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CONTENTS
Volume 94, Number 1, April10 2025
 

Abstract
The longitudinal flexibility of the center tower in three-tower cable-stayed suspension bridges(3TCSSB) significantly reduces structural stiffness, rendering these systems highly vulnerable to seismic actions. In this work, the dynamic characteristics and seismic performance of a 3TCSSB with double 1400 m main spans were numerically investigated using MIDAS/Civil software. Nonlinear time-history and response spectrum analyses were conducted to evaluate the structural responses under horizontal and vertical seismic excitations. A comparative analysis with three-tower cable-stayed(3TCSB) and suspension bridges(3TSB) of equivalent spans reveals that 3TCSSB exhibits superior seismic performance due to its balanced stiffness and reduced seismic responses. The findings propose 3TCSSB as an optimal structural system for kilometer-scale multi-tower cable-supported bridges in seismically active regions.

Key Words
dynamic characteristics; nonlinear time-history analysis; response spectrum analysis; seismic response; threetower cable-stayed suspension bridge

Address
Xin-Jun Zhang: College of Civil Engineering, Zhejiang University of Technology, Hangzhou 310023, P.R. China; Key Laboratory of Civil Engineering Structures & Disaster Prevention and Mitigation Technology of Zhejiang Province,
Hangzhou 310023, P.R. China
Zhi-Yong Hu: College of Civil Engineering, Zhejiang University of Technology, Hangzhou 310023, P.R. China
Dong-Jie Xu: College of Civil Engineering, Zhejiang University of Technology, Hangzhou 310023, P.R. China

Abstract
Modular expansion joint achieve overall deformation through the coordination and relative motion of multiple components. The relative motion causes wear. To explore the relative motion laws between the components, it is necessary to establish traffic loads, structural model, and analysis indicators at the component level. To achieve precise determination of traffic loads, a method of using a measured wheelbase to match the length of the front and rear suspensions to determine the size of each vehicle model and a method of using the shadow vehicle method to formalize the vehicle lane changing process are proposed. Then, using a double-layer beam as the basic structure of the expansion joint, the connection problem between the bridge and expansion joint is handled in a multipoint constraint manner, and the loading method for vehicle loads are refined, thus establishing a vehicle-bridge expansion joint analysis system. Finally, analysis indicators for the wear of modular expansion joint are established, and the wear of modular expansion joint under different traffic flows is analyzed. It is concluded that the cumulative relative displacement between the supporting crossbeam and each displacement box is not significantly different and the sliding and compression support between them can be made into uniform specifications. The cumulative relative displacement of point pairs between the middle beam and supporting crossbeam follows a W-shaped pattern, while that of the compression and stretching of the control springs between each middle beam follows a W-shaped and n-type pattern. The compression and sliding supports and the shear springs need to be differentiated design. The law of cumulative relative displacement can provide guidance for selecting materials and cross-sectional parameters in the design of expansion-joint supports and shear springs.

Key Words
microscopic traffic flow; modular expansion joint; vehicle-bridge-expansion joint; wear law

Address
Ning Liu and Huanju Liu: School of Civil Engineering, Hebei University of Engineering, Handan, 056038, China

Abstract
Steel structures are typically recognized for their high ductility and strength under seismic loads. However, following the Northridge earthquake, several instances of brittle failure were reported in welded connections. As a solution, extended endplate connections have been proposed. This study experimentally investigates the behavior of four-bolted extended end-plate connections under cyclic loading, focusing on bolt configurations and the presence of the stiffener. Twelve specimens were designed, consisting of six stiffened and six unstiffened extended end-plate connections (SEECs and UEECs). Key parameters such as the bolt distance from the beam's flange (pf) and gage distance (g), were varied to examine their influence on the moment capacity. In addition, the experimental results were compared with the theoretical equations from existing literature. When the test results were evaluated, the maximum and plastic moment capacities increased with the decrease of pf value and g value. The effects on pf and g were more pronounced in SEECs. The stiffener increased the moment capacity but decreased the rotational capacity. AISC predicts the moment capacity of the SEECs more accurately than that of UEECs, conversely, Eurocode 3 predicts the moment capacity of the UEECs more accurately than that of SEECs. Moreover, the prediction of moment capacity proposed by Özkiliç (2023a, 2023b) gave more accurate estimates than other models. This prediction is better as pf and g values decrease.

Key Words
end-plate connection; extended end-plate connection; stiffened; unstiffened

Address
Fatih Yilmaz and Yasin Onuralp Özkiliç: Department of Civil Engineering, Faculty of Engineering, Necmettin Erbakan University, Konya 42000, Turkey

Abstract
Turkiye is an earthquake country with active faults. On February 6, 2023, there were two major destructive earthquakes with magnitudes of 7.7 and 7.6, with the epicenters in Kahramanmaraş Pazarcik and Kahramanmaraş Elbistan, and affected 11 cities. The region has a population of approximately 13.5 million. More than 50000 people lost their lives. It was determined that there were 61772 buildings that were heavily damaged, destroyed or needed to be demolished. Based on this bitter experience, it was desired to take attention to the structural deficiencies and mistakes made. It is thought that the points emphasized will be guiding for new constructions. Selection of unappropriate ground and foundation for construction, low concrete quality used, insufficient and flat reinforcement, errors and deficiencies in project design, application and inspection are the main reasons for demolitions. As a result of investigations, it was observed that the buildings that received adequate engineering services had good material and construction quality, and did not experience any deficiencies in inspection and implementation survived the earthquake without any damage or with very minor damage. It is noteworthy that the residences built by the Public Housing Administration (PHA) in the region did not suffer any catastrophic damage. The most important features of these houses can be listed as: ground surveys before application, raft foundation, tunnel formwork system, use of quality concrete and reinforcement, project implementation and controls during the construction phase. The difficulty of reaching aid due to collapsed buildings blocking the roads after the earthquake once again revealed the importance of planned urbanization.

Key Words
damage; Earthquake, Kahramanmaraş; Elbistan; fault; Pazarcik; planned urbanization; structure; tunnel formwork; Turkiye

Address
Sule Bakirci Er: Department of Civil Engineering, Faculty of Engineering and Natural Science, Kirikkale Unversity, Kirikkale, Turkiye
Eda Avanoglu Sicacik: Department of Civil Engineering, Faculty of Technology, Gazi Unversity, Ankara, Turkiye
Mustafa Kaya: Faculty of Engineering, Department of Civil Engineering, Aksaray Unversity, Aksaray, Turkiye

Abstract
This study aims to investigate the micromechanical behavior of composite materials reinforced with linear and curvilinear fibers, focusing on the influence of fiber orientation and matrix type on mechanical performance. The motivation behind this research stems from the need to optimize composite structures by understanding how different fiber-matrix combinations affect their mechanical response, particularly in elastic deformation. A finite element analysis (FEA) was conducted using Abaqus 6.17.1, where a representative elementary volume (REV) approach was employed. The study compares the behavior of glass/epoxy, glass/polypropylene, alfa/epoxy, and alfa/polypropylene composites by varying fiber orientations from 0o to 90o and analyzing the resulting force-displacement curves. The results indicate that fiber orientation significantly impacts the elastic resistance of the composite, with 0o fiber alignment yielding the highest stiffness. Additionally, glass/epoxy composites demonstrated superior mechanical performance compared to the other material combinations. Notably, the inclusion of curvilinear fibers influenced the stress distribution, particularly in glass/polypropylene composites, where resistance decreased as fiber orientation increased.

Key Words
fibrous composite materials; finite element analysis; micromechanical behavior; Representative elementary volume

Address
Habib Achache: Institute of Maintenance and Industrial Safety, University of Oran2 Mohamed Ben Ahmed, B.P 1015, El M'naouer, 31000, Oran, Algeria; Laboratory of Physical Mechanics of Materials Sidi Bel Abbes, Algeria
Ghezail Abdi: nstitute of Maintenance and Industrial Safety, University of Oran2 Mohamed Ben Ahmed, B.P 1015, El M'naouer, 31000, Oran, Algeria
Rachid Zahi: Relizane University, Relizane, Algeria
Djaafar Ait Kaci: Laboratory of Physical Mechanics of Materials Sidi Bel Abbes, Algeria; Department of Mechanical Engineering, University of Djillali Liabes Sidi Bel Abbes, 22000, Algeria
Rachid Boughedaoui: Department of Matter Engineering Yahia Fares Medea, Algeria

Abstract
This paper, we propose a method for considering uncertainties based on the projection on polynomial chaos. The proposed approach is used to study the nonlinear dynamic response of one stage gear transmission system with uncertainty associated to eccentricity defect and this uncertainty must be considered in the analysis of the dynamic analysis of this system. The simulation results are obtained by the polynomial chaos approach for dynamic analysis under uncertainty. The proposed method is an efficient probabilistic tool for uncertainty propagation. It was found to be an interesting alternative to the parametric studies. The polynomial chaos results are compared with Monte Carlo simulations.

Key Words
eccentricity defect; gear system; Monte Carlo simulation; polynomial chaos method; uncertainty

Address
Ahmed Guerine, Ali El Hafidi and Philippe Leclaire: Université Bourgogne Europe, DRIVE UR 1859, 58000, Nevers, France

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