Advanced Materials and Technologies for Structural Performance Improvement

• Published in: Advances in Materials Science and Engineering
• Main Authors: SORACE Stefano, BLOCKEN Bert, BORRI Claudio, CARACOGLIA Luca, MOLINA RUIZ Francisco Javier, MÜLLER Gerhardt
• Language: English
• Published: HINDAWI PUBLISHING CORP 2016
• Subjects: Molina; permafrost
• Online Access: https://publications.jrc.ec.europa.eu/repository/handle/JRC102050; http://www.hindawi.com/journals/amse/2016/1854839/; https://doi.org/10.1155/2016/1854839

The development of advanced materials and technologies forapplication to new and existing structures, infrastructures,and equipment, aiming at improving their response to serviceand extreme loads, represents an emerging issue both froman academic and a professional viewpoint. Relevant performanceassessment procedures, based on effective experimentalverification methods [1] and refined numerical simulationmodels [2], are quickly evolving as well.New or improved building materials and innovative protectiontechnologies offer updated solutions to the constantlyincreasing capacity requirements in structural, geotechnical,plant, and mechanical engineering design and rehabilitation.At the same time, they open novel and challenging researchand application perspectives.The objective of this special issue was to provide readerswith a representative outlook of the latest achievements inthis field, including emerging aspects in modelling, testing,manufacturing, and practical implementation studies. Theresponse of the scientific community was encouraging, withover 100manuscripts submitted. The published papers offer aselected and articulated overview of the examined topics.Several papers are dedicated to concrete, reinforcedconcrete (R/C) members, and cement composites. J. Zhangand J. Li develop a semi-implicit constitutive integrationalgorithm for elastoplastic damage models, specially implementedfor concrete. Literature mechanical tests of reinforcedconcrete components are numerically simulated, showing theeffectiveness of the numerical method in history-dependentenergy estimation within this class of nonlinear problems. H.Ding et al. examine the failure criteria and the constitutiverelation of early-age concrete,with the aimof providing a theoreticalbasis for a novel strategy in early dismantling formworkconstruction of floors, aimed at accelerating formworkrecycling as well as at reducing construction costs. Y. Shenet al. propose a paper spool-inspired anchoring method anda pretension procedure for carbon fiber reinforced polymer(CFRP) sheets, for themanufacturing of prestressed concreteflat slabs. Laboratory flexural tests confirm the feasibility ofthis novel reinforcement technique, showing that uniformityof the fiber stress during tensioning is a key aspect for the successfulapplication of prestress. Improved flexural calculationmodels for R/C members built with ultrahigh performanceconcrete (i.e., with cubic compressive strength exceeding200MPa) are presented by B.-I. Bae et al., who revise thenormal stress distribution schemes adopted for standard concreteclasses. The models are verified and validated by meansHindawi Publishing CorporationAdvances in Materials Science and EngineeringVolume 2016, Article ID 1854839, 3 pageshttp://dx.doi.org/10.1155/2016/18548392 Advances in Materials Science and Engineeringof laboratory flexural tests on representative specimens inthis case too. High strength concrete materials, with cubiccompressive strength ranging fromabout 80MPa to 110MPa,are examined in the paper of L. Zeng et al., as constitutingmaterials of R/C beam-to-column joints encasing I-shapedhot-rolled steel profiles. An extensive campaign of cyclictests on half-scale weak-type joints allows evaluating thebeneficial influence of the adopted concrete classes in termsof strength and at the same time a minimal decrease inductility, as compared to the cyclic performance of similarjoints cast with standard concretes. Composite concretesteeltubular columns are the topic of the article by S.Jayaganesh et al. An experimental programme is carried outto evaluate the effects of the partial compression of square andcircular cross sections, highlighting a reduction in strengthin comparison to full compression, more accentuated in thecase of the square shape. The correlation of the test resultswith the predictions of the analytical models proposed in theliterature to account for these effects seems rather satisfactory.Another experimental activity is reported in the paper by J.Deng et al., dedicated to a campaign of pseudostatic cyclictests of one-fifth scale prototype R/C bridge piers, damagedand repaired by means of a steel-tube jacketing traditionaltechnique, or by wrapping interventions based on the useof CFRP or basalt fiber reinforced polymer (BFRP) sheets.The results attest satisfactory performance in all cases, with asignificant increase in lateral stiffness and strength providedby jacketing as compared to the original response capacity,and its complete restoration in the case of the two FRP-basedretrofitmeasures.The advantages of the lattermethod consistin lower physical intrusion and quicker installation times.The postprocessing study of an experimental programmecarried out by the pseudodynamic method on a set of 13 R/Cshear walls is presented in the article of F. J. Molina et al.,where the results of the seismic tests are elaborated by aninnovative strategy that allows deriving a capacity-linemodel.With this approach it is possible to understand better thedifferent safety margins that are observed in the experimentsdepending on the assigned eigenfrequency in relation to theearthquake response spectra. The effects of the amount ofreinforcement and normal load are also assessed. Enhancedcement composite materials are investigated in the articlesby H. Choi et al. and J. Lai et al. The former deals withthe experimental characterization of an innovative Portlandcement mortar, prepared by incorporating multiwalled carbonnanotubes in the mixture.The experimentally measuredcompressive strength is greater than the one offered bystandard Portland mortars, as a consequence of the bridgingaction of the nanotubes, which prevents the progression ofmicrocracks and helps reducing the space between the voidsin the hydration material. In J. Lay et al.’s paper, cement fly ashgravel is examined as constituting material of pile compositefoundations, for their updated use in saturated tailing dams.A finite element analysis of the settlements of this typeof foundation, calibrated on the experimental investigationcarried out by other authors, assesses a stable and ratherhomogeneous response under the design embankment loads.Three articles are dedicated to advanced seismic protectiontechnologies. In the paper byM. Ismail et al., a numericalstudy of a base isolation system incorporating Roll-in-Cagedevices recently developed by the authors is carried outby simulating its incorporation in a three-span prestressedR/C box girder-type bridge. The results show a remarkableglobal performance of the system, also in comparison withother seismic isolation solutions, highlighting its benefits inthe potential application to bridge structures. The article ofF. Mazza and A. Vulcano reports a shaking table testingprogramme developed on a one-third scale base-isolated steelframe structure equipped with an in-parallel combination ofsteel-PTFE sliders and elastomeric bearings (HDRBs). Theexperimental response confirms the high level of protectionoffered by the isolation technology and establishes adatabase for a refined numericalmodelling of the constitutingdevices. J. W. Hu and M.-H. Noh present a study on selfcenteringfriction dissipative steel braces including specialcomponents fabricated with shape-memory alloy wires andfriction-type dampers. A numerical investigation carriedout on single-degree-of-freedom models allows formulatinga design methodology aimed at mutually optimising therecentering and energy dissipation capacities of the passiveprotection system, with a view to its practical implementation.Two more papers deal with the application of innovativeFRP composite materials in various fields of engineering.N. B. Baba et al. examine the mechanical and physicalbehaviour of a hybrid glass FRP (GFRP) fabricated with threedifferent types of glass fibers—3D, woven, and chopped—combined with a mixture of polyester resin and hardener.Fiber arrangement and volume are varied to evaluate thecombination capable of providing the best performance interms of tensile strength and water absorption, which isidentified by means of the characterisation test developedin the study. In the article by M. E. Tas¸delen et al. thetorsional behaviour of novel braided sleeve composite shaftsconsisting of carbon and glass fibers is investigated. Vacuumassisted resin transfer molding and vacuum baggingare adopted as manufacturing methods. The results of theexperimental programme and the relevant finite elementsimulations underline that, for the same configuration of layupsequences, the highest torque and tensile strengths areobtained for test specimens manufactured with the formermethod. Furthermore, hybrid carbon-glass solutions strikethe best balance between strength performance and costs.Special issues are dealt with in the remaining three articles.By considering the growing applications of piezoelectricstructures in innovative technical areas, L. M. Zhou et al.implement a mixed cell-based smoothed/extended finite elementmethod for a careful electromechanical crack analysis ofthe constituting material. The case study examples presentedin the paper show that this mixed method is more accurateand quickly converging than a standard finite elementcalculation, also bypassing the mapping process inherent tothe latter, which significantly increases the complexity of thecalculation. J.Chen et al. report an on-site experimental studyof the cooling effect of crushed rock-based embankments onslope wetlands situated along a railway line. A monitoringsystem installed in an embankment of notable dimensionsallows reconstructing the temperature fields and the freezingAdvances in Materials Science and Engineering 3history with time. The surveyed data show that only theembankment shady side can be effectively cooled downin a warm permafrost region, and the crushed rock-basedembankment can cool the entire embankment in a coldpermafrost region. Finally, in the paper by Y. Ou et al.an innovative self-propagating high-temperature synthesis(SHS) process to prepare amorphous boron powder, whichis an attractive material in several enhanced engineeringapplications, is discussed. The new technique proposedin this study consists in combining the SHS process andthe traditional magnesium thermal reduction method. Theeffectiveness of the resulting technique suggests its possibleindustrial application and adoption as a common approachto prepare various inorganic materials. JRC.E.4 - Safety and Security of Buildings