Site-Specific Response Spectra and Accelerograms on Bedrock and Soil Surface

Abstract

This paper is aimed at serving the needs of structural engineering researchers who are seeking accelerograms that realistically represent the time histories of earthquake ground in support of their own investigations. Every record is identified with a specific earthquake scenario defined by the magnitude–distance combination and site conditions; the intensity of the presented records is consistent with ultimate limit state design requirements for important structures in an intraplate region. Presented in this article are accelerograms that were generated on the soil surface of two example class Ce sites and two example class De sites based on site response analyses of the respective soil column models utilizing bedrock excitations as derived from the conditional mean spectrum (CMS) methodology. The CMS that were developed on rock sites were based on matching with the code spectrum model stipulated by the Australian standard for seismic actions for class Be sites at reference periods of 0.2, 0.5, 1 and 2 s for return periods ranging from 500 to 2500 years. The reference to Australian regulatory documents does not preclude the adoption of the presented materials for engineering applications outside Australia. To reduce modeling uncertainties, the simulation of the soil surface ground motion is specific to the site of interest and is based on information provided by the borelogs. The site-specific simulation of the strong motion is separate to the CMS-based accelerogram selection–scaling for obtaining the bedrock accelerograms (utilizing strong motion data provided by the PEER). The decoupling of the two processes is a departure from the use of the code site response spectrum models and has the merit of reducing modeling uncertainties and achieving more realistic representation of the seismic actions.

Nonlinear Dynamic Analyses Utilising Macro-Models of Reinforced Concrete Building Structures and Site-Specific Accelerograms

“…The RNLTHA procedure involves three routines: (Routine 1) generation of two to six soil surface accelerograms for each reference period of 0.2 s, 0.5 s, 1 s and 2 s using the procedure introduced in Refs. [10,11], which has been implemented into 'quakeadvice.org'; (Routine 2) dynamic modal analysis of the building to obtain the eigen solutions (presented in Section 2.1); and (Routine 3) conducting fast-tracked nonlinear time history analysis of the stick model, which serves the purpose of determining the time history response for a given ground motion excitation. The breakdown of Routine 3 is presented below:…”

“…The selection scheme, which is presented diagrammatically in Figure 8 (showing the number of accelerograms for each reference period), was based on the recommendations in Ref. [10]. The listing of the selected earthquake records is presented in Table A1 in Appendix C. The bore log presented in Ref.…”

“…The first challenge is to do with obtaining a large enough ensemble of strong motion accelerograms that are representative of the targeted site for a given intensity of seismic hazard. In addressing this challenge, methods of generating and sorting code-compliant accelerograms on bedrock and soil surfaces have been developed [7][8][9][10] and incorporated into "quakeadvice.org" [11]. The second challenge is the high computational cost of modelling the whole building for the prediction of its dynamic behaviour throughout the duration of the response.…”

Seismo-VLAB: An Open-Source Software for Soil–Structure Interaction Analyses

“…It is believed that SVL's features are necessary for efficiently solving SSI problems regarding (1) modeling of spatial variability of soil properties for uncertainty quantification in linear and nonlinear models of engineering structures [41][42][43][44][45][46], (2) inverse problems for parameter estimation as well as reliability-based performance analysis in nonlinear finite element models of engineering structures [31,[47][48][49][50][51][52][53], (3) site response analysis for the study of amplification or deamplification of seismic waves considering topographic and basin effects [54][55][56][57][58][59][60][61][62], and (4) specific topics concerning SSI models with time lag effects [63], 3D seismic wave propagation [64], seismic fragility and demand hazard analyses for earth slopes [65], coupled FEM techniques for SSI analyses [66], and earthquake-induced structural pounding between buildings [67]. Thus, SVL's innovativeness lies in its open-source nature, integration of advanced techniques, parallel computing capabilities, modeling of wave propagation in half-spaces, user friendliness, versatility, and applicability to diverse SSI scenarios.…”

Generation of Site-Specific Accelerograms and Response Spectra Involving Sampling Information from Borehole Records

“…The procedure should provide a more accurate evaluation of the potential site hazard than the widely adopted code approach of determining the design response spectrum of a site based on broad site classifications [1][2][3]. The input motions transmitted from the bedrock should have the frequency contents that represent real earthquake events, and are to be derived by adopting the conditional mean spectrum (CMS) methodology as introduced in a companion article of the special issue [4]. A scheme of selecting input motions in accordance with the natural period of both the site, and that of the structure, is presented.…”