Abstract
Sizing optimization of nonlinear inelastic steel truss structures poses significant challenges due to
computational intensity from repeated nonlinear analyses and limitations of existing metaheuristic algorithms in
handling high-dimensional problems with geometric and material nonlinearities. This paper proposes LEpDE, an
enhanced differential evolution algorithm tailored for this task. LEpDE integrates: (1) a pbest mutation scheme
balancing local and global searches, (2) a linear population size reduction (LPSR) transitioning from large to small
populations for improved initial diversity and final convergence, (3) novel formulas for scale factor (F) and crossover
(CR), and (4) an earlier constraint evaluation stop (ECES) to efficiently reduce unnecessary structural analyses.
LEpDE's performance was evaluated on three examples (planar 10-bar truss, 47-bar power line truss, and planar 39
bar truss) against EpDE, Rao, a success-history-based parameter adaptation for DE (SHADE), and a LPSR
application for SHADE (LSHADE). LEpDE consistently achieved superior best, worst, average, and standard
deviation results, with statistical significance confirmed by Student's t-test. Despite a modest 7–10% increase in
computation time over EpDE, the substantial gains in solution quality justify this trade-off. These findings establish
LEpDE as a robust and efficient tool for nonlinear structural optimization with broad engineering applications.
Key Words
differential evolution; linear population size reduction; nonlinear inelastic analysis;
optimization; pbest mutation; truss
Address
Faculty of Civil Engineering, Thuyloi University, 175 Tay Son, Kim Lien, Hanoi 100000, Vietnam
Abstract
This study investigates the nonlinear thermomechanical buckling and postbuckling behavior of porous
sandwich cylindrical shells. The shells consist of a graphene-origami-reinforced auxetic metamaterial core and porous
carbon nanotube (CNT)-reinforced face sheets, supported by a Winkler–Pasternak elastic foundation and subjected to
external pressure in a thermal environment. To assess the influence of porosity, various porosity distribution models
are examined across the shell thickness. Governing equations are formulated based on Reddy's third-order shear
deformation theory (TSDT) and solved via the Galerkin method. Validation against established solutions in the
literature demonstrates the high accuracy and reliability of the proposed model. A comprehensive parametric study is
conducted to examine the effects of porosity characteristics, temperature variations, auxetic core, and Winkler
Pasternak foundation properties on the buckling and postbuckling responses. The findings reveal that both porosity and
temperature significantly influence the nonlinear buckling behavior, underscoring the necessity of accounting for these
effects in designing advanced auxetic sandwich structures.
Key Words
carbon nanotube-reinforced composite; cylindrical shells; graphene-origami reinforced auxetic
metamaterial; nonlinear thermomechanical buckling; porosity effects; temperature effects
Address
Farzad Ebrahimi:Department of Mechanical Engineering, Faculty of Engineering, Imam Khomeini International University, Qazvin, Iran
Mohammadhossein Goudarzfallahi:Department of Mechanical Engineering, SR.C., Islamic Azad University, Tehran, Iran
Ali Alinia-ziazi:Department of Mechanical Engineering, SR.C., Islamic Azad University, Tehran, Iran
Abstract
Composite box girders integrating concrete webs (CWs) and corrugated steel webs (CSWs) constitute an
innovative structural solution for long-span bridges. To investigate the spatial behavior of this complex system, a
novel finite element (FE) model, termed the Spatial Grillage Model (SGM), was developed exclusively with beam
elements. In the SGM, hybrid webs are discretized into cruciform grids to capture orthotropic stiffness, while
concrete flanges are simulated as planar grillages interconnected with the web grids. Comparative validation against
high-fidelity solid/shell FE models demonstrated the accuracy of the SGM, with discrepancies consistently below
5% under diverse loading conditions. Subsequently, the model was employed to analyze the structural behavior of a
practical extradosed cable-stayed bridge, incorporating the construction process, live loads, and other relevant factors.
The results indicate that CWs generally sustain a greater share of shear force compared with the CSWs, particularly
within cable-stayed zones. When concrete creep effects are considered, shear forces redistribute among hybrid webs,
leading to a substantial increase in the CSWs. Under eccentric live loads, the outer CSWs exhibit 25%-30% higher
shear force than the inner ones. Concrete flanges demonstrate pronounced overall positive shear lag adjacent to the
CWs, combined with localized negative shear lag at web locations. This study establishes an efficient computational
framework and provides new insights into the behavior of hybrid-web girders.
Key Words
composite bridge; corrugated steel webs; extradosed cable-stayed bridge; hybrid webs; shear
distribution; spatial effect; spatial grillage model
Address
Yu Zhang:School of Civil Engineering, Shandong University, 17923 Jingshi Rd., Jinan 250061, China
Yibo Wang:School of Civil Engineering, Shandong University, 17923 Jingshi Rd., Jinan 250061, China
Shouyu Zhu:Department of Civil Engineering, National University of Singapore, 21 Lower Kent Ridge Rd., Singapore 119077, Singapore
Yujie Zeng:School of Civil Engineering, Chongqing University, 83 Shabei Street, Chongqing 400045, China
Li Tian:School of Civil Engineering, Shandong University, 17923 Jingshi Rd., Jinan 250061, China
Hetao Hou:School of Civil Engineering, Shandong University, 17923 Jingshi Rd., Jinan 250061, China
Abstract
This study investigated the behavior of concrete-filled steel tubes (CFST) under extreme fire conditions,
focusing on two key fire performance indicators: the fire resistance rating (FRR) and residual strength index (RSI).
Advanced prediction models were developed using neural networks optimized with a particle swarm optimization
algorithm. A comprehensive experimental database and a diverse range of neural network architectures were utilized.
The models demonstrated superior predictive accuracy, as validated through multiple performance metrics and
comparisons with existing prediction equations. Furthermore, causal inference techniques were applied to identify the
influence and relative importance of each variable. Visualization tools were instrumental in uncovering patterns and
correlations that would be difficult to detect through numerical data alone. The proposed FRR and RSI models offer a
cost-effective, non-destructive method for assessing and designing CFST elements in concrete structures.
Key Words
concrete-filled steel tubes; fire resistance rating; machine learning; neuro-swarm; residual
strength index
Address
Andrei Art Geronimo:Department of Civil Engineering, Adamson University, Ermita, Manila, Philippines
Dann Carlo Reformado:Department of Civil Engineering, Adamson University, Ermita, Manila, Philippines
Abstract
The upgrade plan for the next-generation HPR1000 nuclear power plants aims to fully adopt modular
construction technology. Half steel plate-concrete composite (HSC) slab-to-reinforced concrete (RC) wall joints are
critical connections in modular nuclear power plants, yet their failure mechanisms remain largely unexplored and
limited research. This study investigates the shear and force-transfer behavior of HSC slab-RC wall joints through
experiments and numerical simulation. Two connection methods were proposed and evaluated: the normal rebar-to
steel-plate lap-splice (NR-SL) connection and a newly developed anchored rebar-to-steel-plate lap-splice (AR-SL)
connection. Cyclic loading tests were conducted on six large-scale joint specimens, varying the tie-bar steel ratio and
connection methods. Comparison results proved that the AR-SL connection has excellent force-transfer performance
similar to that of the NR-SL connection, with advantages in both efficiency and cost-effectiveness. The nonlinear finite
element models were used to perform parametric analysis, further clarifying the influence of the tie-bar steel ratio, lap
length, location, and tensile force ratio of lapped rebars. Finally, based on the force-transfer model, a joint design
method was proposed for engineering applications.
Key Words
force transfer; half steel plate-concrete composite slab; joint; lap-splice; nuclear power plant
Address
Yongwang Lei:1)School of Transportation Science and Engineering, Beihang University, Beijing 100191, China
2)College of Transportation and Civil Engineering, Fujian Agriculture and Forestry University, Fuzhou,350108, Fujian China
Quanquan Guo:School of Transportation Science and Engineering, Beihang University, Beijing 100191, China
Yue Yu:China Nuclear Power Engineering Corporation Limited, Beijing 100840, China
Abstract
This study investigates the axial compression behavior of circular Concrete-Filled Aluminum Tube (CFAT)
short columns, emphasizing the influence of the confinement effect coefficient. Sixteen specimens fabricated from
6063-T5 and 6061-T6 aluminum alloys were tested, demonstrating effective composite action with concrete.
Specimens failed primarily by buckling or shear: buckling failures occurred when the confinement effect coefficient
exceeded 0.91, whereas low coefficients below 0.31 combined with diameter-to-thickness ratios (D/t) ≥ 50 led to large
diagonal cracks and poor ductility. Finite element analysis showed minimal interaction between aluminum tube and
concrete in the elastic stage, which increased gradually in the inelastic phase. The ultimate load capacity rose by up to
26.48% and 33.25% with increases in concrete strength and tube wall thickness, respectively. Due to aluminum's
relatively low elastic modulus, introducing the confinement reduction factor (kal) and modulus reduction coefficient
(ka) into existing Concrete-Filled Steel Tube (CFST) formulas significantly improved accuracy, aligning predictions
with experiments. Theoretical analysis further indicates that when the aluminum content ratio (a) is below 0.1, ka
approximates 1, allowing direct calculation using CFST theory without reduction. These results provide valuable
theoretical guidance for the design and engineering application of CFAT short columns.
Key Words
axial compression behavior; concrete-filled aluminum alloy tube; confinement effect coefficient;
finite element analysis; modulus of elasticity reduction coefficient
Address
Liangzhi Wang:1)School of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, China
2)Shengjing Hospital of China Medical University, Shenyang 110004, China
Bing Li:School of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, China
Songlin Li: School of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, China
Bo Zhou:School of Civil Engineering, Shenyang Jianzhu University, Shenyang 110168, China
Jiaxu Li:School of Management, Shenyang Jianzhu University, Shenyang 110168, China
