Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Paper format. 07-Str-A5 Advanced Structural Design, National Exams, May 2014 — 3 hours, closed book (handbooks and textbooks permitted, no notes on them; Casio or Sharp approved calculator). Seven questions of equal value; any five constitute a complete paper and only the first five presented are marked. All seven are solved here, because the set is intended as a study resource. All loads printed on the figures are unfactored.
Design data given on the paper (SI). Concrete $f'_c = 30$ MPa; structural steel $F_y = 350$ MPa; reinforcing steel $f_y = 400$ MPa. Prestressed concrete: $f'_{ci} = 35$ MPa at transfer, $f'_c = 50$ MPa, $n = 6$, $f_{pu} = 1750$ MPa, $f_{py} = 1450$ MPa, $f_{pi} = 1200$ MPa, losses $= 240$ MPa, hence $f_{pe} = 1200 - 240 = 960$ MPa.
Reference texts. CSA S16 Design of Steel Structures with the CISC Handbook of Steel Construction — plastic design (Cl. 8.6, 13.7), lateral–torsional buckling (Cl. 13.6), beam-columns (Cl. 13.8), plate girders (Cl. 14), composite beams (Cl. 17), welded connections (Cl. 13.13, 21); CSA A23.3 Design of Concrete Structures — flexure and shear (Cl. 10, 11), slenderness (Cl. 10.13–10.16), deflection (Cl. 9.8), footings (Cl. 15), prestressed concrete (Cl. 18); NBCC for load combinations; C. G. Salmon, J. E. Johnson & F. A. Malhas, Steel Structures: Design and Behavior; J. G. MacGregor & J. K. Wight, Reinforced Concrete: Mechanics and Design; T. Y. Lin & N. H. Burns, Design of Prestressed Concrete Structures; L. S. Beedle, Plastic Design of Steel Frames.
Check: load factors. The paper states only that the printed loads are unfactored, and gives no dead/live split. Every question below therefore treats each printed concentrated load as specified live load and factors it by $\alpha_L = 1.5$ (NBCC principal case $1.25D + 1.5L$); member self-weight, wherever it matters, is taken from the trial section and factored at $1.25$. A candidate assuming a different split obtains proportionally different sizes; the method is what is examined.
Check: section properties. Every steel section selected below is quoted by its plate dimensions (flange $b \times t$, web $h \times w$) and every property — $A$, $I_x$, $I_y$, $S$, $Z$, $J$, $C_w$, $r_x$, $r_y$ — is computed from those dimensions with root fillets neglected, which is slightly conservative. This makes every line checkable without a handbook; a rolled W-shape of equal or greater properties may be substituted directly.
Check: readings taken from the examination drawing. Three details are shown on the drawing but not stated in the question text. In Figure 1 the bases at A and D carry the fixed-support hatching and the question text says "the frame is fixed at the bases A and D", so both bases are fixed and the frame is three times statically indeterminate. In Figure 4 the 100 kN arrow at D points towards the column, i.e. to the left; A and E both carry pin symbols, making that frame indeterminate to the first degree. In Figure 5 the deck is 3 + 3 = 6 m wide over three beams spaced at 2.5 m, leaving 0.5 m overhangs — the slab-thickness annotation is not legible on the printed figure, so the deck thickness is designed in Question 7 rather than read off.
[Figure not reproduced: Figure 1 as printed on the examination paper: rectangular steel portal, fixed at A and D, beam capacity 1.5 M₊ and column capacity M₊. All loads shown are unfactored. See the official exam paper.]
