Bolla, Junie Airo O.
Dr. Gilford B. Estores
2022 290073
October 2, 2023
A Research Critique
on
‘Shake table tests of special concentric braced frames
under short and long duration earthquakes’
A. Hammad, M. Moustafa
2019
Introduction and Review of Related Literature
As stated in the introduction of the study, the researchers aimed to investigate the effect of earthquake duration
to the collapse capacity of special concentric braced frames (SCBFs). The researchers have cited cases of recent
earthquakes in different time and locations in which their duration was observed to be long, reaching up to 90 seconds.
This supports the importance of conducting the research because it was shown in the cited previous studies that
earthquake duration has strong correlation to cumulative damage or energy measures due to repeated cycles. Contrasts
between the methods of the previous studies and methods of the present study are described. The mentioned reason
for the conduct of the present study is clearly stated and thoroughly justified. Aside from the statement of the main
objective, importance, and methodology of the study, a beneficiary to which the study contributes is also mentioned.
Through this study, the earthquake duration has a high potential to be considered by Project 17 in developing seismic
hazard maps. This study also validates the results of the numerical and statistical studies.
Problem Description
The researchers observed in previous studies that most of the low‐cycle fatigue models are usually statistical or
regression models utilizing the data from the previous experimental studies. Several of these recent models are not studied
using principles of physics or not analytical. Thus, they lack dynamic or realistic tests. Hence, the researchers focused on the
effect of long duration earthquakes on steel frame that are concentrically braced through experimental methods.
Experimental Program, Modeling, Results, Analysis, and Conclusion
The experiment is a half scale of 49m x 36.5m braced steel structure. The specimens were assembled based
on IBC 2006 Structural/Seismic Design Manual (Volume 3). This is a good start to the experiment as it provides proper
proportioning of the member sizes for the entire structure. The connections were also designed using AISC 2010 and
its details were presented through drawings. Having said this, the methodology of the research is well‐structured. It
comprehensively describes the experimental setup and test protocol, including information on the test specimens,
loading protocol, and instrumentation used. The description of data collection methods is adequate. Furthermore,
the criteria for short and long duration earthquakes could be more explicitly defined to improve the accuracy of the
study. The presentation of results is clear and was presented effectively through illustrations. The researchers have
performed a comparative analysis between the results from the tests on specimens having short and long duration
earthquakes. In the discussion section, a deeper examination of the findings' practical effects and their contribution
to the field of earthquake engineering would increase the paper's significance. Lastly, the conclusion summarizes
the important findings but does not restate the research objectives explicitly.
Comment and Suggestion
In general, the paper provides useful experimental data on the behavior of special concentric braced
frames under various seismic conditions. The research methodology is sound, and the findings are presented
clearly. However, the study could benefit from a clearer discussion of statistical methods and their application,
and a comprehensive conclusion that provides actionable insights. Despite these flaws, the study adds to the
existing body of knowledge and deserves more attention and potential follow‐up research.