Abstract
The current study examines the experimental and numerical performance of reinforced concrete (RC) channel slabs
made of ferrocement that have been reinforced with fiber glass, expanded steel mesh, and welded steel mesh. As part of the testing program, ten RC channel slabs with dimensions of 500 mmx40 mmx2500 mm were loaded flexibly. The three main
factors that can be altered are the mesh layer count, the type of reinforcing materials, and the reinforcement volume fraction. The main objective is to assess the effects of fortifying composite RC channel slabs with novel inventive materials. ANSYS-16.0 Software was used to simulate the behavior of composite channel slabs using nonlinear finite element analysis (NLFEA). It also shows how parametric analysis can be used to pinpoint variables like variations in slab dimensions that could significantly affect the mechanical behavior of the model. The obtained experimental and numerical results showed that finite element (FE) simulations had a tolerable degree of accuracy in estimating experimental values. It is crucial to show that specimens
strengthened with fiber glass meshes gained about 12% less strength than specimens strengthened with expanded or welded steel meshes. In addition, RC channel slab reinforcement made of welded steel meshes has a 24% higher strength than expanded steel meshes. Tested under flexural loads, ferrocement specimens outperform conventional reinforced concrete specimens in terms of ultimate loads and energy absorption.
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
In the current paper, the various responses of concrete rectangular liquid storage containers under seismic load, each isolated by a lead-rubber bearing subjected to bi-directional earthquake forces are investigated. A parametric study is conducted to investigate the effects of isolation period, yield strength of the isolator and the effects of soil-foundation interaction for nonisolated and base-isolated tanks located on different soil types. In most cases, the value of base shear, base moment, wall displacement and hydrodynamic pressure is reduced by the effect of the isolators whose effective frequency is within the appropriate range. The sloshing displacement is amplified due to seismic isolation of the tanks for both tall and shallow tank configurations. Also, it is found that the seismic isolation technique is more efficient for the more flexible tank. Studying various soil types indicates that, unlike the responses of non-isolated tanks which change drastically for different soil types, the responses of base-isolated structures are less affected. Finally, it is observed that the variation in structural responses is not only related to the superstructure configuration and bearings properties but also depends on the earthquake specifications.
Address
Mohammad Hossein Aghashiri: Young Researchers and Elite Club, Eqlid Branch, Islamic Azad University, Eqlid, Iran
Shamsedin Hashemi: Department of Civil Engineering, Yasouj University, Yasouj, Iran
Mohammad Reza Kianoush: Department of Civil Engineering, Toronto Metropolitan University, Toronto, Canada
Abstract
This paper presents an innovative theoretical and numerical model to predict the lateral-torsional buckling (LTB) of
simply supported steel I-beams with external prestressed tendons. The model incorporates an updated prestressing force, accounting for thermal effects and various external loadings. Critical multipliers are determined by solving an eigenvalue problem derived from applying Galërkin's approach to a set of nonlinear equilibrium equations. Validation is carried out through Finite Element Method (FEM) simulations, incorporating a new expression for an equivalent thermal expansion coefficient for the beam-tendon system, addressing both mechanical and thermal deformations. The primary aim is to estimate critical conditions considering material property degradation due to fire. The present results are generally in good agreement with those provided by the literature.
Key Words
cable; fire; LTB; prestressed I beams; steel
Address
Abdellah Mahieddine, Noureddine Ziane, Mohamed Zidi, Sid Ahmed Meftah: Laboratoire des Structures et Matériaux Avancés dans le Génie Civil et Travaux Publics, Université de Djillali Liabes, Sidi Bel Abbes, Algeria
Giuseppe Ruta: Department of Structural and Geotechnical Engineering, University "La Sapienza", Rome, Italy
Rachid Zahi: University of Relizane, Relizane, Algeria
Abstract
This work aims to present an analysis of the structural reliability of reinforced concrete (RC) columns designed
according to the general method outlined in Eurocode 2 (EN 1992-1-1 2004). Probabilistic analyses are conducted by integrating the Monte Carlo method with metamodels (or surrogate models) generated using Kriging and some machine learning techniques. The study was developed based on an algorithm that verifies the columns subject to biaxial bending, considering the physical and geometric nonlinearities. Columns were analyzed assuming sign inversion of end bending moments (with reverse curvature), which portray the typical situations in conventional structures of RC buildings. The probabilistic results reveal that the typical RC columns in buildings designed according to the design procedures of the studied standard, whether they are located at the center, corner, or edge, exhibit reliability levels surpassing those deemed acceptable within the technical community. Furthermore, the integration of surrogate models proves beneficial by alleviating the computational burden associated with evaluations while preserving accuracy.
Address
Arthur de C. Preuss and Herbert M. Gomes: Graduate Program in Civil Engineering, Federal University of Rio Grande do Sul, Av. Osvaldo Aranha, 99, 3o. Andar, Porto Alegre, RS, Brazil
Abstract
In the present work generalized thermoelasticity of a piezoelectric layer is analysed under various shock loading
conditions. The generalized thermoelasticity is based on the Lord-Shulman model. The governing equations are solved in the space domain using the finite element method and for solving the equations in the time domain the Newmark method is used. Two kinds of shock loading, temperature shock, and stress shock loading are considered. The results are compared with same results presented in other works and a very close agreement is observed. Finally, the results for each loading condition are presented in various locations and times.
Key Words
finite element; generalized thermoelasticity; Lord-Shulman; piezoelectric
Address
F. Kheibari: Department of Mechanical Engineering, Shahrekord University, Shahrekord, Iran
Y. Tadi Beni, Y. Kiani: Faculty of Engineering, Shahrekord University, Shahrekord, Iran; Nanotechnology Research Institute, Shahrekord University, Shahrekord, Iran
Abstract
Discarded cigarette butts in the environment have caused significant pollution. Therefore, providing solutions to
address these environmental issues is of great importance. Concrete is known as one of the most widely used materials around the world. Hence, this study investigates the feasibility of using cigarette butts to product concrete. For this purpose, cellulose acetate fibers obtained from cigarette butt filters were added to silica fume concrete in 10 different volume ratios. Then, the mechanical properties of the concrete samples, including compressive strength, Brazilian tensile strength, and flexural tensile strength, were examined. Based on the results, adding fibers to silica fume concrete improved the mechanical properties of the
concrete. Among the 10 mixing designs, adding 0.2% by volume of fibers to silica fume concrete yielded the highest
compressive and tensile strengths. In other words, adding 0.2% by volume of fibers resulted in a 16% and 34% increase in compressive strength and a 70% and 38% increase in Brazilian tensile strength at 7 and 28 days, respectively, compared to the state without cellulose acetate fibers. Additionally, the flexural tensile stress capacity increased by 56%. Furthermore, the vertical deformation tolerance in beam specimens increased by 287%, and the energy absorption capacity of the concrete beam also significantly increased. Consequently, along with the significant improvement in the mechanical properties of concrete, this study proposes a new and practical strategy to address the environmental issues caused by waste cigarette butts.
Key Words
cigarette butt; environmental pollution; mechanical properties of concrete; silica fume concrete
Address
Hamid Reza Ahmadi, Mehdi Rezaie and Taher Khojasteh Zinjanab: Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Maragheh 55136-553, Iran
Abstract
The crack propagation path can be considered as a boundary problem in which the crack advances towards the interior of the domain. Consequently, this poses an optimization problem wherein the local crack-growth direction angle can be treated as a design variable. The advantage of this approach is that the continuous minimization of strain energy naturally leads to the mode I propagation path. Furthermore, this procedure does not rely on the precise characterization of the stress field at the crack tip and is independent of stress intensity factors. This paper proposes an algorithm based on internal point exploration as well as shape sensitivity optimization and strain energy minimization to determine the crack propagation direction. To implement this methodology, the algorithm utilizes a modeling GUI associated with an academic analysis program based on the Dual Boundary Elements Method and determines the propagation path by exploiting the elastic strain energy at points in the domain that are candidates to be included in the boundary. The sensitivity of the optimal solution is also assessed in the vicinity of the optimum point, ensuring the stability and robustness of the solution. The results obtained demonstrate that the proposed methodology accurately predicts the crack propagation direction in Mode I opening for a single crack (lateral and central). Furthermore, robust optimal solutions were achieved in all cases, indicating that the optimal solution was not highly sensitive to changes in the design variable in the vicinity of the optimal point.
Key Words
crack propagation; dual boundary elements method; local energy minimization; shape optimization; strain energy
Address
Beatriz Ferreira Souza and Gilberto Gomes: Department of Civil Engineering, University of Brasilia (UnB), Campus Darcy Ribeiro, Brasilia, 70910-900, Distrito Federal, Brazil
Abstract
Sampling methods are powerful approaches to solving the problems of structural reliability analysis and estimating
the failure probability of structures. In this paper, a new sampling method is proposed offering lower variance and lower computational cost for complex and high-dimensional problems. The method is called Optimal Latinized partially stratified sampling (OLPSS) as it is based upon the Latinized Partially Stratified Sampling (LPSS) which itself is based on merging Stratified Sampling (SS) and Latin Hypercube Sampling (LHS) algorithms. While LPSS has a low variance, it may suffer from a lack of good space-filling of its generated samples in some cases. In the OLPSS, this issue has been resolved by employing a new columnwise-pairwise exchange optimization procedure for sample generation. The efficiency of the OLPSS has been tested
and reported under several benchmark mathematical functions and structural examples including structures with a large number of variables (e.g., a structure with 67 variables). The proposed method provides highly accurate estimates of the failure probability of structures with a significantly lower variance relative to the Monte Carlo simulations, Latin Hypercube, and standard LPSS.
Key Words
Latin hypercube sampling; Latinized partially stratified sampling; space-filling optimization; structural reliability analysis
Address
Majid Ilchi Ghazaan and Amirreza Davoodi Yekta: School of Civil Engineering, Iran University of Science and Technology, P.O. Box 16846-13114, Iran
