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Technical will suffer an increase, in some cases 30% or more. This is largely due to the diagonal, is in line for a meaningful increase in design force. tapering (to the point of withdrawal at h/d = 5) of the 0.85 factor for lack-of- correlation, which BS6399-2 applied irrespective of height or slenderness. Conclusion Updated UK wind code or harmonized Eurocode? Perhaps it should be Partial Factors conceded that this new regime is neither fish nor fowl. Europhiles and Arguably the most serious impact on our structures, of any height, will be traditionalists alike may find its presentation unappetizing. Yet after a little made not by EN1991-1-4 but by EN1990. This dictates a partial factor of 1.5 effort with the knife and fork, and some chewing over, its digestibility may where wind action is the leading variable action, as in lateral design or an surprise us all. uplift situation. This is an increase from the factor of 1.4 previously applied. Wind is now taken just as seriously as any other variable action when it is ‘leading’. A vestige of its traditional underassertiveness remains in the relatively low combination factor applied when wind is an ‘accompanying’ variable action. This is cold comfort because situations in which wind governs are commonly those in which it is the only variable action, countered by unfactored permanent (dead) load alone. Note that equivalent horizontal force represents an inclination of the gravity action and is factored as such. It is not an independent variable action. Implications for future design By comparison with a pre-Eurocode design, it seems likely that lateral forces will increase, at least for the higher buildings in which they matter most. Impact on member sizes will vary from building to building, and from member to member, but clearly lateral forces will be more demanding of attention. There will be consequences, not least for connection design, in moment- resisting frames. In braced buildings, columns under tension gain a little relief from enhanced holding down power of reinforced concrete floor slabs whose density is taken as 25 not 24 kN/m3. On the compression side increased factors on wind will tend to be compensated by the reduced factors on Would it be far-fetched to suggest that despite appearances this might be gravity (though combination-factored wind will contribute to ultimate design the best wind code yet? We need a good one, as EN1990 partial factors make compression, which is tedious). Any member resisting wind alone, such as a future structures work harder against wind. NEW ON-LINE TRAINING presented by the SCI As the experts in steel design, the SCI have prepared a number of its courses to be presented on-line. Our courses will include:  Steel Building Design to EC3 On-line training offers flexibility and facilitates access to wider  Portal Frame Design audiences. Delegates can attend courses from the comfort of an  Stability of Steel office or home, without incurring travel and accommodation costs.  Connection DesignFrame Buildings For more details of course content please visit: www.steel-sci.org/courses October 10 33NSC


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