International Journal of Sustainable Materials and Structural Systems (22 papers in press)
Compression behavior of Composite Sandwich Panels with Corrugated Core
by Nagwa Elzayady, Eltahry Elghandour
Abstract: The corrugated-core of composite structures is low-density for sandwich panels and has excellent anisotropic properties. More efforts are needed to understand the behavior of such composites under mechanical loads. A flexible design is proposed for manufacturing polymeric composite corrugated cells to be utilized for producing a wide cellular honeycomb-like core. Unit cell specimens with varying lengths and heights have been made of woven prepreg composite (fiberglass-epoxy). Manufacturing and experimental testing have been carried out to understand the behavior of the specimens in both linear and non-linear stages of edgewise compression tests. The results indicated a significant increase in the stiffness and crushing force values with increasing specimen length. Stiffness was found to be height dependent while the crushing force was not. The total energy increased strongly with the increase in length. Specific properties relative to the specimens weight are emphasized in this study. Failure modes of different conditions were discussed.
Keywords: Sandwich panels; Corrugated core; Fiberglass; Composite laminated; Stiffness crushing; Edgewise compression; Specific stiffness; ligaments; Failure mode.
Analyzing properties of concrete made with stone dust and jute fiber using response surface methodology
by Sourav Ray, Mohaiminul Haque, Minhaz Monwar Auni, Shriful Islam
Abstract: In this study, the fresh and hardened properties of concrete produced from stone dust as fine aggregate and with the incorporation of jute fibre were analysed by employing the response surface methodology. Two independent variables, i.e., cut length (015 mm) and volumetric percent of jute fibre (00.15%) and their five responses (7-day and 28-day compressive strength, 7-day and 28-day splitting tensile strength and slump value) were considered to develop statistical models. From the response surface plot, it was observed that both compressive strength and tensile strength increases with the increase of both variables. Moreover, it was observed that the maximum compressive and split tensile strength is obtained for 15 mm cut length and with the addition of 0.10% and 0.15% jute fibre respectively. Furthermore, the slump values show a declining trend with the increase of both variables. Finally, the probabilistic models have been found statistically significant from the analysis of variance.
Keywords: jute fibre; stone dust; response surface; compressive strength; split tensile strength; slump.
Comparison between Honeycomb and Composite Corrugated Cores in Sandwich Panels under Compression Loading
by Eltahry Elghandour, Nagwa Elzayady
Abstract: The study is to evaluate the compression properties of the polymeric composite corrugated-core sandwich structure against the honeycomb-core structure. The skin facings are from the prepreg carbon fiber composite laminate, while the core is made of different materials. Four core types are suggested; carbon fiber corrugated-core, fiberglass corrugated-core, Nomex honeycomb-core, and Kevlar honeycomb-core. The study is based on an experimental work of edgewise compression testing, and the comparison between alternatives are based on the specific properties -to-weight ratio. The analyzed results prove there is superior compression capacity of the polymeric composite corrugated-core sandwich members to the honeycomb-core members, in particular in the non-linear stage of compression test. The bonded surface between the honeycomb structure and the skins is often less than that of the corrugated profile for the same sandwich panel sizes. This contact area between the core and skin facings play an important role in carrying load mechanism.
Keywords: Corrugation core; honeycomb core; sandwich structure; Edgewise compression; and aerospace application.
Numerical Analysis Study to Validate Experimental Vibration Results of CubeSats
by Pedro Rivera, Eltahry Elghandour, Xi Wu
Abstract: CubeSats are cost-effective nanosatellites that undergo dynamic testing for launch qualification (NASA, 2013). The work presented here recreates a vibration test setup using Finite Element Analysis (FEA) in order to predict and validate the dynamic response of a CubeSat test assembly. A Poly Picosatellite Orbital Deployer (P-Pod) is used as the housing and ejection mechanism for CubeSats. For modeling purposes however, a simplified P-Pod (test pod) was used, along with a mass model to represent a CubeSat. Sine sweep and random vibration tests were performed for the test pod and mass model. CAD geometry and material properties were imported into the FEA solver Abaqus to analyze the modes, natural frequencies, and damped response of the CubeSat assemblies. Comparing the FEA results to experimental data, the first six natural frequencies of the test pod were generated with an average 7% error and an average 4% error for the first eight modes of the test pod with mass model assembly. The validated FEA template was then applied to CubeSat CPX, a concept design structure used to demonstrate the application of the FEA models developed in this work.
Keywords: CubeSat; Nano-satellite; Finite Element Analysis; Vibration data comparison; FEA model validation; Dynamic response prediction.
Damage reduction countermeasures for short span bridges focusing on restorability of structural joints
by Teruhiko Yoda, Weiwei Lin
Abstract: Disaster-related losses cause short- as well as long-term adverse effects on econ-omy, society, health, culture and the environment. Then, resilient infrastructure with less cost will be hoped for. The resilience of infrastructure and built envi-ronment are long-term issues. This means cooperation is required with the gov-ernment, municipalities and other related organs to ensure network continuity so that the different organizations can cooperate smoothly. In Japan, the events of March 11, 2011 highlighted the need for the related government agencies, munic-ipalities, research organizations and universities to work together in formulating and implementing a holistic and comprehensive policy approach for damage re-duction countermeasures. In this paper, damage reduction countermeasures for bridge structures are presented, with a view to earthquakes, tsunamis, floods, de-terioration.
Keywords: Bridge superstructure; Damage reduction; Earthquake; Tsunami; Flood; Resilience; Deterioration of bridges; Performance-based design.
Present and future resilience research driven by science and technology
by Marco Domaneschi, Gian Paolo Cimellaro, Lili Xie, Michel Bruneau, Zhishen Wu, Max Didier, Mohammad Noori, Aftab Mufti, Xilin Lu, Xinzheng Lu, Jinpin Ou, Shamim Sheikh, Ying Zhou
Abstract: Community resilience against major disasters is a multidisciplinary research field that garners an ever-increasing interest worldwide. This paper provides summaries of the discussions held on the subject matter and the research outcomes presented during the Second Resilience Workshop in Nanjing and Shanghai. It, thus, offers a community view of present work and future research directions identified by the workshop participants who hail from Asiaincluding China, Japan, and Korea, Europe, and the Americas.
Keywords: Community resilience; Critical Infrastructure; Regional Assessment.
From event to performance function-based resilience analysis and improvement processes for more sustainable systems
by Ivo Häring, Jörg Finger, Mirjam Fehling-Kaschek, Kai Fischer, Georg Vogelbacher, Katja Faist, Werner Riedel, Benjamin Scharte, Katharina Ross, Elena-Maria Restayn, Alexander Stolz, Tobias Leismann, Stefan Hiermaier
Abstract: The rising variety of threats due to increasing complexity, interconnected-ness and intelligence of socio technical systems as well as increasing ex-tremes of threats, e.g., due to stronger natural threats and more sophisticat-ed terroristic events, ask for improved approaches for overall risk control and resilience enhancement. This holds in particular for critical infrastructures and public spaces. The present paper reviews and discusses advanced ap-proaches for several example domains: risk and resilience quantification of single explosions in civil contexts; susceptibility, vulnerability, averaged risk and recovery analysis in case of terroristic events in urban public spaces; quantification of cascading effects in coupled supply grids; questionnaire-based scoring approach for critical infrastructures for overall risk control and resilience enhancement; and a semi-quantitative tabular resilience analysis and management approach applied to telecommunication networks. In each case, the main process and its steps, selected typical methods for process steps and results of the approach are summarized. It is shown that most of the schemes focus on risk event assessment for single or multiple threat or disruptive events only. However, more recent approaches ask for the identi-fication, determination and use of time-dependent system performance (ser-vice) functions and their assessment in case of disruptions. While classical risk management identifies objectives of stakeholders and quantifies risk events countering these objectives, time-dependent system (non) perfor-mance function resilience assessment is argued to allow a more direct quan-tification of overall risk control objectives, since it assesses main system ser-vice functions before, during and post disruptions. Also, it is more suitable for communication with the public, management, and for dashboard mobile visualization. Hence, in each case, it is shown how to link more classical risk analysis approaches and results with time-dependent system performance function risk and resilience quantification.
Keywords: Resilience and risk quantification and management; System (non) performance function; Explosive quantitative risk analysis; Terrorism susceptibility; vulner-ability and averaged risk and resilience analysis; Coupled supply grid analy-sis; Semi-quantitative residence analytics; Tabular telecommunication grid risk and resilience analysis.
Special Issue on: Smart Structures, Structural Control and Health Monitoring – A Special Issue in Honour of Professor Fabio Casciati and Professor Lucia Faravelli
GROUND-PENETRATING RADAR INVESTIGATION FOR THE RESTORATION OF AL-AZHAR HISTORICAL MINARETS
by Ashraf Osman, Ayman Hamed, Nevin Ali
Abstract: Ground-Penetrating Radar (GPR) is a modern geophysical tool that was developed for prospecting the ground subsurface. Recently, it has shown great potential for providing valuable information about the integrity of masonry structures, thus helping with their preservation and restoration. In this study, GPR was used to study and evaluate the state of bulk mason walls utilized as base foundation for the historical minarets of Al-Azhar mosque in Cairo, Egypt. Five minarets having different architectural configurations and constructed in different historical periods extending from Mamluk era to Ottman era were examined. The obtained results provided useful knowledge concerning the composition of the minaret bases. They showed that the external stone casing for these bases has a varying thickness ranging between 35 to 40 cm constructed from well-cut stones. This casing is followed by a layer of rubble fill of inhomogeneous shapes as shown from the radargram. Furthermore, multiple anomalies were recognized, indicating cavities that mostly are located higher than 4 m above the ground level and probably are caused by a migration of fine filling materials downward due to humidity fluctuations. Limits of internal water content were clearly identified and salinity inside the wall filling was recognized. Based on these results, a decision was taken to re-inject the fine material lost through time inside the bases, to regain their structural integrity.
Keywords: Ground Penetrating Radar (GPR); Cultural heritage; Historical buildings; Walls; Foundations; Humidity.
Design of a New Wireless Data Acquisition System for Civil Structural Monitoring
by Lijun Wu
Abstract: Traditional civil structure wired monitoring systems suffer complicated wiring, high cost, poor flexibility, and available wireless sensors network (WSN) based wireless monitoring systems are inconvenient to access the Internet. In this paper, based on the IPv6 over low-power personal area networks (6LoWPAN) WSN, a new wireless data acquisition system is proposed for structural monitoring applications, which consists of data acquisition nodes, a border node, and a remote monitoring center. The hardware design of the wireless data acquisition system is based on the CC2538 wireless transceiver, and inertial sensors and temperature and humidity sensors are integrated. Based on the Contiki3.0 embedded operating system, the embedded application software of 6LoWPAN data acquisition nodes and border router nodes are designed. The remote monitoring center of structural monitoring system is developed using the graphical user interfaces development environment (GUIDE) tool of the MATLAB software. Experimental testing results show that the system is stable and reliable and can realize interconnection between 6LoWPAN network and traditional IPv4 network. Moreover, the network performance is satisfactory. Therefore, the proposed wireless structural monitoring system has a good practical engineering application value.
Keywords: Wireless sensor network; Civil structural monitoring; 6LoWPAN protocol; RPL routing protocol; Contiki operating system.
Condition Assessment of a Supertall Structure by an Improved Hilbert-Huang Transform and Empirical Mode Decomposition Method
by Raed AlSaleh, Yi Qing Ni
Abstract: The development of structural health monitoring (SHM) has currently become the highlight of researches and applications in civil structures, mainly to provide real-time data for the assessment of a structure after extreme events. Canton tower in Guangzhou-China is one of the instrumented structures with a sophisticated SHM system that imparted a fertile ground for researchers to develop various investigations and implementations of different methodologies in response data processing, leading to more reliable system identification, and condition assessment. Canton tower is considered as test bed in this study, and its condition upon the exposure to some extreme events occurred in the tower region is investigated. The tower condition assessment is performed by three different approaches. The first approach is based mainly on the Hilbert-Huang Transform (HHT) and the Empirical Mode Decomposition (EMD) techniques, which is applied by performing an online assessment. The frequency and phase angle relations with time, produced by HHT from signals obtained during extreme wind event are investigated. In the second approach, the tower is assessed after another extreme event, by evaluating some mode-shape dependent indexes, considering mode shapes obtained by an Improved-HHT approach applied on decomposed signals by EMD technique, after being filtered by an adaptive band-pass filtering approach. The results of this approach are then verified by the same indexes evaluated based on mode shapes obtained by the frequency domain decomposition method. In the third approach, a new formulation of an index based on the energy of the intrinsic modal functions produced by the EMD method is proposed, and the results of this index application in the tower assessment after an extreme event are verified. The results of assessment obtained by the entire adopted methodologies confirmed that the tower did not suffer any damage caused by the considered extreme events. Nevertheless, the benefits of these approaches varied from one desired assessment to the other.
Keywords: Hilbert-Huang transform; Condition assessment; Supertall Structures; Modal analysis; On-line assessment.
State of the art: shape memory alloys, for monumental consolidation and base isolation
by Karim Hamdaoui
Abstract: This paper is a state of the art of the experience gathered by the author on the use of Shape Memory Alloys (SMA) in civil engineering. Since 2005, efforts have been focused on the invention of a new concept of base isolation and the retrofitting of monuments. First, an innovative system consisting of several SMA bars of particular geometry was proposed. Its numerical model was built, realised and experimentally tested. It was concluded that for cyclic loading, a large amount of energy was dissipated. Then, and following conclusions drawn from laboratory tests, SMA wires were inserted practically and numerically on a number of monuments: the aqueduct of Larnaca (Cyprus), the minaret of Ajloun (Jordan) and the minaret of Mansourah (Algeria). The monuments were reinforced with different SMA devices distributed over different positions. The proposed technique was proved as significant via the improvement seen in the dynamic response of monuments.
Keywords: shape memory alloys; base isolator; monuments; system identification; retrofitting; dynamic analysis; ambient vibrations; energy dissipation; numerical modelling; shaking table test.
Identification of Indicators, Metrics and Level of Service for the Resilience of Transport Critical Infrastructure (TCI)
by Clemente Fuggini, Fabio Bolletta
Abstract: This paper proposes an approach to Resilience Engineering for Transport Critical Infrastructure (TCI) that is based on a commonly used paradigm, that starting from indicators and metrics, allows the estimation of the Level of Service (LoS) of a transport infrastructure and its variation (sensitivity analysis) with respect to disturbances (e.g. events) that might determine a change in the expected LoS.
As such the paper first describes the concept of Resilience Engineering and presents its adoption for TCI with particular emphasis to the link among the Resilience approach and the various phases of a transport infrastructure project, spamming from evaluation and planning up to emergency operations.
Then it analyses the challenges and opportunities of the application of Resilience approach for TCI, with a focus on understanding how, so far, with few exceptions worldwide, this concept is not fully exploited in operation.
Following up, it deals with metrics and indicators in general, with a view on identifying their applicability and potential use afterwards for TCI, as a mean to enable the adoption, in practice and in operation of the Resilience approach.
Finally provides useful considerations on the variation of the LoS of a TCI in terms of Resilience, so that to offer an actionable tool to really cope with variations of the LoS due to disturbances and events and how they affect prevention, detection, response and recovery phases.
Keywords: Resilience Engineering; Critical Infrastructure; Business Continuity; Indicators; Metrics; Level of Service.
Experimental study of structural change detection using data-driven reduced-order models
by Miguel Hernandez-Garcia, Sami Masri
Abstract: This paper presents a comparison of the effectiveness of three different data-driven vibration-based approaches in detecting and locating structural changes in a 1/4 scale six-story single-bay steel frame laboratory structure from measured experimental input-output data obtained from band-limited white-noise base-excitation tests. The implemented methodologies are based on reduced-order models obtained using three input-output system identification approaches: a system realization algorithm using information matrices, a general time-domain least-squares identification method, and a non-parametric chain-like system identification approach. Variations in the estimated reduced-order models are then used to indicate the presence and infer the location of actual structural changes in the test structure. The results of this experimental study show that even though the changes introduced by the various levels of damage in the structure were robustly detected in the presence of modeling, measurement, and data processing errors using reduced-order representations, the identified change locations in the reduced-order model could not be, in some cases, reliably correlated with the actual damage location in the structure.
Keywords: Reduced-order models; structural health monitoring; statistical damage detection; data-driven vibration-based identification; scaled-down structure; shake table tests.
Application of Vibration-based Damage Detection Algorithms to Experimental Data from Multi-story Steel Structures
by Yizheng Liao, Konstantinos Balafas, Anne Kiremidjian, Ram Rajagopal, Chin-Hsiung Loh
Abstract: Recently, vibration-based statistical pattern recognition (SPR) has received significant attention in the field of structural health monitoring (SHM). There has been remarkable progress in the development of data acquisition systems and statistical damage detection algorithms. However, many of them have not been validated or calibrated by experimental data. This paper presents and analyzes a recent shake table experiment of two three-story steel frame structures. In this experiment, the structural damage was introduced in a systematic and controlled way and the structures were tested with different levels of earthquakes. Three types of analyses were conducted. First, SnowFort, a wireless sensor system designed for infrastructure monitoring, was deployed and vibration measurements obtained from the system were compared to conventional wired sensors. It is shown that the wireless sensors used within the SnowFort system achieve the same accuracy as the wired sensors. Second, the Rotation Algorithm is applied to the obtained data to estimate residual displacements in the structures. Excellent agreement is found between the estimates and the residual displacements obtained from direct measurements using the linear variable differential transducers. And third, a Continuous Wavelet Transform-based damage detection algorithm is applied to the experimental data. The results show that the distributions of wavelet model parameters are sensitive to the state of damage and loading conditions and thus can be used for damage diagnosis.
Keywords: Structural Health Monitoring; Wireless Sensor Network; Damage Detection; Experimental Study; Statistical Pattern Recognition.
Structural health monitoring of in-service tunnels
by Marco Domaneschi, Sara Casciati, Necati Catbas, Gianpaolo Cimellaro, Daniele Inaudi, Giuseppe Marano
Abstract: This work presents an overview of some of the most promising technologies for the structural health monitoring (SHM) of in-service tunnels. The common goal of damage or unusual behavior detection is best pursued by an integrated approach based on the concurrent deployment of multiple technologies.rnTypically, traditional SHM systems are installed in problematic or special areas of the tunnels, giving information on conditions and helping manage maintenance. Deformation of the inner lining, stress variations of the shotcrete and groundwater level, among others, can be monitored either in real time or at periodic intervals. In most cases, the deformation data is compared with the prescribed safety criteria so that, when the deformation exceeds a certain level, alarms are automatically sent to the maintenance engineer. rnHowever, these methodologies often have the drawbacks of forcing the interruption of traffic for SHM system installation and of monitoring only selected portions. Alternative solutions that would make it possible to keep the tunnel in normal operation and/or to analyze the entire infrastructure development through successive and continuous scanning stages, would be beneficial. rnIn this paper, the authors will briefly review some traditional monitoring technologies for tunnels. Furthermore, the work is aimed at identifying possible alternatives and solutions that can be used, limiting or avoiding traffic interruptions. In particular, distributed fiber optical methods and infrared technology are discussed, and reference is made to existing case-studies. The potential offered by visual based methods is also preliminarily investigated by laboratory testing.rn
Keywords: Tunnels and underground structures; structural health monitoring; distributed optical fiber sensing; infrared thermography; digital image correlation.
Optimal Thickness of a Spherical Shell Subjected to Double-Sided Corrosion
by Isaac Elishakoff, Mark Fridman
Abstract: In this paper we study the corrosion of the thin spherical shell containing and surrounded by corrosive media, generally of different corrosion coefficients. Two alternative corrosion models are studied. Optimization study is also conducted with a view to determine the optimum thickness.
Keywords: Spherical shell; hydrostatic pressure; Dolinsky’s linear model; Gutman and Zaynullin’s exponential model; optimal thickness.
Intrinsic differences between thinner and thicker wires in NiTi SMA
by Vicenc Torra, Francisco C. Lovey
Abstract: The use of shape memory alloys (SMA) in dampers device can reduce the oscillations in civil structures induced by earthquakes or the oscillations in stayed cables for bridges induced by wind, rain or traffic. The studies conducted on standard cables located in existing facilities show the reliable efficiency of SMA wires in damping oscillations of stayed cables. The damping requires the absorption of the mechanical energy and its conversion to heat via the action of hysteresis cycles. rnrnGenerally, the SMA is a favorable material for damping due to the particular properties of the martensitic transformation, i.e., a first-order solid-solid phase transition between the metastable phases with hysteresis. The civil engineering equipment, such as the bridges, were located outside the laboratory equipment and were subject to the direct effect of the external temperatures. In moderate climates, the summer and winter temperatures vary between -10
Keywords: Phase transition; pseudoelastic cycles; strain aging; martensitic transformation; NiTi; thick and thin wires; hysteresis.
Vibration Control of Wind Turbines: Recent Advances and Emerging Trends
by Biswajit Basu, Breiffni Fitzgerald
Abstract: The wind energy sector globally is expanding and developingrntechnically at a rapid pace. Demand for renewable energy is soaring and there is a need for increasing the efficiency and design life of wind turbine structures. The concept of using approaches and techniques developed in the field of structural control for control of wind turbine vibrations is extremely attractive and topical at present.We review the contributions of work on vibration control of wind turbines. We provide an overview on the recent literature focussing on theoretical and experimental work. Passive, semi-active and active control schemes are discussed. The development of bespoke auxiliary damping systems is also discussed as are novel turbine control algorithms utilising existing pitch/generator torque/yawrncontrol hardware
Keywords: Wind turbine; vibration control; passive control; active control; semiactive controlrn.
Automatic Detection and Damage Quantification of Multiple Cracks on Concrete Surface from Video
by Satish Nagarajaiah, Sutanu Bhowmick
Abstract: The condition assessment of large-scale concrete structures such as a bridge or a dam is performed by specialists who visually inspect the surface of each component of concrete structure for local damages in the form of cracks. This makes the overall process of manual inspection of large scale infrastructure timeconsuming. Moreover, many regions are extremely challenging to gain access to. In the aftermath of a natural hazard like an earthquake or a hurricane, fast and reliable condition assessment reports are needed to plan evacuation and relief response strategies, which becomes infeasible relying only on manual inspections of the infrastructure networks. The process of manual inspection primarily depends on the visual sensing of humans. The same information is acquired using a camera, which is processed using Computer Vision algorithms to detect damages on the surface. In the last decade, several methods to detect damages from images of the concrete surface to attain the goal of creating a fast and efficient, vision-based autonomous condition assessment system of civil infrastructures have been studied. But the mere detection of cracks is not sufficient as concrete surfaces comprise of thermal as well as small cracks which has breathing effect under time-varying service loads. All cracks must be tracked over time to quantify individual cracks propagation and intensity of the damage varying with time. In order to address the aforementioned objective, real-time detection of multiple cracks from a video stream of a concrete surface is addressed in this paper. Furthermore, the propagation of individual cracks is tracked as well as the amount of damage is quantified over time to distinguish the less harmful thermal and breathing cracks. Robust Principle Component Analysis is used to detect multiple cracks forming at different instances of time in an unsupervised manner using the Gini index as a metric to quantify the presence of an observable crack. The optical features around the observed crack are detected and their evolution over time is monitored using Kanade-Lucas-Tomasi feature tracking algorithm. The evolution of the optical features around the observed crack directly correlates with the propagation of the crack. Hence, the relative positions of the relevant pixels around the crack at each frame of the video are used to compute Hus invariant moments which acts as a robust damage indicator. The proposed method is experimentally validated using two small scale under-reinforced beams undergoing three-point bending tests. The method successfully detects the onset of multiple cracks, at different locations and at different instances of time. It also tracks the propagation of individual cracks over time.
Keywords: Robust Principle Component Analysis; Kanade-Lucas-Tomasi
algorithm; Gini index; Hu’s invariant moments.
Special Issue on: 2nd International Workshop on Resilience Resilience in the World Share the Knowledge, See the Future, Help Communities
Resilience and Sustainability of FRP-Retrofitted Concrete Structures
by S. Mukhtar Homam, Shamim Sheikh
Abstract: Damaged, deteriorated and deficient structures can prove to be among the biggest obstructions in an otherwise resilient community. An innovative rehabilitation technique using fibre reinforced polymers (FRP) was developed to build resilience in such structures. Lab investigations found that deteriorated concrete columns sustained about 20% loss in strength and larger reduction in ductility and energy dissipating capacity as a result of corrosion induced deterioration. Experimental results showed that utilizing FRP and special grouts not only recovered but enhanced the mechanical performance of these structures.
Long-term testing in the lab and observations in the field found excellent durability in FRP and FRP-retrofitted structures. This innovative repair technique resulted in remarkable reduction in risk of deterioration and performance degradation. It was concluded that resilience can be built into deficient or damaged structures through incorporation of innovative retrofitting techniques and utilization of durable materials that are economical and superior to traditional methods.
Keywords: Glass fibre reinforced polymer; bridge column; durability; freeze thaw cycles; temperature cycles; alkali solutions; ultraviolet radiation; long term performance; coupons; single lap bond.
Special Issue on: IJSMSS 2nd International Workshop on Resilience Resilience in the World Share the Knowledge, See the Future, Help Communities
Resilience and recoverability enhancement of concrete structures
by Zhishen WU, Mohamed Fahmy
Abstract: This study addresses the importance of enhancing the recoverability of reinforced concrete (RC) structures. A summary of the efforts and achievements done by the research community to improve the recoverability of RC structures is dis-cussed. In addition, the resilience of existing structures designed according to modern codes as well as under designed structures has been evaluated. Finally, the application of fiber reinforced polymer (FRP) composites in existing and modern structures to enhance post-earthquake recoverability and to provide a new controllability-tool is discussed. Recoverability and controllability can be realized using FRP composites.
Keywords: Resilience; damage-controllable systems; FRP; RC structures.
Resilient Isolation-Structure Systems with Super-Large Displacement Friction Pendulum Bearings
by Jinping Ou, Peisong Wu, Xinchun Guan
Abstract: This paper presents a super-large displacement friction pendulum bearing (SLDFPB) and isolation system with SLDFPB. SLDFPB has one or several spherical shells of large span and large curvature radius as an integrated sliding isolation layer. Superstructure can sustain large horizontal displacement through relative sliding between large spherical shell and sliding blocks. The proposed SLDFPB has two main advantages: i) avoid damage of isolation layer during super-strong earthquakes owing to large lateral deformation capability; and ii) have better isolation effectiveness because of smaller horizontal stiffness and isolation frequency. This study also investigates mechanical property of SLDFPB including equivalent radius and equivalent friction coefficient. Suggested designed method of SLDFPB is given based on seismic mitigation and reset ability of isolation layer. Two isolation structure systems with multi isolation layers are studied. The results show that large ratio of mass and optimized parameters contributes to good control effect.
Keywords: friction pendulum bearing; sustainable structural system; isolation system; equivalent radius; equivalent friction coefficient.