A Novel Numerical Study of Reservoir-Induced Subsidence and Upheaval Effects on Bearing Capacity of Offshore Piles

Author(s):  
Jakub Rybicki ◽  
Kamelia Atefi-Monfared
2020 ◽  
Vol 82 (2) ◽  
pp. 215-224
Author(s):  
V.I. Erofeev ◽  
I.A. Samokhvalov

A numerical study of the survivability of the flange assembly is carried out upon reaching a critical load and in the presence of a defect in one of the design areas, taking into account the calculated values of the aerodynamic coefficients. An experiment is being carried out to determine the values of the wind load acting on the supporting legs of a metal tower. The calculation of the stressstrain state is performed using software system as SCAD Office and IDEA StatiCa 10.0. After calculating the forces in the core model of the structure, a threedimensional plate model of the assembly is formed and prepared for calculation. According to the results of the experiment, a graph was compiled with the values of aerodynamic coefficients, which were used in calculating the stressstrain state of the node. The analysis of the calculation results revealed that in the design (defectfree) state of the structure, the safety factor of the bearing units and elements is 35-40% (equivalent stresses were 165 MPa). If there is a defect in the metal structures of the belt in the region of the flange, the equivalent stresses increase to 247.6 MPa in the region of the cleavage (defective hole), thus, the margin in bearing capacity drops to 0.4%. As a result of the assessment of the survivability of the flange connection, it was revealed that the connection has a high potential survivability, in turn, the flange itself is able to work in the presence of some defects without reducing its bearing capacity to a critical level. The aerodynamic coefficients obtained in this work will determine the wind load on this type of profile and can be used in design calculations of tower structures for wind loads.


2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Zhanzhan Tang ◽  
Zhixiang He ◽  
Zheng Chen ◽  
Lingkun Chen ◽  
Hanyang Xue ◽  
...  

For an RC beam, the strength of steel rebar, the bonding strength between the concrete and reinforcement, and the bite action between the aggregates will deteriorate significantly due to corrosion. In the present study, 10 RC beams were designed to study the impact of corrosion on the shear bearing capacity. The mechanism of corrosion for stirrups and longitudinal bars and their effects were analyzed. Based on the existing experimental data, the correlation between the stirrup corrosion factor and the cross section loss rate was obtained. An effective prediction formula on the shear bearing capacity of the corroded RC beams was proposed and validated by the experimental results. Moreover, a numerical analysis approach based on the FE technique was proposed for the prediction of the shear strength. The results show that corrosion of the reinforcements could reduce the shear strength of the RC beams. The corrosion of stirrups can be numerically simulated by the reduction of the cross section. The formulae in the literature are conservative and the predictions are very dispersed, while the predictions by the proposed formula agree very well with the experiment results.


2020 ◽  
Vol 218 ◽  
pp. 108123
Author(s):  
Shuangxi Xu ◽  
Ziwen Gu ◽  
Wei Shen ◽  
Qiheng Lei ◽  
Weiguo Tang

2013 ◽  
Vol 671-674 ◽  
pp. 226-229
Author(s):  
Jun Jie Wu ◽  
Jin Jian Chen ◽  
Shuai Jun Liu ◽  
Jian Hua Wang

Large-scale deep excavation may affect the bearing capacity of piles inside the excavation zone. It does not only cause the loss of friction, but also change the stress state of the subsoil. In this paper, nonlinear finite element technique is employed to investigate the bearing capacity of piles influenced by the deep excavation. Parameters of soil are obtained by back analysis on the pile static load test results. The bearing capacity of the piles during excavation is analyzed by performing FEM modeling under three conditions using the calibrated parameters. The numerical study shows that the loss ratio of vertical bearing capacity of pile foundation caused by excavation unloading is 34%.


Author(s):  
Mohammad Reza Ghaemdoust ◽  
Omid Yousefi ◽  
Kambiz Narmashiri ◽  
Masoumeh Karimian

In view of development and repair costs, support of structures is imperative. Several factors, for example, design and calculation errors, absence of appropriate installation, change of structures application, exhaustion, seismic tremor, fire and natural conditions diminish their strength. In such cases, structures have need of rehabilitation and restoration to achieve their original performance. One of the most up to date materials for retrofitting is carbon fiber reinforced polymer (CFRP) that can provide an amount of restriction to postpone buckling of thin steel walls. This paper provides a numerical and experimental investigation on CFRP strengthened short steel tubes with initial horizontal and vertical deficiency under compression. Ten square and circular specimens were tested to study effects of the following parameters: (1) position of deficiency, horizontal or vertical; (2) tube shape, square or circular; (3) CFRP strengthening. In the experiments, axial static loading was gradually applied and for the numerical study three-dimensional (3D) static nonlinear analysis method using ABAQUS software was performed. The results show that deficiency reduces load-bearing capacity of steel columns and the impact of horizontal deficiency is higher than the impact of vertical deficiency, in both square and circular tubes. Use of CFRP materials for strengthening of short steel columns with initial deficiency indicates that fibers play a considerable role on increasing load bearing capacity, reducing stress at the damage location, preventing deformation caused by deficiency and delaying local buckling. Both numerical and experimental outcomes are in good agreement, which underlines the accuracy of the models adopted.


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