Effect of Cross Passage Construction on the Structural Safety of Collapse Reinforcement Segment of Existing Tunnel

2013 ◽  
Vol 779-780 ◽  
pp. 538-543 ◽  
Author(s):  
Kong Jian Shen ◽  
Shui Wan ◽  
Xiao Chun Zhang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Reference Value ◽  
Element Model ◽  
Surrounding Rock ◽  
Practical Significance ◽  
Structural Safety ◽  
Tunnel Structure ◽  
Tunnel Engineering ◽  
Supporting Structure

On the basis of the engineering background of cross passage construction in the Chen Yu Tunnel project, the collapse section above the intersection of the existing tunnel is selected to establish finite element model. Considering the effect of cross passage construction and the local weakening area of surrounding rock on the safety of existing tunnel structure, the strength of the shotcrete supporting structure of existing tunnel intersection is checked, and the security of the existing tunnel is evaluated. This research is of great practical significance and a certain reference value for the plan and design upon the construction of tunnel engineering.

scholarly journals Vibration-based Bayesian model updating of civil engineering structures applying Gaussian process metamodel

2019 ◽  
Vol 22 (16) ◽  
pp. 3487-3502
Author(s):  
Hossein Moravej ◽  
Tommy HT Chan ◽  
Khac-Duy Nguyen ◽  
Andre Jesus
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Bayesian Approach ◽  
Model Updating ◽  
Numerical Models ◽  
Element Model ◽  
The Body ◽  
Structural Safety ◽  
Discrepancy Function ◽  
The Finite Element Model

Structural health monitoring plays a significant role in providing information regarding the performance of structures throughout their life spans. However, information that is directly extracted from monitored data is usually susceptible to uncertainties and not reliable enough to be used for structural investigations. Finite element model updating is an accredited framework that reliably identifies structural behavior. Recently, the modular Bayesian approach has emerged as a probabilistic technique in calibrating the finite element model of structures and comprehensively addressing uncertainties. However, few studies have investigated its performance on real structures. In this article, modular Bayesian approach is applied to calibrate the finite element model of a lab-scaled concrete box girder bridge. This study is the first to use the modular Bayesian approach to update the initial finite element model of a real structure for two states—undamaged and damaged conditions—in which the damaged state represents changes in structural parameters as a result of aging or overloading. The application of the modular Bayesian approach in the two states provides an opportunity to examine the performance of the approach with observed evidence. A discrepancy function is used to identify the deviation between the outputs of the experimental and numerical models. To alleviate computational burden, the numerical model and the model discrepancy function are replaced by Gaussian processes. Results indicate a significant reduction in the stiffness of concrete in the damaged state, which is identical to cracks observed on the body of the structure. The discrepancy function reaches satisfying ranges in both states, which implies that the properties of the structure are predicted accurately. Consequently, the proposed methodology contributes to a more reliable judgment about structural safety.

scholarly journals Structural Safety Analysis Based on Seismic Service Conditions for Butterfly Valves in a Nuclear Power Plant

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Sang-Uk Han ◽  
Dae-Gyun Ahn ◽  
Myeong-Gon Lee ◽  
Kwon-Hee Lee ◽  
Seung-Ho Han
Keyword(s):  
Finite Element ◽  
Power Plant ◽  
Nuclear Power Plant ◽  
Finite Element Model ◽  
Nuclear Power ◽  
Dynamic Properties ◽  
Element Model ◽  
Structural Safety ◽  
Butterfly Valve ◽  
Design Response Spectrum

The structural integrity of valves that are used to control cooling waters in the primary coolant loop that prevents boiling within the reactor in a nuclear power plant must be capable of withstanding earthquakes or other dangerous situations. In this study, numerical analyses using a finite element method, that is, static and dynamic analyses according to the rigid or flexible characteristics of the dynamic properties of a 200A butterfly valve, were performed according to the KEPIC MFA. An experimental vibration test was also carried out in order to verify the results from the modal analysis, in which a validated finite element model was obtained via a model-updating method that considers changes in thein situexperimental data. By using a validated finite element model, the equivalent static load under SSE conditions stipulated by the KEPIC MFA gave a stress of 135 MPa that occurred at the connections of the stem and body. A larger stress of 183 MPa was induced when we used a CQC method with a design response spectrum that uses 2% damping ratio. These values were lower than the allowable strength of the materials used for manufacturing the butterfly valve, and, therefore, its structural safety met the KEPIC MFA requirements.

scholarly journals Topology optimization of transmission gearbox under multiple working loads

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401881345 ◽  
Author(s):  
Mingxuan Liang ◽  
Jianhong Hu ◽  
Shuqing Li ◽  
Zhigao Chen
Keyword(s):  
Finite Element ◽  
Topology Optimization ◽  
Finite Element Model ◽  
Lightweight Design ◽  
Dynamic Performance ◽  
Reference Value ◽  
Element Model ◽  
Optimization Method ◽  
Dynamic Excitation ◽  
Topology Optimization Method

This article is concerned with topology optimization of transmission gearbox under multiple working loads by taking dynamic performance as research object. First, the dynamic excitation model and finite element model are established, the vibration responses of the key points on gearbox are obtained by applying dynamic excitation on finite element model based on modal dynamic method, and the simulation responses are compared with testing results to validate finite element model. Finally, the gearbox structure is optimized by utilizing topology optimization method, and the lightweight model of transmission gearbox structure is redesigned. The dynamic performance indexes such as natural frequency are improved obviously, which indicates that the topology optimization method is very effective in optimizing dynamic performance of complex gearbox structure. The research has an important theoretical significance and reference value for lightweight design of transmission gearbox structure.

scholarly journals Effect of Long-Term Soil Deformations on RC Structures Including Soil-Structure Interaction

2020 ◽  
Vol 6 (12) ◽  
pp. 2290-2311
Author(s):  
Kamel Bezih ◽  
Alaa Chateauneuf ◽  
Rafik Demagh
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Soil Structure ◽  
Element Model ◽  
Soil Structure Interaction ◽  
Structural Safety ◽  
Soil Behavior ◽  
Rc Structures ◽  
Structure Interaction

Lifetime service of Reinforced Concrete (RC) structures is of major interest. It depends on the action of the superstructure and the response of soil contact at the same time. Therefore, it is necessary to consider the soil-structure interaction in the safety analysis of the RC structures to ensure reliable and economical design. In this paper, a finite element model of soil-structure interaction is developed. This model addresses the effect of long-term soil deformations on the structural safety of RC structures. It is also applied to real RC structures where soil-structure interaction is considered in the function of time. The modeling of the mechanical analysis of the soil-structure system is implemented as a one-dimensional model of a spring element to simulate a real case of RC continuous beams. The finite element method is used in this model to address the nonlinear time behavior of the soil and to calculate the consolidation settlement at the support-sections and the bending moment of RC structures girders. Numerical simulation tests with different loading services were performed on three types of soft soils with several compressibility parameters. This is done for homogeneous and heterogeneous soils. The finite element model of soil-structure interaction provides a practical approach to show and to quantify; (1) the importance of the variability of the compressibility parameters, and (2) the heterogeneity soil behavior in the safety RC structures assessment. It also shows a significant impact of soil-structure interaction, especially with nonlinear soil behavior versus the time on the design rules of redundant RC structures. Doi: 10.28991/cej-2020-03091618 Full Text: PDF

Research on Vibration Characteristics of the Three-Bearings Supporting Structure with Cracks in the Rotor of the 25Cr2Ni4MoV Exciter

2019 ◽  
Vol 893 ◽  
pp. 33-38
Author(s):  
Qing Meng Zeng ◽  
Zhi Min Liu ◽  
You Liang Chen ◽  
Fan Yang Meng
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Critical Speed ◽  
Case Analysis ◽  
Element Model ◽  
Vibration Characteristics ◽  
Supporting Structure ◽  
Response Characteristics ◽  
Model Based ◽  
Set Up

Finite element model based on a unit with cracks in the rotor of the exciter is set up. Andthen critical speed is calculated that compared to actual measured value to verify the rationality of themodel. Lastly response characteristics of the three-bearings supporting structure are studied when thefirst critical speed of the exciter with cracks is closed to the working speed. And the reliability ofconclusions is further verified by case analysis.

scholarly journals Improvement design of bus structure to satisfy frontal safety

2015 ◽  
Vol 18 (4) ◽  
pp. 72-76
Author(s):  
Tam Thanh Nguyen
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Structural Safety ◽  
Frontal Impact ◽  
Existing Problems ◽  
Front Structure ◽  
Simulation Testing ◽  
Bus Structure ◽  
The Finite Element Model

The finite element model of bus was developed and LS – DYNA software was used to simulate structural safety of the bus when frontal impact happens. Based on the existing problems of the bus front structure, some improving methods for the bus structure were proposed, and simulation testing was conducted. Simutaion results showed that, the bus structure to satisfy safety condition. However, the collision engergy absorption of bus front structure was designed, as a results the collision acceleration was decreased, and passengers safety were increased.

scholarly journals DYNAMIC SIMULATION AND TEST ANALYSIS OF SPACE TRUSS AND LOAD STRUCTURE

2020 ◽  
Vol 5 (3) ◽  
pp. 123-133
Author(s):  
Haitao Luo ◽  
Peng Wang ◽  
Tingke Wu ◽  
Haonan Wang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Simulation ◽  
Dynamic Characteristics ◽  
Structural Model ◽  
Reference Value ◽  
Decisive Role ◽  
Element Model ◽  
Space Truss ◽  
The Finite Element Model

The dynamic characteristics of aerospace products play a decisive role in environmental adaptability of products, because aerospace products are subjected to vibration environment during launching process. This paper describes the design of a space truss and the load structure, in order to get the dynamic characteristics, finite element modal analysis and modal test is done on the structural model, through correlation analysis to determine the degree of conformity of the finite element model with the experimental model. It is determined that the finite element mode of truss and load structure is similar to the test mode, the finite element model is acceptable; The dynamic simulation of the structure is carried out by the qualified finite element model, and the dynamic simulation results are verified by the vibration test; The method for obtaining the dynamic characteristics of aerospace products and the way of dynamic simulation for launching process is of great reference value for the design of aerospace products.

scholarly journals Structural safety and fatigue reliability assessments of a metro-train bolster

2019 ◽  
Vol 11 (1) ◽  
pp. 168781401882175 ◽  
Author(s):  
Jiexin Hu ◽  
Liyang Xie ◽  
Weiguang Sun ◽  
Xinkang Li ◽  
Xiao Lv ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Test Method ◽  
Structural Safety ◽  
Atmospheric Conditions ◽  
Fatigue Reliability ◽  
Static Test ◽  
Weak Points ◽  
Reliability Assessments

This article presents an economical and efficient way to assess the structural safety and fatigue reliability of the bolster, a key structure for the metro-train. First, its finite element model was validated based on the comparison between numerical results and experimental data of stresses and displacements recorded during a static test. Then, the fatigue life of the bolster under loading scheme was predicted using Gerber diagram, in which the validated finite element model was applied to determine the weak points, and its structural safety was also evaluated by a full-scale fatigue test and non-destructive test method. Finally, the metro-train bolster was modeled as a series system of weak points, and a new fatigue reliability model for mechanical component derived based on stress-life interference model was used to assess its fatigue reliability under the application of the design passenger number spectra. The results show that not only does this bolster satisfy the structural safety requirement during its service life, but also its fatigue reliability is more than 99.993% after 30-year service under normal atmospheric conditions.

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