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CONTENTS
Volume 26, Number 4, April 2024
 

Abstract
In this paper, the thermal post-buckling behavior of graphene platelets reinforced metal foams (GPLRMFs) plate with initial geometric imperfections on nonlinear elastic foundations are studied. First, the governing equation is derived based on the first-order shear deformation theory (FSDT) of plate. To obtain a single equation that only contains deflection, the Galerkin principle is employed to solve the governing equation. Subsequently, a comparative analysis was conducted with existing literature, thereby verifying the correctness and reliability of this paper. Finally, considering three GPLs distribution types (GPL-A, GPL-B, and GPL-C) of plates, the effects of initial geometric imperfections, foam distribution types, foam coefficients, GPLs weight fraction, temperature changes, and elastic foundation stiffness on the thermal post-buckling characteristics of the plates were investigated. The results show that the GPL-A distribution pattern exhibits the best buckling resistance. And with the foam coefficient (GPLs weight fraction, elastic foundation stiffness) increases, the deflection change of the plate under thermal load becomes smaller. On the contrary, when the initial geometric imperfection (temperature change) increases, the thermal buckling deflection increases. According to the current research situation, the results of this article can play an important role in the thermal stability analysis of GPLRMFs plates.

Key Words
GPLRMFs plate; initial geometric imperfections; nonlinear elastic foundations; thermal effect; thermal postbuckling

Address
Yin-Ping Li, Gui-Lin She and Lei-Lei Gan: College of Mechanical and Vehicle Engineering, Chongqing University, Chongqing 400044, China
H.B. Liu: College of Mechanical and Electric Engineering, Hunan University of Science and Technology, Xiangtan, 411201, China

Abstract
With the increase in the exploitation depth of offshore oil and gas, it is possible to control the global buckling of deep-sea pipelines by the snake lay method. Previous studies mainly focused on the analysis of critical buckling force and critical temperature of pipelines under the snake-like laying method, and pipelines often suffer structural failure due to seismic disasters during operation. Therefore, seismic action is a necessary factor in the design and analysis of submarine pipelines. In this paper, the seismic action of steel pipes in the operation stage after global buckling has occurred under the active control method is analyzed. Firstly, we have established a simplified finite element model for the entire process cycle and found that this modeling method is accurate and efficient, solving the problem of difficult convergence of seismic wave and soil coupling in previous solid analysis, and improving the efficiency of calculations. Secondly, through parameter analysis, it was found that under seismic action, the pipe diameter mainly affects the stress amplitude of the pipeline. When the pipe wall thickness increases from 0.05 m to 0.09 m, the critical buckling force increases by 150%, and the maximum axial stress decreases by 56%. In the pipe soil interaction, the greater the soil viscosity, the greater the pipe soil interaction force, the greater the soil constraint on the pipeline, and the safer the pipeline. Finally, the pipeline failure determination formula was obtained through dimensionless analysis and verified, and it was found that the formula was accurate.

Key Words
failure criterion; global buckling; parameter analysis; seismic action; snake lay method

Address
Jianshuo Wang: Tianjin Key Laboratory of Civil Structure Protection and Reinforcement, Tianjin Chengjian University, Tianjin 300384, China
Tinghao Meng: Department of Civil Engineering, Tianjin Chengjian University, Tianjin 300384, China
Zechao Zhang: Science and Technology Research Institute of China Three Gorges Corporation, Beijing 430010, China
Zhihua Chen: 1) Department of Civil Engineering, Tianjin Chengjian University, Tianjin 300384, China,
2) Department of Civil Engineering, Tianjin University, Tianjin 300072, China
Hongbo Liu: Hebei Province Key Laboratory for Low-Carbon Construction and Resilience Enhancement of Construction Engineering, Hebei University of Engineering, Handan 056038, China

Abstract
When a reinforced concrete (RC) structure is exposed to a corrosive environment for an extended period of time, the material qualities deteriorate, resulting in a loss in seismic performance. Engineered Cementitious Composites (ECC) have been used to reinforce the corroded RC structure, which can achieve reinforcement effectiveness for a small change in cross-section size. In this work, finite element models of unjacketed RC pier and ECC jacketed pier were established and verified by experimental tests, with the buckling effect of longitudinal reinforcement considered. Compared with the unjacketed pier, the displacement of the pier top of the ECC jacketed pier was reduced by about 9.52% under earthquake action. In the case of moderate and major earthquakes, the probability of exceedance of ECC jacketed pier is significantly reduced. For the case of rare earthquake loading, with the ECC jacket, the e of the pier experiencing serious damage and complete damage states is reduced by 10.29% and 29.78%, respectively.

Key Words
damage index; ECC; RC pier; seismic fragility; time-varying

Address
Yan Liang, Jing-Xiao Shu, Cheng-Xin Zhao and Xi Dong Wang: School of Civil Engineering, Zhengzhou University, Zhengzhou, 450001, China
Guang Yu Yang: Wsgri Engineering & Surveying Incorporation Limited, Wuhan, 430080, China

Abstract
Due to the imbalanced vibration of the adjacent buildings, the pounding phenomenon occurs as a result of an insufficient gap between them. Providing enough gap between adjacent structures is the most efficient approach to preventing the pounding effect. This paper calculated the required separation gaps between adjacent buildings, including two, four, eight, twelve and twenty stories steel moment-resisting frames, and investigated their related influencing parameters such as time periods, damping ratios, and the number of bays. The linear and nonlinear dynamic time-history analyses under real seismic event records were conducted to calculate the required separation gaps by obtaining relative displacement and velocity functions of two adjacent frames. The results showed that the required separation gap increased when the time periods of adjacent frames were not the same. The resulting separation gaps values of linear and nonlinear analyses were similar only for two and four stories frames. In other frames, the resulting separation gap values of linear analyses surpassed the corresponding nonlinear analyses. Although increasing the damping ratios in adjacent frames causes a decrease in the required separation gaps, the number of bays had no significant effect on them.

Key Words
adjacent buildings; damping ratio; dynamic analysis; random vibration; separation gap; time period

Address
Atefeh Soleymani: Department of Civil Engineering, Shahid Bahonar University of Kerman, Kerman, Iran
Denise-Penelope N. Kontoni: 1) Department of Civil Engineering, School of Engineering, University of the Peloponnese, GR-26334 Patras, Greece, 2) School of Science and Technology, Hellenic Open University, GR-26335 Patras, Greece
Hashem Jahangir: Department of Civil Engineering, University of Birjand, Birjand, Iran

Abstract
The present paper develops application of third-order shear deformation theory (TSDT) and modified couple stress theory (MCST) to size-dependent bending analysis of a functionally graded cylindrical micro-shell. The radial and axial displacement components are described based on TSDT for more accurate analysis. The effect of small scales is accounted based on MCST. The principle of virtual work is used for derivation of bending governing equations. The solution is presented for a simply-supported boundary condition to account the influence of various important parameters such as micro length scale parameter, in-homogeneous index and some dimensionless geometric parameters such as length to radius and length to thickness ratios on the bending results. A comparative analysis is presented to examine the effect of order of employed shear deformation theory on the axial and radial displacements.

Key Words
axial and radial displacements; functionally graded cylindrical micro-shell; micro length scale parameter; modified couple stress theory; third order shear deformation theory

Address
Faculty of Mechanical Engineering, Department of Solid Mechanics, University of Kashan, Kashan 87317-51167, Iran

Abstract
Transmission tower structures are particularly susceptible to damage and even collapse under strong seismic ground motions. Conventional seismic analyses of transmission towers are usually performed by considering only ground motion uncertainty while ignoring structural uncertainty; consequently, the performance evaluation and failure prediction may be inaccurate. In this context, the present study numerically investigates the seismic responses and failure mechanism of transmission towers by considering multiple sources of uncertainty. To this end, an existing transmission tower is chosen, and the corresponding three-dimensional finite element model is created in ABAQUS software. Sensitivity analysis is carried out to identify the relative importance of the uncertain parameters in the seismic responses of transmission towers. The numerical results indicate that the impacts of the structural damping ratio, elastic modulus and yield strength on the seismic responses of the transmission tower are relatively large. Subsequently, a set of 20 uncertainty models are established based on random samples of various parameter combinations generated by the Latin hypercube sampling (LHS) method. An uncertainty analysis is performed for these uncertainty models to clarify the impacts of uncertain structural factors on the seismic responses and failure mechanism (ultimate bearing capacity and failure path). The numerical results show that structural uncertainty has a significant influence on the seismic responses and failure mechanism of transmission towers; different possible failure paths exist for the uncertainty models, whereas only one exists for the deterministic model, and the ultimate bearing capacity of transmission towers is more sensitive to the variation in material parameters than that in geometrical parameters. This research is expected to provide an in-depth understanding of the influence of structural uncertainty on the seismic demand assessment of transmission towers.

Key Words
failure path; seismic responses; sensitivity analysis; transmission tower; ultimate bearing capacity; uncertainty analysis

Address
Zhaoyang Fu, Li Tian, Xianchao Luo and Haiyang Pan: 1)Shandong Research Institute of Industrial Technology, Jinan, Shandong Province 250098, PR China, 2) School of Civil Engineering, Shandong University, Jinan, Shandong Province 250061, PR China
Juncai Liu: School of Civil Engineering, Shandong University, Jinan, Shandong Province 250061, PR China
Chuncheng Liu: Northeast Electric Power University., Jilin, Jilin Province, 132012, PR China

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