Abstract
Code response spectrum models, which are used widely in the earthquake-resistant design of buildings, are simple to apply but they do not necessarily represent the real behavior of an earthquake. A code response spectrum model typically incorporates ground motion behavior in a diversity of earthquake scenarios affecting the site and does not represent any specific earthquake scenario. The soil amplification phenomenon is also poorly represented, as the current site classification scheme contains little information over the potential dynamic response behavior of the soil sediments. Site-specific response spectra have the merit of much more accurately representing real behavior. The improvement in accuracy can be translated into significant potential cost savings. Despite all the potential merits of adopting site-specific response spectra, few design engineers make use of these code provisions that have been around for a long time. This lack of uptake of the procedure by structural designers is related to the absence of a coherent set of detailed guidelines to facilitate practical applications. To fill in this knowledge gap, this paper aims at explaining the procedure in detail for generating site-specific response spectra for the seismic design or assessment of buildings. Surface ground motion accelerograms generated from the procedure can also be employed for nonlinear time-history analyses where necessary. A case study is presented to illustrate the procedure in a step-by-step manner.
Highlights
The conventional approach of seismic design employs code response spectrum models for defining seismic actions on the structure
A code response spectrum model is derived by enveloping response spectra associated with a diversity of earthquake scenarios, some of which may not be applicable in specific instances
The procedure consists of the following routines: (1) interpretation and analysis of information presented in a borelog for estimating the shear wave velocity (SWV) profile and dynamic properties of the soil layers; (2) selection and scaling of accelerograms for defining input motion transmitted onto the bedrock; and (3) execution of dynamic analysis of the soil column model for generating accelerograms and response spectra on the soil surface
Summary
The conventional approach of seismic design employs code response spectrum models for defining seismic actions on the structure. Ground motion data collected from multiple sites can have resonant spikes occurring at different periods This explains why the averaging process in the derivation of a code spectrum model can smear the individual spikes occurring in the raw records, thereby understating the real extent of soil amplification. The procedure consists of the following routines: (1) interpretation and analysis of information presented in a borelog for estimating the shear wave velocity (SWV) profile and dynamic properties of the soil layers; (2) selection and scaling of accelerograms for defining input motion transmitted onto the bedrock; and (3) execution of dynamic analysis of the soil column model for generating accelerograms and response spectra on the soil surface. A step-bystep guide to generating CMS by applying representative ground motion models and performing probabilistic seismic hazard analyses can be found in Ref. [21]
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