Abstract
Significant interface slip may occur between the slab and steel beam in steel-concrete composite beams
under prestressing. Owing to their lower stiffness, GFRP-concrete slabs may induce larger interface slip and higher
shear demands on connectors than conventional concrete slabs. This study presents a refined analytical method for
predicting the slip behavior of prestressed GFRP-concrete-steel composite beams. Extending conventional sectional
analysis, the proposed model explicitly incorporates the influence of the GFRP plate, shear connector stiffness, and
shear connector arrangement. To verify the accuracy of the theoretical method, two GFRP-concrete-steel composite
beam specimens were fabricated and tested. In parallel, a series of numerical models were developed to further validate
the analytical method. Comparisons among experimental, theoretical, and numerical results confirmed the reliability
and accuracy of the proposed analytical model. Furthermore, parametric studies are conducted to investigate the effects
of key design parameters on slip between composite slabs and steel beams. The results demonstrate that incorporating
GFRP plates increases the interface slip, whereas densifying shear connectors near the prestressing load zone
effectively reduces slip in the composite beams. The proposed analytical approach provides a practical and accurate
tool for analyzing and optimizing the shear connector arrangements of GFRP-concrete-steel composite beams under
prestressing loads.
Key Words
composite beam; GFRP-concrete-steel; numerical analysis; prestress; slip
Address
Zhaojie Tong:College of Engineering, Fujian Jiangxia University, Fuzhou 350108, China
Bingqing Luo:Department of Mathematics and Physics, Fujian Jiangxia University, Fuzhou 350108, China
Hailong Zhang:Shenzhen Municipal Design & Research Institute Co., Ltd., Shenzhen 518029, China
Shuge Zhang:1)College of Engineering, Fujian Jiangxia University, Fuzhou 350108, China
2)College of Transportation and Civil Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002, China
Abstract
With the revision of seismic design standards, there is a growing need to focus on seismic retrofitting of
existing reinforced concrete structures. In particular, for reinforced concrete columns that do not incorporate seismic
reinforcement detailing, there is a high risk of brittle shear failure during an earthquake. Moreover, when observing
the most severely damaged buildings after actual earthquakes, it is often found that the majority of these buildings did
not have seismic design provisions. In this study, four full-scale RC columns were constructed using aramid FRP.
After reinforcing the bending and shear regions of I-shaped RC columns, cycle loading experiments were conducted.
The experimental results closely matched the expected design strength. The study confirmed the effectiveness of
aramid FRP in enhancing the strength and ductility of the columns. It is anticipated that aramid FRP reinforcement
will be highly effective for elements with inadequate seismic design or those in need of repair and reinforcement.
Abstract
Epoxy joints exhibit shorter curing times and simpler construction compared to wet joints, significantly
improving the construction efficiency of prefabricated steel-concrete composite (PSCC) beams. To assess the
applicability of PSCC beams with epoxy joints in the negative bending moment regions, a single-point bending test
was performed on one PSCC beam with epoxy joints and one ordinary steel-concrete composite (SCC) beam without
joints, followed by a comparative analysis of their mechanical behavior. Furthermore, parametric analyses were carried
out using a finite element simulation method validated by the tests, focusing on the shape, location, and number of
epoxy joints. The results show that the yield and ultimate loads of PSCC beams decreased by 12.1% and 10.4%,
respectively, compared to SCC beams. Under prestress, however, the cracking load and ductility increased by 33% and
17.6%, respectively, while sectional rotation performance was enhanced. Moreover, keyed and stepped joints
demonstrated better ultimate load capacity and ductility in comparison to linear joints. As the joint location shifted
closer to the mid-span and the number of joints increased, both ultimate load capacity and ductility gradually decreased.
Design recommendations were provided to offer valuable references for the intelligent construction of PSCC beam
bridges with epoxy joints.
Abstract
Helicopter rotor blades made of composite materials operate in a highly dynamic and unsteady
aerodynamic environment, sometimes resulting in delamination and cracking of the blade skin. In this study, the in
plane tensile and flexural properties of [(0/±45/90)2]f and [(±45)8]f woven carbon and glass fiber-epoxy matrix
composites, which are commonly used as blade skin materials, were investigated experimentally under tension and
bending loads using ASTM standards. A skinny anti-adhesion PTFE tape was placed in the neutral plane of the
samples while laying to artificially generate delamination. The results revealed that carbon woven fiber epoxy
laminates are preferable owing to their rigidity, strength, and low density. However, with a significantly more brittle
structure, carbon fiber epoxy laminates are more sensitive to delamination; therefore, tighter control measures are
necessary during both manufacturing and operation.
Key Words
composite material; delamination; flexure; quasi-isotropic; tension
Abstract
Multiple cracks frequently observed in welded connection of orthotropic steel bridge decks, highlighting
the need for a systematic understanding of their co-evolution mechanisms. This study investigates the interaction of
coexisting surface and embedded cracks using the numerical simulations via Abaqus–FRANC3D. The stress fields of
both crack types are analyzed under coplanar and non-coplanar conditions. Furthermore, the effects of crack spacing,
embedded crack aspect ratio, and depth on stress intensity factors, crack propagates rates, and fatigue life are system
atically evaluated. Results indicate that the relative positioning of cracks significantly affects fatigue behavior: coplanar
configurations accelerate crack propagation, while non-coplanar configurations shield it. Key parameters, including
initial crack spacing, embedded crack depth, and aspect ratio of the embedded crack all affect the fatigue life of welded
joints. It is worth noting that under coplanar conditions, increased crack spacing accelerates propagation and signifi
cantly shortens fatigue life. In contrast, under non-coplanar conditions, greater spacing enhances the shielding of the
embedded crack, leading to earlier crack arrest. These findings offer valuable insights into the interaction mechanisms
of multiple cracks and contribute to the improved lifecycle management of welded structures.
Abstract
The presented work concerns the analytical formulation of a shear deformation theory for beams. First, a
review of recent studies on various shear deformation theories used in modelling beams, plates, and shells is
provided. The principal objective is to develop an effective and simple individual shear deformation theory of beams
derived from the classical shear stress formula. Unlike many existing approaches, the solution is obtained analytically
in closed form without predefining specific shear deformation functions. The formulation enables the analysis of
sandwich beams with constant or variable width and stiffness, including non-homogeneous materials. Parametric
functions are introduced to describe these variations, allowing a broad range of beam geometries and stiffness profiles
to be examined. The analytical results exhibit very good quantitative agreement with finite element analyses, with
peak relative differences of 0.714 % in maximum deflection and 0.223 % in maximum shear stress. Applications
include the standard I200 beam and non-homogeneous sandwich beams.
