Abstract
This paper investigates the ductility demands of steel frames equipped with self-centring fuses under near-fault earthquake motions considering multiple yielding stages. The study is commenced by verifying a trilinear self-centring hysteretic model accounting for multiple yielding stages of steel frames equipped with self-centring fuses. Then, the seismic response of single-degree-of-freedom (SDOF) systems following the validated trilinear self-centring hysteretic law is examined by a parametric study using a near-fault earthquake ground motion database composed of 200 earthquake records as input excitations. Based on a statistical investigation of more than fifty-two (52) million inelastic spectral analyses, the effect of the post-yield stiffness ratios, energy dissipation coefficient and yielding displacement ratio on the mean ductility demand of the system is examined in detail. The analysis results indicate that the increase of post-yield stiffness ratios, energy dissipation coefficient and yielding displacement ratio reduces the ductility demands of the self-centring oscillators responding in multiple yielding stages. A set of empirical expressions for quantifying the ductility demands of trilinear self-centring hysteretic oscillators are developed using nonlinear regression analysis of the analysis result database. The proposed regression model may offer a practical tool for designers to estimate the ductility demand of a low-to-medium rise self-centring steel frame equipped with self-centring fuses progressing in the ultimate stage under near-fault earthquake motions in design and evaluation.
Address
Lu Deng: Key Laboratory for Damage Diagnosis of Engineering Structures of Hunan Province, Hunan University, Changsha, China
Min Zhu: Key Laboratory for Damage Diagnosis of Engineering Structures of Hunan Province, Hunan University, Changsha, China; Department of Building and Real Estate, The Hong Kong Polytechnic University, Hong Kong, China
Michael C.H. Yam: Department of Building and Real Estate, The Hong Kong Polytechnic University, Hong Kong, China; Chinese National Engineering Research Centre for Steel Construction (Hong Kong Branch), The Hong Kong Polytechnic University, Hong Kong, China
Ke Ke: Key Laboratory of New Technology for Construction of Cities in Mountain Area, School of Civil Engineering, Chongqing University, Chongqing, China
Zhongfa Zhou: Beijing Institute of Architectural Design, Beijing, China
Zhonghua Liu: Zhejiang Jinggong Steel Building Group Co., Ltd., Shaoxing, China
Abstract
This study, it was tried to evaluate the asphalt behavior under tensile loading conditions through indirect Brazilian and direct tensile tests, experimentally and numerically. This paper is important from two points of view. The first one, a new test method was developed for the determination of the direct tensile strength of asphalt and its difference was obtained from the indirect test method. The second one, the effects of particle size and loading rate have been cleared on the tensile fracture mechanism. The experimental direct tensile strength of the asphalt specimens was measured in the laboratory using the compression-to-tensile load converting (CTLC) device. Some special types of asphalt specimens were prepared in the form of slabs with a central hole. The CTLC device is then equipped with this specimen and placed in the universal testing machine. Then, the direct tensile strength of asphalt specimens with different sizes of ingredients can be measured at different loading rates in the laboratory. The particle flow code (PFC) was used to numerically simulate the direct tensile strength test of asphalt samples. This numerical modeling technique is based on the versatile discrete element method (DEM). Three different particle diameters were chosen and were tested under three different loading rates. The results show that when the loading rate was 0.016 mm/sec, two tensile cracks were initiated from the left and right of the hole and propagated perpendicular to the loading axis till coalescence to the model boundary. When the loading rate was 0.032 mm/sec, two tensile cracks were initiated from the left and right of the hole and propagated perpendicular to the loading axis. The branching occurs in these cracks. This shows that the crack propagation is under quasi-static conditions. When the loading rate was 0.064 mm/sec, mixed tensile and shear cracks were initiated below the loading walls and branching occurred in these cracks. This shows that the crack propagation is under dynamic conditions. The loading rate increases and the tensile strength increases. Because all defects mobilized under a low loading rate and this led to decreasing the tensile strength. The experimental results for the direct tensile strengths of asphalt specimens of different ingredients were in good accordance with their corresponding results approximated by DEM software.
Key Words
asphalt; direct tensile strength; experimental test; indirect tensile strength; PFC2D
Address
Q. Wang: School of Highway, Henan College of Transportation, Zhengzhou 451460, China
D.C. Wang: School of Civil Engineering and Transportation, North China University of Water Resources and Electric Power, Zhengzhou, 450046, China
J.W. Fu: School of Civil Engineering and Transportation, North China University of Water Resources and Electric Power, Zhengzhou, 450046, China
Vahab Sarfarazi: Department of Mining Engineering, Hamedan University of Technology, Hamedan, Iran
Hadi Haeri: Department of Mining Engineering, Higher Education Complex of Zarand, Shahid Bahonar University of Kerman, Kerman, Iran
C.L. Guo: China Railway 14th Bureau Group Tunnel Engineering Co. LTD., Jinan, China
L.J. Sun: China Railway 14th Bureau Group Tunnel Engineering Co. LTD., Jinan, China
Mohammad Fatehi Marji: Department of Mine Exploitation Engineering, Faculty of Mining and Metallurgy, Institute of Engineering, Yazd University, Yazd, Iran
Abstract
Stability analysis and support system estimation of the Beheshtabad water transmission tunnel is investigated in this research. A combination approach based on the rock mass rating (RMR) and rock mass quality index (Q) is used for this purpose. In the first step, 40 datasets related to the petrological, structural, hydrological, physical, and mechanical properties of tunnel host rocks are measured in the field and laboratory. Then, RMR, Q, and height of influenced zone above the tunnel roof are computed and sorted into five general groups to analyze the tunnel stability and determine its support system. Accordingly,
tunnel stand-up time, rock load, and required support system are estimated for five sorted rock groups. In addition, various empirical relations between RMR and Q i.e., linear, exponential, logarithmic, and power functions are developed using the analysis of variance (ANOVA). Based on the significance level (sig.), determination coefficient (R2) and Fisher-test (F) indices, power and logarithmic equations are proposed as the optimum relations between RMR and Q. To validate the proposed relations, their results are compared with the results of previous similar equations by using the variance account for (VAF), root mean square error (RMSE), mean absolute percentage error (MAPE) and mean absolute error (MAE) indices. Comparison results showed that the accuracy of proposed RMR-Q relations is better than the previous similar relations and their outputs are more consistent with actual data. Therefore, they can be practically utilized in designing the tunneling projects with an acceptable level of accuracy and reliability.
Key Words
Beheshtabad water transmission tunnel; hybrid empirical method; stability analysis; support system
Address
Mohammad Rezaei and Hazhar Habibi: Department of Mining Engineering, Faculty of Engineering, University of Kurdistan, Sanandaj, Iran
Abstract
This study aims to simulate the mechanical behavior of the total prosthesis model of Charnley (CMK3) by the 3D
finite element method and to determine the state of the stresses in the femoral components (prosthesis, cement, and bone). The components are subjected to a dynamic load due to three activities (normal walking, climbing stairs, and standing up a chair). Static loading is by selecting the maximum load for the same activities mentioned. The results show that the maximum stresses in the proximal part of the cement are very important. Moreover, new results obtained for different parameters were discussed in detail. It is understood that current research provides important lessons for the surgeon to contribute to the clinical diagnosis of
durable implantations and a better understanding of the process of bone remodeling and bone prosthesis.
Key Words
finite element method; static and dynamic loading; stress analysis; total hip prosthesis
Address
Mohammed El Sallah Zagane, Abdelmadjid Moulgada: University of Tiaret, City Zaârourra BP 78, Tiaret 14.000, Algérie; LMPM, Department of Mechanical Engineering, University of Sidi Bel Abbes, City Ben Mhidi BP 89, Sidi Bel Abbes, 22000, Algérie
Murat Yaylaci: Biomedical Engineering MSc Program, Recep Tayyip Erdogan University, 53100, Rize, Turkey; Department of Civil Engineering, Recep Tayyip Erdogan University, 53100, Rize, Turkey
Sahli Abderahmen: LMPM, Department of Mechanical Engineering, University of Sidi Bel Abbes, City Ben Mhidi BP 89, Sidi Bel Abbes, 22000, Algérie
Mehmet Emin Özdemir: Department of Civil Engineering, Cankiri Karatekin University, 18100, Çankiri, Turkey
Ecren Uzun Yaylaci: Technology Transfer Office, Recep Tayyip Erdogan University, 53100, Rize, Turkey
Abstract
It is recognized that the installation of energy dissipation devices, such as the tuned mass damper (TMD), decreases
the dynamic response of structures, however, the best parameters of each device persist hard to determine. Unlike many works that perform only a deterministic optimization, this work proposes a complete methodology to minimize the dynamic response of footbridges by optimizing the parameters of multiple tuned mass dampers (MTMD) taking into account uncertainties present in the parameters of the structure and also of the human excitation. For application purposes, a steel footbridge, based on a real structure, is studied. Three different scenarios for the MTMD are simulated. The proposed robust optimization problem is solved via the Circle-Inspired Optimization Algorithm (CIOA), a novel and efficient metaheuristic algorithm recently developed by the
authors. The objective function is to minimize the mean maximum vertical displacement of the footbridge, whereas the design variables are the stiffness and damping constants of the MTMD. The results showed the excellent capacity of the proposed methodology, reducing the mean maximum vertical displacement by more than 36% and in a computational time about 9% less than using a classical genetic algorithm. The results obtained by the proposed methodology are also compared with results obtained through traditional TMD design methods, showing again the best performance of the proposed optimization method. Finally, an analysis of the maximum vertical acceleration showed a reduction of more than 91% for the three scenarios, leading the footbridge to acceleration values below the recommended comfort limits. Hence, the proposed methodology could be employed to optimize MTMD, improving the design of footbridges.
Key Words
Circle-Inspired Optimization Algorithm; footbridges; human-induced vibrations; multiple tuned mass dampers; probabilistic approach; robust optimization
Address
Letícia Fleck Fadel Miguel: Department of Mechanical Engineering (DEMEC), Federal University of Rio Grande do Sul (UFRGS), Graduate Program in Mechanical Engineering (PROMEC), Graduate Program in Civil Engineering (PPGEC),
Av. Sarmento Leite 425, 2o andar, 90050-170, Porto Alegre, RS, Brazil
Otávio Augusto Peter de Souza: Graduate Program in Civil Engineering (PPGEC), Federal University of Rio Grande do Sul (UFRGS), Av. Osvaldo Aranha, 99, 3o andar, 90035-190, Porto Alegre, RS, Brazil
Abstract
Freeze-thaw cycles induce strength loss at the frozen soil-concrete interface and deterioration of bonding, which causes construction engineering problems. To clarify the deterioration characteristics of the interface under the freeze-thaw cycle, a frozen soil-concrete sample was used as the research object, an interface scanning electron microscope test under the freeze-thaw cycle was carried out to identify the micro index information, and an interface shear test was carried out to explore the loss law of interface shear strength under the freeze-thaw cycle. The results showed that the integrity of the interface was destroyed, and the pore number and pore size of the interface increased significantly with the number of freeze-thaw cycles. The connection form gradually deteriorates from surface-to-surface contact to point-to-surface contact and point-to-point contact, and the interfacial shear strength decreases the most at 0-3 freeze-thaw cycles, with small decreases from to 3-8 cycles. After 12 freeze-thaw cycles, the interfacial shear strength tends to be stable, and shear the failure occurs internally in the soil.
Address
Liyun Tang, Yang Du: Architecture and Civil Engineering School, Xi'an University of Science and Technology, Xi'an 710054, China
Liujun Yang, Xin Wang: School of Resources and Civil Engineering, Northeastern University, Shenyang 110819, China
Long Jin: CCCC First Highway Consultants Co. Ltd., Shaanxi, Xi'an 710000, China
Miaomiao Bai: Architecture and Civil Engineering School, Xi'an University of Science and Technology, Xi'an 710054, China
Abstract
Determining the properties of pile from cone penetration test (CPT) is costly, and need several in-situ tests. At the
present study, two novel hybrid learning models, namely PSO-RF and HHO-RF, which are an amalgamation of random forest
(RF) with particle swarm optimization (PSO) and Harris hawks optimization (HHO) were developed and applied to predict the
pile set-up parameter "A" from CPT for the design aim of the projects. To forecast the "A," CPT data along were collected from different sites in Louisiana, where the selected variables as input were plasticity index (PI), undrained shear strength (Su), and over consolidation ratio (OCR). Results show that both PSO-RF and HHO-RF models have acceptable performance in predicting the set-up parameter "A," with R2 larger than 0.9094, representing the admissible correlation between observed and predicted values. HHO-RF has better proficiency than the PSO-RF model, with R2 and RMSE equal to 0.9328 and 0.0292 for the training phase and 0.9729 and 0.024 for testing data, respectively. Moreover, PI and OBJ indices are considered, in which the HHO-RF model has lower results which leads to outperforming this hybrid algorithm with respect to PSO-RF for predicting the
pile set-up parameter "A," consequently being specified as the proposed model. Therefore, the results demonstrate the ability of the HHO algorithm in determining the optimal value of RF hyperparameters than PSO.
Key Words
cone penetration test; Harris Hawks Optimization; particle swarm optimization; pile set-up parameter "A"; random forest model; sensitive analysis
Address
Yun Dawei, Zheng Bing, Gu Bingbing, Gao Xibo: Department of Information Engineering, Hainan Vocational University of Science and Technology, No. 18 Qiongshan Avenue, Haikou 571126, China
Behnaz Razzaghzadeh: Civil Engineering Department, University of Mohaghegh Ardabili, Ardabil, Iran
Abstract
This study aims to examine the structural response of glass fibre-reinforced polymer (Glass-FRP) reinforced geopolymer electronic waste aggregate concrete (GEWC) compression elements under axial compression for sustainable development. The research includes the fabrication of nine GEWC circular compression elements with different reinforcement ratios and a 3-D nonlinear finite element model using ABAQUS. The study involves a detailed parametric analysis to examine the impact of various parameters on the behavior of GEWC compression elements. The results indicate that reducing the vertical distance of glass-FRP ties improves the ductility of GEWC compression elements, and those with eight longitudinal rebars have higher axial load-carrying capacities. The finite element predictions were in good agreement with the testing results, and the put forwarded empirical model shows higher accuracy than previous models by involving the confinement effect of lateral glass-FRP ties on the axial strength of GEWC compression elements. This research work contributes to minimizing the carbon footprint of cement manufacturing and electronic waste materials for sustainable development.
Key Words
ductility; E-waste aggregate; finite element analysis; geopolymer concrete; glass-FRP
Address
Mohamed Hechmi El Ouni: Department of Civil Engineering, College of Engineering, King Khalid University, P.O. Box 394, Abha 61411, KSA
Ali Raza: Department of Civil Engineering, University of Engineering and Technology Taxila, 47050, Pakistan
Bisma Khalid: Department of Transportation Engineering and Management, University of Engineering and Technology Lahore, 54890, Pakistan
Afzal Ahmed: Department of Civil Engineering, University of Engineering and Technology Taxila, 47050, Pakistan
Muhammad Sohail Jameel: Department of Transportation Engineering and Management, University of Engineering and Technology Lahore, 54890, Pakistan
Yasser Alashker: Department of Civil Engineering, College of Engineering, King Khalid University, P.O. Box 394, Abha 61411, KSA
