Abstract
This study presents an advanced non-linear finite element analysis (FEA) of composite flooring systems comprising
cold-formed steel (CFS) joists and reinforced concrete slabs, aiming to address the limited representation of such hybrid systems
in current design standards. The research develops a validated 3D ANSYS model incorporating multi-linear material behaviour,
contact interactions, and large deformation effects under static and cyclic loading. Key phenomena—including bolt slip, plastic
hinge formation, and strain redistribution—were captured, with validation against benchmark experiments yielding a mean
absolute error (MAE) of 23.75 kN and root mean squared error (RMSE) of 33.72 kN. Fatigue performance was assessed using
both stress-life (S–N) and strain-life (ε–N) methods, with results showing a critically low life of 0.85 cycles at the upper slab in
stress-based analysis and 75.45 cycles at support zones in strain-based analysis, validating the latter's applicability for brittle
concrete fatigue modelling. Crack sensitivity was investigated using a J-Integral fracture approach applied to a 25 mm notch at
mid-span, revealing high stress intensity prior to arrest by reinforcement. A targeted numerical investigation of different
reinforcement layouts indicated that reducing rebar spacing by 10 mm produced an average 8% decrease in peak J-Integral,
underscoring the importance of layout configuration in fracture control. The study
Address
Omar A. Shamayleh: School of Civil and Environmental Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney (UTS), Sydney, Australia
Harry Far: School of Civil and Environmental Engineering, Faculty of Engineering and Information Technology,
University of Technology Sydney (UTS), Sydney, Australia
Abstract
Steel-reinforced concrete (SRC) columns are widely used in high-rise buildings, yet the seismic performance of
beam-to-SRC column connections requires further study. This research introduces a novel connection featuring a steel profile
encased within the reinforced concrete beam (Transition Part) near the SRC column joint. Three specimens were tested under
cyclic loading at the beam ends and axial loading on the columns: a reinforced concrete (RC) beam-to-column joint, an RC
beam-to-SRC column joint, and an RC beam-to-SRC column joint with a transition part. The specimen with the transition part
increased load-bearing capacity by 8% and 16.5% compared to the RC beam-to-SRC column and RC beam-to-column
specimens, respectively. Additionally, the RC beam-to-SRC column specimen exhibited an 8% higher load-bearing capacity
than the RC beam-to-column specimen. The transition part also improved ductility by 4.5% and 12.4% compared to the RC
beam-to-SRC column and RC beam-to-column specimens, respectively. These results indicate that incorporating a steel profile
within the beam enhances the seismic performance of beam-to-SRC column connections, offering a promising design approach
for high-rise buildings.
Key Words
ductility; joint; reinforced concrete beam; steel-encased reinforced concrete column; transition part
Address
Seyedeh Marzieh Qiyami Taklymi: Department of Civil Engineering, Semnan University, Iran
Ali Kheyroddin and Omid Rezaifar: Department of Civil Engineering, Semnan University, Iran
Abstract
The main aim of this study is to propose an innovative hybrid fiber-reinforced polymer (FRP)-concrete-steel
double-skin (HyFRP-CSDS) tubular monopile foundation for supporting offshore wind turbines. The HyFRP-CSDS design is
specifically intended for the high-stress region of the turbine's support structure between the mudline and water level. The
construction of the HyFRP-CSDS section involved filling an ultra-high-performance cementitious layer between an inner steel
tube and a concentric FRP tube at the periphery of the cross-section. A 3D nonlinear finite element model was developed to
assess the performance and effectiveness of the proposed HyFRP-CSDS as a support structure. The model investigated different
diameter ratios, which represent the correlation between the outer FRP tube and the prototype monopile diameter. Through a
comprehensive analysis of maximum applied horizontal force, bending moment, lateral displacement, pile rotation, and global
buckling ratio, it was determined that the HyFRP-CSDS support structure demonstrates sufficient lateral stability, reduces total
external loads, and mitigates damage in the high-stress region of the turbine's support. Consequently, due to the synergistic effect
of FRP, steel, and concrete, the proposed cross-shaped section holds the potential for enhancing support structure design.
Investigation of pile displacement and rotation shows that the new hybrid foundation improves the reliability of power
production and availability by reducing the displacements and rotations in comparison with conventional and other composite
foundations. This can limit excessive vibrations and the need for costly repair and interruptions in power production.
Additionally, the implementation of HyFRP-CSDS allows for stress redistribution within the monopile by strengthening critical
segments.
Key Words
damage; innovative support structure; lateral stability; offshore wind turbine; synergy effect
Address
Masoud Ahmadi: 1)Department of Civil Engineering, Faculty of Engineering, Ayatollah Boroujerdi University, Boroujerd, Iran
2) Faculty of Earth Sciences Engineering, Arak University of Technology, Arak, Iran
Mehdi Ebadi-Jamkhaneh: School of Engineering, Damghan University, Damghan 3671641167, Iran
Ali Khodam: Faculty of Earth Sciences Engineering, Arak University of Technology, Arak, Iran
Ebrahim Fadaei: Faculty of Earth Sciences Engineering, Arak University of Technology, Arak, Iran
Abstract
This study investigated a D-shaped yielding damper (DSYD) in a new configuration. In the proposed model, the
DSYD is angled relative to the direction of the force, which alters its behavior. Parametric studies were conducted to assess the
impact of the damper's dimensions and its angle in the model. All analyses were performed based on a validated model. After
conducting cyclic analyses and extracting hysteresis curves, seismic parameters were derived from these results. The seismic
parameters included effective and elastic stiffness, yield and maximum strength, energy dissipation, and equivalent damping
coefficient (EDC). To facilitate quicker estimation of these results, approximate equations based on the curve fitting method
were proposed, which provided results closely matching the numerical outcomes. Finally, the most influential variables on the
results were identified. The numerical study results demonstrated that an increase in the damper angle leads to improved
outcomes for a damper with a rectangular cross-section. In contrast, decreasing the damper angle produced better results for a
damper with a square cross-section. Increasing the thickness and reducing the radius of the damper improved all of its seismic
parameters. The damper angle had the most significant impact on EDC, followed by yield force and initial stiffness.
Key Words
D-shaped damper; energy dissipation; hysteretic behavior; metallic passive dampers; numerical method
Address
Kambiz Cheraghi: Department of Civil Engineering, Faculty of Engineering, Razi University, Kermanshah, Iran
Mehrzad TahamouliRoudsari: Department of Civil Engineering, Kermanshah Branch, Islamic Azad University, Kermanshah, Iran
Abstract
The bending moment has an extreme value at the middle support in steel-composite beam structures, while the
concrete plate is liable to crack owing to the large tensile stress. In this study, based on a typical steel-concrete composite beam
bridge, fatigue tests were carried out on two double-layer steel-composite beams. The results demonstrated that a significant
nonlinear stage appeared before the failure of the shear nail and confirmed that the stiffness decline caused by slip can be
ignored under the fatigue load, and the composite beam can be regarded as a complete shear connection. As the fatigue loading
cycles increased, the stiffness of the steel-composite beam exhibited a nonlinear downward trend, with the declining speed
increased rapidly at approximately 80% of the fatigue life. It can be stated that the slip growth theory of CEB-FIP MC90 can be
adopted to predict the growth of crack width of steel-composite beam under static load test, which usually suffers from large
prediction error under fatigue test owing to the strong constraints of the steel flange and welded nails. The conclusions of the
study provide a reference for understanding the crack extension mode in the negative bending moment region of the steel
composite beam under fatigue load and effectively controlling the crack width, which ultimately achieves the purpose of
optimizing the performance of bridges and prolonging the service life of bridges.
Key Words
crack propagation; fatigue test; negative bending moment region; steel-composite beam; stiffness of cross
section
Address
Kuan Li: School of Infrastructure Engineering, Dalian University of Technology, Dalian, 116024, China
Yuanxun Zheng: School of Water Conservancy and Transportation, Zhengzhou University, Zhengzhou, Henan, 450001, China
Pan Guo: School of Water Conservancy and Transportation, Zhengzhou University, Zhengzhou, Henan, 450001, China
Pu Gao: Technology Center, China Construction Sixth Engineering Division Corp, Ltd., Tianjin, 300451, China
Chao Wen: China Railway Engineering of Zhengzhou Seven Innings Group Co. Ltd., Zhengzhou, Henan, 450052, China
Abstract
This paper analyzes the axial and transverse dynamic response of thermoelectric carbon nanotube-reinforced
composite (CNTRC) beams under moving harmonic load resting on an elastic foundation which is not done for moving load
mode. The governing equations of thermoelectric CNTRC beam are obtained based on the shear deformation beam theory. The
beam resting on the Pasternak foundation, including Winkler spring and shear layer, are considered. The boundary conditions
considered for this study are simply-supported. The exact solution for the axial and transverse dynamic response is presented
using the Laplace transform. A comparison of previous studies has been published, where a good agreement is observed. Finally,
some examples were used to analyze such as excitation frequency, voltage, temperature, spring constant factors, the volume
fraction of Carbon nanotubes (CNTs), the velocity of a moving harmonic load, and their influence on axial and transverse
dynamic and maximum deflections.
