Question

The column layout for a portion of a proposed building is shown in the figure. Three boreholes are located within this area with the subsequent SPT data shown. The Groundwater Table was measured to be at el. 775 at 2 weeks after drilling for BH3. Determine the satisfactory sizes for the column footings A2 and C3. The loads on these columns are given as: A2: Dead Load-100 KN, Live Load - 300 KN C3: Dead Load - 55 kN, Live Load - 175 kN The design criteria are based on local codes require the maximum settlement to be 25 mm and the minimum depth of the footing to be 300 mm. BH 60.3 m ---------- -------- ---------- BH3 - ---------- ------- --------- - BH2 8m- 1 - ET TO - 19.7 m 0 2 4 6 Horizontal distance (m) 8 10 12 14 16 18 784 20 BH-3 BH-1 BH2 Finished grade 140 Law No . 18 km Layer 2 N-33 Y20 kN/ Layer 3 N-41 48.00 Y-20.5 kN/m Elevation (m) Layer 4 N26 Y = 19 kN/m N-64 6604 21 kN/m 760 EOB20 EOB21 758

Answer 1

Given Ground water table Depth of ground water level 775 m from top sungaie of soil 784 - 775 = gm. = 18 kolm? = 20 KN IM? Dmin = 300 mm V ·load On Column AR - Live Load = 300kn Dead load= lookN LL=175 KN DL= 5SKN lead on Column C3 - Dasa for column A SET Value N = 16 No = 33 bulk densiy of layer I V = 18 Kulm? V = 20KNIM Water table and SPT Value shows that its the Clay Soil with Medium Stiffness on Sant Greg for Clay Soil d = एक let asume 2 22.5 and a square footing then Value q- No Unconifned compressive Strength of Soil with medium stiffness = (W) - 48 96 - 72 KN m² c = 2 = 36 kNlM2 q = 36x9 = 324 KN) m2

I total load on Self weight of Column forsing = a 300 tloo = 400KN lot of Column land tutul coad уусче kW = 440 I required I LB = 440 400g ицо 324 ooge B = m u ime 1.50 m L = 1.47 - Actual area of total word on fousing Column = 1x1.5 = 1 2 6-3 = 115+55 +0:1x 230 - 253 KN LX B = 253 in 253 324 Long BX0 = b = 0 of 9 m L = l-lou 7 oerom I lolom acural area of fiewing = 0.77 m² B