Product category:
Steel and Structural Frames
News Release from: Molabolt | Subject: Firebolt
Edited by the Buildingtalk Editorial
Team on 21 April 2005
New Firebolt anchor fixing
Andrew Orton, Marketing Development Engineer at Corus explains why he encouraged Molabolt to develop the Firebolt.
Andrew Orton, Marketing Development Engineer at Corus explains why he encouraged Molabolt to develop the Firebolt Like many others, 9/11 has had a significant impact on Andrew Orton, an engineer in charge of market development at Corus Tubes
This article was originally published on Buildingtalk on 8 Sep 2004 at 8.00am (UK)
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Although Corus had been looking at the issues surrounding the use of steel construction in fire before 9/11, that fatal day added an impetus to the research which has taken up much of Andrew's time since.
One area of special interest is the performance of steel connections in fire.
His attention was drawn to the Molabolt and he recognised in its unique qualities a good solution to the problem of reliably connecting steel beams to concrete filled columns, which are one of the most rugged types of column there is under fire conditions.
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On discussing it with Molabolt it was decided to develop the Firebolt.
Designed and patented by ABS Molabolt, the Firebolt is a unique fixing which will allow for maximum benefit to be derived from the combined use of steel and concrete in major construction projects.
Says Andrew: "Corus has been looking at composite construction for many years, researching and testing concrete filled structural hollow sections under all kinds of fire conditions".
"The concrete adds strength, disperses heat and helps the steel maintain its shape in high temperatures".
"We believe that one of the key issues in maximising the life-saving benefits of combining steel and concrete columns with steel beams lies in the design of the joints - and in particular the fixings used to secure those joints".
"We believe that the Firebolt will turn out to be one of the best solutions, available on the market today, for this kind of connection".
"Fire retardants can be dispensed with in many cases".
Recent debates within the structural engineering community have centred on the relative merits of steel structures versus concrete.
Andrew Orton believes that this is a misleading debate and that the priority must be to make sure that the frame, as the basic structural element, is as strong as it needs to be to maintain its form in high temperatures.
The use of fire retardants has a place, but in many cases it can be dispensed with.
In Andrew's view: "The issue is not whether steel is stronger, cheaper or easier to fix than concrete but rather that, by using a combination, we have an opportunity to dramatically improve the evacuation times available in the event of fire by creating a more robust kind of construction." Gino Dimola, Head of Research and Development at Advanced Bolting Solutions goes on to say "We satisfied Andrew's demands with the new Firebolt".
"Based on the Molabolt Peg Anchor it had a number of advantages over competitors on the market and we are very happy that we have been able to work with Corus on a product which we believe will bring major advances to structural designers and building services design engineers worldwide." Early indications are that the Firebolt exceeds all requirements for shear and tensile loadings.
Such is its design that, under test, it has proved to be stronger than the structure used in application.
Its unique design both disperses heat away from the steel frame and provides a major anchor into the concrete.
The University of Manchester, School of Structural Engineering is now working on exacting fire testing specifications designed to prove the robustness of the Firebolt under extreme heat conditions.
Additional Protection The ABS Firebolt provides excellent tensile properties and, at the same time, it also maximises the structural benefits of the concrete by providing a vehicle for heat displacement away from the steel outer frame into the concrete itself." Gino continues: "Hundreds of people might be alive today if the twin towers had remained structurally sound for an additional 30 minutes.
In this time the majority of those beneath the point of impact could have been saved".
"Fires, which generate intense heat, for example as a consequence of explosive substances, have taken on a heightened focus for those involved in major steel construction projects.
Previously, the concern to provide buildings with additional structural protection against fire was restricted in the main to known earthquake risk zones.
Since 9/11, that focus is increasingly falling on new high-rise buildings worldwide.
The issue is that the characteristics of steel changes with high temperatures, its strength decreases and it becomes less rigid.
In the past, this problem was addressed with the application of fire protection materials and sprinkler systems.
The primary objective of this approach has been to protect the steel for long enough to give fire-fighters time to evacuate the building and also to contain and, where possible, extinguish the blaze." Fundamental Gino added: "Clearly on September 11th 2001 this failed.
The twin towers remained upright for 45 minutes and 90 minutes after impact.
Research now indicates that their dramatic collapse was caused by the floors beneath the point of impact being unable to hold the static load when the physical properties of the main structure had been altered by the particularly fierce heat of the fires which engulfed the buildings"".
"The relationship between the columns and the floors was fundamental to the design of the towers".
"The ability of the vertical steel columns and floor steel work to hold on to each other under stress was critical and it appears that it failed too quickly and too easily".
"This point is also true of many other steel structures in cities across the UK, and worldwide, and the issues raised in a post 9/11 world need to be addressed." As part of Arup Fire's Research Work with the University of Edinburgh (as reported in New Civil Engineer 24 February 2005), analysis of high-rise building response to real fires they are finding very interesting structural responses.
These so far show very little relationship between time to collapse and quantity of fire proofing, but restrained thermal expansion of structural elements has a major effect.
In the light of these findings, Corus and ABS now firmly believe that the combination of steel and concrete building design and construction, and the use of the Firebolt to provide a fit-for-purpose anchor fixing, will truly herald a new era in the building of multi-storey structures worldwide.
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