A comprehensive review on modal parameter-based damage identification methods for beam- or plate-type structures is presented, and the damage identification algorithms in terms of signal processing...

Vibration-based Damage Identification Methods: A Review and Comparative Study:

Vibration based condition monitoring refers to the use of in situ non-destructive sensing and analysis of system characteristics –in the time, frequency or modal domains –for the purpose of detecting changes, which may indicate damage or degradation. In the field of civil engineering, monitoring systems have the potential to facilitate the more economical management and maintenance of modern infrastructure. This paper reviews the state of the art in vibration based condition monitoring with particular emphasis on structural engineering applications.

Vibration Based Condition Monitoring: A Review:

Development in vibration-based structural damage detection technique

The abundant availability and accessibility of plant fibres are the major reasons for an emerging new interest in sustainable technology. While focusing on the composite materials, the main points to be considered are environment friendliness and light weight, with high specific properties. This century has witnessed remarkable achievements in green technology in the field of materials science through the development of high-performance materials made from natural resources is increasing worldwide. Plant fibres are a kind of renewable resources, which have been renewed by nature and human ingenuity for thousands of years. The greatest challenge in working with plant fibre reinforced composites (PFRCs) is their large variation in properties and characteristics. A PFRCs properties are influenced by a number of variables, including the fibre type, environmental conditions, processing methods, and modification of the fibre. A detailed systematic review on these sustainable and renewable green materials is presented in this paper. The overall characteristics of plant fibres used in bio-composites, including source, type, structure, composition, as well as properties, will be reviewed. Finally, the review will conclude with recent developments and future trends of PFRCs as well as key issues that need to be addressed and resolved.

Plant fibre based bio-composites: Sustainable and renewable green materials

Structural health monitoring (SHM) using wireless sensor networks (WSNs) has gained research interest due to its ability to reduce the costs associated with the installation and maintenance of SHM systems. SHM systems have been used to monitor critical infrastructure such as bridges, high-rise buildings, and stadiums and has the potential to improve structure lifespan and improve public safety. The high data collection rate of WSNs for SHM pose unique network design challenges. This paper presents a comprehensive survey of SHM using WSNs outlining the algorithms used in damage detection and localization, outlining network design challenges, and future research directions. Solutions to network design problems such as scalability, time synchronization, sensor placement, and data processing are compared and discussed. This survey also provides an overview of testbeds and real-world deployments of WSNs for SH.

Structural Health Monitoring Using Wireless Sensor Networks: A Comprehensive Survey

Damage identification in beam-type structures: frequency-based method vs mode-shape-based method

One of the uncertain damage parameters to jeopardize the safety of existing PSC bridges is the loss of the prestress force A substantial prestress-loss can lead to severe problems in the serviceability and safety of the PSC bridges In this paper, a nondestructive method to detect prestress-loss in beam-type PSC bridges using a few natural frequencies is presented An analytical model is formulated to estimate changes in natural frequencies of the PSC bridges under various prestress forces Also, an inverse-solution algorithm is proposed to detect the prestress-loss by measuring the changes in natural frequencies The feasibility of the proposed approach is evaluated using PSC beams for which a few natural frequencies were experimentally measured for a set of prestress-loss cases Numerical models of two-span continuous PSC beams are also examined to verify that the proposed algorithm works on more complicated cases

Identification of prestress-loss in PSC beams using modal information

A vibration-impedance-based monitoring method is proposed to predict the loss of prestress forces in prestressed concrete (PSC) girder bridges. Firstly, a global damage alarming algorithm using the change in frequency responses is formulated to detect the occurrence of damage in PSC girders. Secondly, a local damage detection algorithm using the change in electro-mechanical impedance features is selected to identify the prestress-loss in tendon and anchoring members. Thirdly, a prestress-loss prediction algorithm using the change in natural frequencies is selected to estimate the extent of prestress-loss in PSC girders. Finally, the feasibility of the proposed method is experimentally evaluated on a scaled PSC girder model for which acceleration responses and electro-mechanical impedances were measured for several damage scenarios of prestress-loss.

Vibration and impedance monitoring for prestress-loss prediction in PSC girder bridges

A design optimization problem for steel box girder sections is formulated and a numerical solution procedure is presented. The formulation is based on the load and resistance factor design (LRFD) procedure. The application of genetic algorithms (GAs) for a class of numerical examples is investigated. The steel box girder may have longitudinal stiffeners on flanges and webs and transverse intermediate stiffeners. Thus, the design variables may be continuous or discrete, which naturally makes the use of GAs attractive. Design constraints represent the LRFD versions of the Standard Specifications of Korean Highway Bridges. The dimensions of concrete slab and other appurtenance are assumed to be pre-determined and minimization of the unit weight of the steel box girder is taken as a design objective. As the numerical optimizers, the Internet version of simple GA (SGA) and micro-GA (μGA) are used and their performance and results are compared. In addition, the sequential quadratic programming algorithm is also applied for purposes of comparison. It is found that μGA with the population size of 5 is a suitable and reliable tool for the design optimization of steel box girder sections. The resulting design can be effectively used as an initial design for practical proportioning

LRFD-Based Design Optimization of Steel Box Girder Sections Using Genetic Algorithms

The purpose of this study was to provide fundamental data for an anchor collision simulation of an FCM (flexible concrete mattress). Numerical material models (elastic-perfectly plastic model, Drucker-Prager model, and RHT concrete model) were compared. ANSYS Explicit Dynamics was used for collision analyses. An FE model was used for the anchor, FCM, andreinforcement bars. The results showed that the behavior of the FCM was verydifferent that those ofthe material models. In particular, the effect of the pressure dependen t strength was most noticeable among the properties of concrete.

Hyun-Man Cho

Papers

Damage identification in beam-type structures: frequency-based method vs mode-shape-based method

Identification of prestress-loss in PSC beams using modal information

Vibration and impedance monitoring for prestress-loss prediction in PSC girder bridges

LRFD-Based Design Optimization of Steel Box Girder Sections Using Genetic Algorithms

Collision Behavior Evaluation of Flexible Concrete Mattress Depending on Material Models