Search

In recent years, the safety and comfort problems of bridges are not uncommon, and the operating conditions of in-service bridges have received widespread attention. Many large-span key bridges have installed structural health monitoring systems and collected massive amounts of data. Monitoring data is the basis of structural damage identification and performance evaluation, and it is of great significance to analyze and evaluate its quality. This paper takes the acceleration monitoring data of the main girder and arch rib of a long-span arch bridge as the research object, analyzes and summarizes the statistical characteristics of the data, summarizes 6 abnormal data conditions, and proposes a data quality evaluation method of convolutional neural network. This paper conducts frequency statistics on the acceleration vibration amplitude of the bridge in December 2018 in hours. In order to highlight the end effect of frequency statistics, the whole is amplified and used as network input for training and data quality evaluation. The results are good. It provides another new method for structural monitoring data quality evaluation and abnormal data elimination., This paper is supported by the National Key R&D Program of China (2019YFB1600702), the National Natural Science Foundation of China (51978508), and the Ministry of Hosing and Urban-Rural Development (K2019690). The authors are indebted to the Spanish Ministry of Economy and Competitiveness for the funding provided through the research project BIA2017-86811-C2-1-R directed by José Turmo., Postprint (published version)

The molten core-concrete interaction (MCCI) is treated as one of the important phenomena that may lead to the late containment failure by basemat penetration in a hypothetical severe accident of light water reactors (LWRs). The earlier research has showed that heat transfer limitation exists for the coolability of ex-vessel corium by atop water flooding due to crust formation on the melt/water interface that will isolate melt from water. However, several cooling mechanisms were identified in a series of intense investigations. A code (CORQUENCH) was developed and updated to incorporate the newly identified cooling mechanisms for the better predictions of cavity erosion and corium cooling behaviors. A description about such cooling mechanisms (i.e., bulking cooling, water ingression, eruption and crust breach) and the concrete ablation models implemented in the code is presented in this thesis. The technical work in the thesis includes two parts: first, the verification and validation of the code were performed against the CCI tests from the OECD/MCCI projects; and then a reactor-scale simulation was carried out for MCCI and ex-vessel corium coolability of a reference PWR with LCS concrete. The calculations of CCI tests have a plausible agreement with the experimental data. The calculation predicts an optimistic result for the reactor case, and a fast quenching achieved at about 145 minutes. In addition, a sensitivity study was also conducted on several important parameters, i.e., concrete type, corium composition, water flooding time, atmosphere pressure, concrete ablation temperature, initial temperature, decay power, cavity geometry, concrete decomposition model and melt upper heat transfer model. An attempt to explain the physics of the different predicted phenomena is presented as well. Finally, comparative calculations were performed by the other codes (ASTEC and FinCCI) for the same reactor-scale configuration. Discrepancies are found in the results. Some sugg