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Fatigue damage analysis of ballastless slab track in heavy-haul railway tunnels

Underground Space 2022年第3期7卷 440-452页

作者： Zi-qiang Li Zheng Li Wei-wei Huang Hong-rui Zhang Hang Zhang School of Civil Engineering and Architecture Chongqing University of Science&TechnologyChongqing 41331China Chongqing City Construction Investment(Group)Co. Ltd.Chongqing 400023China Key Laboratory of New Technology for Construction of Cities in Mountain Area Ministry of EducationChongqing UniversityChongqing 400045China School of Mechanical and Electrical Engineering Hainan UniversityHainan 570228China

A ballastless slab track,which is commonly used in the track structures of heavy-haul railway tunnels,was analysed based on field measurement data of the Fuyingzi Tunnel on the Zhangtang *** accordance with the measured data,the dynamic load thresholds and distributions on the surface and bottom of the ballastless slab track were investigated.A fatigue damage analysis of the ballastless slab track was performed based on the dynamic load time–history *** results show that the ballastless slab track can accomplish train load attenuation and reduce the dynamic load from heavy-haul trains by 47.22%from the surface to the *** addition,the distribution at the bottom of the ballastless slab track exhibited a triangular shape,and the dynamic load threshold at the line centre accounted for 78.67%of that at the track ***,the distribution at the surface was saddle-shaped;the dynamic load threshold at the track position accounted for 79.55%of that at the line centre *** fatigue damage of the ballastless slab track was analysed effectively by combining the measured data and the linear fatigue damage ***,the accuracy of the calculation results was verified based on the measured dynamic stress of the ballastless slab track *** dynamic action of the train load led to more-concentrated damage to the track bed,and the damage occurred earlier than that in the ordinary *** axle load was the primary influencing factor of the track bed fatigue damage,and the damage mainly occurred in the track *** results provide a theoretical basis for performing stress analysis and designing parameters for ballastless slab tracks in heavy-haul railway tunnels.

关键词： Heavy-haul railway tunnel Numerical simulation results Ballastless slab track Fatigue damage

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Flood Management Strategies in Indonesia: A Lesson Learned from Pepe River, Central Java 5th

Flood Management Strategies in Indonesia: A Lesson Learned f...

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5th International Conference on Rehabilitation and Maintenance in civil engineering, ICRMCE 2021

作者： Prastica, Rian Mantasa Salve Wijayanti, Amalia Civil Engineering Department Gadjah Mada University Yogyakarta55281 Indonesia Water Infrastructure Construction Technology Study Program Public Works Polytechnic Semarang50275 Indonesia

ISBN: (纸本)9789811693472

Floods occur every year and threaten communities worldwide. Indonesia is among the countries faced with this problem and still struggling to seek practical solutions to date. Further, as the country’s centers of trade, business, and technology, the island of Java cannot even perform better in dealing with floods. To further understand possible damage and losses, this research investigated structural mitigation measures as part of flood management in the Pepe River, notably river channelization to increase hydraulic efficiency. For the analysis, it used HEC-RAS to observe the river capacity. Existing conditions revealed that the river could not accommodate the predicted floods based on the return periods derived from the synthetic unit hydrograph of Nakayasu. However, after running the mitigation scenario wherein hydraulic modification was applied, flood risk could be reduced by lowering the river water level. Based on the results, it can be concluded that Indonesia needs to pay more attention to other aspects: ecology, green infrastructure, and water governance, to achieve more effective flood mitigation measures because structural mitigation only provides a temporary solution. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Rivers

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Static Simple Shear Tests on Mechanical Behavior of Interface Between Coral Sand and Concrete

Static Simple Shear Tests on Mechanical Behavior of Interfac...

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International Conference on Green Building, civil engineering and Smart City, GBCESC 2022

作者： Jiang, Chunyong Ding, Xuanming Yang, Gang College of Civil Engineering Chongqing University Chongqing400045 China Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing University Chongqing400045 China

ISBN: (纸本)9789811952166

There are various concrete foundations and retaining structures on the islands and reefs, which are subjected to various static and dynamic loads. The interaction characteristics of the contact surface between coral sand and concrete is the key to affect the stress and deformation of rock and soil mass and structure. The static simple shear test of the contact surface between coral sand and concrete was carried out using the simple shear tester. The influence of normal stress, different roughness, particle size and relative density on the static shear characteristics of the surface of contact was studied. The relation between axial displacement, shear stress and tangential displacement of interface. The experimental results indicate that the magnitude of the normal stress has a certain effect on the normal displacement and shear stress of the contact surface, and there is a direct proportional relationship between shear strength and applied normal stress.;the roughness of the contact surface is relatively dense with the coral sand The degree also has a positive effect on the shear stress of the contact face;The particle size has a certain influence on the shear stress and normal displacement of the contact surface. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Surface roughness

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Site effects based on time varying horizontal-to vertical spectral ratio 67

Site effects based on time varying horizontal-to vertical sp...

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67th International Conference on Vibroengineering

作者： Cao, Fuchao Dong, Yinfeng Xie, Yiming Wang, Yiping Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing University Ministry of Education Chongqing China School of Civil Engineering Chongqing University Chongqing China

Horizontal to vertical spectral ratio (HVSR) based on seismic ground motion is an important index to study site conditions and dynamic characteristics (seismic effect). Due to the influence of the vertical dynamic amplification effect of the site, the Fourier spectral ratio calculated according to the surface motion and downhole motion is quite different from that of the horizontal and vertical ground motion in the case of strong vibration input. However, our recent research shows that when considering the time-varying characteristics of ground motion, the time-varying surface-downhole spectral ratio and time-varying HVSR are almost the same. Based on this discovery, the time-varying HVSR is used to study the dynamic characteristics of the site (site effect). First, a new method for calculating the natural period and damping ratio of the site is proposed. Secondly, based on tremendous strong motion records, the prediction formulas of natural period and damping ratio are studied. Finally, the effects of various influencing factors on the natural period and damping ratio are compared. The results of this paper can provide a basis for selecting and synthesizing appropriate ground motions in structural seismic design. Copyright © 2023 Fuchao Cao, et al.

关键词： damping ratio epicenter distance HVSR natural frequency transfer function

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CYCLIC TESTS ON AN INNOVATIVE FRICTION DISSIPATIVE DEVICE FOR SEISMIC RETROFIT WITH CLT PANELS 13

CYCLIC TESTS ON AN INNOVATIVE FRICTION DISSIPATIVE DEVICE FO...

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13th World Conference on Timber engineering: Timber for a Livable Future, WCTE 2023

作者： Boggian, Francesco Aloisio, Angelo Tomasi, Roberto Faculty of Science and Technology Norwegian University of Life Sciences Norway WSP Norge Norway Department of Civil Construction-Architectural and Environmental Engineering University of l'Aquila Italy

ISBN: (纸本)9781713873297

Seismic renovation is a topic of crucial importance for many countries in the southern part of Europe, where the high levels of seismic hazard, combined with the presence of old RC frame structures, poses a severe risk to the lives of many. The e-CLT system, part of the European project e-Safe, proposes a seismic retrofit system for existing RC frame buildings by attaching CLT panels to the facade and connecting them to the existing structure with innovative friction dissipative devices. The authors conducted an experimental campaign at component level for this novel connector, with two different setups, with and without a CLT panel. This paper presents the cyclic test results on these friction devices, with particular attention to the influence of the timber connection on friction behaviour. © 13th World Conference on Timber engineering, WCTE 2023. All rights reserved.

关键词： Energy dissipation

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Characteristics of self-compacting green concrete

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Discover civil engineering 2024年第1期1卷 1-14页

作者： Lim, Hung Ling Mannan, Mohammad Abdul Fakhri, Rana Shamseldeen Dawood, Eethar Thanon Teo, Delsye Ching Lee Tasnim, Sadia Department of Civil Engineering Faculty of Engineering Universiti Malaysia Sarawak (UNIMAS) Kota Samarahan Malaysia Department of Building and Construction Engineering Technical College of Mosul Northern Technical University Mosul Iraq Bachelor of Engineering Technology (Civil) Program Department of Business and Construction (Higher Education) Melbourne Polytechnic Epping Australia Applied Engineering South Metropolitan TAFE Munster Australia

Locally, conventional concrete is still created utilizing river sand and crushed stone as filer materials. The massive quarry dust by-product remain untapped in the production of concrete. The coal-fired power station produce significant quantities of Type F fly ash. Self-compacting concrete (SCC) provides many advantages for creating high-quality concrete. Consequently, the main objective of this research is to create a mix design for high-strength SCC utilizing a binary blends, hybrid fibers and fine aggregates that meet both hardened and fresh concrete characteristics. The study is conducted in amendment of w/b ratio, superplasticizer, proportion of fine aggregate to coarse aggregate, optimumal cement replacing by fly ash, dosage of low macro fibre and micro fibre. Mix-50c-X is the best mix design that was produced. The mix quantity for 1m3 concrete was 315 kg Class F fly ash, 315 kg OPC, 630 kg quarry dust, 508 kg river sand, 400 kg coarse aggregate, 0.7% superplasticizer,0.32% w/b, 0.10% macro fiber, and 0.01% micro fiber. This SCC mixture showed fresh characteristics as well as compressive strengths of more than 22 MPa and 62 MPa after 1 day and 28 days, respectively. The results of high-strength SCC demonstrated the enormous potential for the local construction, especially precast product.

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Acceleration spikes in strong earthquake ground motion induced by dilatancy cyclic mobility mechanism 66

Acceleration spikes in strong earthquake ground motion induc...

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66th International Conference on Vibroengineering

作者： Su, Qingshuang Dong, Yinfeng Guo, Feiyu Zhang, Xingyu Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing University Ministry of Education Chongqing China School of Civil Engineering Chongqing University Chongqing China

Strong motion records with acceleration spikes have occurred frequently in recent major earthquakes, acceleration spikes contribute to the peak ground accelerations (PGAs) and the amplitudes are significantly higher than the predicted values based on present attenuation relation. The generation mechanism of acceleration spikes is revealed based on long-term monitoring after the 2008 Mw 8.0 Wenchuan earthquake. The horizontal accelerogram with obvious spikes from the Mw 9.0 Tohoku-Oki earthquake is reproduced by using numerical simulation, and it’s found that the dilatancy cyclic mobility (DCM) mechanism can explain the generation of acceleration spikes. The support vector machine (SVM) is used to efficiently identify DCM sites. We found that the spatial distribution of DCM sites is parallel to the earthquake source fault and the corresponding PGAs of ground motions recorded in DCM sites differ significantly from those recorded in non-dilatancy cyclic mobility (NDCM) sites. Copyright © 2023 Qingshuang Su, et al.

关键词： Support vector machines

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Characteristic period of response spectrum for surface and borehole ground motions 67

Characteristic period of response spectrum for surface and b...

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67th International Conference on Vibroengineering

Determining the characteristic period of ground motions (Tg) is an essential step in the seismic design of structures, but a critical problem that needs to be solved is figuring out how to do so when bedrock ground motion is utilized as an input. In this paper, the relationship between surface and borehole temperature data is investigated, and the main factors affecting the Tg are analyzed. Then, the algorithm for predicting Tg is presented. It is found that two factors, i.e., peak ground acceleration (PGA) and fault distance have significant effects on the value of Tg. By comparing the values of Tg for borehole and surface motions, we find that, contrary to expectation, Tg for borehole motions is usually larger than that for surface motions in most cases. Finally, the conversion equation between the Tg for borehole and surface motions is given using regression analysis. Copyright © 2023 Qingshuang Su, et al.

关键词： characteristic period earthquake ground motion maximal information coefficient prediction relation

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The threshold value of ground motion acceleration characterizing the nonlinear response of sites 66

The threshold value of ground motion acceleration characteri...

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66th International Conference on Vibroengineering

作者： Zhang, Xingyu Dong, Yinfeng Wei, Lejun Guo, Feiyu Su, Qingshuang Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing University Ministry of Education Chongqing China School of Civil Engineering Chongqing University Chongqing China

Assessing the nonlinearity of a site plays a crucial role in earthquake engineering. For some building structures and lifeline projects that need safety assessment after earthquakes, the analysis of nonlinear degree of sites can help accurately revealing the amplification effect of sites and evaluating the damage degree of buildings which is convenient for subsequent reinforcement and demolition work. The quantitation of nonlinear threshold of sites is an important method to evaluate the degree of site nonlinearity. In this paper, a nonlinear characteristic index reflecting the degradation of shear modulus is proposed based on the instantaneous frequency of the site calculated by using the vector auto-regression moving average (VARMA) model. Then, seismic records of class Ⅰ, Ⅱ, Ⅲ and Ⅳ sites specified as per code for seismic design of buildings in China are selected from the KiK-net network in Japan, and the threshold value of ground motion acceleration characterizing the nonlinear response of sites are provided. Finally, the variation of the nonlinear characteristic index (shear modulus degradation) vs. different (peak ground acceleration) PGA for four types of sites are presented. Copyright © 2023 Xingyu Zhang, et al.

关键词： Elastic moduli

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Analytical investigation of the influence of various void shape and spacing on the load-bearing behavior of concrete hollow core slabs

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Journal of Building Pathology and Rehabilitation 2022年第1期7卷 1-12页

作者： Kumar, M. Vinod Alzein, Razan Ganesh, A. Chithambar Kumar, K. Rajesh Gurumoorthy, N. Adesina, Adeyemi Department of Civil Engineering Vel Tech Rangarajan Dr.Sagunthala R&D Institute of Science and Technology Tamil Nadu Chennai 600062 India Department of Civil Engineering Sree Vidyanikethan Engineering College Tirupati India Centre for Construction Methods and Materials SR University Warangal Telangana India Department of Civil Engineering PSNA College of Engineering and Technology Dindigul 624622 Tamil Nadu India Department of Civil and Environmental Engineering University of Windsor Windsor Canada

The self-weight of a structure is of great importance as it directly affects the cost of the structure. With concrete slabs being one of the biggest and heaviest structural members in buildings, it is essential to devise novel ways to reduce the self-weigh of slabs without significant reduction in the load-carrying capacity. One of such solutions that can be used to reduce the self-weight of slabs is the use of hollow-core slabs. In addition to the reduction in self-weight with the use of hollow-core slabs, a reduction in the cost and workmanship associated with the production of the slabs can be achieved. In this context, this analytical study was carried out to investigate the effect of various void shapes and spacings on the load-bearing behaviour of hollow-core slabs using the Finite Element Analysis (FEA) program ANSYS. Slabs with a uniform dimension of 2600 mm × 1200 mm × 140 mm with the same reinforcement are designed with various void shapes of the same area of 1963.5 mm² (Group 1) and spacing (Group 2). The outcome of this study showed the presence of hollows in the slabs resulted in a reduction in the load-bearing capacity of the slabs. Nonetheless, the use of elliptical void shape was found to be optimum among other shapes and increasing the void spacing to 120 mm can be used to increase the capacity of the slabs. On a positive note, the presence of voids in the slabs resulted in a reduction in self-weight in the range of 9.2%–15.1%. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.

关键词： Finite element analysis (FEA) Finite element analyzing software ANSYS Hollow core slabs Self-weight reduction

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