Abstract
In this study, a CNN (Convolutional Neural Network) based image recognition model is proposed to address the
challenges in diagnosis and inspection of deteriorated buildings. With approximately 42.6% of buildings nationwide classified as
aging, regular inspections are critical, yet current visual assessments are prone to a shortage of specialized personnel. While
existing deep learning studies focus primarily on surface defects, this research targets the failure modes of beam-column joints
which are critical elements for overall safety of structural system. Based on data collected from existing literature, a dataset was
constructed by classifying the failure modes of beam-column joints in reinforced concrete and precast concrete structures
according to the crack patterns at the joints. Using libraries such as TensorFlow and Grad-CAM++, the model was trained, and
its performance was evaluated. The classification of joint failure modes based on the ACI 352R-02 code resulted in an accuracy
of approximately 64%. In contrast, the 5-fold cross-validation results showed an accuracy of 77% and AUC (Area Under the
Curve) of 80%, demonstrating the potential to develop a system that enables even non-experts to easily assess the damaged
structures.
Address
Dongho Kim:Department of Architecture and Architectural Engineering, Hankyong National University,
Jungang-ro 327, Anseong, Gyeonggi 17579, Republic of Korea
Jinhyeong Heo:Department of Architecture and Architectural Engineering, Hankyong National University,
Jungang-ro 327, Anseong, Gyeonggi 17579, Republic of Korea
Minho Lee:School of Engineering and Digital Sciences, Nazarbayev University, 53 Kabanbay Batyr Ave., Astana 010000, Republic of Kazakhstan
Deuckhang Lee:Department of Architectural Engineering, Chungbuk National University, 1 Chungdae-ro, Cheongju, Chungbuk 28644, Republic of Korea
Hyunjin Ju:School of Architecture and Architectural Engineering, Hankyong National University,
Jungang-ro 327, Anseong, Gyeonggi 17579, Republic of Korea
Abstract
This paper presents an experimental, numerical, and analytical investigations into the behavior of square concrete
filled cold formed stiffened steel tubular stub columns with ring (hoop) stirrups (SC-CFSST) under axial compression. The
proposed composite column is fabricated by cold-bending four plates to form four parts of lipped angles, which are assembled
by argon welding. Ring stirrups are inserted through the perforations along the longitudinal lips to provide additional
confinement. To explore the combined enhancement effects of stirrups and stiffeners, six SC-CFSSTs confined with stirrups and
three concrete-filled stiffened steel tubular (CFSST) stub columns without stirrups were tested. Experimental procedures, and
results are discussed in detail. A finite element (FE) model was developed to simulate the models of specimens and validated
against experimental results. The validated model was employed to conduct a parametric study to better understand the behavior
of SC-CFSST columns with different parameters. The results demonstrate that installing ring stirrups significantly enhances
confinement effect, improving both ultimate strength and enhances post-peak performance. In addition, international design
provisions were utilized to predict the ultimate axial load of CFSSTs and SC-CFSSTs. The results were compared with
experimental and numerical results, showing that the DBJ design approach provides the most accurate predictions. A new
formula was introduced to estimate the ultimate strength of CFSSTs and SC-CFSSTs, considering combined confinement
effects. The formula showed improved accuracy in predicting ultimate strength compared to both FE simulations and existing
design predictions.
Key Words
axial compression; cold-formed; concrete-filled; design codes; experimental analysis; FE analysis; stirrups
Address
Tarek Sharaf:Department of Civil Engineering, Faculty of Engineering, Port Said University, Port Said, Egypt
Ahmed Hanefa:Department of Civil Engineering, Faculty of Engineering, Port Said University, Port Said, Egypt
Mohamed Dabaon:Department of Civil Engineering, Faculty of Engineering, Tanta University, Tanta, Egypt
Mohamed ElGhandour:Department of Civil Engineering, Faculty of Engineering, Port Said University, Port Said, Egypt
Ashraf ElSabbagh:Department of Civil Engineering, Faculty of Engineering, Port Said University, Port Said, Egypt
Abstract
Presented in this paper is the investigations on the effect of transverse and longitudinal stiffeners at different
locations on the shear behaviour of Hybrid stainless steel (HySS) plate girders using the Finite Element (FE) software
ABAQUS. The HySS plate girder under consideration utilizes two contemporary breeds of stainless steel such as: Duplex
Stainless Steel (DSS) material on the flanges and Lean Duplex Stainless Steel (LDSS) on the web. The plate girder is modelled
to undergo three distinctive failure mechanisms, viz., shear dominant, bending dominant, and combined shear and bending
dominant failure mechanisms through variations of the flange-to-web thickness ratio (tf/tw). The behaviour of transverse and
longitudinally stiffened HySS plate girders is presented in terms of the shear capacity (Vu) by varying the transverse and
longitudinal stiffener locations. The applicability of the current design codes is assessed by comparing the FE results with the
European code, Direct Strength Method (DSM), and modified DSM proposed by other researchers. New design formulations to
improve the existing European code and DSM have been proposed.
Abstract
This study explores the potential for using smaller braces by increasing strength requirements and reducing stiffness,
thereby challenging traditional stiffness-governed design approaches. The buckling load equivalence method (BEM), which
assumes that the buckling load of an imperfect column at infinite lateral displacement equals that of a perfectly straight column,
was evaluated alongside the Castigliano model (CM) and the Winter model (WM). For fully braced systems, CM and WM
produced nonconservative estimates, while BEM yielded more conservative results than finite element analysis (FEA). In
partially braced systems, all three models gave conservative estimates compared to FEA, with CM being the least conservative
and WM the most. FEA results showed that bracing forces in full bracing scenarios exceeded 1% of column strength and
increased with more braces, even when critical stiffness was doubled. This indicates that stiffness alone does not govern brace
force requirements. The study highlights the importance of balanced brace optimization, which emphasizes reduced stiffness and
increased strength to achieve more efficient designs. By applying an optimal varying amplification factor, smaller brace sizes
can meet strength demands per AISC specifications while remaining below linearized stiffness limits. The proposed BEM
approach effectively balances strength, stiffness, and efficiency in brace design.
Abstract
This study investigates the bending deflection and normal stress behavior of functionally graded (FG) plates under
sinusoidal and uniform mechanical loading conditions. Three macroscopic volume fraction models are analyzed: the power law,
trigonometric, and a newly developed four-parameter Viola-Tornabene formulation. Additionally, the effects of various
micromechanical models, including the mixture law (Voigt model), Reuss model, Tamura model, and Mori-Tanaka model, on
the composite behavior are examined. The governing equations are derived using higher-order shear and normal deformation
plate theory, coupled with Navier's solution approach. The predictions of the macroscopic and micromechanical models are
benchmarked against published numerical results, revealing the improved accuracy of the Viola-Tornabene model and the Mori
Tanaka homogenization approach for certain plate configurations and loading cases. Comprehensive parametric studies elucidate
the combined effects of ceramic content, plate geometry, loading profiles, and micromechanical considerations on the mechanics
of FG plates. The findings highlight the potential of the Viola-Tornabene model and the Mori-Tanaka homogenization technique
as efficient analytical tools for the design and analysis of FG plates.
Key Words
functionally graded plates; bending deflection; normal stress; mechanical loading; Navier's solution method;
volume fractions models; homogenization models
Address
Billel Rebai:Faculty of Sciences & Technology, Civil Eng. Department, University Abbes Laghrour, Khenchela, Algeria
Messas Tidjani:Faculty of Sciences & Technology, Civil Eng. Department, University Abbes Laghrour, Khenchela, Algeria
Abdelhak Berkia:Faculty of Sciences & Technology, Mech Eng. Department, University Abbes Laghrour, Khenchela, Algeria
Ashraf M. Zenkour:1) Department of Mathematics, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia
2) Department of Mathematics, Faculty of Science, Kafrelsheikh University, Kafrelsheikh 33516, Egypt
Hamada F. El-Mekawy:Department of Management Information Systems, College of Business and Economics, Qassim University, Buraidah 51452, P.O. Box 6666, Saud Arabia
Abstract
Due to the increase in the use of natural fiber composites, knowing the impact properties and impact strength of
these natural fiber composites will be beneficial in the industry. Therefore, in this study, the impact behaviors and damage
mechanisms of the natural fibers reinforced epoxy composites are investigated experimentally. Eucalyptus, palm and birch
natural fibers were used as reinforcement. By combining the molded pulp production system and the vacuum-assisted resin
transfer system, first the molded natural fiber plates and then natural fiber reinforced composite plates were produced. The low
velocity drop impact testing was performed on the natural fiber composite plates. By the increasing impact energies from 2.5 J to
3.0 J, it was possible to examine the impact responses and damage mechanisms until perforation of the natural fiber composites.
It is seen that the indentation gets deeper and a net shear out (perforation) occurs at the front face of the composites, while bigger
matrix cracks and fiber breakage can be seen at the back face of the composites. As compared with palm and birch fiber
composite samples, it can be said that the impact performance of the eucalyptus fiber composite sample is the best.
open access
