International Journal of Sustainable Materials and Structural Systems (7 papers in press)
Fatigue life prediction for carbon fiber/epoxy laminate composites under spectrum loading using two different neural network architectures
by Wael A. Altabey, Mohammad Noori
Abstract: The objective of this study is to predict the fatigue life of carbon fiber/epoxy composite laminate sheets involving twelve balanced woven bidirectional layers with the same orientation angle [0/90
Keywords: Artificial neural networks; Fatigue life; Residual strength; Composite materials; spectrum loading.
Experimental and Numerical Study on the DADAS Dampers in Steel Frame Structure
by Faezeh Nejati, Mahmood Hosseini, Amir Mahmoudzadeh
Abstract: In this study, a structural system with seesaw motion with respect to a central massive support has been considered for steel buildings with square plan, and the bottom ends of the all circumferential columns at the lowest story have been equipped with Double-ADAS (DADAS) dampers, which dissipate a great portion of the seismic input energy. The hysteretic behavior of DADAS dampers has been investigated by using finite element analysis. At first a set of regular steel multistory buildings with 5 stories have been designed based on the conventional code provisions. Then, the structures of the designed buildings have been changed into the structure with seesaw motion by using, at the base level of the building, a massive central column, eliminating other middle columns, and equipping circumferential columns with DADAS dampers. The damper is modeled at structural laboratory of Earthquake Engineering Research Institute in small scale and tested under harmonic loaded. Experimental results show the proper conduct of the damper prototype is under load. To show the efficiency of the proposed structural system and dampers, a series of nonlinear time history analysis (NLTHA) were performed by using a set of 3-component acceleration of some selected earthquakes. Numerical results of NLTHA show that the proposed rocking structures can efficiently decrease the seismic damage in the building.
Keywords: Double-ADAS Damper (DADAS); Experimental Study; Finite Element Modeling; Nonlinear Time History Analysis; Seesaw Motion of Structures.
Damages caused by alkali reactive concrete in structural elements
by Fouzia Bouabdallah, Mohamed Fouzi Habita, Noureddine Ferhoune, Nadjette Rehamnia
Abstract: Slow reaction occurs between concrete aggregates and cement alkalis; the alkali reaction(noted by AR) is the most famous internationally concrete pathology actually. With: potential reactive aggregate, height rate of alkalis and RH>80%. Destroying solid gel results generates an internal expansive force causing cracks and checking, so the fall concrete structures in the mechanical properties. To simulate (AR), evolutionary universal tests ASTM, CSA and AFNOR are used in our laboratory works: Civil Engineering Annaba University. For concrete and reinforced concrete one Dreux-composition is tested with: Aging method, doping alkali method and the same Limestone aggregates (p). Damages with volume effect are: expansions with (S) shape, cracks have (Y) shape (1.5mm max- concrete B).
Keywords: Concrete; Alkali; Crack; Expansion; Reaction; Aggregate; Gel; Experiment;
Modern Methods of Railway Track Safety Inspection
by Ta-Lun Yang, Wael A. Altabey
Abstract: Railway and transit tracks are designed and constructed as smooth segments of straight lines and circular curves linked by transitional spirals. Dynamic traffic loads, material wear and environmental cycles gradually produce deviations in the track from the original smooth geometry. Such deviations lead to rough ride in the vehicles and furthermore higher dynamic vehicle-track interaction forces which lead to faster deviation growth. To monitor the geometric condition of the track and to guide maintenance and repair, hand tools were used to take consecutive measurements by track walkers. Modern state-of-the-art technology has since replaced the traditional slow and painful measurement practice. Inspections are now done from a moving vehicle at hundreds of km per hour without contacting the track. All track geometry parameters are measured up four times per meter; data are analyzed in real time by onboard software to identify the location and magnitudes of deviations which exceeds the acceptable tolerance. Historical measurements are stored in data bases which are used to establish degradation trends and to guide the planning of maintenance. With the help of high-speed imaging technology, automated video inspection systems are installed on some vehicles to detect other faults in the track structure. Four types of such modern inspection tools are introduced in the paper presentation. These are: a single-car comprehensive inspection vehicle; a dedicated inspection train; a highway-railway dual usage truck and an unmanned inspection system. Actual operational systems are used as examples to illustrate the design and capabilities of each of these types of inspection tools.
Keywords: Railway and transit tracks; vehicles; Track structure; Dynamic traffic loads; Inspections; Imaging technology; Video inspection systems.
Special Issue on: FUTURE TRENDS IN CIVIL ENGINEERING
Ultrasonic Zero-lag Cross Correlation based on Frequency-wavenumber Domain Analysis for Internal Delamination Detection
by Zhiqi Shen, Yun-Kyu An, Zhishen Wu
Abstract: This paper proposes a zero-lag cross correlation (ZLCC) method based on frequency-wavenumber (f-k) domain analysis for internal delamination detection in composite structures. The proposed ZLCC method is able to identify and localize hidden delamination inside composite layers without relying on baseline data accumulated from the pristine condition of a target structure, making it possible to minimize false alarms caused by environmental effects. The ZLCC method is theoretically developed by investigating the physical relationship between ZLCC and ultrasonic wave interaction with delamination. Then, it is numerically validated using a 2D finite element model. The finite element analysis results reveal that internal delamination is successfully localized and highlighted by ZLCC.
Keywords: Ultrasonic; Zero-lag cross correlation; Standing wave; Composite structures; Structural health monitoring; Non-destructive testing.
A Hybrid Instrumented/Computational Modelling Framework with Lab-on-sensor Design and Calibration for Structural Behaviour Monitoring
by Genda Chen, Ying Huang
Abstract: In this paper, societal needs on the use of SHM in bridge preservation will first be reviewed and used to promote the re-alignment of SHM outcomes to daily practices in bridge inspection and maintenance. A hybrid instrumented/computational modelling framework to extend the emerging concept of lab-on-sensor design and calibration into bridge preservation application will then be envisioned with the acquisition of mission-critical data for structural behaviors. Next, current sensor technologies and future opportunities along this line of research will be discussed with several examples. Finally, the acquired data will be used to quantify the nonlinear behavior of critical structural elements and thus their material parameters and uncertainties. For other structural elements, material prarameters and uncertainties will be statistically correlated to those of the critical structural elements in a multi-scale computational model of representative bridges in a transportation network.
Keywords: Structural health monitoring; structural behavior; computational model; bridge network.
Design and Optimization of a Distributive Model-Based Sensor Fault Detection Method for Automated In-Network Execution in a Wireless Sensor Network
by Chun Lo, Jerome Lynch, Mingyan Liu
Abstract: In this paper, a distributed model-based sensor fault detection method is presented for detecting and identifying spike faults without the requirement of the existence of reference sensors. This method partitions the sensor network into sensor pairs and carries out fault diagnosis within these sensor pairs based on autoregressive with exogenous input time series analysis. The performance of the proposed method is evaluated by implementing the algorithm in a 16 node wireless sensor network deployed to monitor the traffic induced accelerations of the Grove Street Bridge (Ypsilanti, Michigan). Spike faults are generated on-site and superimposed on the acceleration measurement before being acquired by some of the monitoring system wireless sensors. In addition to accuracy evaluation, this study focuses on the relationship between the detection accuracy and three different network partition methods. Based on this relationship, a communication energy saving partition method is presented. The proposed algorithm achieved a detection rate of over 85% yet reduced communication energy by more than 54% when compared to a centralized fault detection method implemented in the monitoring system base station.
Keywords: sensor fault detection; wireless sensor; in-network computing; monitoring.