To shoppers on nearby Oxford Street it is just another building site. But to a team of structural engineers, 70/72 Gros- venor Street is as significant today as was the Crystal Palace in 1851.
New 3D modelling software being used for the first time means the eight storey office development represents a revolution in structural design and project management, believe the team members.
Though computer generated 3D models have existed for some time, it has not been possible before for the engineer, steel fabricator and contractors to work from the same model.
The software has been developed by the pan-European Computer Integrated Manufacturing for Steel Construction (CIMSteel). CIMsteel has been driving towards the harmonisation of design codes and introduction of computer integrated manufacturing techniques for almost a decade. But difficulties in developing translation software robust enough to transfer engineering data between disciplines held up progress. On this project the system is being used in earnest for the first time.
The new system allows engineers to create 'virtual frames' that can be analysed and priced quickly. The structural engineer creates an intelligent 3D model that can also be used by the project contractors. Work carried out generating models does not have to be duplicated, greatly reducing contract lead-in time and removing the possibility of discrepancies.
Sophisticated translation software allows the model to be shared with other parties to the contract. This allows contractors to tender more quickly and accurately using the engineer's model. It also enables fabricators to work straight from the same model. For the Grosvenor Street project, consultant engineer Whitby Bird & Partners produced the original model from which steel fabricator Rowen then worked. It can also be fed into construction management software to show an animated sequence of construction.
Whitby Bird and Rowen had used early versions of the software on a factory development in Kent. 'That was the first time CIMsteel and its translation software was put to the test in anger,' says Richard McWilliams, the Whitby Bird engineer responsible for developing the system.
'Though the project evolved beyond the capabilities of the CIMsteel software available at that time, the feedback we provided to the project developers at Leeds University and Taylor Woodrow allowed them to take the system to the next stage. The improved system is now up and running at Grosvenor Street.'
Whitby Bird generated the Grosvenor Street model using structural modelling package STRUCAD. This was then issued both at tender stage and for construction on CD-Rom. Rowen transferred the model into structural design software Xsteel using the new CIMsteel translation software. This allowed the fabricator to produce fabrication details straight from the structural engineer's model.
'We were very keen to use the CIMsteel translation software on this job,' says Rowen technical director Dave Cunliffe. 'It meant we have had better information because the consultant has been detailing steel elements rather than straight lines. And there were no arguments about what is included at inquiry stage because we were using the engineer's model.'
Cunliffe says there have been major time savings. 'We have saved two weeks in estimating time because of the improved information up front. We also saved in time to site because we did not have to generate another model.'
Cunliffe predicts that this represents the first step towards the ultimate goal of everybody sharing the same online model. This view is shared by the Whitby Bird engineer responsible for creating the Grosvenor Street model, Tony Pocock. 'In the future, everybody will work from the same model. In the meantime it is a case of adding one discipline at a time.'
Though steel fabricators have been using 3D models for some time, it is only in the past two years that structural engineers at Whitby Bird have started producing information in this form.
Developing the model which others can then use 'brings the project closer to us', says Pocock. 'And it reduces the lead in time because contractors do not need to regenerate a model and it removes the problem of contractors using inaccurate models.'
There is however a long way to go to achieve the full potential of the system. 'Issuing revisions is one of the big issues,' say Whitby Bird project engineer Claire Thomas. 'On Grosvenor Street we created the initial model but cannot create a new model every time there is a revision. We do a print of the area in question on a conventional section and show the revision on that detail.'
'We are applying the lessons learnt here to other jobs,' adds Thomas. 'For example, producing steelwork information on conventional general arrangement drawings and on models produced discrepancies. So in future we shall produce the 3D model first and generate the general arrangements from that.' RT