γfL = 1.50 (Ultimate limit state - combination 1) Design HA loading for a metre width of deck : W = 1.5 x 8.66 = 12.99 kN/m KEL = 1.5 x 32.88 = 49.32 kN Maximum mid span Bending Moment with KEL at mid span = Mult Mult = (12.99 x 342)/8 + (49.32 x 34)/4 Mult = 1877 + 419 = 2300 kNm Note: Use of γf3 BS 5400 Pt.3 & Pt.5 - γf3 is used with the design strength so Mult = 2300 kNm. α2 = 0.0137 α2 = 0.0137 = 1.0 Note: For loaded lengths less than 20m the load is proportioned to a standard lane width of 3.65m, i.e. Knife Edge Load = 120 kN (per notional lane) Cl. Loaded length = 34m W = 336(1/L)0.67 kN/m (per notional lane) W = 31.6 kN/m (per notional lane) Cl. Clause 6.2 Problem: How do you work out the HA loading and bending moment for a bridge deck ? Example: Carriageway = 7.3m wide Deck span = 34m (centre to centre of bearings for a simply supported single span) Design for a metre width of deck : Cl.3.2.9.3.1 Number of notional lanes = 2 Notional lane width = 7.3/2 = 3.65m Cl.
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