Making the connection

Senior structural engineer at Trada Technology Ltd, Dr Keerthi Ranasinghe, urges engineers to get behind Eurocode 5 and take advantage of the opportunities offered.

ENGINEERS ARE rather wary of Eurocode 5. This has been apparent among many who have attended TRADA’s introductory and connectionsworkshops. Although there are indeed major differences between EC5 and the comfortingly familiar BS 5268, we can reassure engineers that EC5 will not change the way they design. It will, however, change the way they perform their calculations and admittedly this demands a fundamental shift in approach.

On the other hand, the workshops have equally demonstrated that there is a whole generation of young engineers who come to EC5 without baggage, ready to embrace it wholeheartedly. We as an industry must harness that enthusiasm and support them as they work with this complex but well researched design tool. It is, in our view, arguably the best code ever. It consists of three parts:

• Part 1-1: General – common rules and rules for buildings
• Part 1-2: General – structural fire design
• Part 2: Bridges

Each part has its own National Annex (NA). All three parts have already been published, along with all the National Annexes, most of the supporting standards and most of the harmonised product standards. There is little reason therefore for either designers or product suppliers to hold back - yet everyone appears to be waiting for others to make the first move. This, quite understandably, may partly be due to the market downturn, but if it is down to the apparent threats and challenges that EC5 brings, then they are mistaken.

EC5 is not yet referred to in Part A, but BS 5268 is no longer supported by BSI. Clients are
waiting for this situation to settle down, while architects are waiting for suppliers, who in turn are waiting for demand to drive things forward. Engineers are waiting for everyone else, so at the moment, nothing is happening. Nothing, that is, apart from a worrying market monopoly developing as a handful of champions forge ahead of the pack.

Another issue is that while EC5 has taken almost 30 years to develop, designers have had barely 18 months to digest it, if one considers the time since the completion of publication of all connected Eurocode standards.

Any new code looks daunting at first sight, at least during the early years of implementation. However, wiser practitioners look beyond to identify the hidden strengths and opportunities.

One of its strengths could be said to be its rigorous approach to calculations, but this may also be one of its weaknesses. BS5268 provided tables of values, with all the hard work done behind the scenes. Connections for example pose a unique challenge for designers and probably constitute one of the most detailed yet frequently misunderstood aspects of EC5. It requires the designer to perform lengthy calculations to get the member sizing, fastener sizing and arrangements right.

Current economic conditions and ever tightening project budgets mean that engineers would not be happy to make the transition to EC5 voluntarily, unless they are forced by project specifications and contracts. In recognition of this, TRADA has launched the new timberconnections and timberconnectionsPro software.

Ironically, while designers struggle to grasp the new code, EC5 is opening up opportunities
for timber suppliers. Under BS 5268 it could take months if not years for new products to gain acceptance. Under EC5 this is not so. Designers need a product’s characteristic values for their calculations, while manufacturers and suppliers just need to understand what characteristic values are relevant for their product(s) and use approved or codified methods of testing to obtain them.

A whole range of construction products and materials are already covered by harmonised
product standards or through European Product Approval Guidelines (ETAGs) - structural timber and related products (glued laminated timber, LVL, I-joists and other engineered wood products), wood-based panel products (plywood, OSB, particleboards, fibreboards), fasteners & connectors, trussed rafters and timber frame building ‘kits’.

Notified bodies, like BM TRADA Certification, can also help certify new products not yet covered by harmonised standards or ETAGs, so cannot therefore be CE marked, a further opportunity for manufacturers to identify niche markets, perhaps. In the same way that we are urging engineers not to hold back, suppliers and manufacturers should not delay learning about the essential requirements relevant for their products, to stay ahead when EC5 is used in earnest.

TRADA EC5 support services TRADA’s timberconnections and timberconnectionsPro software will calculate the load capacity of nails, screws, bolts, dowels and coach screws in two and three member combinations of timber and steel.

timberconnections is available free to TRADA members via www.trada., while timberconnectionsPro is available on subscription, at a discount to members.

Subscribers will be able to generate custom PDF reports which summarise all the design parameters and results, useful for calculation reference and Building Control requirements. TRADA Technology is staging further Eurocode 5 Connections workshops on 24th June and 19th
October 2010. The cost is £199 + VAT for TRADA members, or £259 + VAT for non-members, to include two months’ free access to timberconnectionsPro. To book email .