Abstract
This paper presents experimental studies aimed at proposing a refined design for eccentric flange-bolted joints in
steel pipes. The proposed design involves the removal of the externally exposed flange to protect the external finishing material
from potential damage. To assess the stability of the eccentric flange joint, a series of comparative specimens, comprising typical
centric flange-plate (CFP) joints and eccentric flange-plate (EFP) joints, are meticulously manufactured and subjected to
comprehensive tensile performance evaluations. A total of 42 specimens, consisting of 12 CFP joints and 30 EFP joints, are
prepared, varying the thickness of the flange plate and the number of bolts. Specifically, flange plate thicknesses of 3.2, 4.0, 4.5,
6.0, 8.0, and 9.0 mm, as well as 3, 4, 5, and 6 bolts, were considered. The structural performance of the flange joints was
thoroughly analyzed, taking into account parameters such as yield strength, tensile strength, stiffness, and failure mode. The
study further encompasses theoretical calculations and finite element (FE) simulations to introduce eccentric-magnification
factors (EM factors) that establish a clear relationship between CFP and EFP designs, while providing a comprehensive
understanding of the behavior of the flange plate under tensile forces. Notably, the majority of cases exhibited increased yield
strength and maximum strength as the flange plate thickness and the number of bolts were augmented. Moreover, the study
proposes stiffness reduction values and flange EM factors through a meticulous comparison of experimental and theoretical
results. While acknowledging that these factors were derived from detailed guidelines that account for minimal edge clearance,
the proposed flange joint design, characterized by its commendable tensile performance, offers valuable insights for future
design guidelines.
Abstract
This study investigates the seismic performance of reinforced concrete frames retrofitted with a novel link beam
system using numerical modeling and finite element analysis. The research focuses on evaluating the response modification
factor (R factor) for structures with and without retrofitting, emphasizing the influence of ductility, redundancy, overstrength,
and damping factors. Numerical models of 3- and 6-story reinforced concrete frames, both retrofitted and non-retrofitted, were
analyzed to assess the performance under seismic loading. Results demonstrate a significant improvement in the ductility and
energy dissipation of the retrofitted frames, with increases in deformation capacity by factors of approximately 3.54 and 4.42 for
the 3- and 6-story models, respectively. The average value of the R factor in the limit state design method for the numerical
models 3- and 6-story of the reinforced concrete frame retrofitted with the linked column frame system achieved about 8.01 and
8.48, respectively. Also, the R factor compared to the primary frame (without retrofitting) increased about 72% and 68%,
respectively. Additionally, the study finds that the retrofitted frames exhibit enhanced elastic stiffness and better seismic
response, confirming the effectiveness of the linked column frame system in improving structural resilience. The findings
contribute to a deeper understanding of the response modification factor and offer practical insights for optimizing seismic
retrofitting strategies.
Key Words
link beam; linked column frame; numerical method; reinforced concrete frame; response modification
factor; retrofitting
Address
Alireza Ezoddin: Department of Civil Engineering, National University of Skills (NUS), Tehran, Iran
Ali Mohammad Rousta: Department of Civil Engineering, Yasouj University, Yasouj, Iran
Ali Kheyroddin: Structural Engineering Division, Faculty of Civil Engineering, Semnan University, Semnan, Iran
Abstract
The concrete filled steel tubular (CFT) columns have been widely used in steel structures due to many merits,
including large strengths, large stiffness and high construction convenience. Many previous studies of CFTs have verified that
the confinement of the infilled-concrete was significantly affected by the dimensions, deformation levels and shapes of the steel
tubes. Various estimations of the confined strengths of the concrete were previously developed upon the experimental results;
however, apparent deviations were shown. This study presents a comprehensive study on the strengths of CFTs subject to
monotonic loadings, especially the confined strengths of the concrete, through parametric analyses using finite element
modelling (FEM) method. The estimations of the average confined strengths of the infilled-concrete for the CFTs were
established and showed improved accuracy compared to the existing others. To achieve the modelling of the hysteretic behavior
of the CFTs, the general fiber element modelling (FBM) method of CFTs was then developed. The general estimations of stressstrain models of the infilled-concrete of the CFTs were proposed and accurately captured the hysteretic behavior of CFT
columns. Finally, the developed FBM was adopted to establish the general estimations of hysteretic-strength-envelop models of
CFTs.
Key Words
concrete filled tubular columns; confined concrete; cyclic loading; fiber element modelling; finite element
modelling
Address
Po-Chien Hsiao and Ayu Sholikhah: Department of Civil and Construction Engineering, National Taiwan University of Science and Technology,
43, Keelung Rd., Sec. 4, Taipei, Taiwan
Abstract
Enriched meshfree methods have been effectively used to predict the stress intensity factors (SIFs) and crack
trajectories for homogeneous structures, but their applications to heterogenous materials were rarely reported. In this context, an
enriched Petrov-Galerkin natural element method (PG-NEM) is introduced to simulate and examine the crack growth in 2-D
heterogeneous functionally graded (FG) porous plates. The global displacement is approximated using Laplace interpolation
(L/I) functions and enriched by introducing the crack-tip singular displacement and stress fields. The mixed-mode SIFs of FG
plates characterized by the spatially varying elastic modulus are computed by the modified interaction integral method, and the
crack trajectories are predicted by the maximum principal stress (MPS) criterion and the equivalent mode-I SIF. The advantage
of proposed method is verified by comparing with the unriched PG-NEM and ANSYS. It is found that the prediction accuracy in
crack trajectory is remarkably improved such that the crack trajectory of present method coincides well with one of ANSYS.
Moreover, the present enriched method successfully simulates the crack trajectories of FG plates with the porosity as well as the
spatially varying elastic modulus, and it is found that the crack growth characteristics are remarkably influenced by these
parameters.
Abstract
The mechanical representation of fibre-reinforced polymer composite materials is currently of major interest with
their expanding utilization in the industry. These progressive materials have excellent material characteristics, which can be
obtained numerically or by experimental tests. This paper presents different approaches for obtaining the longitudinal Young's
modulus of thin unidirectional laminated carbon fibre-reinforced polymer (CFRP) composite based on the microstructure model,
cohesive zone model, tensile test, three-point bending test, and the Impulse Excitation Technique. Experimental results are
juxtaposed to the results obtained from the numerical homogenization technique and numerical delamination in mode I for
evaluation of the accuracy of the different approaches. Within the micro-level numerical approach, the fictitious periodic
microstructure model is used. With the use of Karamba 3D FEM analysis, the longitudinal Young's modulus was obtained using
simulation of a tensile test. A quasi-static formulation of an interface damage model which incorporates Rayleigh damping of
viscoelastic CFRP composite is presented. The interface traction-relative displacement response assumes a thin adhesive layer
with behaviour that is analogous to cohesive zone models. The solution to the delamination problem is sought by a semi-implicit
time-stepping procedure. The obtained results demonstrate the applicability of the described numerical and experimental
models.
Key Words
carbon fibres; delamination modelling; FEM analysis; impulse excitation technique; laminates; longitudinal
Young's modulus; micro-mechanics; tensile test; three-point bending test
Address
Eva Kormanikova: Technical University of Kosice, Faculty of Civil Engineering, Institute of Structural Engineering and Transportation Structures, Kosice, Slovakia
Hugo Sol: 1)Vrije Universiteit Brussel, Mechanics of Materials and Structures, Brussels, Belgium
2) BYTEC BV, Merksplas, Belgium
Jun Gu: 1)BYTEC BV, Merksplas, Belgium
2)Vrije Universiteit Brussel, Physical Chemistry and Polymer Science, Department MACH, Brussels Belgium
Kamila Kotrasova: Vrije Universiteit Brussel, Mechanics of Materials and Structures, Brussels, Belgium
Lenka Kabosova: Technical University of Kosice, Faculty of Arts, Department of Architecture, Kosice, Slovakia
Peter Sabol:Technical University of Kosice, Center for Research and Innovation in Construction, Kosice, Slovakia
Abstract
This study investigates the cyclic performance of hollow square steel braces that incorporate infilled materials. The
proposed infill brace design features gusset plates at both-ends, a prismatic square hollow section, and a solid infilled material to
reduce the stress concentration in the mid-span region of the brace member. Numerical simulations based on the parameters of
equivalent plastic strain and von Mises stress were conducted to evaluate the behavior of different infill materials, including
wood, glued-laminated timber, and H-beam. A series of full-scale brace specimens using glulam infill materials were subjected
to experimental cyclic tests to assess failure mode, strength, stiffness, ductility, and energy dissipation. This proposed strategy
effectively spreads stress concentration in the mid-span, improves ductility and energy-dissipation capacity, and maintains
similar strength and stiffness compared to conventional braces, which are beneficial for retrofitting existing structures at risk of
insufficient resistance to low-cycle fatigue. The design parameters proposed should be followed in two steps to achieve the
favorable mechanisms of this method in practical applications.
Key Words
buckling; ductility; energy dissipation; fracture; glulam; hysteretic behavior; infill material; steel brace
Address
Chui-Hsin Chen:Department of Civil Engineering, National Yang Ming Chiao Tung University, 1001, University Rd, Hsinchu 300, Taiwan
Po-Yu Chen:Department of Civil Engineering, National Yang Ming Chiao Tung University, 1001, University Rd, Hsinchu 300, Taiwan
Huang-Ming Chen:Department of Civil Engineering, National Yang Ming Chiao Tung University, 1001, University Rd, Hsinchu 300, Taiwan
Ananda Insan Firdausy: 1)Department of Civil Engineering, National Yang Ming Chiao Tung University, 1001, University Rd, Hsinchu 300, Taiwan
2)Department of Civil Engineering, Brawijaya University, 169, MT. Haryono St, Malang 65145, Indonesia
