Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Paper format. National Exams, December 2015 — 07-Str-A5 Advanced Structural Design. Three hours, "closed book" (textbooks and design handbooks permitted, no notes). Seven questions; any five constitute a complete paper and all are of equal value, the printed mark split being 20 marks each. All loads shown on Figures 1–4 are unfactored. All seven questions are answered here.
Design data printed on page 1 and used throughout. Concrete \(f'_c = 30\ \text{MPa}\); structural steel \(F_y = 350\ \text{MPa}\); reinforcing steel \(f_y = 400\ \text{MPa}\); prestressed concrete \(f'_{ci} = 35\ \text{MPa}\) at transfer and \(f'_c = 50\ \text{MPa}\) in service, \(n = 6\); \(f_{pu} = 1750\ \text{MPa}\), \(f_{py} = 1450\ \text{MPa}\), \(f_{p,\text{initial}} = 1200\ \text{MPa}\), losses \(= 240\ \text{MPa}\), hence \(f_{pe} = 960\ \text{MPa}\) and the loss ratio \(\eta = 0.80\).
Check: load factors and figure data. The paper states only that "all loads shown are unfactored" and gives no load classification, so every printed load is treated as a specified live load and factored at 1.5, while member and element self weight is treated as dead and factored at 1.25 (NBCC 2020 Case 2, \(1.25D + 1.5L\)). Resistance factors are \(\phi = 0.90\) (steel), \(\phi_w = 0.67\) with the additional 0.67 of CSA S16 Cl. 13.13.2.2 (welds), \(\phi_{sc} = 0.80\) (shear studs), \(\phi_c = 0.65\), \(\phi_s = 0.85\), \(\phi_p = 0.90\) (CSA A23.3). Figure 2 has a free tip at A, a roller at B and a pin at C; Figure 4 has a hatched fixed base at A and a hatched fixed end at C, with the 200 kN arrow pointing towards the frame at mid-height of the column.
Reference texts for 07-Str-A5.
