Site with Multiple Boreholes

QUAKE ADVICE_Seismic Design Response Spectrum Report

Generation of Site Specific Earthquake Ground Motion

1. Input Parameters:

No. of Boreholes:

I. Probability Factor x Hazard Design Factor (k_pZ):
II. Fundamental Natural Period of the Structure (sec):
III. Bedrock Shear Wave Velocity (m/s):
IV. Bedrock Density (kg/m³):
V. Energy Ratio (N₆₀/N_measured):

VI. Soil Characteristics:

Soil Type:

Note:

The program offers two selection options for the soil types: "Sand Only" and "User Specified". If the site contains solely of sandy soil, you can choose the "Sand Only" option. Otherwise, you should select the "User Defined" option.
The "Sand Only" option necessitates providing the thickness and Standard Penetration Test (SPT-N) values of each soil layer. When selecting this option, the program utilizes the "Ohta & Goto" shearwave velocity model and "Hardin & Drnevich" material model as default soil models.
The "User Defined" option requires providing the thickness, SPT-N, soil type, soil age, and water content for each soil layer. When selecting this option, the program offers the "Imai & Tonuchi" and "PEER" shearwave veocity models, and three material models:"Hardin & Drnevich", "Vucetic and Dobry", and "Darendeli".
If all entries to a particular “thickness” column are left blank, the program will automatically fill in a default thickness of 1.5 m.
SPT-N values obtained from testing very stiff materials need to be corrected to a penetration depth of 300 mm. For example, if an SPT-N value of 50 is obtained at a penetration depth of 100 mm, it should be corrected to 150. When SPT-N values are not available in the borelog, they can be determined from the soil description, as shown in the table below.
When selecting the "User Defined" option, enter the soil type according to the specifications in AS 1726: "GP, GW, GM, GC, SP, SW, SM, SC, ML, MH, CL, CI, CH". If the soil type is unknown, it is suggested to use 'SW' for coarse soil and 'MH' for fine soil.
Soil age (when required): enter 'Q' for Quaternary, 'H' for Holocene, and 'P' for Plesitocene for each layer. If the soil age is unknown, it is suggested to use 'Q'.
Water content (when required): enter according to the specifications in AS 1726 as shown in the table below. If the water content is unknown, it is suggested to use 'M' for coarse soil and 'W1' for fine soil.
The table can be filled manually or by performing a copy (CTRL+C) and paste (CTRL+V) of data from Excel spreadsheet.

	Borehole 1		Borehole 2		Borehole 3		Borehole 4		Borehole 5		Borehole 6		Borehole 7		Borehole 8		Borehole 9		Borehole 10		Borehole 11		Borehole 12		Borehole 13		Borehole 14		Borehole 15		Borehole 16		Borehole 17		Borehole 18		Borehole 19		Borehole 20
	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N	Thickness(m)	SPT-N
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1. Input Parameters

2. Results: Soil Surface Ground Motion Ensemble

The site-specific soil surface accelerograms presented here are generated following the 6 Routines shown below. For more details of each Routine, readers are referred to Ref [1].

Routine 1: The conditional mean spectrum (CMS) methodology is employed to calculate event-specific bedrock response spectra for use in ground motion selection as the target spectrum. CMS at four distinctive reference periods (i.e., 0.2, 0.5, 1, and 2 seconds) are generated to cover the periods of interest for low- to mid-rise building structures. For each CMS, the controlling magnitude-distance (M-R) combinations are identified by hazard disaggregation analyses for the seismic intensity defined at the bedrock (refer to Input 1).

Routine 2: The event-specific response spectrum is developed by raising the medium response spectral value at the reference period to the same value as the code response spectrum and applying correlation values to the spectrum at periods other than the reference period (the medium and standard deviation of response spectral acceleration calculated by adopting ground motion prediction expressions).

Routine 3: Accelerograms representing rock outcrop motions conforming to the controlling scenario (refer to Table 2) are extracted from the PEER database. The extracted accelerograms are scaled so that their calculated response spectra closely match the CMS in the period range of 0.2T* to 2T*. With each CMS, the "best six" accelerograms having the least sum of squared errors (SSE) are selected.

Routine 4: The sampling of the two most critical/conservative soil columns involves selecting those with (1) the highest period or lowest shear wave velocity and (2) the lowest damping. For more details, please refer to Ref. [2].

Routine 5: Simplifying the critical soil column models into models with 5 layers. The shear wave velocity profiles of the original and the simplified soil models are shown in Figure 1. For more details, please refer to Ref. [2].

Routine 6: 12-16 accelerograms and response spectra representing motions on the soil surface are obtained for each critical boreholes by performing equivalent linear analysis of the simplified soil column model (refer to Figure 1).

I. Dynamic Analysis of the Soil Column Models

This section focuses on the analytical modeling of the soil columns to calculate dynamic material properties, including density, Plasticity Index (PI), Shear Wave Velocity (SWV), shear modulus degradation, and damping ratio, which governs the amplification of seismic excitations. The density and PI values for each soil layer are determined based on its soil type using Table A1 and A2. The SWV is determined using the "SWV Models", while the shear modulus and damping properties are determined using the "Material Models" specified in the input section. The calculated density, SWV, and PI values for the simplified soil column models are presented in Table 1. For more details on different SWV and material models, please refer to .Ref. [1].

	Borehole 1				Borehole 2				Borehole 3				Borehole 4				Borehole 5				Borehole 6				Borehole 7				Borehole 8				Borehole 9				Borehole 10				Borehole 11				Borehole 12				Borehole 13				Borehole 14				Borehole 15				Borehole 16				Borehole 17				Borehole 18				Borehole 19				Borehole 20
	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age	Thickness(m)	SPT-N	Soil Type	Soil Age
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VII. Water Level (m):
VIII. Initial Vertical Stress from Structure (kPa):

QUAKE-ADVICE

Site with Multiple Boreholes