The validity of the provisions of both the British and the European codes of practice for design in composite slabs of shear connection for beams has been questioned in recent publications, based on test results that show sub-standard shear resistance and low slip capacity. These issues are explained and discussed. The provisions of EN 1994-1-1 are generally more relevant and conservative than those of BS 5950, but its coverage of the problem areas is not complete. Although further research is needed, it is recommended that published guidance to designers of beams that support composite slabs should at once be revised to take account of the Eurocode rules, and of the conclusions given here. Some combinations of parameters where particular care is needed are described. R. P. Johnson, FREng, FIStructE, FICE Emeritus professor, University of Warwick
This paper describes the development of a technical solution for the two offshore platforms of the Sakhalin II project, in order to cope with the special characteristics of the arctic and seismic environments. The emphasis is on describing the design challenges and how they were addressed during the Front-End-Engineering-Definition leading to the concepts currently going through detailed design. Transportation and installation aspects, in such a remote environment with a limited weather window, form an integral part of concept development and needed to be addressed early on. The structural solutions for the two offshore platforms comprise a four-legged concrete gravity based structure (GBS), supporting an integrated deck that includes a seismic isolation system between topsides and GBS. In addition to providing seismic isolation, this system also effectively isolates the topsides from wave, sea ice and thermal contraction loadings and hence simplifies the design considerably. The structural concepts, which at the time of writing are at the final stages of detailed design, provide effective solutions taking due consideration of constructability, transportation, installation and operation for 30 years. Christopher S. J. Clarke, AMEC Oil and Gas Robert Buchanan, AMEC Oil and Gas Michael Efthymiou, Sakhalin Energy Investment Company Ltd Christopher Shaw, AMEC Oil and Gas