Erol Kalkan

Erol Kalkan
QuakeLogic Inc. · www.quakelogic.net

Ph.D., P.E.
CEO of QuakeLogic Inc.

About

173
Publications
75,139
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
3,200
Citations
Introduction
I, Dr. Erol Kalkan, am a CEO and founder of QuakeLogic Inc (www.quakelogic.net). QuakeLogic offers AI-powered disaster risk management solutions. I earned my B.Sc. degree in Civil Eng. and M.Sc. degree in Eng. Seismology from the Middle East Technical University. My second M.Sc. degree in Structural Eng. is from the Bosphorus (Bogazici) University in Turkey. My doctorate degree is in Structural Eng. (major) and Geotechnical Eng. (minor) from the University of California, Davis. My postdoctoral studies were conducted at the University of California, Berkeley. I was the recipient of the “2008 American Society of Civil Engineers Raymond C. Reese Research Prize in Structural Engineering”. I have been also granted “2008 EERI-FEMA NEHRP Professional Fellowship in Earthquake Hazard Reduction”.
Additional affiliations
October 2008 - present
United States Geological Survey
Position
  • Research Structural Engineer
July 2003 - October 2005
University of California, Davis
Position
  • Research Assistant
July 2002 - May 2003
Rensselaer Polytechnic Institute
Position
  • Research Assistant

Publications

Publications (173)
Article
We systematically evaluate data sets, functional forms, independent parameters of estimation and resulting ground motion predictions (as median and aleatory variability) of the Graizer-Kalkan (2015, 2016; hereafter referred to as GK15) ground motion prediction equation (GMPE) with the next generation of attenuation project (NGA-West2) models of Abr...
Article
Real‐time structural damage detection is one of the main goals of establishing an effective structural health monitoring system. However, due to the lack of training data for possible damage patterns, supervised methods tend to be difficult for such applications. This article therefore proposes a novel unsupervised real‐time damage detection method...
Article
The dynamic responses of an instrumented twenty-story steel-moment frame office building were identified with the data from mainshock (M 7.1) occurred on November 30, 2018 and its six aftershocks ranging from M4.2 to 5.7 in the Alaska-Aleutian subduction zone. The deconvolution-based seismic interferometry was used to identify the traveling waves a...
Article
Nonlinear response history analysis has been a powerful tool in performance-based earthquake engineering for validating the proposed design of new structures or evaluating existing ones. When it is applied to structural systems with a large number of degrees of freedom, such as three-dimensional (3D) models of tall buildings, bridges, or dams, the...
Article
An improved ASCE/SEI 7-10 ground-motion scaling procedure for three-dimensional (3D) response history analysis (RHA) of buildings is presented. In this procedure, different scale factors for two horizontal components of the ground motion are used, and their spectral shapes are considered in selection stage. The accuracy of the improved procedure is...
Article
We used waveforms from the 2018 M W 7.1 Anchorage earthquake and six selected aftershocks, ranging from M W 4.2 to 5.7, to quantify site properties including shear-wave velocity profile, predominant frequencies, borehole amplification, soil-damping ratio, and shear modulus at Delaney Park in downtown Anchorage, Alaska. The waveforms were recorded b...
Technical Report
Full-text available
We systematically evaluate datasets, functional forms, independent parameters of estimation, and resulting ground-motion predictions (as median and aleatory variability) of the Graizer and Kalkan (2015, 2016) (GK15) ground-motion prediction equation (GMPE) with the next generation of attenuation project (NGA-West2) models of Abrahamson and others (...
Poster
Full-text available
Strong-ground motion data recorded at the Delaney Park Geotechnical Array in Anchorage, Alaska during several recent earthquakes including the 2018 M7.1 Anchorage event and its M5.8 aftershock were used to extract deformations and rotational motions at different depths and different intensities of motion. Propagating seismic waves were measured at...
Presentation
This short presentation summarizes five instrumented buildings in Anchorage, Alaska by USGS's National Strong Motion Project. The buildings are Atwood, BP, Frontier, Hilton and VA hospital. This presentation also provides recorded peak ground level and peak structural accelerations from these buildings during the 2018 M7 Anchorage earthquake.
Conference Paper
Full-text available
Accurate automated onset time determination of S phases is important for the automatic real-time location of local, regional and teleseismic events. A new method is developed for automatic detection of S phases in single-component acceleration or broadband velocity records. The algorithm "S PHASE P ICKER " transforms the signal into a response doma...
Conference Paper
Full-text available
Processing and Review Interface for Strong Motion data (PRISM) software (Jones et al. 2017) was developed by the National Strong Motion Project (NSMP) of the U.S. Geological Survey (USGS). PRISM can be used in combination with the Advanced National Seismic System Quake Monitoring System (AQMS) to provide automated processing of strong-motion record...
Code
cornerFreqs automatically detects appropriate bandpass filter corner frequencies to be used for Butterworth filtering by using the seismic signal's frequency content.
Code
smoothSpectra offers different smoothing options for Fourier amplitude spectrum. Default window function is Konno-Ohmachi.
Code
Time series may contain undesired transients and spikes. This function replace spikes exceeding the threshold value by interpolating among previous and subsequent data points. The threshold is defined as mean +/- a number of standard deviations of windowed data centered at spike locations. This code uses histogram method of Solomon et al. (2001) to...
Technical Report
Full-text available
PRISM automatically processes raw ground-motion acceleration records to generate data products that include corrected acceleration, velocity, and displacement time series; acceleration, velocity, and displacement response spectra; Fourier amplitude spectra; and standard earthquake-engineering intensity measures.
Conference Paper
The design or evaluation of structures with certain degree of complexity re-quires non-traditional methods to estimate their seismic performance. Alt-hough structural engineering profession still relies on nonlinear static analy-sis for estimating seismic demands, the nonlinear response history analysis (RHA) is being now increasingly used for desi...
Article
Full-text available
This paper experimentally evaluates four methods to scale earthquake ground-motions within an ensemble of records to minimize the statistical dispersion and maximize the accuracy in the dynamic peak roof drift demand and peak inter-story drift demand estimates from response-history analyses of nonlinear building structures. The scaling methods that...
Article
A continually increasing number of high-quality digital strong-motion records from stations of the National Strong Motion Project (NSMP) of the U.S. Geological Survey, as well as data from regional seismic networks within the United States, calls for automated processing of strong-motion records with human review limited to selected significant or...
Poster
Full-text available
We compare data sets, functional forms, estimation parameters and the resulting ground motion estimates (median and aleatory variability) of the Graizer-Kalkan (2015; hereafter referred to as GK15) with next generation of attenuation project (NGA-West2) models of Abrahamson et al. (2014; ASK14) and Boore et al. (2014; BSSA14) for application to ear...
Article
A continually increasing number of high-quality digital strong- motion records from stations of the National Strong Motion Project (NSMP) of the U.S. Geological Survey, as well as data from regional seismic networks within the United States, calls for automated processing of strong-motion records with human review limited to selected significant or...
Code
Please see the demo.m as an example. FRFaccelerometer.m is a function that computes transfer function of single-degree-of-freedom system with damping and natural frequency. In other words, this code generates FRF of an accelerometer.
Conference Paper
Seismic interferometry by deconvolution is used for system identification of a twenty-story steel, moment-resisting frame building (Robert B. Atwood Building) in downtown Anchorage, Alaska. This regular-plan mid-rise structure is instrumented with a 32-channel accelerometer array at ten levels. The impulse response functions (IRFs) are computed bas...
Conference Paper
Full-text available
Nonlinear response history analysis (RHA) has been a powerful tool in performance-based seismic engineering for validating proposed design of new or performance assessment of existing structures. In this approach, the seismic demands are determined by nonlinear RHAs of the structure excited by several ground motion acceleration records. When it is...
Poster
Full-text available
A robust automated data processing procedure is essential to ensure high-quality accelerograms and derived products for immediate use in earthquake-engineering applications and for seismological studies. In this poster, the automated Processing and Review Interface for Strong motion data (PRISM) software developed at the U.S. Geological Survey is d...
Technical Report
Full-text available
A series of benchmark tests was run by comparing results of the Processing and Review Interface for Strong Motion data (PRISM) software version 1.0.0 to Basic Strong-Motion Accelerogram Processing Software (BAP; Converse and Brady, 1992), and to California Strong Motion Instrumentation Program (CSMIP) processing (Shakal and others, 2003, 2004). The...
Presentation
Full-text available
Performance of the Graizer-Kalkan 2015 (GK15) ground motion prediction equation (GMPE) is tested against more than 30,000 ground-motion data from small to moderate ”induced” events from Oklahoma, Kansas and Texas. The mixed effects residuals analyses demonstrate that the intra-event residuals have no noticeable bias with respect to moment magnitude...
Technical Report
Full-text available
A continually increasing number of high-quality digital strong-motion records from stations of the National Strong-Motion Project (NSMP) of the U.S. Geological Survey (USGS), as well as data from regional seismic networks within the United States, call for automated processing of strong-motion records with human review limited to selected significa...
Code
A robust automated data processing procedure is essential to ensure high-quality accelerograms and derived products for immediate use in earthquake-engineering applications and for seismological studies. The PRISM version 1.0.0 is platform independent (coded in Java), open source, and does not depend on any closed-source or proprietary software. Al...
Data
This is a 3D OpenSEES nonlinear finite element model of a 52-story office building in downtown Los Angeles, California. The building was designed in 1988, constructed in 1988-1980, and instrumented by CSMIP in 1990. Structural system consists of three main components: a braced-core, twelve columns, and eight deep outrigger beams at each floor (Vent...
Data
A robust deconvolution function to study wave propagation. Low pass filtering and resampling the input signals to higher sampling rates may help to eliminate noise and improve pick peaking.
Article
Waveforms recorded at various borehole depths were used to quantify site properties including shear-wave velocity profile, predominant frequencies, site amplification, soil damping and shear modulus at Delaney Park in downtown Anchorage, Alaska. The waveforms recorded by surface and six boreholes (up to 61 m depth) three-component accelerometers we...
Data
A robust deconvolution function to study wave propagation. Low pass filtering and resampling the input signals to higher sampling rates may help to eliminate noise and improve pick peaking. An example MatLAB routine with actual input signals to replicate the plot shown here is included in zip file.
Data
Full-text available
Article
Deconvolution and cross-correlation techniques are used for system identification of a twenty-story steel, moment-resisting frame building in downtown Anchorage, Alaska. This regular-plan mid-rise structure is instrumented with a 32-channel accelerometer array at ten levels. The impulse response functions (IRFs) and correlation functions (CFs) are...
Code
Computes P-phase arrival time in windowed digital single-component acceleration or broadband velocity record without requiring threshold settings using AKAIKE INFORMATION CRITERION. Returns P-phase arrival time index.
Code
Robust MatLAB function to integrate discrete time-signal in frequency domain by dividing its Fourier spectrum with -iw (w = cyclic frequency); also see diffFD (frequency-domain differentiation function).
Code
Robust MatLAB differentiation function to compute derivative of discrete time-signal in frequency domain by multiplying its Fourier spectrum with iw (w = cyclic frequency) ; also see inteFD (frequency-domain integration function).
Code
A robust interpolation function using a SINC kernel to convolve the original input time series in order to get resampled time series. A simple example is provided in comment section to illustrate how resampleSINC works. See also resampleFDZP for frequency domain zero padding (FDZP) resampling.
Code
This function does the same as interpft of MatLAB, but it is much simpler and makes it easy to understand how the frequency domain zero padding (FDZP) resampling works.
Chapter
Full-text available
In performance assessment and design verification of complex structural systems including base-isolated buildings, high-rise structures and structures utilizing advanced lateral force resisting components (e.g., viscous dampers), nonlinear response history analysis (RHA) is now a common engineering tool to estimate seismic demands. The accurate and...
Code
This code computes the target displacement according to the ASCE 41-06 Displacement Coefficient Method, which is originally from FEMA-440.
Article
Presented is a new approach for picking P-phase arrival time in singlecomponent acceleration or broadband velocity records without requiring detection interval or threshold settings. The algorithm PPHASEPICKERtransforms the signal into a response domain of a single-degree-of-freedom (SDOF) oscillator with viscous damping and then tracks the rate of...
Data
Downloadable zip file provides a MatLAB function for GK15 GMPE and an example routine to generate a site-specific response spectrum for given hazard conditions. Readers may find further details about GK15 in the U.S. Geological Survey (USGS) open-file report available at http://pubs.usgs.gov/of/ 2015/1009/
Article
We present a revised ground-motion prediction equation (GMPE) for computing medians and standard deviations of peak ground acceleration (PGA) and 5% damped pseudo-spectral acceleration response ordinates of the horizontal component of randomly oriented ground motions to be used for seismic hazard analyses and engineering applications. This GMPE is...
Data
The Graizer–Kalkan (GK15) ground-motion prediction equation is available in MatLAB. The zip file contains its MatLAB function with an example routine to generate a site-specific response spectrum for given hazard conditions.
Article
Full-text available
This article describes a novel, small-scale nonlinear beam-column connection and an associated six-story frame test structure for the experimental dynamic response investigation of multi-story buildings subjected to earthquake loading. The objective is to create a re-configurable, reusable experimental platform on which several aspects of nonlinear...
Data
Full-text available
Data
Full-text available
Article
California Building Code requires at least two ground motion components for three-dimensional (3D) response history analysis (RHA) of structures. For near- fault sites, these records should be rotated to fault-normal/fault-parallel (FN/FP) directions, and two RHA analyses should be performed separately. This approach is assumed to lead to two sets...
Article
a magnitude 6.0 earthquake struck northern California. Its epicenter was located 9 km south-southwest of the city of Napa, which was impacted drastically by the event. The recorded peak horizontal ground acceleration in downtown Napa was as high as 62%g. This earthquake was the largest earthquake to strike northern California during the past 25 yea...
Conference Paper
In performance assessment and design verification of complex structural systems including base-isolated buildings, high-rise structures and structures utilizing advanced lateral force resisting components (e.g., viscous dampers), non-linear response history analysis (RHA) is now a common engineering tool to estimate seismic demands. Today, majority...
Conference Paper
Nonlinear response history analysis (RHA) is now being increasingly used to estimate engineering demand parameters (EDPs)—floor displacements, story drifts, member forces, member deformations, etc.—of buildings and special structures subjected to ground motions. As an input, RHA requires a small set of earthquake records. These records should be pr...
Conference Paper
The modal pushover-based scaling (MPS) procedure explicitly considers structural strength, and determines a scaling factor for each record to match an inelastic target deformation value, and then selects a small set of scaled records that lead to accurate and efficient estimates of engineering demand parameters (EDPs). This paper extends the MPS pr...
Conference Paper
The modal-pushover-based-scaling (MPS) procedure explicitly considers structural strength, and determines a scaling factor for each record to match an inelastic target deformation value, and then selects a small set of scaled records that lead to accurate and efficient estimates of engineering demand parameters (EDPs). This paper extends the MPS pr...
Conference Paper
Van is a major Eastern Anatolian city, located on the east of the eponymous lake basin, and surrounded by the Van, East Anatolian and Bitlis Fault zones. In 2011, this urban area was hit severely by an M7.2 earthquake and a swarm of aftershocks due to the Van Fault zone. This east-west direction extended thrust fault zone, passing 20 km north of th...
Article
The influence of the ground motion rotation angle on engineering demand parameters (EDPs) is examined in the companion paper based on three-dimensional (3-D) computer models of single-story structures. Further validations are performed here using 3-D models of nine-story buildings that have symmetric and asymmetric layouts subjected to a suite of h...
Article
The Graizer-Kalkan ground-motion prediction equation (GMPE) for peak ground acceleration (PGA) constitutes a series of filters, each of which represents a certain physical phenomenon affecting the radiation of seismic waves from the source. The performance of this GMPE is examined by using about 14,000 records from 245 worldwide shallow crustal eve...
Article
SUMMARY The task of selecting and scaling an appropriate set of ground motion records is one of the most important challenges facing practitioners in conducting dynamic response history analyses for seismic design and risk assessment. This paper describes an integrated experimental and analytical evaluation of selected ground motion scaling methods...
Conference Paper
This paper describes an experimental investigation on the scaling of ground motion records for use in the nonlinear response history analysis of building structures. The study is based on the measured response from small-scale shake-table experiments of nonlinear multi-story building frame structures under ground motion suites that have been scaled...
Conference Paper
This paper describes recent collaborative efforts made by the United States Geological Survey and Department of Veterans Affairs (VA) in real-time seismic monitoring of VA hospital buildings located in seismically active regions. The instrumentation in each building encompasses accelerometers deployed on all floors, a multi-channel recorder, and a...
Article
Full-text available
According to the regulatory building codes in the United States (e.g., 2010 California Building Code), at least two horizontal ground motion components are required for three-dimensional (3D) response history analysis (RHA) of building structures. For sites within 5 km of an active fault, these records should be rotated to fault-normal/fault-parall...
Conference Paper
Nevada is one of the Nation's most seismically active States, and a strong earthquake could cause significant damage in the heavily populated Las Vegas region. The region occupies a fault-bounded basin filled with alluvium (sediments deposited by flowing water) as much as 3 miles deep, making the region especially prone to earthquake shaking. Earth...
Article
U.S. national building codes refer to the ASCE/SEI-7 provisions for selecting and scaling ground motions for use in nonlinear response history analysis of structures. Because the limiting values for the number of records in the ASCE/SEI-7 are based on engineering experience, this study examines the required number of records statistically, such tha...
Conference Paper
Ground motion selection and scaling comprises one of the most important components of any seismic risk assessment study that involves response history analysis. The related research to date has been based on analytical studies of mostly single-degree-of-freedom systems, with fewer studies conducted using multi-degreeof- freedom systems. By contrast...
Conference Paper
Building codes in the U.S. require at least two horizontal ground motion components for three-dimensional (3D) response history analysis (RHA) of structures. For sites within 5 km of an active fault, these records should be rotated to fault-normal/fault-parallel (FN/FP) directions, and two RHA analyses should be performed separately (when FN and th...
Conference Paper
In United States, the seismic provisions require at least two horizontal ground motion components for three-dimensional (3D) response history analysis (RHA) of structures. For sites within 5 km of an active fault, these records should be rotated to fault-normal/fault-parallel (FN/FP) directions, and two RHA analyses should be performed separately (...
Conference Paper
: We evaluated spectral amplification factors of long-period ground motions (3 to 10 s) in the Los Angeles (LA) basin with respect to its surrounding reference hard-rock sites from the Mw7.2 April 4, 2010 El Mayor-Cucapah earthquake records and presented period-specific maps of amplification factors for long periods. This earthquake was the first e...
Conference Paper
This paper describes the current progress in the development of a structural health monitoring and alerting system to meet the needs of the U.S. Department of Veterans Affairs to monitor hospital buildings instrumented in high and very high seismic hazard regions in the U.S. The system, using the measured vibration data, is primarily designed for p...