• Structural Monitoring and Maintenance
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• v.3 no.1
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• pp.51-69
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• 2016

Monitoring the performance and estimating the remaining useful life of aging civil infrastructure in the United States has been identified as a major objective in the civil engineering community. Structural health monitoring has emerged as a central tool to fulfill this objective. This paper presents a review of the major structural monitoring programs that have been recently implemented in the United States, focusing on the integrity and performance assessment of large-scale structural systems. Applications where response data from a monitoring program have been used to detect and correct structural deficiencies are highlighted. These applications include (but are not limited to): i) Post-earthquake damage assessment of buildings and bridges; ii) Monitoring of cables vibration in cable-stayed bridges; iii) Evaluation of the effectiveness of technologies for retrofit and seismic protection, such as base isolation systems; and iv) Structural damage assessment of bridges after impact loads resulting from ship collisions. These and many other applications show that a structural health monitoring program is a powerful tool for structural damage and condition assessment, that can be used as part of a comprehensive decision-making process about possible actions that can be undertaken in a large-scale civil infrastructure system after potentially damaging events.

• Earthquakes and Structures
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• v.10 no.5
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• pp.1181-1212
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• 2016

Fragility and loss functions are developed to predict damage and economic losses due to earthquake loading in Reinforced Concrete (RC) structural components with smooth rebars. The attention is focused on external/internal beam-column joints and ductile/brittle weak columns, designed for gravity loads only, using low-strength concrete and plain steel reinforcing bars. First, a number of damage states are proposed and linked deterministically with commonly employed methods of repair and related activities. Results from previous experimental studies are used to develop empirical relationships between damage states and engineering demand parameters, such as interstory and column drift ratios. Probability distributions are fit to the empirical data and the associated statistical parameters are evaluated using statistical methods. Repair costs for damaged RC components are then estimated based on detailed quantity survey of a number of pre-70 RC buildings, using Italian costing manuals. Finally, loss functions are derived to predict the level of monetary losses to individual RC components as a function of the experienced response demand.

• Structural Engineering and Mechanics
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• v.43 no.1
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• pp.127-145
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• 2012

One of the most important and challenging steps in seismic vulnerability and performance assessment of highway bridges is the determination of the bridge component damage parameters and their corresponding limit states. These parameters are very essential for defining bridge damage state as well as determining the performance of highway bridges under a seismic event. Therefore, realistic damage limit states are required in the development of reliable fragility curves, which are employed in the seismic risk assessment packages for mitigation purposes. In this article, qualitative damage assessment criteria for ordinary highway bridges are taken into account considering the critical bridge components in terms of proper engineering demand parameters (EDPs). Seismic damage of bridges is strongly related to the deformation of bridge components as well as member internal forces imposed due to seismic actions. A simple approach is proposed for determining the acceptance criteria and damage limit states for use in seismic performance and vulnerability assessment of ordinary highway bridges in Turkey constructed after the 1990s. Physical damage of bridge components is represented by three damage limit states: serviceability, damage control, and collapse prevention. Inelastic deformation and shear force demand of the bent components (column and cap beam), and superstructure displacement are the most common causes for the seismic damage of the highway bridges. Each damage limit state is quantified with respect to the EDPs: i.e. curvature and shear force demand of RC bent components and superstructure relative displacement.

• Steel and Composite Structures
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• v.42 no.4
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• pp.501-511
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• 2022

Earthquake Resistant Design Philosophy seeks (a) no damage, (b) no significant structural damage, and (c) significant structural damage but no collapse of normal buildings, under minor, moderate and severe levels of earthquake shaking, respectively. A procedure is proposed for seismic design of low-rise reinforced concrete special moment frame buildings, which is consistent with this philosophy; buildings are designed to be ductile through appropriate sizing and reinforcement detailing, such that they resist severe level of earthquake shaking without collapse. Nonlinear analyses of study buildings are used to determine quantitatively (a) ranges of design parameters required to assure the required deformability in normal buildings to resist the severe level of earthquake shaking, (b) four specific limit states that represent the start of different structural damage states, and (c) levels of minor and moderate earthquake shakings stated in the philosophy along with an extreme level of earthquake shaking associated with the structural damage state of no collapse. The four limits of structural damage states and the three levels of earthquake shaking identified are shown to be consistent with the performance-based design guidelines available in literature. Finally, nonlinear analyses results are used to confirm the efficacy of the proposed procedure.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.10a
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• pp.550-557
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• 2004

In this paper, structural damage in PSC bridges is monitored by using model-based damage detection methods. First numerical experiments on the test structure are described. Dynamic responses of the test structures are obtained fur several damage scenarios. The change in natural frequency and the change in nude shape curvature are selected as features to represent the states of the structure. Next a damage localization algorithm from monitoring the changes in natural frequency is outlined. Also, the damage localization algorithm from monitoring the changes in nude shapes is outlined. Finally, the damage localization algorithms are used to predict damage in the test structure. The results of the analysis indicate that the model-based damage detection methods correctly predicted damage in the test structure.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.225-231
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• 2006

The purpose of this study is to develop a promising hybrid structural health monitoring system for structural joints. For this propose, the combined use of vibration-based techniques and electro-mechanical impedance technique is employed. For the verification of the proposed health monitoring scheme, a series of damage scenarios are designed to simulate various situations at which the connection joints can experience during their service life. The obtained experimental results, modal parameters and electro-magnetic impedance signatures, are carefully analyzed to recognize the connecting states and the target damage locations. From the analysis. it is shown that the proposed hybrid health monitoring system is successful for acquiring global and local damage information on the structural joints.

• Structural Engineering and Mechanics
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• v.34 no.1
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• pp.39-60
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• 2010

In Turkey, majority of industrial facilities are composed of precast buildings. However, precast buildings have suffered extensive damage during Kocaeli and Duzce (1999) and Adana-Ceyhan (1998) earthquakes. Therefore, in this study, fragilities of existing building stock and damage probabilities of precast buildings were studied. For this purpose, building inventories were prepared and variation of structural parameters was determined by investigating the design project of 65 precast buildings constructed in Denizli, Turkey. Twelve analysis models which reflect the stiffness, strength and ductility properties of building inventory were constructed. After the definition of strain based displacement limits and corresponding damage states for buildings, displacement demands were calculated by using non linear time history analysis. During the analyses 360 strong ground motion records were used. Exceedence ratios of concerned damage limits was calculated by checking the displacement demands and then PGV based fragility curves were constructed. Efficiency of strength, stiffness and ductility properties of existing precast buildings were investigated by comparing the fragility curves. The results have shown that the most effective parameters that govern the damage probabilities of precast buildings are stiffness and ductility. It was also stated that the results of fragility analysis and damage and failure observations performed after Kocaeli and Duzce Earthquakes are compatible.

• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.2747-2756
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• 2023

Reinforced Concrete (RC) shear walls are one of the civil structures in nuclear power plants to resist lateral loads such as earthquakes and wind loads effectively. Risk-informed and performance-based regulation in the nuclear industry requires considering possible accidents and determining desirable performance on structures. As a result, rather than predicting only the ultimate capacity of structures, the prediction of performances on structures depending on different damage states or various accident scenarios have increasingly needed. This study aims to develop machine-learning models predicting drifts of the RC shear walls according to the damage limit states. The damage limit states are divided into four categories: the onset of cracking, yielding of rebars, crushing of concrete, and structural failure. The data on the drift of shear walls at each damage state are collected from the existing studies, and four regression machine-learning models are used to train the datasets. In addition, the bagging ensemble method is applied to improve the accuracy of the individual machine-learning models. The developed models are to predict the drifts of shear walls consisting of various cross-sections based on designated damage limit states in advance and help to determine the repairing methods according to damage levels to shear walls.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.3
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• pp.178-188
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• 2005

This paper introduces a structural damage identification method to identify 4he multiple directional damages generated within a cylindrical shell by using the measured frequency response function (FRF). The equations of motion for a damaged cylindrical shell are derived. by using a theory of continuum damage mechanics in which a small material volume containing a directional damage is represented by the effective orthotropic elastic stiffness. In contrast with most existing vibration-based structural damage identification methods which require the modal Parameters measured in both intact and damaged states, the present method requires only the FRF-data measured at damaged state. Numerically simulated damage identification tests are conducted to verify the feasibility of the Proposed structural damage identification method.

• Journal of Mechanical Science and Technology
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• v.18 no.12
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• pp.2114-2124
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• 2004

In this paper, a structural damage identification method (SDIM) is developed for cylindrical shells and the numerically simulated damage identification tests are conducted to study the feasibility of the proposed SDIM. The SDIM is derived from the frequency response function solved from the structural dynamic equations of damaged cylindrical shells. A damage distribution function is used to represent the distribution and magnitudes of the local damages within a cylindrical shell. In contrast with most existing modal parameters-based SDIMs which require the modal parameters measured in both intact and damaged states, the present SDIM requires only the FRF-data measured in the damaged state. By virtue of utilizing FRF-data, one is able to make the inverse problem of damage identification well-posed by choosing as many sets of excitation frequency and FRF measurement point as needed to obtain a sufficient number of equations.