However, in order to consider the asymptotic types.
The Gumbel distribution is based on the principle that the failure occurs when a determined set of values exceeds the safety value  and is frequently applied to modelling environmental phenomena, as for example wind velocity ; in addition the Gumbel distribution has been recently used in SHM systems for service life prediction [ 8 , 11 , 13 ]. The elevated water reservoir [ Figure 1 -A] is a slender structure of reinforced concrete with a height of The reservoir instrumentation was done by employing a bi-axial optical accelerometer developed and tested by Antunes , positioned in the structure top, as shown in the [ Figure 1 - C].
The implemented monitoring system was connected to a data acquisition system located in the Institute of Telecommunications of Aveiro, Portugal, by m of optical fiber [ Figure 1 -B]. In order to collect data on structural displacements due to wind action, the elevated reservoir has been monitored since January aiming the identification of changes in the structural behavior that can compromise the safety state.
In this way, the bi-axial optic accelerometer has the function of collecting information in the transversal D1 and longitudinal D2 directions, essential accelerations for determining the natural frequency and relative displacements. The natural frequency is given by the expression 7 , where the mass m is characterized as inversely proportional of the square of the natural frequency, , and directly proportional to square of the stiffness ratio k.
In this analysis the stiffness ratio k was considered constant, and that only the m value could influence the frequency value, due to water level variation inside the water reservoir. The structural displacements were collected only for cases in which the wind presents the same direction. In this way, the wind action was restricted to southeast direction, in order to coincide with the structure's face with higher area, through which the wind action is supposed to present a greater effect on structure displacements in transversal and longitudinal directions.
From the data offered by bi-axial optic accelerometer, the linear relative displacements of the elevated reservoir were obtained according to expression 8 , where s t is the displacement in function of the time and a t represents the acceleration in function of the time.
From analysis of a large data set, were selected the wind actions described in A and B, as shown in the [ Table 1 ]. In D1 direction transversal the values of natural frequencies in the situation A and B presented the same frequency value, namely 0. However, taking into account the greater length of D2 longitudinal direction relative to D1, the possible mass variation influenced by changes in the water level presented influence in the natural frequency value, respectively 0. The spectrums of the natural frequency collected are shown in [ Figure 2 ], where A and B represent the wind behavior and D1 and D2 are transversal and longitudinal direction of the water reservoir respectively.
It is also important to refer that for each measurement realized were considered s of data record time, that correspond to Once the acceleration spectrum was known, the velocity and structural relative displacements in the transversal and longitudinal directions were obtained and considered in function of the time, as can be seen by [ Figure 3 ]. In terms of data processing of structural relative displacements, the maximum values of structural displacements in both directions were obtained and processed as absolute values [ Figure 4 ]. Then, a new data set was obtained and these values were employed in this work for evaluation of the reliability index.
Based in the relative displacements of the elevated reservoir under wind action, for both wind conditions A and B, and also based in the relations stablished by expression 7 , the structure presents a higher stiffness in the direction D2, for which smaller values of natural frequency already were expected.
Structural reliability assessment based on optical monitoring system: case study
From the maximum relative displacements in both directions D1 and D2, were obtained the histograms showed in the [ Figure 5 ]. The histograms AD1 and BD1 refer to maximum displacements in the transversal direction, and the histograms AD2 and BD2 refer to maximum displacements in the longitudinal direction of the water reservoir, for wind characteristics according to condition A and B. The direction D1 presents a more sensibility to wind action than the direction D2, for example, for wind velocity of In order to consider the frequency distribution of the maximum values of relative displacement of the elevated reservoir were drawn GEV curves, as can be seen in the [ Figure 6 ].
It is noted that, when the wind velocity changes from 8.
State-of-the-art of probabilistic performance based structural fire engineering
This variation represents that when the wind velocity changes from 8. However, the increase in the failure probability is more dramatic in the D1 direction, where it is observed that the wind velocity increase represents a For the predictive reliability analysis, it was estimated that the annual number of times the water elevated reservoir is under conditions A and B is of The details of the predictive analysis are shown in [ Table 2 ].
However, for a most accurate reliability prediction the results presented by Figure 8 should be associated with the water reservoir deterioration analysis. This work presents a reliability monitoring system based on bi-axial optical accelerometer and a new methodology for reliability assessment based on maximum relative displacements. The reliability assessment methodology uses acceleration data provided by an optical sensor implemented in the top of a water reservoir located in the University of Aveiro, which has the aim.
From the maximum displacements collected by the.
In this perspective, the reliability monitoring system based on bi-axial optical accelerometer. The methodology of reliability assessment proposed in this work proved of easy application and adequate to data collecting, especially by utilization of GEV as a way to improve the modeling of the structural behavior induced by action of random variables, as wind velocity, in the case of this work. Parte 2: Requisitos para os elementos estruturais.
Laing, D. Homa, R. Harman, and C. Betz, G.
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Thursby, and B. Antunes, J. Dias, T. Mesquita, H. Varum, and P. January, Domingues, T. Paixao, E. Mesquita, N. Alberto, A. Frias, R. Ferreira, H. Varum, P.
Antunes, and P. Andre, "Liquid hydrostatic pressure optical sensor based on micro-cavity produced by the catastrophic fuse effect," IEEE Sens. Cremona, Structural Performance: probabilistic-based assessment, 1st ed. London: ISTE, Dissanayake and P.
Structural Performance: Probability-Based Assessment
State-of-the-Art and Engineering Example of Study on Damage-Based Seismic Performance for Bridge Abstract: The double-parameter seismic damage model considering deformation and energy dissipation can well explain the nature of structural seismic damage, and the damage-based analysis method for seismic performance is always a hot research point in this field. However, there are still some problems existing in the research of the damage-based multi-dimensional seismic performance of bridge structure, such as combination method of double-parameter seismic damage indexes, the construction of damage indices from material, component to whole structure considering multi-dimensional seismic effects, and damage-based probabilistic seismic design method, et al.
In this paper, the relevant research was systematically summarized, and the state-of-the-art and development prospect of the seismic performance analysis based on the damage model were analyzed. It is thought that the probability distribution of the existing structural parameters can be well obtained by finite element model validation, and the combination of the damage model considering the multi-dimensional seismic action and the vulnerability analysis will provide a good method to solve the problem of multi-dimensional seismic performance assessment.
Finally, based on the seismic damage assessment of reinforced concrete box piers under multidimensional earthquake, the application example of damage-based assessment method was given and provided a useful reference for the damage-based multi-dimensional seismic performance assessment for bridge structure. Article :. DOI: Need Help?