Discussion on How Can We Get the Cover we Need? by Professor L.A. Clark

Mr R.A. Webb (Prescott Consulting Engineers) I would like to ask for futher information on the following points from Mr Maranian’s paper. (1) Fig 1 types 3 (b) & (c) show cracks starting away from the backing strip, and thus it is assumed that they started at some form of inclusion. Is it known how good the original NDE work was -were any inclusions within the Code limit? If so, do these need modifying?

Republic Plaza, with a structural height of 281m, is the tallest building in Singapore. This paper describes measurements of dynamic properties made during the construction period and the detailed modal description obtained for the completed, but unoccupied, structure. The dynamic characteristics show that, despite the apparent simple symmetry, which leads to two very close fundamental translational natural frequencies, many of the higher modes have strong torsional components whose nature has been determined in the measurements. Finite element modelling of the core wall/steel framing system gives reasonable agreement with the measured translational fundamental frequencies but, without a high level of refinement, cannot reflect the torsional behaviour. There is no evidence that the curtain wall system affects stiffness or damping properties of the structure at low excitation levels. J.M.W. Brownjohn, T-C. Pan and H-K. Cheong

Comparisons are made between the provisions for the earthquake-resistant design of reinforced concrete (RC) buildings in Eurocode 8 and those from three countries with a long tradition in seismic Code development, i.e. the USA, New Zealand, and Japan. The paper gives particular emphasis to the design of frame structures. Likely future developments to Codes in the four regions are outlined, and critical aspects of the provisions that should be reviewed during the process of development of a truly international Code, probably within the framework of the International Federation for Concrete (fib) activities, are identified. E.D. Booth, A.J. Kappos and Professor R. Park