St George Wharf

1. St George Wharf

2. Team Members • Marcus Blake - St George South London • Tim Dodd - White Young Green • Richard Moss - BRE • Martin Stephenson- Stephensons

3. St George Wharf • Proposed innovations, expected improvements, implementation and results

4. Electronic Exchange of rebar information • Expected Improvement • Significant savings in time on the part of the rebar supplier • Some savings in time on the part of the frame contractor and the main contractor

5. Electronic Exchange of rebar information • Method of Measurement • Anecdotal evidence on reduction in number of mistakes • Cost and time comparison by the rebar supplier • Cost and time comparison by the rebar detailer • Cost and time comparison by the contractor

6. Electronic Exchange of rebar information Electronic Exchange of rebar information • Implementation • Introduced part-way through project • Run in parallel with conventional approaches due to need for familiarisation and failure of large rebar manufacturer in the UK • Little perceived benefit by the detailer - tight existing programme • Greater potential for use where schedules produced electronically • Simple call-offs arranged - limited benefit in terms of control by the contractor

7. Electronic Exchange of rebar information

8. Rationalisation of main reinforcement • Expected Improvement • 15% reduction in man hours • 15% reduction in combined steel supply and fixing costs

9. Rationalisation of main reinforcement • Method of Measurement • Feedback on experience of use by designer/ contractor • Direct comparison between rationalised/non-rationalised by frame contractor • Out-turn cost on steel fixing from frame contractor

10. Rationalisation of main reinforcement • Implementation • Previous rationalisation already undertaken • Opted for standard 12m long stock length bars -Speed and simplicity of fixing + minimum material cost • Further comparisons required between consultant detailed slabs on first phase and trade contractor detailed slabs on subsequent phases • Man hours and costs being processed to quantify benefits

11. Use of prefabricated punching shear reinforcement • Expected Improvement • From manufacturer's literature (up to 80% saving in man hours) • From manufacturer's literature (up to 50% in overall cost)

12. Use of prefabricated punching shear reinforcement • Method of Measurement • No. of man hours per column head from frame contractor • Overall costs per column head from frame contractor

13. Use of prefabricated punching shear reinforcement • Implementation • Two shear stud systems investigated • Comparison with traditional links • Shear steel obviated wherever possible by increasing main steel over column heads • Limited benefits unless large number of links required

14. Use of prefabricated punching shear reinforcement

15. Accurate prediction of deflections • Expected Improvement • Greater predictability of actual deflections occurring leading to savings on future blocks on architectural details to accommodate deflections (i.e. cladding/internal finishes)

16. Accurate prediction of deflections • Method of Measurement • Actual deflections measured compared with predicted deflections using simple /sophisticated models

17. Accurate prediction of deflections • Implementation • Improved knowledge of actual deflections • Improved understanding of deflection behaviour • Greater confidence in predicting actual deflections in future • Further validation of the work from Cardington

18. Early age strength assessment using LOK tests • Expected Improvement • Quicker confirmation of slab strength • Cheaper and less time consuming than making and testing cubes • Manufacturers correlation may be relied upon • Cubes no longer required for early age strength assessment

19. Early age strength assessment using LOK tests • Method of Measurement • Direct comparison of costs and availability of test results using LOK tests as opposed to cubes • Accuracy and spread of test results • Need for correlation

20. Early age strength assessment using LOK tests • Implementation • LOK test run in parallel with cubes • Highlighted difficulty of accurately gauging concrete strengths at early ages • Further work required to convince all parties on reliability of LOK tests • Limited benefits on this phase owing to desired age at striking • No direct cost benefit

21. Early age strength assessment using LOK tests

22. Site comparison

23. New criteria for striking • Expected Improvement • Benefits to speeding up floor cycle with/without limitation posed by vertical elements • Increased certainty of delivering existing programme • Speeding up of existing programme

24. New criteria for striking • Method of Measurement • Comparison of criteria used and limitations on age at which striking can be undertaken

25. New criteria for striking • Implementation • Detailed comparisons of new and old criteria • Limited benefit in terms of striking strength owing to assumptions made • Limited benefit in early striking in general owing to time taken to construct vertical elements

26. New criteria for design of backpropping • Expected Improvement • Reduced requirement for backproping with consequent savings in labour and materials (50%)

27. New criteria for design of backpropping • Method of Measurement • Comparison of backpropping arrangements and in particular numbers of levels of backpropping required

28. New criteria for design of backpropping • Implementation • Benefit from pre-loading props clearly demonstrated • Resulting distribution through slabs closer to conventional assumptions • Difficult to predict/control level of preloading

29. Conclusions Prerequisites • Earlier contractor involvement • Contractor detailing - Minimise/eliminate shear reinforcement - Construction of vertical elements is a constraint. Benefits of innovations limited until impact of this removed or reduced - cost/benefits of novel methods of doing this being investigated