1. Selection and Scaling of
Natural Earthquake Records
for Inelastic Analysis of
Reinforced Concrete
Structures
MSc Dissertation by
Konstantinos Myrtsis
Project Supervisor: Dr. J.E Martinez-Rueda
School of Environment and Technology
MSc Civil Engineering
September 2015

2. Konstantinos Myrtsis – MSc Civil Engineering 2
Abstract
This dissertation addresses the influence of selection and scaling of natural earthquake
records on the variability of the estimated seismic demands of inelastic reinforced concrete
structures when analysed through non-linear time-history analysis. By using a database of
148 input ground motions which were recorded on firm soil, sample sizes of 4, 7, and 11
earthquake records with best, average, and worst spectral matching with the associated EC8
target design spectrum were generated. The implemented scaling criteria were based on four
spectral intensity scales, as well as three levels of seismicity. The combined criteria under
consideration required a total of 396 non-linear time-history analyses, while the total
earthquake cases which produced the output of this research is calculated to 2214 cases of
earthquakes. The results are assessed in terms of the estimation of the structural responses
expressed as mean and peak displacement ductility demands of the critical floors of the three-
storey structure under study.

3. Konstantinos Myrtsis – MSc Civil Engineering 3
Chapter 1
Introduction
Preview
This chapter includes introductory information on the challenge of using appropriately
modified natural earthquake records for performing non-linear structural analysis. A
detailed outline of this present scientific research on selection and scaling of natural
earthquake records for inelastic analysis of reinforced concrete structures is included,
followed by a description of the aim, the objectives and the importance of the project.

4. Konstantinos Myrtsis – MSc Civil Engineering 4
Chapter 2
Background
Preview
This chapter contains information and the suggested output from existing literature
about the application of selecting and modifying ground motions for performing
inelastic analysis of structures. Reference on current seismic code provisions in
Europe and the United States is given, as well as a brief introduction on seismology is
included.

5. Konstantinos Myrtsis – MSc Civil Engineering 5
Chapter 3
Methodology
Preview
This chapter contains detailed information on the methodology which was followed
for the selected analyses to investigate the effect of selecting and scaling natural
accelerograms on the response of inelastic reinforced concrete structures. The method
includes all stages of procedure in a step by step sequence relative to the actions
which were taken, from modelling and setting the properties of the inelastic
reinforced concrete structure, defining the loads on the structure to processing the
database of natural earthquake motions which were used for the purpose of this
research.

6. Konstantinos Myrtsis – MSc Civil Engineering 6
Chapter 4
Results
Preview
This chapter contains the research results. The output from processing the natural
earthquake records is presented, the computed scaling factors are provided, the
outcome of the pushover analysis as well as the output of the time-history analysis are
contained in this chapter. This section also illustrates the response of the RC structure
under consideration from randomly selected cases of earthquake excitations.

7. Konstantinos Myrtsis – MSc Civil Engineering 7
Chapter 5
Discussion of results
Preview
In the following chapter, the elaboration of the results of the inelastic analysis will be
given. The main focus of the discussion is on the influence of the number of records
for analysis, the spectral matching under consideration and the scaling procedure
which was used for analysis, as well as to identify correlation with the findings of
existing experimental procedures in the current literature. Additionally, although
assessing the structural integrity of the reinforced concrete structure may be beyond
the scope of this study, a brief reference to the seismic performance of the structure
subjected to a randomly selected earthquake motion will be provided.

8. Konstantinos Myrtsis – MSc Civil Engineering 8
Chapter 6
Conclusions
Preview
This section contains the implementation of the suggested output of this research
regarding the influence of selecting and scaling real accelerograms on the output of
non-linear time-history analysis. Additionally, recommendations for possible future
studies will be provided.

9. Konstantinos Myrtsis – MSc Civil Engineering 9
List of References
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