Papers by Keyword: Damage Index

Abstract: In this paper, the seismic behavior of the main nave and cloister of the Guadalupe Church and San Diego Convent is studied, a structure dating from the 18th century and built in the historic center of the city of Morelia, Mexico, considering a set of 9 real seismic acceleration records of September 19 2017 earthquake obtained at seismic stations located near the epicenter but at almost 100 kilometers from this building, which were used first without any scale factor and then a scale factor was applied to reach the expected maximum peak accelerations of the ground at the site for probabilistic return periods of 475 years and 975 years.

Abstract: Airworthiness authorities require that composite materials in primary structures must be undamaged all in-service life long, resulting in an oversizing of structural components and in a general increasing of weight. To allow structures working in presence of damages but showing an acceptable residual strength, in recent years a significant interest has been pointed out in the capability of ultrasonic guided waves as candidate tool for Structural Health Monitoring (SHM) of composites. The continuous assessment of the structural integrity, that can be accomplished by means of SHM systems, would provide, in fact, a less-conservative design and significant benefits in repair operations. In this work, a description of two numerical techniques based on Finite Element Method (FEM) for the simulation of Lamb wave propagation in a damaged Glass Fibre Reinforced Polymer composite winglet is presented. The interaction between damage and guided-waves has been investigated under two central frequencies: 100 kHz and 150 kHz. Root Mean Square Deviation Damage Index has been used to compare the baseline signals (achieved under the pristine configuration) and the respective signals achieved under the impacted/damaged one. Numerical models have been assessed against an experimental tests campaign.

Abstract: An empirical methodology to evaluate damage by the use of two damage indicators for 2D steel/concrete composite structures is proposed. This methodology has been established with aid of the results of an extensive parametric study regarding the non-linear behaviour of 48 steel/concrete composite frames subjected to 100 far-fault records. A large number of inelastic dynamic analyses are conducted by increasing the earthquake motions to lead the frames to several levels of non-linear response. The results of the analyses show that the characteristics of the structure and the ground motions affect damage of the structures. The results are post-processed by the use of statistical methods to generate expressions, which show the effect of the abovementioned parameters and give an evaluation of the damage indicators utilised here. In particular, given the characteristics of the frames and the record, someone can compute the maximum damage found in beams and columns. Finally, one example serves to show the use of the developed formulae and demonstrates their validity.

Abstract: The historical masonry buildings are characterised by a great vulnerability regard the seismic action, as the recent events occurred in Central Italy have highlighted. During the seismic emergency the authors, in collaboration with the Civil Protection Department as part of the ReLUIS activities, have carried out usability inspections, analysing also the case study described in this paper. The structure, a school in Teramo, was already affected by previously seismic damages and it has been highly involved by the seismic events abovementioned. In this work the results of first inspection, reported in the AeDES form, and a more accurate visual inspection are presented in terms of detection of the crack patterns and evaluation of the seismic damages index. Moreover the vulnerability index has been calculated according to the GNDT 2° level method. The vulnerability index is finally used to calculate the damage index expected for the seismic intensity registered during the seismic event of October 30, 2016, and compared with the observed post-seismic damage level.

Abstract: Existing non-destructive test methods are usually ineffective in detection of surface breaking cracks with large depths in concrete structure. This paper introduces a method suitable for detection of deep cracks based on surface wave time reversal theory. A numerical simulation based on the finite element model is performed to investigate surface cracks detection. A damage index was defined based on the correlation coefficient between the actuated and the reconstructed wave signals. The results demonstrated that the presence of crack had a significant influence on the propagation characteristics of surface waves along concrete. Cracks in different sizes were introduced and correlated with the damage index. Enlarging the crack depth resulted in an increase in the distortion of reconstructed signals, and a higher damage index was obtained. The results illustrated the effectiveness of the surface wave time-reversal process in identifying cracks in concrete structures.

Abstract: L shaped braided composites under fatigue load was researched, using piezoelectric sensors and active Lamb wave monitoring technology. HHT transform based signal envelope obtaining method and the damage index method based on signal energy change were used to monitor the damage extending of the braided composites.

Abstract: The paper presents an evaluation of medium-rise reinforced concrete building in Johor which is subjected to low intensity earthquake effects. Even-though Malaysia is outside the earthquake region, the country had experienced and did suffer from major cases due earthquake in the past like tsunami. Engineers should concern and consider the loading for reinforced concrete building due to earthquake in the building design procedure. The study addresses the performance of critical frame reinforced concrete building when subjected to earthquake motion. The building of Marlborough College Malaysia chooses as model. The building was analyzed using Finite Element Modelling (FEM) using IDARC (2D) with respect to various earthquake intensities obtained from Time History Analysis (THA) data. The yield point at the beam-column connections was analyzed to determine the damage index and damage level of the building subjected to the various earthquake intensities. The building performed the early yielding point at 4.2650 sec for beam element at the intensity of 0.15g. Based on the results, it was found that the critical frame of Condominium Marlborough College Malaysia can stand an earthquake occurrence with intensity up to 0.20g. There is no structural damage some non-structural damage is expected in the non-linear analysis of modal frames. The building was also categorized as the one in the light damage level.

Abstract: The choice of damage index and quantify of the performance goal is an important part of the theory of performance-based seismic design. This paper introduces research results of shear wall structure damage model at home and abroad, combined with the experimental study on the seismic behavior of shear wall structure at home and abroad, and discusses the application in practical engineering of the shear wall structure damage, puts forward the remains problem to be further in-depth study.

Abstract: The feasibility and applicability of delamination damages localization methods with various defined damage indexes for the damaged composite laminated beam were studied. The results indicate that, for the modal strain energy method, damage indexes defined by strain energy difference are more effective to locate the delamination damage than that of strain energy ratio. For energy response method, damage index defined by the second difference can effectively locate the delamination damage in the composite laminated beams.

Abstract: Starting with damage identification index method on the basis of the curvature mode, the first-order curvature mode ratio is proposed, and then it is made a numerical simulation analysis for a single span simple beam bridge with ANSYS. The identification of structure damage degree under the damage on the single position is studied. The fitted polynomial based on the derivation of the first-order curvature mode ratio can estimate the damage degree; it has a good reference value for the damage detection of structures in practical engineering.