Bi Steel Technical Report

7/30/2019 Bi Steel Technical Report

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Bi-Steel Technical Report Civil Engineering Construction

BEng of Civil Engineering Civil 3

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1.0 INTRODUCTION

It was required as part of my BEng of Civil Engineering coursework to complete a technical

report regarding a new innovative material or technique used in modern civil engineering

construction. After careful considerations to the various areas of the civil engineering industry

using the resources available via the library network I finally decided that Bi-Steel; a relatively

new material would be the topic of my technical report.

Bi-Steel is a British made material consisting of two steel plates connected together usingtransverse bars with the remaining void to be filled with ready mixed concrete providing a

material with outstanding strength. This report will discuss a more in-depth analysis of the

innovative material including its background, advantages and benefits, reasons for development

as well as its application in civil engineering industry, and its structural behaviour. All

information was obtained from E-journals available on the college library network as well as

approved websites. It’s also worth mentioning the Corus Construction website was an excellent

source of information on the material.

The report will be divided into chapter and sub-chapters in an explanatory order. The chapters

are laid out as follows:

Background

Advantages & Disadvantages

Safety & Cost

Applications

Structural Behaviour

Personal Comments where relevant





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2.0 BI-STEEL: A BACKGROUND

2.1 REASONS FOR DEVELOPMENT

As mentioned above the Bi-Steel material consists of two steel plates connected together using

transverse bars and filling the remaining void with concrete providing a material with

outstanding strength. This form of sandwich construction is new, unique and patented system;

however the double skinned composite system has been known for years but never put into

practice due to its impractical nature.

Previous double skinned panels were fabricated on site and when filled with concrete dealt a

large amount of pressure onto the panels which lead to hydrostatic bulges, driving the panels

apart. In an industry famous for cutting corners to reduce costs this system proved more trouble

than it was worth.

The major advantages (see sub-chapter 2.2) which are incorporated with this material were too

important to ignore and this is evident from the heavy investment of several millions of pounds

into the development of these double skinned composites over the last five years. The result: asteel concrete-steel composite product, called British Bi-Steel comprising of two steel plates

held apart by a welded array of transverse bars (see photo 2.1) The panels are factory produced

to tight tolerances in flat or curved form, and provide a modular system which addresses the

build ability issues

Photo 2.1 The Bi-Steel Panel





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2.2 ADVANTAGES & DISADVANTAGES

Upon discussing the development of the Bi-Steel material engineers believed the product had

big advantages had they found a way of manufacturing the product simply and making it cost

effective. Certainly when analysed the advantages far outweigh the disadvantages.

The pros of Bi-Steel include:

Improved ductility

Superior impact resistance

Water penetration resistance

Light structure in comparison to traditional RC designs

Less welding required than traditional stiffened steel

Less need for regular inspection

Less area to coat

Easy set up on site (see photo 2.2).

The cons of Bi-Steel include:

High cost as there are three materials considered (see sub-chapter 2.3)

Lack of investment in offshore markets like here in Ireland

Photo 2.2 Panels Erected on Site





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2.3 COST OF BI-STEEL

As mentioned above one of the few disadvantages of the Bi-Steel product is the cost.

This means that the products unique selling point, a double skinned panel, is also its

greatest downfall as the cost of all these combined materials are not cheap. The sellers,

Corus Construction are based in the UK meaning that here in Ireland there would also

be a substantial importation cost. Unfortunately the otherwise very helpful website

www.corusconstruction.com failed to include a standard price which is also

understandable with current rates for construction materials fluctuating.

Curiosity had got the better of me and I sent the company an e-mail regarding typical

costs of the material which was redirected to Tata Steel. After a week and still no reply I

took it upon myself to ring the company. Several calls later, the very helpful business

development engineer Robert Fisher got back to me with a quote stating:

“The total in-situ price for a typical Bi-Steel wall, for example a lift shaft for a 15 storey

high building would be about £380 (€430) per metre squared of wall area.”

http://www.corusconstruction.com/







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2.4 SAFETY ISSUES

There are few additional safety issues regarding the Bi-Steel product that isn’t already

considered when doing your typical concrete pour or erecting a steel structure, however both

these are potential hazards and are essential to understand before use of the product. Care is also

needed with regards Bi-Steel when:

Welding the steel plates with the transverse bars

Transporting to site

Erecting on site, aside from what is mentioned above all Personal Protective Equipment

is necessary to avoid any accidents or damage on site

Pouring concrete, as above all PPE is necessary including hi-visibility jackets, hard hat,

gloves etc (see photo 2.3).

Photo 2.3 Concrete Pour Safety





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2.5 APPLICATIONS

The Bi-Steel product has become increasingly specified for structural building cores as it is

superior to modern reinforced concrete cores. However there is a second and far more vital

application to the product and that is in the construction of blast chambers. Bi-Steel can be used

in applications for security and defence in the construction of high integrity blast protection

buildings that require superior levels of physical security to protect against terrorist bomb

attack.

Funding was provided and these systems are now set up in places like Whitehall and the

National Barrier Asset as well as the New Scotland Yard (see photo 2.4) to provide security to

key Government and high security areas. Refer to Bi-Steel presentation for more information on

some of these projects.

Photo 2.4 New Scotland Yard Bi-Steel Barriers





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2.6 PERSONAL COMMENTS

In a world with corrupt leaders in countries like Libya who turn on their people or terrorist

attacks which are becoming more deadly and globalised, this product it vital for the protection

of the people. It has proved effective in key Government areas in London and they have since

expanded into the European market. Bi-Steel has outstanding benefits for the extra pound and

its simplicity is in its fast construction on site and quick concrete pours.

On the other hand in a construction industry that has all but crashed there is little need to spent

money on materials that have extra benefits but rather on those that get the job done and just

about! From working in an engineering consultancy I have experienced clients and/or

management changing or removing materials and products from jobs simply because it’s not

entirely necessary and to help reduce costs.





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3.0 STRUCTURAL BEHAVIOUR

3.1 INTRODUCTION

From previous chapters we have learned what the Bi-Steel panel is and its benefits but one of

the important aspects of these new innovative materials is how it actually works. Structurally

speaking it is vital to know how a material works before putting it to use. The notion of

sandwich construction (steel-concrete-steel) refers to the steel panels resisting bending while the

core resists shear. This chapter outlines the structural behaviour of the product including the

following:

Manufacture

Behaviour of sandwich beam

Connections

Cracking





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3.2 MANUFACTURE

After heavy investment of £1m into a new friction welding machine it is worth note how the

process works. The welding machine illustrated in photo 3.1 below spins the bars around

consecutively resulting in opposing forces to the plate at both ends of each bar until the required

temperature is reached for fusion to occur. The welding process causes a small deflection

inwards purely dependant on the thickness of the plate and its bar spacing. This deflection is

countered by the small outward deflection due to the pressure of the wet cement.

Photo 3.1 The Bi-Steel Welding Machine

Similar products have had factory set dimensional limits and the Bi-Steel product is no

exception. Fig. 3.1 illustrates the typical factory produced units for manufacture for the Bi-Steel

panel.

Fig. 3.1 Factory dimensional limits





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3.3 SANDWICH BEAM BEHAVIOUR

As we already know the panels resist bending and the core which refers to the transverse bars

resist both longitudinal and transverse shear. They also however, aid the prevention of plate

buckling which occurs outwards. The bars themselves depending on their sizes are subject to

shear, tension and bending.

The shear forces of each bar are found by measuring the strains between the bars. Experiments

have shown that for beams with small length/depth ratio the friction between the steel plate and

the concrete can have significant effects on the bar shear. Figure 3.2 indicates the ultimate stress

of the bars.

Fig. 3.2 Ultimate shear stress of embedded bars

The tension and bending are indicated by internal strain gauges. The tension is over estimated inexperiments as the concrete itself resists most of the shear. It is when cracking occurs that the

predicted tension in realised. Photo.3.2 shows the arrangement for experimental testing.

The concrete cracking that occurs in testing first would be vertical and appear at the bar

positions and the diagonal cracking stems from these vertical cracks but have no apparent effect

on bar tension or indeed the deflection. Typically as the load increases more independent cracks

appear.





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Photo 3.2 Test Arrangement for beams

3.3.1 FATIGUE TESTING

Fatigue failure occurs when a material is subject to constant loading and unloading in its testing

and it is all part of the experimentation of the Bi-Steel product. The proposed method of the

design guide for Bi-Steel of connections under fatigue loading is based on BS5400. The process

is simple, the fatigue life of the connection should be found by calculating the plate tension

failure separate from the bar shear failure and take the worst case scenario. Photo 3.3 below

illustrates plate tension and bar shear failure modes.

Photo 3.3 Beam plate tension and bar shear fatigue failure modes





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3.4 PERSONAL COMMENTS

The testing process was extensive and so it should have been for it to match the massive

investments. The testing of the material showed its strength, ductility and most importantly its

containment which is its unique selling aspect. However, testing has also revealed the products

capability of being used in tall building cores, where its rapid construction is again ideal.

Structurally the material is impressive as the results have indicated and it is easy to see the

importance of a material with such outstanding overall strength being used in areas that are of

great public or indeed private importance.





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4.0 CONCLUSION

It is clear from what is discussed above the importance of the Bi-Steel product in the modern

world. The simplicity of combining two very different, yet, effective materials into one

exceedingly strong material is encouraging for an industry which is quite frankly in an era of

transition.

The benefits of the material are impressive as very few, if any, can match its overall properties.

Its blast resistance is second to none and has been implemented as mentioned above in

numerous Government and public areas of importance.

Its cost is not surprising considering the material can in fact save lives but in a construction

industry, particularly here in Ireland, which will cut and change things deemed not necessary or

vital to the construction, I expect it to be a long day before we see the Bi-Steel panel utilised to

its fullest in this country.

After heavy investment by the British Government the material has finally hit the ground

running and after all the necessary extensive testing mentioned above it is great as a student of

Civil engineering to see a new innovative material be implemented so quickly and to such

importance. This material is proof that industry can still be moved forwards and it is in our

hands to promote and encourage projects like this in modern day society.





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5.0 REFRENCES

JOURNALS

“Developments in Sandwich Construction”

Journal of Constructional Steel Research Volume: 62 Issue: 11

Chapman, JC & Xie, Min 2006

“The System That Cuts Construction Time”

Professional Engineering Volume 10, Issue 13

Greek, Dinah 1998

WEBSITES

www.corusconstruction.com

www.tatasteel.com

www.wikipedia.org



http://www.tatasteel.com/


http://www.wikipedia.org/









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6.0 APPENDICES

APPENDIX A: COMPANY BROCHURE





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http://www.corusconstruction.com/file_source/StaticFiles/Construction/Bi-

steel/Corefast%20Brochure%20DPS%20Final%20Approved%20130607%20.pdf

http://www.corusconstruction.com/file_source/StaticFiles/Construction/Bi-steel/Corefast%20Brochure%20DPS%20Final%20Approved%20130607%20.pdf





Bi Steel Technical Report

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