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Published byImani Brumby Modified over 2 years ago

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Oasys SIREN

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Bedrock Soil Surface Output motion F = F Input motion Displacement

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Response spectrum

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The use of SIREN in the Seismic Design of Stonecutters Bridge Jack Pappin Site Response Liquefaction Foundation Design

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Bedrock ? Site Response

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Mexico City ground conditions

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Ground conditions

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SIREN - input parameters Soil profile Density Small strain shear modulus G 0 g G/G with shear strain amplitude Input time history – selected to match target bedrock outcrop response from the seismic hazard assessment

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Geophysical methods for G 0 Down hole insitu test G 0 = V S 2

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Down hole shear wave testing

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Time Signals received by orthogonal sensors Shear wave arrival through the ground Reverse polarity signals generated by hitting beam from opposite directions P waves or S waves travelling through casing or grout column Interpretation of Down-hole Seismic Survey

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G sec G0G0 1 0 10.00010.0010.010.110 Cyclic shear strain (%) 15 0 30 50 100 PI = 200 OCR = 1 - 15 Variation of G/G0 with shear strain amplitude

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G 0(ij) = v s(ij) 2 where G 0(ij) is the elastic shear modulus is the bulk density of soil and v s(ij) is the shear wave velocity through soil V s(vh) V s(hh) V s(hv) v Soil triaxial specimen Bender element Bender element (v s(vh) ) Bender element embedded in base platen Bender element (v s(hv) ) Bender element (v s(hh) ) Bender element probe Hall-effect gauge (radial) Hall-effect gauge (axial)

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Bedrock Soil Surface Output motion F = F Input motion Displacement Oasys SIREN

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Calculated Site response effects Serviceability

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Calculated Site response effects Ultimate

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Calculated Site response effects Structural Integrity Limit State - SILS

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Liquefaction

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Philippines 1989 Liquefaction

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Philippines 1989 Liquefaction

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Standard method of assessing the likelihood 50 0 102030 0.2 40 0.1 0.3 0.4 0.5 Corrected SPT N value (N 1 ) Average peak shear stress / vertical effective stress Percent fines (%) 35 15 <5 No Liquefaction Liquefaction 0 Note: figure applies for a magnitude 7.5 earthquake From SIREN Liquefaction

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Predicted likelihood of liquefaction Serviceability SILS Ultimate

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Bedrock CDG Alluvium Fill 500 250 Bending Moment (kNM) 0 5 10 15 Horizontal displacement (mm) Soil displacement from SIREN Pile displacement 100 : 30 combination rule Foundation design - Lateral Loads on Piles

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Large Diameter Bored Piles Pile Caps

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Pile group modelling Soil Profile Piles Interface elements Free field soil lateral displacement Acceleration

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Bending moments induced in piles

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