Abstract
The results of a study that looked at the experimental and numerical performance of ferrocement RC beams with
openings reinforced with welded steel mesh, expanded steel mesh, fiber glass mesh, and polyethylene mesh separately are
presented in this article. The research program included casting and testing of fourteen 200x100x2000mm reinforced concrete beams under flexural loadings. The primary factors that change are the type of reinforcing materials, the volume fraction of reinforcement, the quantity of mesh layers, and the quantity of stirrups. Understanding the effects of using novel, alluring materials to reinforce RC beams with openings is the main objective. Nonlinear finite element analysis (NLFEA) was used to demonstrate the behavior of composite RC beams with openings using ANSYS-16.0 Software. A parametric study is also carried out to discuss the factors, such as the number of openings that can most significantly affect the mechanical behavior of the
suggested model. The obtained experimental and numerical results showed that the FE simulations provided an acceptable level of experimental value estimation. Furthermore, it is significant to show that, in comparison to specimens reinforced with expanded or welded steel meshes, the strength gained of specimens reinforced with fiber glass meshes was reduced by about 38%. Additionally, using expanded steel meshes to reinforce RC beams with openings results in a 16% increase in strength when compared to welded steel meshes. In general, ferrocement beams with openings demonstrate higher-level ultimate loads and
energy-absorbing capacity than conventional beams when tested under flexural loadings.
Address
Yousry B.I. Shaheen: Civil Engineering Department, Faculty of Engineering, Menoufia University, Menoufia, Egypt
Ashraf M. Mahmoud: Civil Engineering Department, Faculty of Engineering, Modern University for Technology and Information (MTI), Al-Mokattam, Cairo, Egypt
Abstract
This paper revisits our recent work on rapid and accurate design of reinforced concrete (R/C) columns and bridge
piers using Artificial Neural Networks (ANNs). Both rectangular and circular, solid and hollow sections are treated. The new functions for rectangular sections now accommodate a much greater aspect ratio, making them suitable for all sections typically used for bridge piers, without sacrificing performance. For the first time, to the best of our knowledge, new design functions for T-beams and singly-reinforced rectangular beams are also derived. The error estimation is presented in detail using extremely
extensive test sets, while auxiliary ANNs are employed to screen out improper data input. All design functions are sufficiently accurate, unconditionally stable, and orders of magnitude faster than any iterative section analysis procedure. The forward feed of the final ANNs has been translated into optimized code in all popular programming languages, which can be easily used without the need of specialized software, even on a spreadsheet.
Address
Aristotelis E. Charalampakis: Department of Civil Engineering, University of West Attica, 12241, Athens, Greece
Vassilis K. Papanikolaou: School of Civil Engineering, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece
Abstract
The primary strength of the enriched finite element method (enriched FEM) is its ability to enhance solution accuracy without mesh refinement. It also allows for the selective determination of cover function degrees based on desired accuracy. Furthermore, there is an adaptive enrichment strategy that applies enriched elements to targeted areas where accuracy may be lacking rather than across the entire domain, demonstrating its powerful use in engineering applications. However, its application to solid and structural problems encounters a linear dependence (LD) issue induced by using polynomial functions as cover functions. Recently, enriched finite elements that address the LD problem in linear analysis have been developed. In light of these advancements, this study is devoted to a robust extension of the enriched FEM to nonlinear analysis. We propose a nonlinear formulation of the enriched FEM, employing 3-node and 4-node 2D solid elements for demonstration. The formulation employs a total Lagrangian approach, allowing for large displacements and rotations. Numerical examples demonstrate that the enriched elements effectively improve solution accuracy and ensure stable convergence in nonlinear analysis. We also present results from adaptive enrichment to highlight its effectiveness.
Key Words
adaptive enrichment; enriched finite element method; finite element method; geometric nonlinear analysis; total Lagrangian approach
Address
Hyung-Gyu Choi: Ground Technology Research Institute, Agency for Defense Development, Daejeon 34060, Republic of Korea
Chaemin Lee: Department of Safety Engineering, Chungbuk National Univesity, Cheongju-si, Chungcheongbuk-do 28644, Republic of Korea
San Kim: Department of Mechanical Convergence Engineering, Gyeongsang National University, Changwon-si, Gyeongsangnam-do 51391, Republic of Korea
Abstract
This paper proposes a three-dimensional (3D) dynamic interaction analysis algorithm between the Hypertube
Express (HTX) and its guideway. HTX, which utilizes superconductive electromagnets, travels in a magnetically levitated state by leveraging the principles of induction and repulsion with the levitation and guidance coils of the guideway. This reduces frictional resistance, enabling high-speed travel. The guideway experiences dynamic loads due to the levitation and magnetic forces, while HTX is influenced by the irregularity and deformation of the guideway. The dynamic interaction between HTX and the guideway has a significant impact on both design and safety considerations. To address this, we aim to predict the dynamic behavior of both HTX and the guideway numerically. The system matrices of HTX and the guideway, along with their interaction forces, are calculated to perform a 3D dynamic interaction analysis. The guideway is modeled using shell finite elements, and to ensure realistic results, we apply a nonlinearly varying interaction stiffness based on the cruising speed and displacement of HTX. The irregularity of the guideway, which has a critical effect on the interaction, is incorporated into the model. The results of this analysis help to clarify the dynamic characteristics of both the HTX and its guideway. The proposed algorithm provides a foundation for the initial design of HTX and its guideway, contributing to future high-speed transportation
systems.
Key Words
3D dynamic interaction analysis; dynamic characteristics; guideway; Hypertube Express (HTX); irregularity; shell finite element; superconductive electromagnets
Address
Seunghwan Park: Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
Seung-Min Baek, Hyung-Jo Jung: Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
Phill-Seung Lee: Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
Man-Cheol Kim: Korea Railroad Research Institute, 176, Cheoldobangmulgwan-ro, Uiwang-si, Gyeonggi-do 16105, Republic of Korea
Abstract
This study explores the use of Ultra-High-Performance Concrete (UHPC) to enhance joint strength in prefabricated
concrete structures, addressing challenges posed by rapid construction demands and natural disasters, particularly earthquakes. Joint failures are a key vulnerability, and UHPC, with its superior bond strength, reduces lap splice length and stirrup quantities in connection zones. The study focuses on the cyclic response of UHPC-infused precast beam-column connections, aiming to optimize structural resilience using a "strong connection, weak component" approach. Three precast specimens (PC1, PC2, PC3) with varying lap lengths and stirrup ratios are compared against a monolithic benchmark (ML) to evaluate performance under cyclic loading.
Key Words
beam-column connection; cyclic loading; fibres; high strength concrete; UHPC
Address
R. Anandlal, K.P. Jaya and K.V. Jayashree: Department of Civil Engineering, Anna University, Chennai, 600025, India
Abstract
To investigate the mechanical behavior of unbonded prestressed reinforced concrete (PRC) beam with high-strength spiral stirrups, the shear capacity formula of the beam was proposed in this study based on modified variable angle truss and arch models. Considering the effect of the spiral stirrups and unbonded tendons, the theoretical formula of the shear capacity of the beam was derived. Furthermore, the coefficients related to the formula, such as the equivalent angle and stress of spiral stirrups, the ratio of shear span to effective depth, and the concrete compression zone depth of the arch model were determined.
The complicated theoretical formula was further simplified for ease of use by engineers. In addition, the finite element model of the PRC beam was established and verified by test data. The additional FE model of PRC beam with spiral stirrups was established and parametric analysis was carried out. Finally, the proposed formula was validated by numerical results of the beam with spiral stirrups. The calculated values of the formula are in good agreement with the numerical simulation data. This study may enrich the understanding of the shear capacity of the unbonded PRC beam with high-strength spiral stirrups.
Key Words
finite element model; high strength spiral stirrups; PRC beam; shear capacity; truss and arch model; unbonded tendons
Address
Hao Zhang, Wei Huang: School of Civil Engineering, Xi
Abstract
In severe intensity seismic zones, the conventional detailing of reinforcement in the exterior beam-to-column joint causes congestion of steel that affects the ease of construction. This article evaluates the behaviour of exterior beam-column joints with different anchorage/connection methods suitable for avoiding steel congestion. Sub-assemblages having six-joint connections were cast and tested under reverse cyclic loading at the tip of the beam under displacement control. Of these, four
connections are non-conventional reinforcement detailing were detailed as per ACI 352R-02 and IS-456 along with confinement as per IS-13920, Straight-Headed Bar, X Cross-Headed Bar and the remaining specimens are detailed as a conventional confined specimen. The experimental results from the specimens with different anchorages are compared with the monolithic connection. The study revealed that the X cross-headed bar considerably enhanced the joint's seismic performance in terms of strength, ductility, and energy dissipation. A numerical model (ABAQUS) that considers the nonlinear behaviour of steel and concrete in the beam-column joint is also considered in this study. The results of the experimental tests and the numerical differed by less than 10% on average. The developed headed-bar connection at the beam-column joint is evaluated by calculating the possible shear stress in the joints theoretically and the estimated values lie well within the values specified in standards/codes.
Key Words
ABAQUS; beam-to-column joint; nonlinear behaviour; reverse cyclic loading; straight-headed bar; x crossheaded bar
Address
W. Balkis Banu and K.P. Jaya: Department of Civil Engineering, College of Engineering Guindy, Anna University, Chennai, Tamil Nadu, India
Abstract
Energy absorbers are crucial for absorbing collision energy, and much research is being done continuously to enhance their performance. These structures are widely applicable in automotive crash boxes and other passive safety systems, where efficient energy absorption and structural stability are essential for occupant protection during collisions. Safety and energy consumption concerns have led researchers to make the structures lighter in addition to better energy absorption. The most significant factors influencing the behavior of energy absorbers are the structure's geometry and material. Conical frustum, aluminum, and composite are among the things been raised in the research. In this research, aluminum structures were produced in two versions and with different geometric specifications. In experimental and numerical studies, aluminum and compositecoated samples were compared. The results show that utilizing an aluminum-composite combination can boost specific energy absorption by up to three times while increasing peak force and mean force. Also, by examining the impact of the parameters involved in the structure's energy absorption in the RSM method, the structure's performance has been significantly impacted by the use of composites. It has reduced the dependence of the energy absorption on the structure's geometry, which, along with controlling the process of regular destruction, has increased energy absorption.
Key Words
crash box; crashworthiness; energy absorption; FML; frustum
Address
Afshin Tafazoli and Masoud Asgari: Passive Safety Research Lab., Mechanical Engineering Faculty, K.N. Toosi University of Technology, Tehran, Iran
