Calculation Sheet
Design of Pump House
Sheet No PH/11
WALL A Geometry and bending moment coefficients lx = 7.300 m lz = 4.325 m, k = lx / lz = 7.300 / 4.325 = 1.69 +MH
–MV top +MV –MV btm –MH
α = 0.032 α = 0.019 α = 0.048 α = 0.011 α = 0.003
Ultimate Limit State (STR) Case 1–Max. External Soil & Water Pressure Completed structure (Stage 6) For ease of calculation, combine lateral soil and groundwater pressures into a single equivalent load. (Note. Apply this loading to all external walls.)
Bending moments
Soil + Groundwater +Surcharge (σmax = 88.7 kPa)
–MV top = 0.032 × 88.7 × 4.725 × 4.325 = 58.0 kNm/m +MV = 0.019 × 88.7 × 4.725 × 4.325 = 34.4 kNm/m –MV btm = 0.048 × 88.7 × 4.725 × 4.325 = 87.0 kNm/m –MH = 0.011 × 88.7 × 7.300² = 52.0 kNm/m +MH = 0.003 × 88.7 × 7.300² = 14.2 kNm/m
Case 2–Internal water pressure (a) In operation Completed structure with backfill (Stage 6) In operation, water pressure in the wet well will act against exterior lateral earth pressure to reduce the net loading on Wall A. By inspection this will not give a critical load combination. (b) Under test Completed structure without backfill (Stage 5) Bending moments Water (σmax = 43.3 kPa) –MV top = 0.032 × 43.3 × 4.325² = 25.9 kNm/m +MV = 0.019 × 43.3 × 4.325² = 15.4 kNm/m –MV btm = 0.048 × 43.3 × 4.325² = 38.9 kNm/m –MH = 0.011 × 43.3 × 7.300² = 25.4 kNm/m +MH = 0.003 × 43.3 × 7.300² = 6.9 kNm/m
By comparison, bending moments from Case 1 are more onerous than from Case 2. 128
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