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Volume 29, Number 2, February 2022

For long underground box utility tunnels, post-tensioned precast concrete is often used. Between precast tunnel segments, sealed waterproof flexible joints are often specified. Fault displacement can lead to excessive deformation of the joints, which can lead to reduction in waterproofing due to diminished contact pressure between the sealant strip and the tunnel segment. This paper authenticates utilization of a finite element model for a prefabricated tunnel fault-crossing founded on ABAQUS software. In addition, material parameter selection, contact setting and boundary condition are reviewed. Analyzed under normal fault action are: the influence of fault displacement; buried depth; soil friction coefficient, and angle of crossing at the fault plane. In addition, distribution characteristics of the utility tunnel structure for vertical and longitudinal/horizontal relative displacement at segmented interface for the top and bottom slab are analyzed. It is found that the effect of increase in fault displacement on the splice joint deformation is significant, whereas the effects of changes in burial depth, pipe-soil friction coefficient and fault-crossing angle on the overall tunnel and joint deformations were not so significant.

Key Words
normal fault displacement; numerical analysis; post-tensioned precast concrete; prefabricated box utility tunnel; structural response

Xiangguo Wu: College of Civil Engineering, Fuzhou University, Fuzhou, 350108, China; Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education, Key Lab of Smart Prevention and Mitigation of Civil Engineering Disasters of the Ministry of the Industry and Information Technology, Harbin Institute of Technology, Harbin, 150090, China
Chenhang Nie: School of Civil Engineering, Harbin Institute of Technology, Harbin, 150090, China
Faqiang Qiu: JianYan Test Group Co., Ltd., Xiamen 361004, China
Xuesen Zhang: CGN New Holdings Co., Ltd., Beijing 100070, China
Li Hong: School of Energy and Architecture Engineering, Harbin University of Commerce, Harbin, 150076, China
Jong-Sub Lee: Department of Civil, Environmental and Architectural Engineering, Korea University, Seoul, 02841, Korea
Thomas H.-K. Kang: Department of Architecture and Architectural Engineering, Seoul National University, Seoul, 08826, Korea; Engineering Research Institute, Seoul National University, Seoul, 08826, Korea

The influence of normal stress perpendicular to the potential shear plane was always neglected in existing researches, which may lead to a serious deviation of the shear strength of concrete members in practice designs and numerical analyses. In this study, a series of experimental studies are carried out in this paper, which serves to investigate the shear behavior of concrete under compression shear loading. Based on the test results, a three-phase shear failure model for cohesive elements are developed, which is able to take into consideration the influence of normal stress on the shear strength of concrete. To identify the accuracy and applicability of the proposed model, numerical models of a double-noted concrete plate are developed and compared with experimental results. Results show that the proposed constitutive model is able to take into consideration the influence of normal stress on the shear strength of concrete materials, and is effective and accurate for describing the complex fracture of concrete, especially the failure modes under compression shear loadings.

Key Words
concrete; shear failure; compression shear tests; damage evolution model; peak shear strength

Xiaojuan Shu, Yili Luo, Chao Zhao, Zhicheng Dai, Xingu Zhong and Tianyu Zhang: Hunan Provincial Key Laboratory of Structures for Wind Resistance and Vibration Control and School of Civil Engineering, Hunan University of Science and Technology, Taoyuan Road, Yuhu District, Xiangtan, China

The degrees of freedom (DOFs) of high-rise structures increase rapidly due to the need for refined analysis, which poses a challenge toward a computationally efficient method for numerical analysis of high-rise structures using the finite element method (FEM). This paper presented an efficient iterative method, an algebraic multigrid (AMG) with a Jacobi overrelaxation smoother preconditioned conjugate gradient method (AMG-CG) used for solving large-scale structural system equations running on heterogeneous platforms with parallel accelerator graphics processing units (GPUs) enabled. Furthermore, an AMG-CG FEM application framework was established for the numerical analysis of high-rise structures. In the proposed method, the coarsening method, the optimal relaxation coefficient of the JOR smoother, the smoothing times, and the solution method for the coarsest grid of an AMG preconditioner were investigated via several numerical benchmarks of high-rise structures. The accuracy and the efficiency of the proposed FEM application framework were compared using the mature software Abaqus, and there were speedups of up to 18.4x when using an NVIDIA K40C GPU hosted in a workstation. The results demonstrated that the proposed method could improve the computational efficiency of solving structural system equations, and the AMG-CG FEM application framework was inherently suitable for numerical analysis of high-rise structures.

Key Words
algebraic multigrid; GPU acceleration; heterogeneous platforms; high-rise structures; Jacobi overrelaxation smoother; numerical analysis; preconditioned conjugate gradient method

Zuohua Li, Qingfei Shan, Jiafei Ning, Yu Li, Kaisheng Guo and Jun Teng: School of Civil and Environmental Engineering, Harbin Institute of Technology, Shenzhen, 518055, China

With the improvements in computer technologies, utilization of image processing techniques has increased in many areas (such as medicine, defence industry, other industries etc.) Many different image processing techniques are used for surface analysis, detection of manufacturing defects, and determination of physical and mechanical characteristics of composite materials. In this study, cementitious composites were obtained by addition of Grounded Granulated Blast-Furnace Slag (GGBFS), Styrene Butadiene polymer (SBR), and Grounded Granulated Blast-Furnace Slag and Styrene Butadiene polymer together (GGBFS+SBR). Expanded Polystyrene (EPS) beads were added to these cementitious composites in different ratios (20%, 40% and 60%). The mechanical and physical characteristics of the composites were determined, and homogeneity indexes of the composites were determined by image processing techniques to determine EPS distribution forms in them. Physical and mechanical characteristics of the produced samples were obtained by applying consistency, density, water absorption, compressive strength (7 and 28 days), flexural strength (7 and 28 days) and tensile splitting strength (7 and 28 days) tests on them. Also, visual examination by using digital microscope, and image analysis by using image processing techniques with open source coded ImageJ program were performed. As a result of the study, it is determined that GGBFS and SBR addition strengthens the adhesion sites formed as it increases the adhesion power of the mixture and helps to get rid of the segregation problem caused by EPS. As a result of the image processing analysis it is demonstrated that GGBFS and SBR addition has positive contribution on homogeneity index.

Key Words
eps beads; image processing; mechanical properties; mineral additive; polymer latex

Bekir Çomak: Düzce University, Faculty of Engineering, Department of Civil Engineering, 81620, Düzce, Turkey
Batuhan Aykanat: Düzce University, Faculty of Engineering, Department of Civil Engineering, 81620, Düzce, Turkey
Özlem Salli Bideci: Düzce University, Faculty of Art, Design and Architecture, Department of Architecture, 81620, Düzce, Turkey
Alper Bideci: Düzce University, Faculty of Engineering, Department of Civil Engineering, 81620, Düzce, Turkey; Düzce University, Faculty of Art, Design and Architecture, Department of Architecture, 81620, Düzce, Turkey

The vibrational characteristic of three-layered cylindrical shell (CS) submerged in fluid with the ring support has been studied. The inner and outer layer is supposed to construct by isotropic layer. The composition of central layer is of functionally graded material type. Acoustic Wave condition has been utilized to present the impact of fluid. The central layer of cylindrical shell (CS) varies by volume fraction law that has been expressed in terms of polynomial. The main shell frequency equation has been obtained by theory of Love's shell and Rayleigh-Ritz technique. The oscillation of natural frequency has been examined under a variety of end conditions. The dependence of axial model has been executed with the help of characteristic beam function. The natural frequencies (NFs) of functionally graded material (FGM) shell have been observed of cylindrical shell along the shell axial direction. Different physical parameters has been used to examine the vibration characteristics due to the effect of volume fraction law. MATLAB software has been used to get result.

Key Words
axial direction; beam function; fraction law; love's shell; MATLAB software; three-layered

Madiha Ghamkhar: Department of Mathematics and Statistics,University of Agriculture, Faisalabad,38000, Pakistan
Muzamal Hussain: Department of Mathematics, Govt. College University Faisalabad, 38000, Faisalabad, Pakistan
Mohamed A. Khadimallah: Civil Engineering Department, College of Engineering, Prince Sattam Bin Abdulaziz, University, BP 655, Al-Kharj, 16273, Saudi Arabia; Laboratory of Systems and Applied Mechanics, Polytechnic School of Tunisia, University of Carthage, Tunis, Tunisia
Hamdi Ayed: Department of Civil Engineering, College of Engineering, King Khalid University, Abha, Kingdom of Saudi Arabia; Higher Institute of Transport and Logistics of Sousse, University Sousse, Tunisia
Muhammad Yasin Naz: Department of Physics, University of Agriculture, Faisalabad,38000, Pakistan
Abdelouahed Tounsi: YFL (Yonsei Frontier Lab), Yonsei University, Seoul, Korea; Department of Civil and Environmental Engineering, King Fahd University of Petroleum and Minerals, 31261 Dhahran, Eastern Province, Saudi Arabia

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