Download pdf - 122925733 Pad Overturning

Symmetrical pierSpread Footing Foundation Pad SizeNote: column size = 3000 x 1500Without Tie DownsLongitudinal OverturningLongitudinal OverturningTransverse OverturningTransverse OverturningLongit Bars:60DH3290D32Longit Bars:60DH3290D32GeometryB (m)88GeometryB (m)88L (m)1210L (m)1210D (m)22D (m)22bL (m)0.4150.470bT (m)0.5390.504Ult bearing pressurefqu (kPa)30003000Ult bearing pressurefqu (kPa)30003000Conservatively use fqu = 3000 kPa (f = 0.8)LoadsNL (kN)10,00010,000LoadsNT (kN)8,0008,000From Geotech fqu = 4500 kPa (f = 0.5)ML (kNm)28,00024,600MT (kNm)53,00045,900Pier effective height8Pier effective height8VL (kN)3,5003,075VT (kN)6,6255,738Use lower capacity to have ultimateNpad (kN)3,8403,200Npad (kN)3,8403,200bearing pressure demands not tooNsoil (kN)1,098906Nsoil (kN)1,098906dissimilar from existing bridgeN* (kN)14,93814,106N* (kN)12,93812,106(where qu required = 1740 kPa)Overturning momentMot (kNm)35,00030,750Overturning momentMot (kNm)66,25057,375Restoring momentMrest (kNm)56,65353,108Restoring momentMrest (kNm)74,14157,477CheckOkayOkayCheckOkayOkayNote: NT is from 0.8DL - EQ = 10000 - 2000With Tie DownsLongitudinal OverturningLongitudinal OverturningTransverse OverturningTransverse OverturningLongit Bars:60DH3290D32Longit Bars:60DH3290D32GeometryB (m)56GeometryB (m)56L (m)67L (m)68D (m)22D (m)22bL (m)0.8220.578bT (m)1.2650.738Ult bearing pressurefqu (kPa)30003000Ult bearing pressurefqu (kPa)30003000LoadsNL (kN)10,00010,000LoadsNT (kN)8,0008,000ML (kNm)28,00024,600MT (kNm)53,00045,900Pier effective height8Pier effective height8VL (kN)3,5003,075VT (kN)6,6255,738Npad (kN)1,2001,680Npad (kN)1,2001,920Nsoil (kN)306450Nsoil (kN)306522N* (kN)11,50612,130N* (kN)9,50610,442Tie DownDist from edge (m)1.251.25Tie DownDist from edge (m)0.750.75T*tie down (kN)3,2830T*tie down (kN)9,4752,850Iterate to determine tie forceOverturning momentMot (kNm)35,00030,750Overturning momentMot (kNm)66,25057,375so that Mot = MrestRestoring momentMrest (kNm)35,00132,887Restoring momentMrest (kNm)66,25257,523CheckOkayOkayCheckOkayOkay3282.7464541514-478.96194694999474.46477378552828.5201285384

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Eccentric pierSpread Footing Foundation Pad SizeNote: column size = 3000 x 1500Without Tie DownsLongitudinal OverturningLongitudinal OverturningTransverse OverturningTransverse OverturningLongit Bars:60DH3290D32Longit Bars:60DH3290D32GeometryB (m)88GeometryB (m)88L (m)1210L (m)1212D (m)22D (m)22Column Eccentricity2.5Column Eccentricity3.5(measured from centre of pad to centrebL (m)0.4150.470bT (m)0.5390.539of 3m wide column)Ult bearing pressurefqu (kPa)30003000Ult bearing pressurefqu (kPa)30003000Conservatively use fqu = 3000 kPa (f = 0.8)LoadsNL (kN)10,00010,000LoadsNT (kN)8,0008,000From Geotech fqu = 4500 kPa (f = 0.5)ML (kNm)28,00024,600MT (kNm)53,00060,000Pier effective height8Pier effective height8VL (kN)3,5003,075VT (kN)6,6257,500Use lower capacity to have ultimateNpad (kN)3,8403,200Npad (kN)3,8403,840bearing pressure demands not tooNsoil (kN)1,098906Nsoil (kN)1,0981,098dissimilar from existing bridgeN* (kN)14,93814,106N* (kN)12,93812,938(where qu required = 1740 kPa)Overturning momentMot (kNm)35,00030,750Overturning momentMot (kNm)66,25075,000Restoring momentMrest (kNm)56,65317,843Restoring momentMrest (kNm)74,14128,858CheckOkayNo goodCheckOkayNo goodNote: NT is from 0.8DL - EQ = 10000 - 2000With Tie DownsLongitudinal OverturningLongitudinal OverturningTransverse OverturningTransverse OverturningLongit Bars:60DH3290D32Longit Bars:60DH3290D32GeometryB (m)56GeometryB (m)57L (m)68L (m)610D (m)22D (m)22.5Column Eccentricity0Column Eccentricity2.5(measured from centre of pad to centrebL (m)0.8220.518bT (m)1.2650.966of 3m wide column)Ult bearing pressurefqu (kPa)30003000Ult bearing pressurefqu (kPa)30003000LoadsNL (kN)10,00010,000LoadsNT (kN)8,0008,000ML (kNm)28,00024,600MT (kNm)53,00080,000Pier effective height8Pier effective height8VL (kN)3,5003,075VT (kN)6,62510,000Npad (kN)1,2001,920Npad (kN)1,2003,500Nsoil (kN)306522Nsoil (kN)306786N* (kN)11,50612,442N* (kN)9,50612,286Tie DownDist from edge (m)1.251.25Tie DownDist from edge (m)0.750.75T*tie down (kN)3,2830T*tie down (kN)9,4758,000Iterate to determine tie forceOverturning momentMot (kNm)35,00030,750Overturning momentMot (kNm)66,250105,000so that Mot = MrestRestoring momentMrest (kNm)35,00134,101Restoring momentMrest (kNm)66,25274,917CheckOkayOkayCheckOkayNo good3282.74645415149474.4647737855

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