Use the Wood Design Manual Joist Selection Tables and Serviceability Table (see this page and the next) to aid you in the following design computations (a) Design single supported floor joists for the following conditions. In other words, choose the most optimal joist section for the conditions below. [28 marks] joist spacing= 400 mm joist span = 3.2 m specified dead load = 1.2 kPa specified live load = 4.8 kPa standard load duration dry service condition untreated joists fully laterally supported by subfloor Case 2 system Use S-P-F No.1/No.2 joist width = 38 mm (b) After the construction, and due to a change in use and occupancy, it is now being proposed to increase the specified dead load to 1.4 kPa without changing the specified live load. Check if the new design is feasible. [22 marks] 38 mm Wood Design Manual Joist Selection Tables Sawn Lumber Species S-P-F Size (bxd) mm 38 x 89 38 x 114 38 x 140 38 x 184 38 x 235 38 x 286 Single member M kNm 0.906 1.31 1.85 2.73 4.09 5.50 V KN 5.17 5.85 6.70 7.55 8.84 9.78 System Case 2 M KNm 23 1.27 1.84 2.58 3.83 5.72 7.70 V KN 724 8.19 9.38 10.6 12.4 13.7 El x10 Nemm 21.2 44.6 82.5 187 390 704 Span 24 26 28 30 32 AHRH~~~ 34 36 Egl 40 Wood Design Manual Serviceability Table Required El (Nemm x 10%) for L/360 deflection Uniform specified load kN/m 0.4 25.9 33.0 41.2 50.6 61.4 73.7 87.5 103 120 0.6 38.9 49.4 81.7 75.9 92.2 111 131 154 180 0.8 51.8 65.9 82.3 101 123 147 175 206 240 1.0 64,8 82.4 103 127 154 184 219 257 300 1.2 77.8 98.9 123 152 184 221 262 309 360 90.7 115 144 177 215 258 306 360 420 1.6 104 132 165 203 246 295 350 412 480 1.8 117 148 185 228 276 332 394 463 540 2.0 130 165 206 253 307 368 437 514 600