A New Damage Detection Method for Aging Offshore Platform Using Two Measurements

2013 ◽  
Vol 479-480 ◽  
pp. 1185-1189
Author(s):  
Fu Shun Liu ◽  
Wen Wen Chen ◽  
Dong Ping Yang ◽  
Jun Fei Qin ◽  
Zhan Gang Yue ◽  
...  

A new damage assessment method is proposed for aging offshore platforms based on dynamic tests. The stiff nesses of the measured model corresponding to the two measurement moments are estimated by a series of stiffness-correction factors, respectively. Based on these stiffness-correction factors a new damage indicator is defined aiming at reducing influences of existed damages accumulated before the first measurement on damage assessment occurred between the two adjacent measurements. One theoretical improvement is that the requirement using the stiffness matrix of FEM to replace the one of the measured model can be ignored in the calculation of MSE of the measured model. The other development is influences of damages accumulated before the first measurement on damage detection occurs between the two measurements could be reduced greatly, which is very important for aging platforms because these platforms have not been tested aiming at damage detection during their previous service life, especially for most platforms in China. A jacket platform is chosen for numerical studies, and numerical results show that the proposed method could identify damages occurred between the two measurements properly, even including damage severity estimation.

2011 ◽  
Vol 250-253 ◽  
pp. 1248-1251 ◽  
Author(s):  
Hang Jing ◽  
Ling Ling Jia ◽  
Yi Zhao

Damage detection in civil engineering structures using the dynamic system parameters has become an important area of research. The sensitivity of damage indicator is of great value to structural damage identification. The curvature mode is an excellent parameter in damage detection of structures, while in case that certain curvature mode curve can’t show existence of damage. In this paper, numerical studies are conducted to demonstrate the deficiency of curvature mode to damage detection. Then a new damage indicator called “curvature mode changing rate” (CMCR) is introduced which is processed by numerical differentiation of curvature mode curve. The simulation results show that the new index is superior to curvature mode for structural damage identification, and it is still sensitive to the damaged location in the mode node.


2020 ◽  
Vol 20 (2) ◽  
pp. 437-458 ◽  
Author(s):  
Félix del Teso ◽  
Jørgen Endal ◽  
Juan Luis Vázquez

AbstractThe classical Stefan problem is one of the most studied free boundary problems of evolution type. Recently, there has been interest in treating the corresponding free boundary problem with nonlocal diffusion. We start the paper by reviewing the main properties of the classical problem that are of interest to us. Then we introduce the fractional Stefan problem and develop the basic theory. After that we center our attention on selfsimilar solutions, their properties and consequences. We first discuss the results of the one-phase fractional Stefan problem, which have recently been studied by the authors. Finally, we address the theory of the two-phase fractional Stefan problem, which contains the main original contributions of this paper. Rigorous numerical studies support our results and claims.


Author(s):  
Chin-Hsiung Loh ◽  
Min-Hsuan Tseng ◽  
Shu-Hsien Chao

One of the important issues to conduct the damage detection of a structure using vibration-based damage detection (VBDD) is not only to detect the damage but also to locate and quantify the damage. In this paper a systematic way of damage assessment, including identification of damage location and damage quantification, is proposed by using output-only measurement. Four level of damage identification algorithms are proposed. First, to identify the damage occurrence, null-space and subspace damage index are used. The eigenvalue difference ratio is also discussed for detecting the damage. Second, to locate the damage, the change of mode shape slope ratio and the prediction error from response using singular spectrum analysis are used. Finally, to quantify the damage the RSSI-COV algorithm is used to identify the change of dynamic characteristics together with the model updating technique, the loss of stiffness can be identified. Experimental data collected from the bridge foundation scouring in hydraulic lab was used to demonstrate the applicability of the proposed methods. The computation efficiency of each method is also discussed so as to accommodate the online damage detection.


2018 ◽  
Vol 89 (11) ◽  
pp. 115005 ◽  
Author(s):  
Guijie Liu ◽  
Shirui Wang ◽  
Yingchun Xie ◽  
Xiaojie Tian ◽  
Dingxin Leng ◽  
...  

2006 ◽  
Vol 129 (4) ◽  
pp. 713-718 ◽  
Author(s):  
Hiroaki Hatanaka ◽  
Nobukazu Ido ◽  
Takuya Ito ◽  
Ryota Uemichi ◽  
Minoru Tagami ◽  
...  

Boiler piping of fossil-fuel combustion power generation plants are exposed to high-temperature and high-pressure environments, and failure of high-energy piping due to creep damage has been a concern. Therefore, a precise creep damage assessment method is needed. This paper proposes a nondestructive method for creep damage detection of piping in fossil-fuel combustion power generation plants by ultrasonic testing. Ultrasonic signals are transformed to signals in a frequency domain by Fourier transform, and a specific frequency band is chosen. To determine the creep damage, the spectrum intensities are calculated. Calculated intensities have a good correlation to life consumption of the weld joints, and this method is able to predict the remaining life of high-temperature piping, which has been already installed.


2016 ◽  
Vol 8 (4) ◽  
pp. 46
Author(s):  
Abdul Hamid Mar Iman ◽  
Edlic Sathiamurthy

Attention to damage assessment is always a priority especially in cases of natural disaster. The state of Kelantan is known to be one of a few Malaysian states with noticeable natural disaster, in particular, flood. In December 2014, an extraordinary magnitude of flood – nicknamed as yellow flood – struck the state causing hundreds of million ringgit of damage to properties. The purpose of this study is to demonstrate a spatial approach to estimating property damage incurred by flood. By selecting a badly affected area, GIS was used to map geo-referenced flood-hit location in Kuala Krai, Kelantan. Flood hazard was modelled and superimposed on estimated property damage. GIS spatial technique was then employed to estimate the flood damage incurred. This study, however, did not make a complete damage assessment of the properties but rather focusing on the methodology of damage assessment to show how it can be implemented. In conclusion, GIS spatial technique can generally be used to provide flood damage rapid assessment method.


2022 ◽  
Author(s):  
Mingzhen Wang ◽  
Lin Gao ◽  
Zailin Yang

Abstract The seismic damage state of building structure can be evaluated by observing the fundamental period change of structure. Firstly, the fundamental period calculation formula that adapts to the deformation pattern and distribution mode of horizontal seismic action for reinforced concrete frame structure is derived. Secondly, the seismic damage assessment standard of building structure considering period variation is established. Then, the seismic damage assessment method of building structure is constructed. Finally, the seismic damage example is used to verify the established evaluation method. The results show that the established research method has high accuracy and good engineering practicability.


Author(s):  
Gomasa Ramesh ◽  

Damage may be assessed using several damage indices with values associated with different structural damage states. The usefulness of a variety of current response-based damage indices in seismic damage assessment is addressed and critically assessed. A novel rational damage assessment method is provided, which measures the structure’s physical reaction characteristics. A practical method based on various analyses is given to evaluate the damaged structures in earthquakes of different intensities. This paper provides an overview of previous research works on the damage assessment of the reinforced concrete structures. This study may be helpful for easy understanding about the damage assessment of reinforced concrete structures and reduce the impacts of disaster and surrounding structures.


2020 ◽  
Vol 15 (3) ◽  
pp. 36-58
Author(s):  
Ashlynn Kogut ◽  
Pauline Melgoza

Abstract Objective – Due to the individualized nature of consultations and institutional constraints, research consultations can be challenging to assess. At Texas A&M University Libraries, subject librarians use research consultations to teach information literacy to upper-division engineering student teams working on a technical paper project. This paper describes an action research project designed to evaluate which assessment method for consultations with student teams would provide the most actionable data about the instruction and the consultation logistics as well as optimize librarian time. Methods – For three semesters, we simultaneously used up to four consultation assessment methods: one-minute papers, team process interviews, retrospective interviews, and questionnaires. We followed the action research cycle to plan the assessments, implement the assessments, reflect on the data collected and our experiences implementing the assessments, and revise the assessments for the next semester. Each assessment method was distributed to students enrolled in an engineering course at a different point in the technical paper project. The one-minute paper was given immediately after the consultation. The team process interviews occurred after project deliverables. The questionnaire was distributed in-person on the last day of class. Focus groups were planned for after the assignment was completed, but low participation meant that instead of focus groups we conducted retrospective interviews. We used three criteria to compare the assessments: information provided related to the effectiveness of the instruction, information provided about the logistics of the consultation, and suitability as an assessment method in our context. After comparing the results of the assessment methods and reflecting on our experiences implementing the assessments, we modified the consultation and the assessment methods for the next semester. Results – Each assessment method had strengths and weaknesses. The one-minute papers provided the best responses about the effectiveness of the instruction when questions were framed positively, but required the most staff buy-in to distribute. The team process interviews were time intensive, but provided an essential understanding of how students think about and prepare for each progress report. Recruiting for and scheduling the focus groups required more time and effort than the data collected about the instruction and logistics warranted. The questionnaire provided student perspectives about their learning after the assignment had been completed, collected feedback about the logistics of the consultations, was easy to modify each semester, and required minimal librarian time. Conclusion – Utilizing multiple assessment methods at the same time allowed us to determine what would work best in our context. The questionnaire, which allowed us to collect data on the instruction and consultation logistics, was the most suitable assessment method for us. The description of our assessment methods and our findings can assist other libraries with planning and implementing consultation assessment.


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