RC Frames Profile

April 2011 Issue 40

CONTENTS

INTRODUCTION

COMPANY DETAILS

GROUP STRUCTURE

ACTIVITIES & SERVICES

HEALTH & SAFETY

AWARDS

SpeCC

CASE STUDIES

ST GEORGE WHARF OVERVIEW

REINFORCEMENT RATIONALISATION AND SUPPLY

SPECIAL CONCRETES

SLAB DEFLECTIONS

CASE STUDY - EARLY AGE CONSTRUCTION LOADING

PUBLISHED ARTICLES

RELEVANT EXPERIENCE

April 2011 Issue 40

LOGOBACKGROUND 100 60 10 5S 100 70 13 10STROKE 100 80 13 20

St George Wharf, Vauxhall, London

Battersea Reach, London

Nightingale Estate, Hackney, London

Kingston Quay, Glasgow

GLA Building, Pile Cap to Core

Learning Resource Centre, Sheffield

Imperial Wharf, Fulham, London

Greater London Authority Building, London

INTRODUCTION

Stephenson was formed in 1962 and over the years has developed a reputation within the industry forintegrity, commitment and performance meeting with Contractor's and clients requirements. TheStephenson Group now encompasses Reinforced Concrete Frames, Shell & Core and DevelopmentDivisions along with Specialist Contracting, Plant Hire and Sales. We are actively involved in developmentand construction partnering packages with key clients. Our areas of operation encompasses all the UK,with the Head Office in Horsham, West Sussex and regional offices in Wales and Scotland.

Our award winning services on the Reinforced Concrete Frames include all aspects of Design Build,Reinforcement Detailing, Design Development, Tunnelform, Post-Tensioning, Jumpform, SlipformFormwork/Falsework, Reinforcement, Concrete, Excavations, Temporary Works, Piling, Drainage,Scaffolding, Structural Steel, Screeding, External Works and Shell & Core.

Within the past years we have worked on some of the most prestigious contracts in the Country and wewere the first Contractor in this Country to use the following:

Outinord Room Forms / Tunnel Forms – Ibis Hotel, EustonIndumat Hydraulic Tables – Friary Town Centre Development, GuildfordGKN Aluminium Kwikshore as a Flying Table – Rose Court, Southwark Bridge, LondonPeri Climbing Wall Form System – Commercial Office Development, Prescott Street, LondonDoka Jump Form Walls System – GLA Building, LondonCordek Trough & Void FormersClimbtrac Jumpform System - Kingston Quay, GlasgowRecycled Plastic Scaffold Board SystemsHalfen Cold Bridging Detail to Precast Balconies - Festival Park, GlasgowIschebeck Screen System, Gun Wharf Quays, PortsmouthHydraulic Climbtrac Jump Form System for Core Construction - Gracechurch Street, LondonCobiax Precast Slab Construction - SheffieldSelf-Compacting Concrete in a Concrete Structure - Echo 2, Leeds

The Company’s experience extends to every RC requirement on the market today. Along with the use anddevelopment of Formwork and Falsework systems, we continue to look into the whole RC Frame concept.We are actively involved through ‘Construct’ in the promotion of Economic and Fast Track design andconstruction techniques for RC Frames which include the incorporation of Precast and Steel elements intothe structure, the now so called ‘Hybrid’. The ‘Hybrid’ RC structure is being used more extensively and wehave been actively involved in their design development and construction.

Examples are: Whitbread Brewery, Chiswell Street, London – 1970’sGuildford Town Centre – late 1970’sRoyal Mint, London – late 1980’sMarsh Lane Student Accommodation – 1990’sHQ QMG, Andover – 1990’sHMP Parc, Bridgend (PFI Contract) – 1990’sClifton Street, London – 1990’sSt George Wharf, London - 2000Sheffield University - 2006Glasgow Harbour - 2008Tesco Orpington - 2009

With each RC Frame we believe we have the experience and positive approach to meet any structuralmethodology and solution.

We look forward to discussing your requirements with you.

COMPANY DETAILS

TRADING NAME STEPHENSON

TELEPHONE NO. 01403 217000FAX NO. 01403 215750

COMPANIES & DATE OF FORMATION 2010 STEPHENSON CONTRACTORS LTD2007 STEPHENSON DEVELOPMENT(SOUTHERN) HOLDINGS LTD2007 STEPHENSON CONSTRUCTION (SOUTH) LIMITED2007 STEPHENSON CONSTRUCTION (NORTH) LIMITED2006 STEPHENSON (SHELL & CORE) NORTHERN LIMITED2006 STEPHENSON (SHELL & CORE) SCOTLAND LIMITED2004 STEPHENSON SHELL & CORE LIMITED2004 STEPHENSON CONSTRUCTION (SCOTLAND) LIMITED2003 STEPHENSON CONSTRUCTION SERVICES LTD2002 M R STEPHENSON LIMITED2002 STEPHENSON LTD1984 SSC CONSTRUCTION SERVICES LTD1962 STEPHENSON SHUTTERING CONTRACTORS LTD (DORMANT)

TAX CERTIFICATION M R STEPHENSON LTD UTR NO. 48735 24327STEPHENSON CONSTRUCTION (SOUTH) LTD UTR NO. 35861 19374STEPHENSON CONSTRUCTION (NORTH) LTD UTR NO. 11599 02730STEPHENSON CONSTRUCTION (SCOTLAND) LTD UTR NO. 12447 16353

INSURANCE DETAILS CONTRACTOR’S LIABILITY MILES SMITH/LLOYDSPolicy No. B0740147090014/CW0000828 exp. 1/11/11EMPLOYER’S LIABILITY MILES SMITH/LLOYDSPolicy No. B0740147090014 exp. 1/11/11ALL RISKS NORWICH UNIONPolicy No. 23910810CTC exp. 10/08/11PROFESSIONAL INDEMNITY QBE/LloydsPolicy No. 010371/01/2011 exp. 28/06/11

GROUP VAT NO. 654 3087 34

BANKERS BARCLAYS BANK PLC43 HIGH STREETSUTTON, SURREYSM1 1DRTel: 0208 919 6700Fax: 0208 919 6820

AUDITORS AKP CHARTERED ACCOUNTANTSOAKWOOD HOUSEGUILDFORD ROADBUCKS GREENWEST SUSSEXRH12 3JJTel: 01403 255550Fax: 01403 257804

HEAD OFFICE PROVENDER MILLMILL BAY LANEHORSHAMWEST SUSSEX RH12 1SSTel: 01403 217000Fax: 01403 215750

BRIDGEND OFFICE INNOVATION CENTREBRIDGEND SCIENCE PARKBRIDGEND CF31 3NATel: 01656 767053Fax: 01656 769238

SCOTLAND OFFICE SUITE 3 (S3), PHOENIX HOUSESTRATHCLYDE BUSINESS PARK, BELLSHILLNORTH LANARKSHIRE ML4 3NJTel: 01698 501430Fax: 01698 501431

GROUP STRUCTURE

M R STEPHENSON LIMITED

PROPERTY CONCRETE STRUCTURES SHELL & CORE

STEPHENSONDEVELOPMENT

(SOUTHERN)HOLDINGS

LIMITED

STEPHENSONCONSTRUCTION

(SOUTH) LIMITED


(NORTH) LIMITED


(SCOTLAND) LIMITED

STEPHENSON(SHELL & CORE)

LIMITED

STEPHENSONSHELL & CORE

(NORTHERN) LIMITED

STEPHENSONSHELL & CORE

(SCOTLAND) LIMITED

DEVELOPMENTS

STEPHENSON

LIMITED

STEPHENSON

CONSTRUCTIONSERVICESLIMITED

SSC

CONSTRUCTIONSERVICES

LIMITED

ACTIVITIES & SERVICES

SUBSTRUCTURE

PilingExcavationTemporary WorksReinforcementFormworkConcreteDrainageExternal Works

SUPERSTRUCTURE

Insitu Concrete FramesFalsework & FormworkScaffoldingScreedingPrecast ElementsStructural Steel

DESIGN

Full Structural DesignDesign DevelopmentReinforcement Detailing

CONSTRUCTION

Shell & CoreGeneral Contracting

CONSTRUCTION MANAGEMENT

Management Services

STEPHENSON DEVELOPMENTS

Property Development

SpeCC LimitedRegistration Scheme

for Specialist Concrete Contractors

SpeCC was launched in April 2002 and over 100 senior figures from the industry were invited to attendthe awards of the first five certificates.

Stephenson was awarded one of the first five certificates.

SpeCC is a non profit making Registration scheme for Specialist Concrete Contractors established with the aidof industry representatives and the DTi, designed to operate and publish a list of reputable contractors capableof undertaking specialist concrete works which meet acceptable standards (confirmed by annual audits)covering:

The Commercial soundness of their businessThe adequacy of their management systems for QualityThe Health & Safety of their work forceThe EnvironmentTechnical capability of deliverabilityStaff & Work Force Training & Competence

Clients benefits:

Confidence in choice of specialist contractorAssurance of technical and business competenceFacilitate tender list selectionBenefit from a co-operative approach

Special contract benefits:

Recognition and proof of competence and professionalismOpportunity to demonstrate status and standingOpens doors to tender lists

The following Contractors have completed the auditrequirements and are now registered with SpeCC

CONTRACTORS CERTIFIED

StephensonJohn Doyle ConstructionLaing O’RourkeBryne Bros (Formwork)Edmund NuttallMitchellson FormworkWhelan & Grant (Contractors)A J Morrisroe & SonsO’Keefe (Greenwich)ScanmoorDunne GroupDuffy ConstructionAnderson StructuresPC Harrington ContractorsMichael J Gallagher Contractors

To the ignorant, pouring concrete might seem a relatively straightforward business. But when the project involvescomplex structural frames, sometimes combining precast and insitu concrete, there is no substitute for skill,experience and competence.

The sector has always had a hard core of specialist professional firms, with teams of workers who seem happiestup to their knees in fresh concrete, and proud foremen boasting decades of second-nature knowledge whosereputation is their last pour. Yet in any market when price often wins, the cowboy sometimes has his day.Typically the result is a seriously dissatisfied client – who will prefer to try the steel option next time. A newinitiative, driven by the industry itself, is striving to end the day of the cowboy contractor and claw back concrete’srightful share of the structural frame market.

This is the Specc certification scheme. In effect a Premier League for specialist concrete contractors. Efforts tomake construction more efficient and deliver better value spurred by Sir Michael Latham and Sir John Egan’sRethinking Construction, have prompted the industry to seek ways of improving standards. But stiff competitionfrom the steelwork sector which still continues to gain the lion’s share of structural frame work in the UK, and adesire finally to root out incompetent and unscrupulous contractors which give the concrete frame industry a badname – and clients a bad job – has also sparked the scheme.

Developed by the concrete structures contractors’ trade group Construct in conjunction with the Department ofTrade & Industry Construction Industry Unit, the scheme aims to provide independent verification that a firmholding SpeCC certification has reached exacting standards. Only five firms so far have made it, although thisnumber is expected to grow as the scheme takes hold.

Martin Stephenson, managing director of one of the first five companies registered, explains the motivation behindSpeCC.

“Construct was set up to promote the use of concrete in structural frames, and to look at technical issuesregarding reinforced concrete frames. Initiatives like the National Structural Concrete Specification launched in2000 have been very successful.”

“But we want to raise our profile, and we think there should be an accredited standard which we should allachieve, a set of criteria which all companies should reach.”

He adds: “We want to demonstrate to clients, architects and engineers that we have a proven record of qualityand efficiency.”

SpeCC focuses on five key areas of a company’s activities: quality, health and safety, training, environmentalpolicy and a firm’s financial standing. The accreditation system is also linked to the International Organisationfor Standardisation quality assurance standards ISO900/9001/9002.

To be awarded certification, a company must pass a series of inspections both of their office systems and sitepractices. Essential to the integrity of the scheme is a means of verification, and independent audits form a keypart of the inspection process.

Keep it up to specConcrete frame specialists have set up their

own premier league to improve standards and winmore market share from steel.

Diarmaid Fleming reportsStandards

NEW CIVIL ENGINEER – SPECIAL REPORT NOVEMBER 2002

Concrete

Standards

“Independent assessors came to the office and audited all our systems and quality plans. Apart from being aninteresting experience in itself, it helps to have a fresh pair of eyes looking at your systems,” says Stephenson.The day-long audit can target anything the inspectors wish to examine, and shortcomings must be rectified ifrequired.

The auditing process is run by Graham Peckham, manager of the SpeCC scheme. Quality assurance (QA)systems over the years have had their fair share of critics with some seeing them as a paper-making exercise ofmore use in widget factories than construction, where projects are generally one-off. The scepticism is recognisedby Peckham.

“We make absolutely sure that the systems companies have in place in the office or on paper are actually in placeon site as well,” he insists. “Issues like ensuring the traceability of steel or concrete for example, following it fromwhen it enters site to its use in the building, are examined.”

“Training and the skills of workers and managers on site, the most critical element to the construction process, arealso monitored carefully. The complete suite of tests aims to provide assurance to clients that a SpeCC certifiedconcrete specialist works to rigorous standards.”

With around £500M of works in concrete frames annually in the UK, it is a sizable market, but those involved wouldlike to see it bigger. Stephenson is frank about some of the motivation behind the scheme. Stiff competition fromthe steel frame sector means concrete wins around only a fifth of the market in structural frames, a share whichcould be increased, he argues.

“Construct and SpeCC is a response, and in some ways a late response, to the steel industry. We want to showthat we are as efficient and as cost effective as the steel industry, and this goes towards that.” Any notion that firmscan provide only a traditional sub-contracting service is to be disabused. Providing an all-in-one engineering andconstruction solution is the key to success and to winning more market share, with design and constructionintertwined.

While arguments of the merits of concrete versus steel have raged for years in the UK, the performance of theWorld Trade Center towers in the September 11 attack has helped stoke the debate further. The failure of steelcolumns and truss connections in the intense heat after the attacks raised questions as to whether greater use ofconcrete in the building would have provided a more robust structure.

Stephenson plays down the effect of the Twin Towers’ tragedy on the market. “There may have been a kneejerkreaction in the media, but you have to look at individual buildings, and each building has its own requirements.”

“Certainly there is a need to look at other possibilities in construction, but we’re talking several years before anymajor change in the market might be felt from this.”

With four firms – John Doyle Construction, R O‘Rourke, Bryne Brothers (Formwork) and Ascon Contracting joiningStephenson as first on the SpeCC register, Stephenson says expanding the scheme is essential.

“We hope to have at least 20 firms accredited by the middle of next year. Without enough members, the schemewon’t be taken seriously.”

Concrete

Standards

Keep it up to spec

NEW CIVIL ENGINEER – SPECIAL REPORT NOVEMBER 2002

Prospect Place, Cardiff, Post Tensioning

East Side Plaza, PortsmouthClimbtrac & External Screen System

Nightingale Estate, Hackney, Tunnelform

St George Wharf, Optimisation of Traditional Reinforced Concrete Frame

St. George Wharf

Overview

1 St George Wharf Project Overview





Reinforcement

Rationalisation

& Supply

1 Reinforcement Rationalisation and Supply





Special Concretes

1 Special Concretes

2 Special Concretes

3 Special Concretes

4 Special Concretes

5 Special Concretes

Slab Deflections

1 Slab Deflections

2 Slab Deflections

3 Slab Deflections

4 Slab Deflections

5 Slab Deflections

Early Age Concrete

Strength Assessment

1 Early Age Concrete Strength Assessment



Force measured by Lok tests

Figure 4: Correlation from cardington between conventional tests onair-cured cubes and lock tests on companion cubes

Batch

Figure 5: Variability between batches of measured 3-day water-curedconcrete strengths at St George Wharf

Air-cured cube strength (N/mm2)

Figure 6: Comparison of concrete strengths derived from Lok testresults from the structure with air-cured cubes at St George Wharf



Early Age Construction Loading

1 Early Age Construction Loading





Concrete MagazineFront Cover

January 2003

Concrete MagazineFront Cover

October 2005

Structural EngineerFront Cover

November 2006

Stephenson is an atypical contractor and although not

as well-known as some of its contemporaries, should

definitely be viewed as being in the same league. The

company is unusually structured. Having no big

overheads, it can achieve greater flexibility.

Stephenson’s concrete frame business turns over

around £35 million a year and is committed to the

whole process of marketing concrete and hybrid

reinforced concrete frames. With its involvement in

concrete research, it is determined to win back market

share lost to steel over the last two decades. It does

not limit itself to producing concrete frames – the

firm’s residential development division turns over a

further £30 million a year.

Stephenson carries its own Falsework system and

has invested heavily in plant. Ischebeck Titan service

and maintain their falsework and Stephenson have a

similar arrangement with DOKA for wall and column

forms. The company is sufficiently flexible to

encompass a range of contracts ranging in value from

£100,000 to £20m. The current portfolio comprises

work from Glasgow to Bournemouth with 75% of its

workload in London and South East, including its third

contract to build a 22-storey frame at the giant St

George Wharf development.

In May 2002, Stephenson was one of the first firms to

be certified under the SpeCC registered scheme for

specialist concrete contractors. The scheme,

developed by the concrete structures group

CONSTRUCT in conjunction with the Department of

Trade and Industry, aims to improve standards and

win more market share from steel.

Forming concrete structures may appear to be

relatively straightforward, but when the project involves

complex structural frames, sometimes combining

precast, steel, and insitu concrete,

there is no substitute for skill, experience and

competence. The SpeCC certification scheme is, in

effect, a premier league for specialist concrete

contractors.

SpeCC focuses on five key areas of a company’s

activities: health and safety; quality; training;

environmental policy, etc; and the company’s financial

standing. The accreditation is linked to the International

Organisation for Standardisation.Figure 1: A 22-storey frame was provided for the St George Wharf development

The scheme aims to provide independent verification that a firm holding

SpeCC certification has reached exacting standards. Only five firms

have achieved this to date.

Stephenson was first formed in 1962 by the father of Martin Stephenson,

the current managing director, and has evolved over time. The company

remains a traditional, family-run firm but is resolutely forward-looking.

Initially, the business was formwork, then reinforcement was added then

concreting.

Figure 2: The St. George Wharf development is a prestigious mixed-use riverside scheme on the southside of the Thames in view of Parliament.

CONCRETE MAGAZINE – January 2003

- frames at

their best

The whole package is now offered – design and build reinforcedconcrete frames, piling, temporary works, earth excavation andremediation. Stephenson’s view is to provide an all-in-oneengineering and construction solution, with design andconstruction intertwined.

Stephenson has pioneered the use of flying forms, a modularformwork system designed for casting successive concrete floors.These are ideal for use in multi-storey buildings or other repetitivereinforced concrete structures. They minimise construction times,labour and material costs.

Figure 4 : Pumping the pile cap for City Hall, new home of the Greater London Authoritylocated on the south bank of the Thames.

The company can also claim to be the first contractor in the

UK to use Outinord tunnel forms, and Cordek trough and

void formers. Stephenson is actively involved in

developing and promoting economic and fast-track design

and construction techniques for reinforced concrete

frames.

While concrete frames remain at the centre of the

business, Stephenson is looking to diversify and intends to

grow. While sticking to traditional reinforced concrete

frames, substructure and superstructure, which is the core

business - the design and build capability will be enhanced

and the company will also be looking at shell and core

projects.

Stephenson’s vast experience and knowledge has placed

them at the forefront of the reinforced concrete business

and as a consequence, through innovation and planning, it

has been privileged to work on some of the most

prestigious contracts in the country. With a flair for mixing

technical innovation with imaginative management,

Stephenson is in a prime position to continue being

successful.

Figure 5 : A cost-effective frame was created for Imperial Wharf,a prestigious redevelopment in Fulham, West London.

Figure 6 : Imperial Wharf nears completion.

Figure 3: The Greater London Authority building begins to take shape.

CONCRETE MAGAZINE – January 2003

Stephenson Holdings LtdOakwood House, Guildford Road

Bucks Green, HorshamWest Sussex, RH12 3JJ

Tel: +44( 0)1403 824960Fax: +44 (0) 1403 824961

[email protected]

Top of frame academy

Stephenson takes a different approach to many of its

concrete frame rivals. Richard Thompson speaks to

managing director Martin Stephenson

FEW companies can have as effective a security system as concrete frame specialist Stephenson.

Even with an appointment to meet managing director Martin Stephenson at the firm’s beautiful head office at Kirdford,

West Sussex, I was nearly denied access by the most over-zealous security guards I have encountered.

I was barely out of my car, which I’d parked beside the converted barn, when I was set upon by three large, extremely

aggressive geese, honking loudly and nipping at my legs.

Stephenson is clearly not your typical contractor. What is surprising, though, it that the firm’s name is not as well known

as some of its concrete frame contemporaries, such as O’Rourke, John Doyle, Bryne Brothers or PC Harrington.

Stephenson should definitely be viewed in the same league as these firms. Not just in terms of size – its concrete frame

business turns over around £35 million a year – but also in terms of attitude. Its involvement in concrete research and

its commitment to marketing the grey stuff puts it at the heart of the sector’s drive to win back market share lost to steel

over the last two decades.

Six months ago, Stephenson, along with John Doyle, O’Rourke, Bryne Bros and Ascon, was one of the first firms to be

certified under trade association Construct’s registration scheme for specialist concrete contractors.

Neither does Stephenson limit itself to simply producing concrete frames – the firm’s development division turns over a

further £30 million a year.

Yet Martin Stephenson readily admits the firm is a bit unusual. “We are structured differently”, he says. “We have no

big overheads, which gives us greater flexibility.”

“Our administration is done from here – a rural location. We carry our own falsework system and have made a big

investment in plant, which is kept at our plant yard in Billingshurst. But we have an arrangement with Ischebeck Titan

to service and maintain our plant. We have a similar deal with Doka for wall forms”.

But the lack of a large plant division and in-house design office does not prevent the firm landing big jobs. Its current

portfolio comprises jobs from Glasgow to Bournemouth, including the £4.5 million contract to build the 22-storey frame

for the third phase of the giant St George’s Wharf development for developer St George in London (pictured on next

page).

This is all a long way from the firm’s humble beginnings in 1962, when Mr Stephenson’s father, a contracts manager

with SGB set up Stephenson Shuttering as a formwork contracting business.

“The business evolved over time,” says Mr Stephenson. “First it was formwork, then we added reinforcement, then

concreting. Now we offer the whole package – design and build frames, piling, temporary works, earthmoving.”

Construction News 7th November 2002

Mr Stephenson set up his own construction management operation in 1984, but when his father died two years

later the two businesses were merged. For anyone wanting to emulate the Stephenson story Mr Stephenson

thinks now could be a good time.

“The market is buoyant at the moment and there’s a bit of a gap. At the top you have the majors like Laing,

O’Rourke, who do the whole thing. Then there are the frame contractors like Harrington, John Doyle, Bryne

and us. Then I think there’s a gap,” he says.

While concrete frames will remain at the centre of the business, Mr Stephenson is looking to diversify. “We will

grow organically,” he says. “We will stick to our traditional RC frame market, substructure and superstructure,

which is our core business.”

“We will enhance our design and build capability, because one of the main problems in RC frames right now is

the flow of information. But we will also look at shell and core projects. We are moving that way.”

About 60 per cent to 70 per cent of Stephenson’s turnover currently comes from residential developments, and

the managing director is optimistic about the future.

“While certain areas may have peaked in terms of pounds per square foot, there is plenty around in terms of

demand. We are looking at a few social housing schemes.”

As I open the door to leave I see Stephenson’s three sentinels waiting for me. There is no doubt this firm is a

bit different. Long may it continue.

Construction News 7th November 2002

“We are structured differently. Wehave no big overheads,which gives usflexibility”

Martin StephensonManaging Director, Stephenson

FIRST UK POST-TENSIONEDSLAB APPLICATION BY STEPHENSON

HIT is winning appreciation on projects from the south coast tothe middle of Glasgow - in a high quality residentialdevelopment on the Banks of the Clyde, in fact. Designed byarchitects RMGM Scotland Ltd with D.R.Murray asengineers, Festival Park features a post-tensioned slabconstruction.

Main contractor Morrison Construction were tasked withavoiding cold bridging in the connection of balconies. HIT wasselected to overcome this, the system being incorporated intothe balconies, which were mainly precast on site and installedby Stephenson’s. The balconies were then offered up to theslabs and simply tied into the slab reinforcement.

This is believed to be the first post-tensioned slab applicationof HIT in the UK.

Cobiax Designed with beams

Specialist concrete frame contractorStephenson has been taking full advantageof the many features of Ischebeck titan’sClimbtrac system to achieve recordproductivity levels on a new city-centreresidential development for Barratt Homesat Kingston Quay, Glasgow. The systemhas also recently been used for Liverpool’sprestigious 30-storey Beetham towerdevelopment.

GARY MORTON, ISCHEBECK TITAN

Hitting a new highat Kingston Quay

The project consists of 380 flats in a steel-framed eight-storey development. Overall structural building frame stability isenhanced by six twin-lift, reinforced concrete shaft cores and a reinforced concrete stair core. It is here that Climbtrac has beenemployed, with four main external platforms, complete with trailing suspended lower platforms, one on either side of a core.Internally, two main platforms together with trailing suspended lower platforms were used.

ClimbtracInitially, main contractor, Ogilvie Construction, considered the use of a standard jump-form core system. However, followingconsultations with Stephenson and Ischebeck Titan, Climbtrac was selected for its unique safety features and the addedstability that it provides to the formwork. Stephenson already had previous experience with Climbtrac and made some minormodifications to their systems to further enhance productivity.

Climbtrac requires a concrete strength of 15MPa at 15 hours for support and Stephenson had to achieve this during a dailycycle. One storey lift per day at Kingston Quay was achieved, enabling an eight-storey core to be completed in eight days.Climbtrac is a vertical track-based system, which enables the user to move a working platform up the building face withoutthe need to disconnect and reconnect the system to the structure itself, together with the necessary formwork. The systemcomprises a pair of triangular frames, with guide wheels and catching devices for support. These run up a vertical track of twosteel beams bolted in sections to the building walls by means of a cone and bolt arrangement. The cones are recovered as workprogresses, whilst the bolts remain cast into the final structure.

Lifting a Climbtrac unit at Kingston Quay

Platform support channels are connected to the frames supporting the workingdeck and formwork rolling equipment. This equipment consists of levellingbrackets and wheels which run on two guide tracks located on the deck. Thesepermit rolling of the formwork to and from the face of the structure beingformed. Safety screens connected to the rear and side of the platform andhigh-tension bolts complete the system.

Lifting the systemDuring construction, the Climbtrac system is lifted vertically along its track bycrane. When one storey is complete, the forms are simply rolled back fromthe concrete face, further track sections are fitted and the system is hoisted tothe next storey. Track sections can either be left in position for removal at alater stage of the project or removed from the platform and passed throughtrapdoors for use on subsequent levels as construction progresses.

Suitable for use on vertical surfaces, such as lift shafts, stair walls, columns and external perimeterwalls, Climbtrac has been designed to facilitate safe crane lifting of platforms together with wallforms, whilst remaining captive on the concrete structure during lifting operations. The systemoffers potential time and cost savings through more efficient working methods. It also makes asignificant contribution towards safety as it eliminates the requirement for potentially dangerousmanoeuvring of the formwork system away from the building duringconstruction.

Concluding remarksClimbtrac has many features that offer benefits in safety, stabilityand productivity. The fact that the entire working platform, togetherwith formwork and rolling formwork gear, remain captive to the faceof the structure throughout the construction period provides manyadvantages over ordinary climbing systems. This is particularly truein exposed areas where high winds can cause downtime. The sturdyconstruction of the system, with solid plywood decking and full-height mesh safety screens on all sides, make an invaluablecontribution to the safety of operatives on the platform itself and thesite below.

The Kingston Quay project team has been quick to recognise thebenefits offered by the system and has achieved levels of productionnot realised elsewhere in the UK.

‘The sturdy construction of the system,

with solid plywood decking and full-height

mesh safety screens on all sides, make an

invaluable contribution to the safety of

operatives on the platform itself

and the site below’

The formwork configuration on all four sides of a coreduring the early stages of the project in March 2003

It is unnecessary tomanoeuvre formwork

away from the buildingduring construction

New Civil Engineer 20 October 2008

Stephenson Bowling Along

These balls replace non-structuralconcrete, reducing weight

A 7,500m2 floor plate, columns on a 16m grid, seven suspended floor slabs - two for a supermarket, two for thesupermarket's heavily loaded car park, two for roof-top residential housing and one more for the residents' car park- and a location smack-bang in the town centre.

Those were the requirements of Tesco for its new superstore in Orpington, Kent. They add up to a fairly heftychallenge for any builder. But BAM Construction met them through a pioneering use of Hanson's Cobiaxdeck semi-precast concrete panels. The system, developed in Switzerland, uses a precast concrete base, or "biscuit" with thereinforcement arranged around plastic balls.

The slab is lifted into place and insitu concrete poured to complete the slab. The effect of the balls is to displaceconcrete in the section of the slab where it has no structural effect but simply adds dead weight. As a result slabscan span longer distances without undue deflection.

"Cobiaxdeck has been ideal," says BAM Construction project manager Mick Kelly. "Tesco wanted to max the carpark, max the retail space, so wanted a 16m grid. Over a 7,500m2 floor plate the number of columns is greatlyreduced." These long spans are breaking new ground. "I've only used post-tensioning up to 10m. I've hadexperience of Cobiaxdeck but nothing on this scale. This has never been done before, and it's going well," saysKelly.

Contractually, Hanson is working in joint venture with contractor Stephenson Shell & Core to provide frame andfloor for a lump sum fixed price - and in just 48 weeks. "It's very clean and tidy for us and takes away the risk on a£10M-plus frame. Overall, the project is worth £42M to BAM," says Kelly. Formwork on the job is minimal and speedof erection is high: "In the straightforward areas we are doing up to 1,500m2 comfortably a week," says Kelly.

Typically 1,000m2 is being achieved. "On a traditional insitu concrete job we would be looking at doing 500m2 aweek. We are doubling that output here and have had 150 men on the job from week 10," adds Stephenson seniorproject manager Mike Lockwood. ""And we are well ahead of programme," adds Lockwood. "Even though 48weeks is a very short programme for seven storeys of 7,500m2 suspended floor slab."

In total 18,000m3 of concrete and 2,100t of steel are being used to create the structure - a completely uniquehybrid, with the seven suspended Cobiaxdeck floors ranging from 450mm in the basement car parks, to 600mm atstore level to a whopping 800mm deep transfer slab at residential level - spanning two-ways onto largely (but notexclusively) steel columns.

"Reinforced concrete columns were coming in at 1m-plus in cross-section and were starting to encroach on carparking, so we did a bit of engineering work with consultant Pinnacle who came up with steel columns. There wasalso a programme advantage as the columns are three storeys high and are lifted in one piece".The frame sits on a variety of piles - essential because of a very high water table. But the lightweight Cobiaxdeckenabled BAM to cut £50,000 out the foundations. In addition there are six concrete stair cores and six lift shafts,

constructed in advance of the frame to provide lateral stability and remove the need for bracing.

Big spans - really big spans - used to be the preserve of post-tensioned concrete. But thanks to plastic balls this is changingfast and supermarket giant Tesco is one of the first benefactors.Mark Hansford sees for himself as he reports from the Kentishcommuter town of Orpington.

New Civil Engineer 20 October 2008

"On a traditional insitu concrete job we would be looking at doing 500m2 a week. Weare doubling that output here"Mike Lockwood, Stephenson Shell & Core

The final structural elements are five ramps for the car parks - two each for access to the upper and lowerbasements and one, 150m-long giant for the residential housing on the roof. "This ramp is key to the job," saysLockwood. "We looked at the precast option, but the biggest concern was tower crane time." Three tower cranesare in use on the site, which highlights one of the few drawbacks of the system - there is a lot of lifting. "It is verycrane dependent and high winds can hit the programme."

Concrete used is predominantly C32/40 with some C50/60 and some C75/80 where steel columns areoccasionally replaced with concrete. Work began on site in January last year and the Stephenson/Hanson JV iscurrently erecting the final two storeys for residential housing set on top of the supermarket. With this sitting ona different grid to the main store and also coming with heavy loads from car park, level three provided the biggestengineering challenge - the massive Cobiaxdeck transfer slab.

"Originally the plan was to combine Cobiaxdeck with steel beams, with the services hung underneath theCobiaxdeck slabs. But the whole series was so drawn out it would have added six weeks to the programme. "Thechallenge was turning Cobiaxdeck into a transfer structure - it's an 800mm thick slab and we did have to keepthe props in the floor area below for a long time," says Kelly.

"Pours for the insitu component are large - up to 1,000m2 in one hit, with the slabs supported by static props.These were needed at every level right down to the lower basement, such was the weight of the slab. But theadvantage was that we could pour in stages, level, and start the residential," says Kelly.

This ability to work in stages across the site was vital, after work was initially held up by a rogue Thames Watersewer which ran the length of one elevation. "Until week 18 we only had 60% of the site to work in. So we workedacross as far as we could, then went up. By week 15 we were working on three floors and seven different workfronts," says Lockwood.

Logistics are a major challenge. Every 10.4m long, 2.4m wide slab is bespoke. "We had an 80-week programme,and everyone thought that was undeliverable," says Kelly. And so, thanks to the sewer, it has proved. But that28 week delay has been cut to 23 and fit out of the supermarket is now scheduled for January with the residentialdue for completion in May.

Cobiaxdeck: how it works:

These precast panels offer several advantages in projects demanding large spans, without beams and with areduced number and size of vertical bearing elements.

Slab thicknesses range from 240mm to more than 600mm.

The system has been designed to remove the non-working, dead load inconcrete slabs while maintaining biaxial strength. This is achieved by placinghollow plastic spheres between the upper and lower static reinforcement of theconcrete slab, displacing concrete where it has no structural benefit. The effectis to decrease the overall weight by up to 35% when compared to a solid slabof the same bearing capacity. The reduced weight allows the quantity anddimensions of vertical bearing elements, such as columns, to be reduced. Yetthe slabs offer very high load carrying capacity and flexibility.

The flat slab produces flat unobstructed soffits because it does not requirebeams and the costs of installing services in a building are also substantiallyreduced. Heavy lifting:

The precast concrete "biscuit" base

Structural Engineer November 2008

STEPHENSON meeting and exceeding targets

STEPHENSON are exceeding targets on Kingston Quay in

Glasgow, a residential apartment development, producing

a floor a day, five floors a week with Ischebeck Titan

Climbtrac access platform and the DOKA Wallform system.

For further details on this method of construction and

Tunnelform, along with Design & Build of both Sub and

Superstructures on Reinforced Concrete Frames call

Stephenson on

+44 (0)1403 824960

Concrete Magazine November 2003

Alfred McAlpine ConstructionHarbour ExchangeBldg 6/7/8 & 9, Isle of DogsBunhill Road, London

Balfour Beaty LtdApollo StreetWoolwich Building Society HQ, Woolwich

BAM ConstructionAddenbrookes NLMB, Cambridge

Berkeley HomesSt Edmunds Terrace, LondonNorth End Road, LondonLawfords Wharf, LondonGun Wharf Quays, PortsmouthEast Side Plaza, Portsmouth

Costain Construction LtdAldersgate Street Car Park, LondonBedfont Lakes, HeathrowBirchin LaneChelmsford Town HallCivic Hall, Phase I & II, Grays, EssexPall MallRose Court, Southwark Bridge, LondonSt. Mary Axe, LondonMetro Store, SouthendCounty HallClyde & Langbourne Wharves, E14Parkwood Phase 6, CanterburyMelrose House, Saville Row, LondonGracechurch Street, LondonWomens Services Redevelopment, GloucesterDeptford Green School, SE14

Costain Skanska J.V.King’s College Hospital PFI

Countryside PropertiesNightingale Estate, Hackney, Phase 7AMaster Gunners Estate, Woolwich

Fairview Homes LtdColindale, NW9

Galliard Construction LtdHigh Road, Ilford

HBG ConstructionArchbishop Grimshaw RC School, BirminghamTesco Development, OrpingtonSmiths Wood Sports College, Birmingham

Higgs & Hill LtdHalkin Street Hotel, LondonWorthing Hospital, Phase II

Holmes BuildingCarlton Gate, W9

James Longley ConstructionLondon Road, CrawleyMagistrates Court, MaidstoneRegents Mews, BrightonTown Hall Car Park, CrawleyKilnmead, CrawleyBedfont Road, Stanwell

John Laing Construction LtdArmour & Union House, London EC2C & A Store, KingstonFrimley HospitalKing’s College Hospital, LondonLondon Road, CrawleyRoyal Mint, LondonSt George’s Hospital, TootingSouthend HospitalHSA Hotel, HeathrowAviation House, WC2

Galliard HomesVison 20, Ilford

Geoffrey OsborneGLA Building, Tower Bridge, SE1Bridge Street, GuildfordLongford Gardens, London

Kyle Stewart LtdEastcheapKewRegent StreetVanson Development, Crawley

Kier LtdEast Surrey Hospital, RedhillWinterton House, Commercial Road,LondonSouth Street, MayfairHammersmith HospitalChiswell Street, LondonButlins Spa Hotel, BognorWhitmore High School, HarrowSouthampton Operations Command UnitSouthampton General Hospital

Leonard Stace ConstructionSouth Quay, Isle of Dogs

Lilley ConstructionMuniciple Insurance Building, MaidstoneRedhill Station

Lovell Construction LtdBrightonLewesSt. James Square, LondonUxbridgeBouverie Street, EC4

MultiplexSentinel Point, Vauxhall

Nicholas King HomesDrayton Green Road, W13

Norwest Holst ConstructionSouthampton Magistrates CourtSouthampton UniversityLangton Close, UCL

Octagon DevelopmentsManor House, Golders GreenWall Hall, WatfordHolne Chase, Hampstead

PersimmonNeptune Way, Southampton

Robert McAlpine ConstructionFrimley Business Park

Shepherd ConstructionCancer Clinic, London

Simons ConstructionHolmes Place, Leisure Centre, Farnborough

St George Properties LtdSmugglers Way, Wandsworth, Block A-DHorizon Building, Canary Wharf, E14Warwick Road, W14, Phase I, II & IIIEFFRA, Vauxhall Bridge – Phase II, III IV, V, VIImperial Wharf, Fulham, SW6 – Phase I & IIImperial Wharf, Fulham, SW6 -- ‘E’ BlockPutney Bridge, LondonBattersea Reach, London Phase I, II & IIIVantage, Southwark, LondonMarketing Suite, The Tower, SW8Vantage, SE1Battersea Reach S Block, London

Stephenson Developments LtdBrimson Mews, Weybridge, SurreyGurnard, Isle of WightWilmington Heights, Totland, Isle of Wight

Tarmac ConstructionLondon Road, StainesStafford Road, Wallington

Taylor WoodrowJohn Lewis Stores, High WycombeHammersmith Broadway, London

Trollope & Colls Ltd55 Moorgate, LondonCurzon Street, LondonFarringdon Road, LondonLeadenhall Street, LondonLondon Road, RedhillPrescott Street, LondonStandard Chartered Bank, BishopgateWorship Street, London

Wates Construction LtdEssex Road, LondonGreat Malborough Street, LondonLondon Road, RedhillNiblett Hall, LondonWimbledon Station Development

Walter Lilley Construction LtdBowling Green Lane Car ParkRoyal Crescent, LondonWelcome Foundation, Beckenham

Willmott Dixon ConstructionClifton Street, EC2

Wimpey Construction LtdAPU University, ChelmsfordEsher Town HallHQ QMG, AndoverMarsh Lane, SouthamptonNorton Folgate, LondonRedbridge Hospital

LONDON & SOUTH

RELEVANT EXPERIENCE

St George Wharf, Vauxhall East Side Plaza, Portsmouth

Albatown DevelopmentsJames Morrison Street, GlasgowCorner Site, Glasgow

Ashleigh Scotland LimitedThe Plaza, Glasgow

AWGFestival Park, Glasgow

Barr LimitedNorth Glasgow College, Glasgow

Barratt East ScotlandBrunswick Road, EdinburghSlateford Road, EdinburghFourth Quarter, EdinburghPlot 22, The Fusion, Edinburgh

Cala HomesEast Fettes, Edinburgh

Costain Construction LtdGeorge Square, GlasgowHunters Square, Edinburgh

DandaraGlasgow Harbour Phase II, Glasgow

Gregor PropertiesBelford Lodge, Edinburgh

HBGGlasgow University

Henry Boot (Scotland) LtdLomond House, Glasgow

Kier Scotland LtdNovotel Hotel, Edinburgh

Lilley ConstructionSt. Andrews Square, Edinburgh

Manor Kingdom ConstructionIngram Street, Glasgow

MillerScottish Centre for Regenerative Medicine,Edinburgh

Robert McAlpineQuartermile 16 & 18, Edinburgh

Ogilvie ConstructionKingston Quay, GlasgowGlasgow Cross, Glasgow

Strathclyde HomesSalamander Street, Edinburgh

WisebuildHopetoun Street, Edinburgh

Yor LimitedCroythorn House, Edinburgh

SCOTLAND

BAM Construction

Filton School, Bristol

Bellway Homes

Prospect Place, Cardiff

Costain Skanska J.V.

HMP Parc Prison, Bridgend PFI

Higgs & Hill Ltd

North Star Swindon

John Laing Construction Ltd

Combined Court Centre, Bournemouth

Eagle Star, Bishops Cleeves, Cheltenham

Bristol Children’s Hospital

Bristol & West HQ, Bristol

Jehu Project Services

SA1 Hotel, Swansea

Kier Build

Hampshire Centre, Bournemouth

Leadbitter

The Learning Zone, Ebw Vale

Midas

Future Inns, Cabot Circus, Bristol

Peninsula Dental School, Plymouth

211 The Strand, Swansea

Morgan Ashurst

Wimborne Road, Poole

Robert McAlpine Construction

Woodland Court, Bristol

Portwall House, Bristol

Rednock School, Dursley

Southgate, Bath

Town Centre Redevelopment, St Austell

Taylor Woodrow

Clinical Centre of Excellence, Bath

WALES &SOUTH WEST

Alfred McAlpine ConstructionGreenquarter, Manchester, Phase 4 & 5

BAM ConstructionSkelmersdale College, Lancashire

Bovis Lend LeaseSpinningfields, Manchester

David McLeanGreat George Street, LeedsPSDA 9, LiverpoolCity Island, LeedsThe West Yorkshire Playhouse, Leeds

Gleeson Building LtdEcho 1 & 2, LeedsDurham Johnson High School, Durham

HBGLRC Sheffield University

Stephenson Developments LtdMedbourne Park, Milton KeynesOuzel Meadow, Middleton, Milton KeynesRiverside Walk, Monkston, Milton Keynes

Westleigh DevelopmentsWoolmonger Street, Northampton

Eric Wright ConstructionThe Picture House, Bolton

NORTH EAST& NORTH WEST

RELEVANT EXPERIENCE

Kingston Quay, Glasgow

Prospect Place, Cardiff

Learning Resource Centre, Sheffield

SUBSTRUCTUREPilingExcavationTemporary WorksReinforcementFormworkConcreteDrainageExternal Works

SUPERSTRUCTUREInsitu Concrete FramesFalsework & FormworkScaffoldingScreedingPrecast ElementsStructural Steel DESIGNFull Structural DesignDesign DevelopmentReinforcement Detailing

CONSTRUCTION General ContractingShell & Core

CONSTRUCTION MANAGEMENTManagement Services

STEPHENSON DEVELOPMENTSProperty Development

Tel: 01403 217000 Fax: 01403 215750

Provender Mill, Mill Bay LaneHorsham, West Sussex, RH12 1SS

www.stephenson-ssc.co.uk [email protected]

[email protected] Tel: 01403 217753

HORSHAM, ENGLAND BRIDGEND, WALES BELLSHILL, SCOTLAND

Documents

RC Frames Profile