blend of 70% cement and 30% PFA, applied in a powder blanket across the surface of the rotovated material, to the extent of 8% by volume of the dry in-situ material. Th e quantity of the strengthening agent was determined from pre-contract materials testing and mixed, in a one-pass operation, in Stabilised Pavements German Wirtgen WR 2500 Recycler, at the designated depth of 180 mm. Water was added into the mix at the same time to achieve the required optimum moisture content. Th e cement and PFA complement each other as the cement provides an initial gain in strength of the recycled road materials, while the PFA slows hydration and contributes to increasing the strength over time.

Stabilised Pavements had to recycle

and strengthen in-situ, 3,868 m2 of Midford Road, to a 180 mm depth of tar-bound hazardous material, and provide a 20-year design life for 2.5 million standard axles. Th e approximate 10 m wide carriageway was treated in two separate halves. Whilst one half of the carriageway was being recycled and strengthened, the other half remained open for one-way tra c along a short diversion route. Once the required levels and compaction were achieved, the surface of the in-situ repaired carriageway was sprayed with a sealing tack coat and gritted as a temporary running surface for tra c. Th e process was then repeated for the other side of the carriageway using the adjacent recycled carriageway for one-way tra c.

I believe in-situ recycling has to be the way forward for treating tar-bound roads in the UK, which also provides the additional bonus of a saving on CO2 emissions, said Mr Gerry Howe, Director, Stabilised Pavements.

Although the in-situ recycled and stabilised base course bulked-up during processing, the Design Group adjusted the centre-line crown levels for the new road surface. Th e crown was raised by 80 mm, and 10 mm along the channels, increasing the cross falls to between 6% and 7%. Atkinss surfacing contractor Bardon Contracting followed on and overlaid Stabilised Pavements rejuvenated full width road base with a 50 mm thick hot rolled asphalt surface course for a fast return to full tra c.

Cold recycling with the WR 2500 S is an economically e cient and environment-friendly method for producing base layers of superior quality.

When cold recycling in-situ, the WR 2500 S granulates the existing pavement material while homogeneously mixing in binding agents and water at the same time. Th is method produces a new construction material mix in just one machine pass.


News & Events

bauma 2010 emphasises positive outlook for

construction industryTh e 29th bauma, the International Trade Fair for Construction Machinery, Building Material Machines, Mining Machines, Construction Vehicles and Construction Equipment, was held from 19 to 25 April 2010, at the New Munich Trade Fair Centre, Munich, Germany.

Organised by Messe Muenchen, bauma 2010 marked a turnaround in the international construction machinery industry, ushering in the hoped-for change in sentiment. Th is was despite the ban on air travel resulting from the volcanic ash cloud from Iceland, which a ected the rst few days of the fair.

Th e mood in the industry shows that in Europe the bottom of the cycle is now behind us. Con dence has returned. Of course, at the start of the fair, the exhibitors felt the lack of many customers from Asia and America, but in the second half of bauma, this improved

considerably. Messe Muenchens crisis management in the days impacted by volcanic ash was outstanding, said Mr Ralf Wezel, Secretary-General of CECE, the Committee for European Construction Equipment.

Although the ban on air travel in Europe, prevented visitors and, in the end, around 50 overseas exhibitors, from coming to the fair, the sentiment at the venue, among the approximately 3,150 registered exhibitors from 53 countries, was

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