Page 28

NSCJuly2016digi

Type of joint Design resistance 28 NSC July/Aug 16 Managing significant base shear deserves careful thought, especially as the UK appears to have an almost unique approach to detailing this interface. Other countries tend to use anchors solidly cast in (so therefore cast with rather more precision than is typical in the UK) and have a mere smear of grout. In the UK, we use bolts cast in conical or cylindrical formers to allow for significant movement, and generally a significant thickness of grout, as shown in Figure kft2 ( 2 n y00 ) (1-) sin1 kn fbt0 sin1 ( ) 2h1 fy0t0 3sin1 ( ) 2h1 3 – which may be deeper in practice due to the variability of the concrete levels. The baseplate tends to have 6 mm oversize holes – so it is unlikely that all the bolts are in bearing on the plate. Friction may transfer shear, as may the bolts, but for significant base shear additional measures may be justified. This may be to consider the grouting operation as special, rather than mundane, and ensure the final result is as specified. More elaborate measures might involve locating Technical Figure 2: Typical joint checks from BS EN 1993-1-8 Figure 7: LTBeam software – stabilising load N1 b1 t1 h1 t0 h0 b0 1 Chord face failure β ≤ 0,85 N1,Rd = + 4 1- /m5 sin1 Chord side wall buckling 1) β = 1.0 2) N1,Rd = + 10t0 /m5 sin1 Brace failure β ≥ 0,85 N1,Rd = fyit1(2h1-4t1+2beff)/γM5 Punching shear 0,85 ≤ β ≤ (1-1/γ) N1,Rd = + 2be,p /m5 sin1 26


NSCJuly2016digi
To see the actual publication please follow the link above