Abstract
Because of its simplicity, quickness, and high accuracy, the frequency-based method has become one of
the most used techniques for cable force identification in engineering. Several scholars have developed cable force
identification methods, such as the "Three Criteria method", based on the traditional frequency method. These
methods are appropriate for complex cable systems, the majority of which have short, thick cables and relatively
complex supporting circumstances. The proposed methodology aims to extract local modal information of cables
from global modal information, thereby establishing a cable force-frequency correlation model that incorporates the
influence of the overall structural system. Based on the "Three Criteria method", this study conducts numerical
experiments under a range of operating conditions to systematically investigate the threshold setting criteria for the
Modal Assurance Criterion (MAC) values for the purpose of more precisely extracting local vibration modes of the
cables. Ultimately, practical engineering was used to confirm the efficacy of the criteria establishing process.
Key Words
Beam String Structure (BSS); cable force identification; frequency domain method; Modal
Assurance Criterion (MAC)
Address
Zeyu Wang and Yuxin Zhang: School of Civil Engineering, Shanghai Normal University, Shanghai 201400, P.R. China
Tao Zhang: Housing Security and Property Management Bureau, Shanghai 201400, P.R. China
Hexin Zhang: School of Computing, Engineering and the Built Environment, Edinburgh Napier University,
Edinburgh EH105DT, Scotland, UK
Lu Zhang: Myers-Lawson School of Construction, Virginia Tech, Blacksburg, VA 24061, USA
Abstract
Developing of approaches for evaluation of structural life of load-bearing functionally graded beam
structures containing longitudinal cracks under creep is a current problem. This is due to the fact that in many cases
longitudinal cracks are observed during routine maintenance check of such structures. The present paper novelty is
that an approach for evaluating the effect of longitudinal cracks on structural life of functionally graded load-bearing
beams which exhibit non-linear creep is developed. In this relation, general time-dependent solution of the strain
energy release rate (SERR) is derived. The beams under consideration are functionally graded in the thickness
direction. The crack is located arbitrary along the thickness. The creep behavior is described by non-linear stressstrain-
time relationship written in general form. The solution of the SERR is derived by analyzing the time-dependent
complementary strain energy. Two cases of behavior (beams with identical creep behavior in tension and
compression and beams with asymmetrical creep behavior in tension and compression) are considered. The general
solution is applied to evaluate the effect of a longitudinal crack on the structural life of a cantilever beam. The timedependent
SERR in the cantilever beam is obtained also by considering the balance of the energy for check-up of the
general solution. It is found that the structural life is extended with increasing thickness to width ratio of the beam.
However, the life of the structure is shortened as the crack length to beam length ratio increases. Furthermore, a beam
with asymmetric creep behavior in tension and compression has a shorter structural life than that of a beam with
identical creep behavior.
Key Words
functionally graded beam; longitudinal fracture; maintenance of structures; non-linear creep;
structural life
Address
Victor I. Rizov: Department of Technical Mechanics, University of Architecture, Civil Engineering and Geodesy, 1 Chr.
Smirnensky blvd., 1046 – Sofia, Bulgaria
Holm Altenbach: Institute of Materials, Technologies and Mechanics, Fakultät für Maschinenbau, Otto-von-Guericke-
Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Deutschland
Abstract
Rapid urbanization worldwide drives the construction of numerous buildings and infrastructure,
essential for both social and economic development. However, these structures face significant risks of partial or
complete damage when exposed to accidental fires. While existing codes prioritize life safety measures, they often
lack comprehensive guidelines for post-fire structural assessment and rehabilitation, potentially resulting in structural
condemnation. This research study introduces an innovative approach utilizing the ultrasonic pulse velocity (UPV)
test to develop a scalar damage model. This model correlates the damage parameter of reinforced concrete (RC)
beams, both with and without fire exposure, to variables such as the nature and intensity of applied stresses, concrete
strength, and steel ratio. The findings indicate a substantial reduction in initial UPV readings for RC beams exposed
to fire, up to 20.51% compared to those without fire exposure, aligned with the existing literature suggesting a
proportional loss in concrete strength. Moreover, the inclination angle of the elastic data trend is proportional to the
damage accumulated by the concrete, notably higher for RC beams with fire damage, particularly under compression
stress. Furthermore, this angle is also influenced by various factors, including the steel ratio and concrete strength,
regardless of fire exposure. Additionally, RC beams subjected to fire damage exhibit reduced deflection, indicating a
less ductile response compared to those without fire exposure. This reduced ductility is attributed to the
decarbonization of the cement binder and the formation of crack networks in the concrete, leading to a decrease in
overall response.
Key Words
fire damage; microcracks; scalar damage; ultrasonic pulses
Address
Gabriel I. Gamana, Edgardo. S. Legaspi: Department of Civil Engineering, Technological University of the Philippines, Manila, Philippines
Jordan. N. Velasco: Department of Electrical Engineering, Pamantasan ng Lungsod ng Valenzuela, Philippines
John Lemar. M. Tirao: Department of Civil Engineering, Pamantasan ng Lungsod ng Valenzuela, Philippines
Abstract
The single plate shear (SPS) connection is a cost-effective choice for beam to column connections. The
failure detection method for the connections helps people to respond and receive an early warning, allowing them to
take action earlier and prevent serious consequences. Thus, a quick solution is needed to address the structural safety
monitoring issue and predict the response of the SPS connection with accuracy and speed. The present study
recommends the behaviour of SPS connection to predict its failure mode using long-short term memory (LSTM)
networks. The LSTM models were designed utilising the datasets generated by applying a finite-element method
(FEM) of SPS connection. Experimental Validated model was used for finite element analysis of 48 SPS connections
with different seven parameters like distance, the depth of the shear plate connection plate, thickness of web,
thickness of shear plate, the number of bolt columns, Grade of bolts, the beam span, and a number of common wide
flange beam shapes. The LSTM model utilise von Mises stresses for analysing the failure mode of the SPS
connection was compared to the results of the artificial neural network (ANN) and the FEM. The output of an LSTM
model was nearly identical to an ANN model, with ANN model performing slightly better. In all three outputs, the
ANN model's performance is satisfactory (r > 0.8). The training and testing of the ANN models required an average
of six seconds, whereas the analysis of the deep LSTM network consumed almost an hour. The comparison shows
that the ANN model predicted stresses more accurately than LSTM, at least for the current work, which reduces the
necessity of using LSTM for the said task.
Key Words
artificial neural network (ANN); finite element analysis; long-short term memory (LSTM);
single plate shear connection; steel structures
Address
Priti R. Satarkar: Department of Civil Engineering, All India Shri Shivaji Memorial Society, College of Engineering, Pune, India
P.R. Dixit, S.N. Londhe and Preeti S. Kulkarni: Department of Civil Engineering, Vishwakarma Institute of Information Technology, Pune, India
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