Journal of Engineering The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. Retracted: Power Consumption, Mixing Time, and Oxygen Mass Transfer in a Gas-Liquid Contactor Stirred with a Dual Impeller for Different Spacing Thu, 11 May 2017 00:00:00 +0000 Journal of Engineering Copyright © 2017 Journal of Engineering. All rights reserved. Seismic Performance of Steel Frames with Semirigid Connections Sun, 30 Apr 2017 12:33:11 +0000 The nonlinear stiffness matrix method was incorporated to investigate the structural performance of steel portal frames with semirigid connections. A portal frame with unstiffened extended end-plate connection was designed to demonstrate the adequacy of the proposed method. Besides, the seismic performance of steel portal frames with semirigid connections was investigated through time history analysis where kinematic hysteresis model was assigned to semirigid connections to account for energy dissipation and unloading stiffness. Based on the results of the study, it was found that generally semirigid connections influenced the force distribution which resulted in the decrease in base shear and lighter frame compared to the rigid one. The results also indicated that there was no direct relationship between maximum displacement at the top and connection stiffness in high-rise frames. Iman Faridmehr, Mahmood Md. Tahir, Tom Lahmer, and Mohd Hanim Osman Copyright © 2017 Iman Faridmehr et al. All rights reserved. Dynamic Response of a Circular Tunnel in an Elastic Half Space Wed, 26 Apr 2017 00:00:00 +0000 The vibration of a circular tunnel in an elastic half space subjected to uniformly distributed dynamic pressure at the inner boundary is studied in this paper. For comparison purposes, two different ground materials (soft and hard soil) are considered for the half space. Under the assumption of plane strain, the equations of motion for the tunnel and the surrounding medium are reduced to two wave equations in polar coordinates using Helmholtz potentials. The method of wave expansion is used to construct the displacement fields in terms of displacement potentials. The boundary conditions associated with the problem are satisfied exactly at the inner surface of the tunnel and at the interface between the tunnel and surrounding medium, and they are satisfied approximately at the free surface of the half space. A least-squares technique is used for satisfying the stress-free boundary conditions at the half space. It is shown by comparison that the stresses and displacements are significantly influenced by the properties of the surrounding soil, wave number (i.e., the frequency), depth of embedment, and thickness of the tunnel wall. İrfan Coşkun and Demirhan Dolmaseven Copyright © 2017 İrfan Coşkun and Demirhan Dolmaseven. All rights reserved. High Performance Concrete Materials with Applications in Building and Civil Engineering Wed, 19 Apr 2017 09:17:52 +0000 Peng Zhang, Song Han, Serina Ng, and Xu-Hao Wang Copyright © 2017 Peng Zhang et al. All rights reserved. Experimental and Simulation Research on the Influence of Stirring Parameters on the Distribution of Particles in Cast SiCp/A356 Composites Wed, 19 Apr 2017 00:00:00 +0000 Achieving the uniform distribution of reinforcement particles in MMCs is very important for the effect of stirring parameters and the flow action of the melt, which should be known. The effect of stirring parameters on the distribution of SiC particles in SiCp/A356 composites was studied by the experimental and numerical methods in this paper. The experimental results show the SiC distribution with different stirring parameters. In addition, the effects of the fluid velocity and volume fraction of SiC particle at different position of crucible on the SiC distribution were analyzed by numerical simulation. The velocity magnitude, axial velocity, and radial velocity were analyzed to explain theoretically the particle distribution. The shearing force, moments, and stirring power of the stirring rod were simulated based on CFD code. The numerical results show that the stirring temperature is lower, the shearing force is greater, the stirring time is longer, and particle dispersion gets better. On the other hand, the higher the stirring speed is, the more uniform the radial and axial flow are, and the better the particles were dispersed. The numerical results were in good agreement with the experimental data. Zhiyong Yang, Like Pan, Jianmin Han, Zhiqiang Li, Jialin Wang, Xiang Li, and Weijing Li Copyright © 2017 Zhiyong Yang et al. All rights reserved. Fatigue Life Assessment of Orthotropic Steel Deck with UHPC Pavement Tue, 11 Apr 2017 00:00:00 +0000 In recent years, a number of large-span bridges with orthotropic steel decks were constructed in China. With increasing traffic volumes and higher wheel loads, many fatigue cracks developed at the welds and the edge of cut-out holes. This paper aims at presenting the numerical analysis on the fatigue performance of the orthotropic steel deck using ultrahigh performance concrete (UHPC) overlay as the deck pavement instead of the conventional asphalt concrete pavement. By using finite element method (FEM) model, stress distribution at fatigue sensitive locations under the action of wheel loads is characterized and the obtained stress ranges indicate that the UHPC pavement significantly reduces the magnitude of the stress peak valued. A suggested truck stream model based on the weigh-in-motion (WIM) data of four bridges in China is employed to calculate the stress variation at specific fatigue details. Furthermore, the fatigue damage accumulation at fatigue details under the UHPC and conventional asphalt concrete pavement is studied based on Miner’s linear cumulative damage rule and the rain-flow method. The results indicate that the UHPC pavement on the orthotropic steel deck can extend the service lives of the concerned regions over 100 years, but the fatigue lives will reduce significantly when the elastic modulus of UHPC decreases to 50% of the original value. Xu Jiang, Yuan Yuan, Chong Wu, and Chengwei Luo Copyright © 2017 Xu Jiang et al. All rights reserved. A Field Study on the Indoor Thermal Environment of the Airport Terminal in Tibet Plateau in Winter Sun, 02 Apr 2017 09:58:44 +0000 In order to study the characteristics of indoor thermal environment in the airport terminal in Tibet Plateau with radiant floor heating in winter, a field measurement of the indoor thermal environment was conducted in Lhasa Gonggar Airport terminal 2. First, the unique climate characteristics in Tibet Plateau were analyzed through comparison of meteorological parameters in Beijing and Lahsa. The thermal environment in the terminal was divided into outer zone and inner zone as well as south zone and north zone. Thermal environment parameters including air temperature, black globe temperature, relative humidity in each zone, and inner surface temperature of envelope were measured and analyzed. Meanwhile, temperature and relative humidity in the vertical direction were measured. In addition, PMV and PPD were calculated for evaluating the thermal environment in the terminal. The findings can provide guidance for the design and regulation of thermal environment in terminals in Tibet Plateau in China. Jianglong Zhen, Jun Lu, Guangqin Huang, Liyue Zeng, Jianping Lin, and Hongtao Xia Copyright © 2017 Jianglong Zhen et al. All rights reserved. Study and Development of a Complete System for Recovery, Recycle, and Disposal of Refrigerant Gas from Existent Plants Tue, 28 Mar 2017 00:00:00 +0000 The increasing attention of international community towards ozone depletion control and global warming issues has encouraged the development of strategies for emission reduction of fluoridate refrigerant gases. In this context innovative industrial plants able to recover, recycle, and dispose the refrigerant gases need to be developed. In this paper the different phases of design, realization, and characterization of a complete plant for used refrigerant gas recovery are described. The analysis of the pollutants present in the refrigerant stream has supported the design and realization of equipment able to control these emissions and to restore the concentration levels compatible with AHRI standards. Corrado Genta, Carmine Marotta, and Fortunato Migliardini Copyright © 2017 Corrado Genta et al. All rights reserved. Model of the Mechanical Behavior of Cementitious Matrices Reinforced with Nanomaterials Mon, 20 Mar 2017 07:41:10 +0000 CNTs and CNFs have been introduced as a nanoscale reinforcing material to cementitious composites, for stiffening and strengthening the microstructure. This technology is motivated by the need to control crack initiation in the cementitious gel before it propagates into visible crack formations. Experimental evidence supports this concept; however, testing at the nanoscale may only be conducted through nanoindentation, which has a limited range only providing localized results that cannot be extrapolated to general stress states. To evaluate the restraining action of nanomaterials in the gel microstructure, a computational mechanistic model has been developed where the material phases (gel, nanotubes, and pores) are modeled explicitly allowing for natural randomness in their distribution and orientation. Repeated analysis with identical input data reproduces the statistical scatter observed in laboratory tests on identical material samples. The formulation uses a discrete element approach; the gel structure is represented by a random network of hydrates and successfully reproduces the known trends in mechanical behavior of cementitious materials (pressure and restraint sensitive material behavior) and the small ratio of tensile to compressive strength. Simulations illustrate that it is possible to computationally reproduce the measured properties and behavior of fiber-reinforced cement composites using information from simple laboratory tests. Victor D. Balopoulos, Nikolaos Archontas, and Stavroula J. Pantazopoulou Copyright © 2017 Victor D. Balopoulos et al. All rights reserved. Effects of Adhesive Connection on Composite Action between FRP Bridge Deck and Steel Girder Thu, 16 Mar 2017 00:00:00 +0000 The FRP-steel girder composite bridge system is increasingly used in new constructions of bridges as well as rehabilitation of old bridges. However, the understanding of composite action between FRP decks and steel girders is limited and needs to be systematically investigated. In this paper, depending on the experimental investigations of FRP to steel girder system, the Finite Element (FE) models on experiments were developed and analyzed. Comparison between experiments and FE results indicated that the FE models were much stiffer for in-plane shear stiffness of the FRP deck panel. To modify the FE models, rotational spring elements were added between webs and flanges of FRP decks, to simulate the semirigid connections. Numerical analyses were also conducted on four-point bending experiments of FRP-steel composite girders. Good agreement between experimental results and FE analysis was achieved by comparing the load-deflection curves at midspan and contribution of composite action from FRP decks. With the validated FE models, the parametric studies were conducted on adhesively bonded connection between FRP decks and steel girders, which indicated that the loading transfer capacity of adhesive connection was not simply dependent on the shear modulus or thickness of adhesive layer but dominated by the in-plane shear stiffness . Xu Jiang, Chengwei Luo, Xuhong Qiang, Henk Kolstein, and Frans Bijlaard Copyright © 2017 Xu Jiang et al. All rights reserved. Telefacturing Based Distributed Manufacturing Environment for Optimal Manufacturing Service by Enhancing the Interoperability in the Hubs Tue, 07 Mar 2017 09:45:06 +0000 Recent happenings are surrounding the manufacturing sector leading to intense progress towards the development of effective distributed collaborative manufacturing environments. This evolving collaborative manufacturing not only focuses on digitalisation of this environment but also necessitates service-dependent manufacturing system that offers an uninterrupted approach to a number of diverse, complicated, dynamic manufacturing operations management systems at a common work place (hub). This research presents a novel telefacturing based distributed manufacturing environment for recommending the manufacturing services based on the user preferences. The first step in this direction is to deploy the most advanced tools and techniques, that is, Ontology-based Protégé 5.0 software for transforming the huge stored knowledge/information into XML schema of Ontology Language (OWL) documents and Integration of Process Planning and Scheduling (IPPS) for multijobs in a collaborative manufacturing system. Thereafter, we also investigate the possibilities of allocation of skilled workers to the best feasible operations sequence. In this context, a mathematical model is formulated for the considered objectives, that is, minimization of makespan and total training cost of the workers. With an evolutionary algorithm and developed heuristic algorithm, the performance of the proposed manufacturing system has been improved. Finally, to manifest the capability of the proposed approach, an illustrative example from the real-time manufacturing industry is validated for optimal service recommendation. V. K. Manupati, M. Gokula Krishnan, M. L. R. Varela, and José Machado Copyright © 2017 V. K. Manupati et al. All rights reserved. Investigation of the Effects of Submerged Arc Welding Process Parameters on the Mechanical Properties of Pressure Vessel Steel ASTM A283 Grade A Sun, 05 Feb 2017 00:00:00 +0000 The pressure vessel steel is used in boilers and pressure vessel structure applications. This research studied the effects of submerged arc welding (SAW) process parameters on the mechanical properties of this steel. The weld sample originated from ASTM A283 grade A sheet of 6.00-millimeter thickness. The welding sample was treated using SAW with the variation of three process factors. For the first factor, welding currents of 260, 270, and 280 amperes were investigated. The second factor assessed the travel speed, which was tested at both 10 and 11 millimeters/second. The third factor examined the voltage parameter, which was varied between 28 and 33 volts. Each welding condition was conducted randomly, and each condition was tested a total of three times, using full factorial design. The resulting materials were examined using tensile strength and hardness tests and were observed with optical microscopy (OM) and scanning electron microscopy (SEM). The results showed that the welding current, voltage, and travel speed significantly affected the tensile strength and hardness ( value < 0.05). The optimum SAW parameters were 270 amperes, 33 volts, and 10 millimeters/second travel speed. High density and fine pearlite were discovered and resulted in increased material tensile strength and hardness. Prachya Peasura Copyright © 2017 Prachya Peasura. All rights reserved. Experimental Study on Strain Reliability of Embroidered Passive UHF RFID Textile Tag Antennas and Interconnections Thu, 02 Feb 2017 00:00:00 +0000 We present embroidered antennas and interconnections in passive UHF RFID textile tags and test their strain reliability. Firstly, we fabricate tag antennas on two different stretchable fabric substrates by five different embroidery patterns and choose the most stretchable ones for testing. Next, the tag ICs are attached by sewing and gluing, and the tag reliability during repeated stretching cycles is evaluated through wireless measurements. Initially, the chosen tags achieve read ranges of 6–8 meters and can strain up to 140–150% of their original length. After 100 stretching cycles to 80% of their maximum strain, the read ranges of the tags with glued interconnections are similar to the initial values. In addition, also the read ranges of the tags with sewed interconnections are still more than 70%–85% of their initial values. However, some challenges with the reproducibility need to be solved next. Xiaochen Chen, Aruhan Liu, Zhigang Wei, Leena Ukkonen, and Johanna Virkki Copyright © 2017 Xiaochen Chen et al. All rights reserved. Elastoplastic Modelling of an In Situ Concrete Spalling Experiment Using the Ottosen Failure Criterion Tue, 31 Jan 2017 07:45:20 +0000 An in situ concrete spalling experiment will be carried out in the ONKALO rock characterization facility. The purpose is to establish the failure strength of a thin concrete liner on prestressed rock surface, when the stress states in both rock and concrete are increased by heating. A cylindrical hole 1.5 m in diameter and 7.2 m in depth is reinforced with a 40 mm thin concrete liner from level −3 m down. Eight 6 m long 4 kW electrical heaters are installed around the hole 1 m away. The experiment setup is described and results from predictive numerical modelling are shown. Elastoplastic modelling using the Ottosen failure criterion predicts damage initiation on week 5 and the concrete ultimate strain limit of 0.0035 is exceeded on week 10. The support pressure generated by the liner is 3.2 MPa and the tangential stress of rock is reduced by −33%. In 2D fracture mechanical simulations, the support pressure is 3 MPa and small localized damage occurs after week 3 and damage process slowly continues during week 9 of the heating period. In conclusion, external heating is a potent way of inducing damage and thin concrete liner significantly reduces the amount of damage. Lauri Kalle Tapio Uotinen and Topias Kalle Aleksi Siren Copyright © 2017 Lauri Kalle Tapio Uotinen and Topias Kalle Aleksi Siren. All rights reserved. Free Vibration of Embedded Porous Plate Using Third-Order Shear Deformation and Poroelasticity Theories Tue, 24 Jan 2017 06:40:14 +0000 This research aims at studying free vibration of rectangular plate made of porous materials in which Y-foam, G-foam, and are used and compared with each other. To obtain the Biot formulation of the constitutive equations for a porous material, linear poroelasticity theory is used. Young modulus and density of porous plate are different in transverse direction versus porosity. In order to increase the accuracy of results in comparison with classical plate and first-order shear deformation theories, Reddy’s theory was utilized in this research. Besides, five coupled equations of motion have been studied using Hamilton’s principle and are solved by differential quadrature method (DQM). Detailed results of this study show the significant effect of aspect ratio, thickness ratio, boundary conditions, and porosity on dimensionless frequency and deflection of porous plate. Results of this study can contribute to the design of pneumatic conveying, handling, and control systems. Ali Ghorbanpour Arani, Zahra Khoddami Maraghi, Mehdi Khani, and Iman Alinaghian Copyright © 2017 Ali Ghorbanpour Arani et al. All rights reserved. Flexural Behavior of High-Volume Steel Fiber Cementitious Composite Externally Reinforced with Basalt FRP Sheet Mon, 26 Dec 2016 11:56:44 +0000 High-performance fiber-reinforced cementitious composites (HPFRCCs) are characterized by unique tensile strain hardening and multiple microcracking behaviors. The HPFRCC, which demonstrates remarkable properties such as strength, ductility, toughness, durability, stiffness, and thermal resistance, is a class of fiber cement composite with fine aggregates. It can withstand tensile stresses by forming distributed microcracks owing to the embedded fibers in the concrete, which improve the energy absorption capacity and apparent ductility. This high energy absorbing capacity can be enhanced further by an external stiff fiber-reinforced polymer (FRP). Basalt fabric is externally bonded as a sheet on concrete materials to enhance the durability and resistance to fire and other environmental attacks. This study investigates the flexural performance of an HPFRCC that is externally reinforced with multiple layers of basalt FRP. The HPFRCC considered in the study contains steel fibers at a volume fraction of 8%. Seungwon Kim and Cheolwoo Park Copyright © 2016 Seungwon Kim and Cheolwoo Park. All rights reserved. Fault Tolerant Operation of ISOP Multicell Dc-Dc Converter Using Active Gate Controlled SiC Protection Switch Wed, 21 Dec 2016 11:46:33 +0000 An active gate controlled semiconductor protection switch using SiC-MOSFET is proposed to achieve the fault tolerant operation of ISOP (Input Series and Output Parallel) connected multicell dc-dc converter. The SiC-MOSFET with high temperature capability simplifies the configuration of the protection circuit, and its on-resistance control by the active gate controller realizes the smooth protection without the voltage and the current surges. The first laboratory prototype of the protection switch is fabricated by using a SiC-MOSFET with a high frequency buck chopper for the active gate controller. The effectiveness of the proposed protection switch is verified, taking the impact of the volume reduction into account. Yusuke Hayashi, Yoshikatsu Matsugaki, and Tamotsu Ninomiya Copyright © 2016 Yusuke Hayashi et al. All rights reserved. Bending and Shear Experimental Tests and Numerical Analysis of Composite Slabs Made Up of Lightweight Concrete Tue, 20 Dec 2016 14:11:10 +0000 The aim of this paper is to understand the structural behaviour of composite slabs. These composite slabs are made of steel and different kinds of concrete. The methodology used in this paper combines experimental studies with advanced techniques of numerical simulations. In this paper, four types of concrete were used in order to study their different structural strengths in composite slabs. The materials used were three lightweight concretes, a normal concrete, and a cold conformed steel deck which has embossments to increase the adherence between concrete and steel. Furthermore, two lengths of slabs were studied to compare structural behaviours between short and long slabs. m-k experimental tests were carried out to obtain the flexural behaviour of the composite slabs. These tests provide dimensionless coefficients to compare different sizes of slabs. Nonlinear numerical simulations were performed by means of the finite element method (FEM). Four different multilinear isotropic hardening laws were used to simulate the four concretes. Coulomb friction contact was used to model the coefficient of friction between steel and concrete. Finally, a chemical bond was included to consider sliding resistance in the contact surface between steel and concrete. Experimental and numerical results are in good agreement; therefore, numerical models can be used to improve and optimize lightweight composite slabs. F. P. Alvarez Rabanal, J. Guerrero-Muñoz, M. Alonso-Martinez, and J. E. Martinez-Martinez Copyright © 2016 F. P. Alvarez Rabanal et al. All rights reserved. Analysis of the Single Toggle Jaw Crusher Force Transmission Characteristics Wed, 07 Dec 2016 11:12:47 +0000 This paper sets out to perform a static force analysis of the single toggle jaw crusher mechanism and to obtain the force transmission characteristics of the mechanism. In order to obtain force transmission metrics that are characteristic of the structure of the mechanism, such influences as friction, dead weight, and inertia are considered to be extraneous and neglected. Equations are obtained by considering the balance of forces at the moving joints and appropriately relating these to the input torque and the output torque. A mechanical advantage, the corresponding transmitted torque, and the variations thereof, during the cycle of motion of the mechanism, are obtained. The mechanical advantage that characterizes the mechanism is calculated as the mean value over the active crushing stroke of the mechanism. The force transmission characteristics can be used as criteria for the comparison of different jaw crusher mechanism designs in order to select the most suitable design for a given application. The equations obtained can also be used in estimating the forces sustained by the components of the mechanism. Moses Frank Oduori, David Masinde Munyasi, and Stephen Mwenje Mutuli Copyright © 2016 Moses Frank Oduori et al. All rights reserved. Changing States of Multistage Process Chains Wed, 30 Nov 2016 10:05:33 +0000 Generally, a process describes a change of state of some kind (state transformation). This state change occurs from an initial state to a concluding state. Here, the authors take a step back and take a holistic look at generic processes and process sequences from a state perspective. The novel perspective this concept introduces is that the processes and their parameters are not the priority; they are rather included in the analysis by implication. A supervised machine learning based feature ranking method is used to identify and rank relevant state characteristics and thereby the processes’ inter- and intrarelationships. This is elaborated with simplified examples of possible applications from different domains to make the theoretical concept and results more feasible for readers from varying domains. The presented concept allows for a holistic description and analysis of complex, multistage processes sequences. This stands especially true for process chains where interrelations between processes and states, processes and processes, or states and states are not fully understood, thus where there is a lack of knowledge regarding causations, in dynamic, complex, and high-dimensional environments. Thorsten Wuest, Christopher Irgens, and Klaus-Dieter Thoben Copyright © 2016 Thorsten Wuest et al. All rights reserved. Collaborative Cloud Manufacturing: Design of Business Model Innovations Enabled by Cyberphysical Systems in Distributed Manufacturing Systems Tue, 22 Nov 2016 13:51:11 +0000 Collaborative cloud manufacturing, as a concept of distributed manufacturing, allows different opportunities for changing the logic of generating and capturing value. Cyberphysical systems and the technologies behind them are the enablers for new business models which have the potential to be disruptive. This paper introduces the topics of distributed manufacturing as well as cyberphysical systems. Furthermore, the main business model clusters of distributed manufacturing systems are described, including collaborative cloud manufacturing. The paper aims to provide support for developing business model innovations based on collaborative cloud manufacturing. Therefore, three business model architecture types of a differentiated business logic are discussed, taking into consideration the parameters which have an influence and the design of the business model and its architecture. As a result, new business models can be developed systematically and new ideas can be generated to boost the concept of collaborative cloud manufacturing within all sustainable business models. Erwin Rauch, Sven Seidenstricker, Patrick Dallasega, and Robert Hämmerl Copyright © 2016 Erwin Rauch et al. All rights reserved. In Situ Determination of the Transport Properties of Near-Surface Concrete Using AC Impedance Spectroscopy Techniques Tue, 22 Nov 2016 13:24:45 +0000 The durability of existing concrete structures has increasingly attracted widespread attention in recent years. The phenomenon of performance degradation is often associated with the intrusion of hazardous ions from outside. As the first barrier to external substances intrusion, the near-surface concrete plays an important role in durability. So the performance of in-service concrete structures often depends on the transport properties of the near-surface concrete. Accordingly, information on service conditions and life prediction can be obtained by testing these transport properties. In this paper, an in situ method for chloride ion diffusion coefficient determination is proposed based on the relationship between the alternating current impedance spectroscopy parameters and the chloride ion diffusion coefficient. By a rational design, the new method can synthetically reflect the transport properties of near-surface concrete and is not affected by the presence of the reinforcing bar. In addition, the experimental results show that the method is in good agreement with “PERMIT” migration test which has been widely used. The proposed method is less time consuming and nondestructive and has good reproducibility. Lipeng Wu, Peng Dai, and Yong Li Copyright © 2016 Lipeng Wu et al. All rights reserved. Single VDTA Based Dual Mode Single Input Multioutput Biquad Filter Thu, 17 Nov 2016 13:30:22 +0000 This paper presents a dual mode, single input multioutput (SIMO) biquad filter configuration using single voltage differencing transconductance amplifier (VDTA), three capacitors, and a grounded resistor. The proposed topology can be used to synthesize low pass (LP), high pass (HP), and band pass (BP) filter functions. It can be configured as voltage mode (VM) or current mode (CM) structure with appropriate input excitation choice. The angular frequency () of the proposed structure can be controlled independently of quality factor (). Workability of the proposed biquad configuration is demonstrated through PSPICE simulations using 0.18 μm TSMC CMOS process parameters. Rajeshwari Pandey, Neeta Pandey, and Navin Singhal Copyright © 2016 Rajeshwari Pandey et al. All rights reserved. Flexural and Shear Behavior of FRP Strengthened AASHTO Type Concrete Bridge Girders Tue, 15 Nov 2016 11:30:06 +0000 Fiber-reinforced polymers (FRP) are being increasingly used for the repair and strengthening of deteriorated or unsafe concrete structures, including structurally deficient concrete highway bridges. The behavior of FRP strengthened concrete bridge girders, including failure modes, failure loads, and deflections, can be determined using an analytical finite element modeling approach, as outlined in this paper. The differences in flexural versus shear FRP strengthening and comparison with available design guidelines are also beneficial to design professionals. In this paper, a common AASHTO type prestressed concrete bridge girder with FRP wrapping was analyzed using the ANSYS FEM software and the ACI analytical approach. Both flexural and shear FRP applications, including vertical and inclined shear strengthening, were examined. Results showed that FRP wrapping can significantly benefit concrete bridge girders in terms of flexure/shear capacity increase, deflection reduction, and crack control. The FRP strength was underutilized in the section selected herein, which could be addressed through decrease of the amount of FRP and prestressing steel used, thereby increasing the section ductility. The ACI approach produced comparable results to the FEM and can be effectively and conveniently used in design. Nur Yazdani, Farzia Haque, and Istiaque Hasan Copyright © 2016 Nur Yazdani et al. All rights reserved. The Hysteresis Performance and Restoring Force Model for Corroded Reinforced Concrete Frame Columns Tue, 15 Nov 2016 09:05:45 +0000 A numerical simulation of the hysteresis performance of corroded reinforced concrete (RC) frame columns was conducted. Moreover, the results obtained were compared with experimental data. On this basis, a degenerated three-linearity (D-TRI) restoring force model was established which could reflect the hysteresis performance of corroded RC frame columns through theoretical analysis and data fitting. Results indicated that the hysteretic bearing capacity of frame columns decreased significantly due to corrosion of the rebar. In view of the characteristics of the hysteresis curve, the plumpness of the hysteresis loop for frame columns decreased and shrinkage increased with increasing rebar corrosion. All these illustrated that the seismic energy dissipation performance of frame columns reduced but their brittleness increased. As for the features of the skeleton curve, the trends for corroded and noncorroded members were basically consistent and roughly corresponded to the features of a trilinear equivalent model. Thereby, the existing Clough hysteresis rule can be used to establish the restoring force model applicable to corroded RC frame columns based on that of the noncorroded RC members. The calculated skeleton curve and hysteresis curve of corroded RC frame columns using the D-TRI model are closer to the experimental results. Guifeng Zhao, Meng Zhang, Yaoliang Li, and Dawang Li Copyright © 2016 Guifeng Zhao et al. All rights reserved. Relating Corroded Seven-Strand, Posttensioned Cable Cross-Sectional Properties to Load Capacity Thu, 27 Oct 2016 08:29:50 +0000 Multistrand anchors have seen widespread use, providing strength and stability at hydraulic Corps facilities. However, these steel tendons are subject to strength reduction as an effect of corrosion. Methods for evaluating the corroded cable strength do not exist to accurately estimate the time until tendon cables would have to be replaced (at great expense). The following five research tasks are used to address this deficiency: laboratory accelerated corrosion; pull-tests on pristine and laboratory corroded cables; optical scanning; data collection correlated with cross-sectional properties of cables; and development of a method to relate this data to the field. The pull-tests provide measured capacities for seven-strand, posttensioned (PT) cables. An optical scan of the corroded cables provides cross-sectional properties of individual wires within the pulled cables. Trendlines are established for the related peak cable capacities and cross-sectional properties in an effort to determine their correlations. Trendlines for minimum wire area and second-moment short axis diameter are found with low error, making them good predictors of loaded cable capacity. This pull-test dataset has been related back to cable failure in the field, assuming a linear rate of corrosion loss for the cross-sectional properties and required PT capacity. Richard Haskins, Barry White, Robert Ebeling, and James Evans Copyright © 2016 Richard Haskins et al. All rights reserved. Determination of the Transport Properties of Structural Concrete Using AC Impedance Spectroscopy Techniques Wed, 26 Oct 2016 10:05:30 +0000 All over the world, particularly in severe environmental conditions, there are reinforced concrete structures that develop nonnegligible phenomena of durability problems. Most of the durability problems are related to hazardous substances invasion. Both engineering practice and scientific studies have revealed that the transport property of near-surface concrete is a main factor in the durability of concrete structures. Among many transport parameters, the chloride ion diffusion coefficient is the most important one, which provides important information on material design and service life prediction. In this paper, AC impedance spectroscopy technology was employed in the measurement of chloride ion diffusion coefficient. The relationship between mesostructure parameters and chloride ion diffusion coefficient was deduced by introducing a reasonable equivalent circuit model. Taking into account the conductivity difference caused by various cementitious material systems, the diffusion coefficient can be corrected, and a diffusion coefficient determination method based on AC impedance spectroscopy technique was established. For the convenience of application, a relationship between the newly proposed method and a widely recognized standard method was obtained. The proposed method can be applied to laboratory testing and establishes the theoretical basis for field tests. Lipeng Wu, Peng Dai, and Yong Li Copyright © 2016 Lipeng Wu et al. All rights reserved. Study on the AFM Force Curve Common Errors and Their Effects on the Calculated Nanomechanical Properties of Materials Sun, 23 Oct 2016 09:35:49 +0000 The atomic force microscope (AFM) force curve has been widely used for determining the mechanical properties of materials due to its high resolution, whereby very low (piconewton) forces and distances as small as nanometers can be measured. However, sometimes the resultant force curve obtained from AFM is slightly different from those obtained from a more typical nanoindentation force curve due to the AFM piezo’s hysteresis. In this study the nanomechanical properties of either a sulfonated polyether ether ketone (SPEEK) treated layer or bare polyether ether ketone (PEEK) were evaluated via AFM nanoindentation and a nanomechanical test system to probe the possible error of the calculated nanomechanical properties due to the AFM piezo’s hysteresis. The results showed that AFM piezo’s hysteresis caused the error in the calculated nanomechanical properties of the materials. D. Almasi, R. Sharifi, M. R. Abdul Kadir, G. Krishnamurithy, and T. Kamarul Copyright © 2016 D. Almasi et al. All rights reserved. Rolling Bearing Fault Diagnosis Based on ELCD Permutation Entropy and RVM Wed, 07 Sep 2016 09:08:58 +0000 Aiming at the nonstationary characteristic of a gear fault vibration signal, a recognition method based on permutation entropy of ensemble local characteristic-scale decomposition (ELCD) and relevance vector machine (RVM) is proposed. First, the vibration signal was decomposed by ELCD; then a series of intrinsic scale components (ISCs) were obtained. Second, according to the kurtosis of ISCs, principal ISCs were selected and then the permutation entropy of principal ISCs was calculated and they were combined into a feature vector. Finally, the feature vectors were input in RVM classifier to train and test and identify the type of rolling bearing faults. Experimental results show that this method can effectively diagnose four kinds of working condition, and the effect is better than local characteristic-scale decomposition (LCD) method. Jiang Xingmeng, Wu Li, Pan Liwu, Ge Mingtao, and Hu Daidi Copyright © 2016 Jiang Xingmeng et al. All rights reserved. Investigating Surface Effects on Thermomechanical Behavior of Embedded Circular Curved Nanosize Beams Tue, 30 Aug 2016 15:40:05 +0000 To investigate the surface effects on thermomechanical vibration and buckling of embedded circular curved nanosize beams, nonlocal elasticity model is used in combination with surface properties including surface elasticity, surface tension, and surface density for modeling the nanoscale effect. The governing equations are determined via the energy method. Analytically Navier method is utilized to solve the governing equations for simply supported nanobeam at both ends. Solving these equations enables us to estimate the natural frequency and critical buckling load for circular curved nanobeam including Winkler and Pasternak elastic foundations and under the effect of a uniform temperature change. The results determined are verified by comparing the results with available ones in literature. The effects of various parameters such as nonlocal parameter, surface properties, Winkler and Pasternak elastic foundations, temperature, and opening angle of circular curved nanobeam on the natural frequency and critical buckling load are successfully studied. The results reveal that the natural frequency and critical buckling load of circular curved nanobeam are significantly influenced by these effects. Farzad Ebrahimi and Mohsen Daman Copyright © 2016 Farzad Ebrahimi and Mohsen Daman. All rights reserved.