دانلود رایگان مقاله بازرسی بنایی طاق های کارآمد به وسیله شبیه سازی مونت کارلو

Abstract

This paper presents a methodology for probabilistic assessment of masonry vaults bearing capacity with the consideration of existing defects. A comprehensive methodology and software package have been developed and adapted to inspection requirements. First, the mechanical analysis model is explained and validated by showing a good compromise between computation time and accuracy. This compromise is required when probabilistic approach is considered, as it requires a large number of mechanical analysis runs. To model the defect, an inspection case is simulated by considering a segmental vault. As the inspection data is often insufficient, the defect position and size are considered to be unknown. As the NDT results could not provide useful and reliable information, it is therefore decided to take samples with the obligation to minimize as much as possible their number. In this case the main difficulty is to know on which segment the coring would be mostly efficient. To find out, all possible positions are studied with the consideration of one single core. Using probabilistic approaches, the distribution function of the critical load has been determined for each segment. The results allow to identify the best segment for vault inspection.

4. Conclusions

An effective probabilistic methodology, aiming to assess the load bearing capacity of damaged masonry vault, is proposed. In the case where the non destructive tests (NDT) cannot provide useful information about the defect, it allows knowing on which segment the coring will be more efficient, which minimizes considerably the number of cores and consequently the diagnosis cost. 2 A. Zanaz et al. / Case Studies in Structural Engineering 5 (2016) 1–12 The consequence of defect on the load bearing capacity of the vault is simulated. A diagnosis case-study is provided by considering the thickness loss caused by water infiltrations. The defect is modeled through three steps: First, the defect extent is assumed as a function of its position in order to consider the effect of gravity. Then, the shape of the defect is approximated by two four-degree polynomials: one on the right and one on the left of the maximum defect location. They are determined by considering slope continuities between the two curves, and between the defect ends and the rest of the vault. Finally, the projection of the defect curve, given by the two polynomials, on the vault thickness is performed and the developed program determines the position and the number of segments that have suffered losses, modifies respectively their thicknesses and computes the mechanical response. Monte Carlo simulations allow to obtain the distribution function of the critical load, which is determined for each segment. The analysis of the obtained distributions allowed identifying the searched segment. It corresponds to the segment which has the largest interval of critical load variation. In fact, for all segments, the maximum values of the critical load are very close, the minimum values and the percentiles in the low extreme values are the varying item. Finally, knowing the critical load distributions for other thickness loss values will allow a finer diagnosis strategy.