Advances in Civil Engineering The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. A Simplified Parametric Study on Occupant Comfort Conditions in Base Isolated Buildings under Wind Loading Sun, 19 Feb 2017 00:00:00 +0000 Vibrations in buildings can cause occupant discomfort in the form of annoyance, headache, or sickness. While occupant comfort is considered in international standards regarding the design of high rise buildings against wind loading, it is neglected in the design of buildings with seismic protective base isolation systems. Nevertheless, due to their low flexibility, base isolated buildings can be prone to wind-induced vibrations, which makes occupant discomfort a potentially significant serviceability limit state. This paper presents a study on occupant comfort conditions in wind-excited base isolated buildings. A numerical simplified parametric procedure is proposed in order to evaluate the return period of wind events causing human discomfort. A parametric investigation is then presented to evaluate the effects of salient parameters on comfort conditions. The procedure is based on (i) the nonlinear dynamic analysis of the structure modeled as a single-degree-of-freedom oscillator with hysteretic base isolators, (ii) the digital generation of time histories of turbulent wind velocity, and (iii) comfort evaluations based on international standards. Results demonstrate that discomfort conditions can occur a few times in a year, depending upon the wind-exposure of the site, what suggests considering this serviceability limit state in the design of base isolated buildings. F. Ubertini, F. Comodini, A. Fulco, and M. Mezzi Copyright © 2017 F. Ubertini et al. All rights reserved. Parameter Analysis on Wind-Induced Vibration of UHV Cross-Rope Suspension Tower-Line Thu, 16 Feb 2017 07:15:31 +0000 This paper analyzes the influences of important structural design parameters on the wind-induced response of cross-rope suspension tower-line. A finite element model of cross-rope suspension tower-line system is established, and the dynamic time-history analysis with harmonic wave superposition method is conducted. The two important structural design parameters such as initial guy pretension and sag-span ratio of suspension-rope are studied, as well as their influences on the three wind-induced vibration responses such as tensile force on guys, the reaction force on mast supports, and the along-wind displacement of the mast top; the results show that the value of sag-span ratio of suspension-rope should not be less than 1/9 and the value of guy pretension should be less than 30% of its design bearing capacity. On this occasion, the tension in guys and compression in masts would be maintained in smaller values, which can lead to a much more reasonable structure. Xilai Li, Dengke Yu, and Zhengliang Li Copyright © 2017 Xilai Li et al. All rights reserved. Moment-Curvature Behaviors of Concrete Beams Singly Reinforced by Steel-FRP Composite Bars Wed, 15 Feb 2017 07:56:42 +0000 A steel-fiber-reinforced polymer (FRP) composite bar (SFCB) is a kind of rebar with inner steel bar wrapped by FRP, which can achieve a better anticorrosion performance than that of ordinary steel bar. The high ultimate strength of FRP can also provide a significant increase in load bearing capacity. Based on the adequate simulation of the load-displacement behaviors of concrete beams reinforced by SFCBs, a parametric analysis of the moment-curvature behaviors of concrete beams that are singly reinforced by SFCB was conducted. The critical reinforcement ratio for differentiating the beam’s failure mode was presented, and the concept of the maximum possible peak curvature (MPPC) was proposed. After the ultimate curvature reached MPPC, it decreased with an increase in the postyield stiffness ratio (), and the theoretical calculation method about the curvatures before and after the MPPC was derived. The influence of the reinforcement ratio, effective depth, and FRP ultimate strain on the ultimate point was studied by the dimensionless moment and curvature. By calculating the envelope area under the moment-curvature curve, the energy ductility index can obtain a balance between the bearing capacity and the deformation ability. This paper can provide a reference for the design of concrete beams that are reinforced by SFCB or hybrid steel bar/FRP bar. Zeyang Sun, Yang Yang, Wenlong Yan, Gang Wu, and Xiaoyuan He Copyright © 2017 Zeyang Sun et al. All rights reserved. Effect of Modified Rubber Particles Mixing Amount on Properties of Cement Mortar Sun, 29 Jan 2017 06:25:51 +0000 The crumb rubber cement mortar is prepared by the crumb rubber aggregates in 60 mesh which are modified by 1% polyvinyl alcohol (PVA) solution. Some mechanical properties of cement mortar with different crumb rubber aggregate amounts are researched including compressive strength, flexural strength, the ratio of compressive strength to flexural strength, impact resistance, and dry contraction percentage. In our tests, we consider six kinds of the rubber contents, 0%, 7.5%, 15%, 19%, 22.5%, and 30%, respectively. The optimal mixing amount of crumb rubber is determined by measuring three indices, the ratio of compressive strength to flexural strength, impact resistance, and dry contraction percentage. It is shown by test that the ratio of compressive strength to flexural strength is the smallest when the mixing amount of rubber is 19%; meanwhile high impact resistance and rational drying shrinkage are observed. The optimal mixing amount of the rubber particles is 19% determined by this test. Gang Xue and Mei-ling Cao Copyright © 2017 Gang Xue and Mei-ling Cao. All rights reserved. Bond Strength between Hybrid Fiber-Reinforced Lightweight Aggregate Concrete Substrate and Self-Compacting Concrete as Topping Layer Mon, 23 Jan 2017 00:00:00 +0000 Structural performance evaluation of composite concrete slabs that were constructed using partially precast concreting system which utilized Hybrid Fiber-Reinforced Lightweight Aggregate Concrete (HyFRLWAC) as stay in-place formwork and self-compacting concrete (SCC) as topping layer was conducted in this research. This paper focused on determining the appropriate strength limit criteria of interface between two different concrete layers. The tensile strength was tested using pull-off test, while concrete cohesion was investigated based on modified bisurface shear test, and dual L-shaped shear test was used to determine the effect of normal force on the shear strength of concrete interface. Sample variants were designed based on the substrate surface conditions, compressive strength of the topping layer, and magnitude of perpendicular normal force acting on interface area. The substrate surfaces were prepared in as-placed and grooved conditions for tensile test, cohesion, and shear strength test. Test results indicate that tensile strength, cohesion, and shear strength of the concrete interface are affected by surface condition of the substrate, compressive strength of the topping layer, and the normal force acting perpendicularly on the concrete interface area. Proposed formulation for bond strength prediction between HyFRLWAC as substrate and SCC as topping layer is also presented in this paper. Slamet Widodo Copyright © 2017 Slamet Widodo. All rights reserved. Experimental Study on the Utilization of Fine Steel Slag on Stabilizing High Plastic Subgrade Soil Tue, 17 Jan 2017 00:00:00 +0000 The three major steel manufacturing factories in Jordan dump their byproduct, steel slag, randomly in open areas, which causes many environmental hazardous problems. This study intended to explore the effectiveness of using fine steel slag aggregate (FSSA) in improving the geotechnical properties of high plastic subgrade soil. First soil and fine steel slag mechanical and engineering properties were evaluating. Then 0%, 5%, 10%, 15%, 20%, and 25% dry weight of soil of fine steel slag (FSSA) were added and mixed into the prepared soil samples. The effectiveness of the FSSA was judged by the improvement in consistency limits, compaction, free swell, unconfined compression strength, and California bearing ratio (CBR). From the test results, it is observed that 20% FSSA additives will reduce plasticity index and free swell by 26.3% and 58.3%, respectively. Furthermore, 20% FSSA additives will increase the unconfined compressive strength, maximum dry density, and CBR value by 100%, 6.9%, and 154%. By conclusion FSSA had a positive effect on the geotechnical properties of the soil and it can be used as admixture in proving geotechnical characteristics of subgrade soil, not only solving the waste disposal problem. Hussien Aldeeky and Omar Al Hattamleh Copyright © 2017 Hussien Aldeeky and Omar Al Hattamleh. All rights reserved. Proposal of Design Formulae for Equivalent Elasticity of Masonry Structures Made with Bricks of Low Modulus Tue, 17 Jan 2017 00:00:00 +0000 Bricks of low elastic modulus are occasionally used in some developing countries, such as Indonesia and India. Most of the previous research efforts focused on masonry structures built with bricks of considerably high elastic modulus. The objective of this study is to quantify the equivalent elastic modulus of lower-stiffness masonry structures, when the mortar has a higher modulus of elasticity than the bricks, by employing finite element (FE) simulations and adopting the homogenization technique. The reported numerical simulations adopted the two-dimensional representative volume elements (RVEs) using quadrilateral elements with four nodes. The equivalent elastic moduli of composite elements with various bricks and mortar were quantified. The numerically estimated equivalent elastic moduli from the FE simulations were verified using previously established test data. Hence, a new simplified formula for the calculation of the equivalent modulus of elasticity of such masonry structures is proposed in the present study. Muhammad Ridwan, Isamu Yoshitake, and Ayman Y. Nassif Copyright © 2017 Muhammad Ridwan et al. All rights reserved. Series-Based Solution for Analysis of Simply Supported Rectangular Thin Plate with Internal Rigid Supports Wed, 04 Jan 2017 12:13:17 +0000 In this study, Navier’s solution for the analysis of simply supported rectangular plates is extended to consider rigid internal supports. The proposed method offers a more accurate solution for the bending moment at the critical section and therefore serves as a better analytical solution for design purposes. To model the plate-support interaction, the patched areas representing the contact between the plate and supports are divided into groups of cells. The unknown internal reactions at the centers of the divided cells are obtained by satisfying the compatibility conditions at the centers of the cells. Three numerical examples are presented to demonstrate the accuracy of the proposed analytical solution. The given examples reveal good agreements with those obtained by the finite element analysis. In addition, they show the advantage of the new solution as compared to the existing analytical solution which inaccurately estimates the location and magnitude of the maximum bending moment. Abubakr E. S. Musa and Husain J. Al-Gahtani Copyright © 2017 Abubakr E. S. Musa and Husain J. Al-Gahtani. All rights reserved. Postheated Model of Confined High Strength Fibrous Concrete Tue, 13 Dec 2016 13:03:37 +0000 HSC normally suffers from low stiffness and poor strain capacity after exposure to high temperature. High strength confined fibrous concrete (HSCFC) is being used in industrial structures and other high rise buildings that may be subjected to high temperature during operation or in case of an accidental fire. The proper understanding of the effect of elevated temperature on the stress-strain relationship of HSCFC is necessary for the assessment of structural safety. Further stress-strain model of HSCFC after exposure to high temperature is scarce in literature. Experimental results are used to generate the complete stress-strain curves of HSCFC after exposure to high temperature in compression. The variation in concrete mixes was achieved by varying the types of fibre, volume fraction of fibres, and temperature of exposure from ambient to 800°C. The degree of confinement was kept constant in all the specimens. A comparative assessment of different models on the high strength confined concrete was also conducted at different temperature for the accuracy of proposed model. The proposed empirical stress-strain equations are suitable for both high strength confined concrete and HSCFC after exposure to high temperature in compression. The predictions were found to be in good agreement and well fit with experimental results. Kaleem A. Zaidi, Umesh K. Sharma, N. M. Bhandari, and P. Bhargava Copyright © 2016 Kaleem A. Zaidi et al. All rights reserved. Hysteresis and Soil Site Dependent Input and Hysteretic Energy Spectra for Far-Source Ground Motions Tue, 06 Dec 2016 12:25:00 +0000 Earthquake input energy spectra for four soil site classes, four hysteresis models, and five ductility levels are developed for far-source ground motion effect. These energy spectra are normalized by a quantity called velocity index (VI). The use of VI allows for the creation of dimensionless spectra and results in smaller coefficients of variation. Hysteretic energy spectra are then developed to address the demand aspect of an energy-based seismic design of structures with 5% critical damping and ductility that ranges from 2 to 5. The proposed input and hysteretic energy spectra are then compared with response spectra generated using nonlinear time history analyses of real ground motions and are found to produce reasonably good results over a relatively large period range. Mebrahtom Gebrekirstos Mezgebo and Eric M. Lui Copyright © 2016 Mebrahtom Gebrekirstos Mezgebo and Eric M. Lui. All rights reserved. Influence of Local Sand on the Physicomechanical Comportment and Durability of High Performance Concrete Thu, 01 Dec 2016 11:18:42 +0000 This research consists of incorporating the crushed sand (CS) in the composition of a concrete and studies the effect of its gradual replacement by the sand dune (SD) on sustainability of high performance concrete (HPC) in aggressive environments. The experimental study shows that the parameters of workability of HPC are improved when the CS is partially replaced by the SD (<2/3). However, a high content of SD (>1/3) additional quantities of water is needed to meet the workability properties. The mechanical strengths decrease by adding the SD to CS, but they reach acceptable values with CS in moderate dosages. The HPC performances are significantly better than the control concrete made up with the same aggregates. The specification tests of durability show that the water absorbing coefficients by capillarity increase after adding SD to the CS. Nadia Tebbal and Zine El Abidine Rahmouni Copyright © 2016 Nadia Tebbal and Zine El Abidine Rahmouni. All rights reserved. Long Term Compression Strength of Mortars Produced Using Coarse Steel Slag as Aggregate Wed, 16 Nov 2016 08:55:43 +0000 The paper reports on some experimental results obtained from the production of mortars prepared using a commercial cement, coarse steelmaking slag, superplasticizer, and water. The behaviour of this reference composition was compared to that of some others containing further additives in order to investigate materials compressive strength after long time ageing. It has been demonstrated that an optimized water/cement ratio coupled with slag particles of size lower than 2.5 mm and proper protocol of preparation leads to the production of materials with good mechanical properties after 28, 90, and 180 days of ageing. The resulting materials therefore appeared as good candidates for civil engineering applications. However, the present research also demonstrates that the mortar samples of all of the compositions prepared suffer from decay and compressive strength decrease after long time ageing in water. In the present paper the results are explained taking account of materials residual porosity and alkali silica reaction which occurs in the samples. Erika Furlani and Stefano Maschio Copyright © 2016 Erika Furlani and Stefano Maschio. All rights reserved. Estimating Compressive Strength of High Performance Concrete with Gaussian Process Regression Model Wed, 12 Oct 2016 11:37:17 +0000 This research carries out a comparative study to investigate a machine learning solution that employs the Gaussian Process Regression (GPR) for modeling compressive strength of high-performance concrete (HPC). This machine learning approach is utilized to establish the nonlinear functional mapping between the compressive strength and HPC ingredients. To train and verify the aforementioned prediction model, a data set containing 239 HPC experimental tests, recorded from an overpass construction project in Danang City (Vietnam), has been collected for this study. Based on experimental outcomes, prediction results of the GPR model are superior to those of the Least Squares Support Vector Machine and the Artificial Neural Network. Furthermore, GPR model is strongly recommended for estimating HPC strength because this method demonstrates good learning performance and can inherently express prediction outputs coupled with prediction intervals. Nhat-Duc Hoang, Anh-Duc Pham, Quoc-Lam Nguyen, and Quang-Nhat Pham Copyright © 2016 Nhat-Duc Hoang et al. All rights reserved. Advancements in Design, Analysis, and Retrofitting of Structures Exposed to Blast Tue, 04 Oct 2016 11:48:52 +0000 Chiara Bedon, Claudio Amadio, Li Chen, Vasant Matsagar, Frank Wellershoff, and Xihong Zhang Copyright © 2016 Chiara Bedon et al. All rights reserved. Durability to Chemical Attack by Acids of Epoxy Microconcretes by Comparison to Cementitious Ones Thu, 29 Sep 2016 16:16:32 +0000 This research deals with the durability of micropolymer concrete (MPC) obtained by mixing an epoxy resin with fine and coarse sand particles. In particular the resistance of the micropolymer concrete to chemical solutions (citric acid C6H8O7, sulfuric acid H2SO4, and hydrochloric acid HCl) is investigated and compared to this of Portland cement microconcrete. Two MPC are tested. The first is formulated with 9% mass fraction of epoxy polymer whereas calcareous fillers have been incorporated in the second formulation in order to reduce the percentage of the epoxy binder. It is shown that a microconcrete designed with 7% of epoxy, 10% of fillers, and 83% of aggregates is characterized by higher physical and mechanical properties than those of the MPC formulated with 9% of epoxy binder. The mechanical properties of the resulting materials after their exposure to the three selected acid solutions at different durations were studied through compressive, three points bending and ultrasonic wave propagation tests. The obtained results are compared to those of microcement concretes (MCC) tested under the same conditions as MPC. The results show that both microepoxy polymer concretes exhibit better mechanical properties and highest resistance to chemical attack than the microcement concrete. Elhem Ghorbel and Murhaf Haidar Copyright © 2016 Elhem Ghorbel and Murhaf Haidar. All rights reserved. Blast Protection of Unreinforced Masonry Walls: A State-of-the-Art Review Wed, 21 Sep 2016 12:51:02 +0000 The recent rise of terrorist attacks has reinforced the need for mitigation of damage caused by blast loading on unreinforced masonry walls. The primary goal of the techniques is to prevent the loss of life while simultaneously preserving the integrity of the structure. This paper presents a compilation of recently available literature on blast protection of unreinforced masonry walls. It seeks to present the state of the art in this field, including mitigation techniques considered as well as testing methods selected. Fiber reinforced polymers and polyurea are the two dominant retrofitting techniques being assessed in the field. Other techniques include but are not limited to polyurethane, steel sheets, and aluminum foam. Since there is no widely implemented standard for blast loading test procedures, direct comparisons between the efficiencies of the mitigation techniques proposed are not always feasible. Although fragmentation is an indicator of the efficiency of retrofits, it is currently measured by subjective observation of postblast debris. Lucas Lantz, Joshua Maynez, Wesley Cook, and Claudia Mara Dias Wilson Copyright © 2016 Lucas Lantz et al. All rights reserved. Fracture Mechanics Models for Brittle Failure of Bottom Rails due to Uplift in Timber Frame Shear Walls Tue, 20 Sep 2016 08:00:07 +0000 In partially anchored timber frame shear walls, hold-down devices are not provided; hence the uplift forces are transferred by the fasteners of the sheathing-to-framing joints into the bottom rail and via anchor bolts from the bottom rail into the foundation. Since the force in the anchor bolts and the sheathing-to-framing joints do not act in the same vertical plane, the bottom rail is subjected to tensile stresses perpendicular to the grain and splitting of the bottom rail may occur. This paper presents simple analytical models based on fracture mechanics for the analysis of such bottom rails. An existing model is reviewed and several alternative models are derived and compared qualitatively and with experimental data. It is concluded that several of the fracture mechanics models lead to failure load predictions which seem in sufficiently good agreement with the experimental results to justify their application in practical design. Joergen L. Jensen, Giuseppe Caprolu, and Ulf Arne Girhammar Copyright © 2016 Joergen L. Jensen et al. All rights reserved. Erratum to “Modeling of Hydrophysical Properties of the Soil as Capillary-Porous Media and Improvement of Mualem-Van Genuchten Method as a Part of Foundation Arrangement Research” Wed, 14 Sep 2016 13:03:22 +0000 Vitaly Terleev, Aleksandr Nikonorov, Vladimir Badenko, Inna Guseva, Yulia Volkova, Olga Skvortsova, Sergey Pavlov, and Wilfried Mirschel Copyright © 2016 Vitaly Terleev et al. All rights reserved. Flutter Derivatives Identification and Aerodynamic Performance of an Optimized Multibox Bridge Deck Sun, 04 Sep 2016 13:24:53 +0000 The bridge deck sections used for long-span suspension bridges have evolved through the years, from the compact box deck girders geometrical configurations to twin-box and three-box bridge decks sections. The latest generation of split and multiple-box bridge decks proved to have better aerodynamic behavior; thus further optimization methods are sought for such geometrical configurations. A new type of multibox bridge deck, consisting of four aerodynamically shaped deck boxes, two side decks for the traffic lanes and two middle decks for the railway traffic, connected between them by stabilizing beams, was tested in the wind tunnel for identifying the flutter derivatives and to verify the aerodynamic performance of the proposed multibox deck. Aerodynamic static force coefficients were measured for the multibox bridge deck model, scaled 1 : 80, for Reynolds numbers up to 5.1 × 105, under angles of attack between −8° and 8°. Iterative Least Squares (ILS) method was employed for identifying the flutter derivatives of the multibox bridge deck model, based on the results obtained from the free vibration tests and based on the frequency analysis the critical flutter wind speed for the corresponding prototype of the multibox bridge was estimated at 188 m/s. Zhida Wang and Elena Dragomirescu Copyright © 2016 Zhida Wang and Elena Dragomirescu. All rights reserved. Experimental Study of the Effectiveness of Sacrificial Cladding Using Polymeric Foams as Crushable Core with a Simply Supported Steel Beam Sun, 04 Sep 2016 10:14:05 +0000 The present paper focuses on the study of the effectiveness of the sacrificial cladding using polymeric foam as crushable core to reduce the delivered blast energy using a simplified structure. The latter consists of a simply supported steel beam under a localized blast load. The tested sacrificial cladding has a cross-sectional area of 80 × 80 mm2. The effect of the front plate mass and the crushable core properties (plateau stress and thickness) is studied. Three polymeric foams are investigated: (a) the expanded polystyrene foam (PS13) with a density of 13 kg/m3, (b) the closed-cell polyurethane (PU30) with a density of 30 kg/m3, and (c) the open-cell polyurethane (PU50) with a density of 50 kg/m3. Four front plate masses are used: 144, 188, 336, and 495 g. All possible combinations are tested to determine their absorption capacity. The obtained results show that the absorption capability increases by increasing the front plate mass, the plateau stress, and the thickness of the crushable core. The open-cell polyurethane PU50 performs better. Disintegration problems are observed on the expanded polystyrene PS13 after the end of the compression process. H. Ousji, B. Belkassem, M. A. Louar, B. Reymen, L. Pyl, and J. Vantomme Copyright © 2016 H. Ousji et al. All rights reserved. Clever House Made by Using a New Kind of the Nanocomposites Thu, 01 Sep 2016 11:49:10 +0000 The materials of this paper concern a new nanocomposites perspective for construction. The development of research in the field of production and application of nanocomposite materials has made it possible to develop building materials, having high exploitation characteristics. One of such materials is a polydisperse armed water soluble epoxy composite coat, named “EpoxyPAN.” This material consists of the water soluble epoxy resin filled by the high strength inorganic fillers and the unique nanocarbon particles, astralenes and nanoporous microfiber. It was found that EpoxyPAN is possible to be used as effective water protection coating and simultaneously as effective electromagnetic waves absorber. The physical and exploitation properties of this nanocomposite and the possible ways of its applications for the Clever House constructions are also described in this paper. Andrey Ponomarev and Timur Plavnik Copyright © 2016 Andrey Ponomarev and Timur Plavnik. All rights reserved. Crystalline Coating and Its Influence on the Water Transport in Concrete Thu, 11 Aug 2016 13:25:54 +0000 The presented paper deals with an experimental study of the efficiency of surface coating treatment based on secondary crystallization as an additional protection of the subsurface concrete structure loaded by moisture or ground water pressure. The aim of the experimental program was the evaluation of the depth impact of the crystalline coating and the assessment of the reliability of construction joints performed on models simulating real conditions of the concrete structure. The evolution of the secondary crystallizing process was monitored using the water absorption test carried out at different depths of the samples. The coefficient of adsorption decreased to 60% of the reference mixture for a surface layer of up to 40 mm at 28 days and to 50% at 180 days after the coating’s application. Furthermore, the electrical resistivity method was applied with respect to the nature of measurement and the low accessibility of real subsurface concrete structures. The results of moisture measurement at a depth of 180–190 mm from the surface treated with a crystalline coating showed an essential decrease in moisture content percentage in comparison with untreated specimens (measured 125 days after the coating’s application). Pavel Reiterman and Jiri Pazderka Copyright © 2016 Pavel Reiterman and Jiri Pazderka. All rights reserved. Modelling Blast Effects on a Reinforced Concrete Bridge Wed, 10 Aug 2016 13:55:00 +0000 The detailed investigation of blast phenomena and their catastrophic effects on existing structures are the main objectives of the present paper. It is well known that blast phenomena may be characterized by significant complexity, often involving complicated wave propagation effects as well as distinguishable material behaviors. Considering the above and in an attempt to provide a simplified modelling approach for the simulation of blast effects, a novel procedure is presented herein based on well-established methodologies and common engineering practices. In the above framework, firstly, the “predominant” deformation shape of the structure is estimated based on elastic finite element simulations under blast loads and then the structural response of the system is evaluated as a result of common computational beam-element tools such as displacement-based pushover analysis. The proposed methodology provides an immediate first estimation of the structural behavior under blast loads, based on familiar engineering procedures. A two-span reinforced concrete bridge was thoroughly investigated and the results provide insightful information regarding the damage patterns and localization. Markellos Andreou, Anastasios Kotsoglou, and Stavroula Pantazopoulou Copyright © 2016 Markellos Andreou et al. All rights reserved. Bioinspired Design of Building Materials for Blast and Ballistic Protection Wed, 10 Aug 2016 11:08:30 +0000 Nacre in abalone shell exhibits high toughness despite the brittle nature of its major constituent (i.e., aragonite). Its specific structure is a major contributor to the energy absorption capacity of nacre. This paper reviews the mechanisms behind the performance of nacre under shear, uniaxial tension, compression, and bending conditions. The remarkable combination of stiffness and toughness on nacre can motivate the development of bioinspired building materials for impact resistance applications, and the possible toughness designs of cement-based and clay-based composite materials with a layered and staggered structure were discussed. Yu-Yan Sun, Zhi-Wu Yu, and Zi-Guo Wang Copyright © 2016 Yu-Yan Sun et al. All rights reserved. Design of Blast-Loaded Glazing Windows and Facades: A Review of Essential Requirements towards Standardization Sun, 07 Aug 2016 07:07:24 +0000 The determination of the blast protection level of laminated glass windows and facades is of crucial importance, and it is normally done by using experimental investigations. In recent years numerical methods have become much more powerful also with respect to this kind of application. This paper attempts to give a first idea of a possible standardization concerning such numerical simulations. Attention is drawn to the representation of the blast loading and to the proper description of the behaviour of the material of the mentioned products, to the geometrical meshing, and to the modelling of the connections of the glass components to the main structure. The need to validate the numerical models against reliable experimental data, some of which are indicated, is underlined. Martin Larcher, Michel Arrigoni, Chiara Bedon, J. C. A. M. van Doormaal, Christof Haberacker, Götz Hüsken, Oliver Millon, Arja Saarenheimo, George Solomos, Laurent Thamie, Georgios Valsamos, Andy Williams, and Alexander Stolz Copyright © 2016 Martin Larcher et al. All rights reserved. Effects of Asphalt Mix Design Properties on Pavement Performance: A Mechanistic Approach Tue, 02 Aug 2016 11:14:28 +0000 The main objective of this study was to investigate the effects of hot mix asphalt material properties on the performance of flexible pavements via mechanistic approach. 3D Move Analysis software was utilized to determine rutting and cracking distresses in an asphalt concrete (AC) layer. Fourteen different Superpave mixes were evaluated by utilizing results of the Dynamic Modulus () Test and the Dynamic Shear Modulus () Test. Results showed that with the increase of binder content, the tendency of rutting in AC layer increased. However, with the increase of binder content, the cracking of AC layer lessened. Furthermore, when different binder grades were evaluated, results showed that with the increase of the upper binder grade number, rutting decreased, and with the increase of the lower binder grade number, rutting increased. Furthermore, analysis showed that with the increase of the lower binder grade number, higher percent of bottom up cracks would result. As a result of the analysis, binder grade should not be solely considered for cracking in AC layer; binder content and aggregate structure play a big role. Finally, results illustrated that the mechanistic approach is a better tool to determine the performance of asphalt pavement than commonly used methods. Ahmad M. Abu Abdo and S. J. Jung Copyright © 2016 Ahmad M. Abu Abdo and S. J. Jung. All rights reserved. Study on Compressive Strength of Quarry Dust as Fine Aggregate in Concrete Thu, 28 Jul 2016 06:59:12 +0000 The concept of replacement of natural fine aggregate by quarry dust which is highlighted in the study could boost the consumption of quarry dust generated from quarries. By replacement of quarry dust, the requirement of land fill area can be reduced and can also solve the problem of natural sand scarcity. The availability of sand at low cost as a fine aggregate in concrete is not suitable and that is the reason to search for an alternative material. Quarry dust satisfies the reason behind the alternative material as a substitute for sand at very low cost. It even causes burden to dump the crusher dust at one place which causes environmental pollution. From the results of experimental investigations conducted, it is concluded that the quarry dust can be used as a replacement for fine aggregate. It is found that 40% replacement of fine aggregate by quarry dust gives maximum result in strength than normal concrete and then decreases from 50%. The compressive strength is quantified for varying percentage and grades of concrete by replacement of sand with quarry dust. K. Shyam Prakash and Ch. Hanumantha Rao Copyright © 2016 K. Shyam Prakash and Ch. Hanumantha Rao. All rights reserved. Study on Mechanical Features of Brazilian Splitting Fatigue Tests of Salt Rock Wed, 27 Jul 2016 13:21:24 +0000 The microtest, SEM, was carried out to study the fracture surface of salt rock after the Brazilian splitting test and splitting fatigue test were carried out with a servo-controlled test machine RMT-150B. The results indicate that the deviation of using the tablet splitting method is larger than that of using steel wire splitting method, in Brazilian splitting test of salt rock, when the conventional data processing method is adopted. There are similar deformation features in both the conventional splitting tests and uniaxial compression tests. The stress-strain curves include compaction, elasticity, yielding, and failure stage. Both the vertical deformation and horizontal deformation of splitting fatigue tests under constant average loading can be divided into three stages of “loosening-tightness-loosening.” The failure modes of splitting fatigue tests under the variational average loading are not controlled by the fracturing process curve of the conventional splitting tests. The deformation extent of fatigue tests under variational average loading is even greater than that of conventional splitting test. The tensile strength of salt rock has a relationship with crystallization conditions. Tensile strength of thick crystal salt rock is lower than the bonded strength of fine-grain crystals. Weichao Wang, Mengmeng Wang, and Xiliang Liu Copyright © 2016 Weichao Wang et al. All rights reserved. Plasticity, Swell-Shrink, and Microstructure of Phosphogypsum Admixed Lime Stabilized Expansive Soil Thu, 21 Jul 2016 08:01:47 +0000 The study involved utilization of an industrial waste, Phosphogypsum (PG), as an additive to lime stabilization of an expansive soil. Three lime dosages, namely, initial consumption of lime (ICL), optimum lime content (OLC), and less than ICL (LICL), were identified for the soil under study for stabilizing the soil. Along with lime, varying doses of PG were added to the soil for stabilization. The effect of stabilization was studied by performing index tests, namely, liquid limit, plastic limit, shrinkage limit, and free swell test, on pulverized remains of failed unconfined compression test specimens. The samples were also subjected to a microstructural study by means of scanning electron microscope. Addition of PG to lime resulted in improvement in the plasticity and swell-shrink characteristics. The microstructural study revealed the formation of a dense compact mass of stabilized soil. Jijo James and P. Kasinatha Pandian Copyright © 2016 Jijo James and P. Kasinatha Pandian. All rights reserved. Advanced Concrete Model in Hydrocode to Simulate Concrete Structures under Blast Loading Tue, 05 Jul 2016 09:57:44 +0000 The formulations of the advanced concrete RHT model adopted in AUTODYN are investigated and numerical studies are conducted to study the RHT model’s actual performances under various loading conditions. It is found that using of default values in the RHT model is not able to simulate the realistic behavior of concrete under various loading conditions. Thus modified parameters in the RHT model are proposed to better capture the realistic behavior of concrete under such loading conditions. Furthermore, numerical simulation of normal concrete slabs and multilayer concrete slabs subjected to blast loading is conducted using AUTODYN with both the default and modified RHT parameters. Experimental readings from field blast tests are used to validate the numerical model developed. It is shown that the results from numerical simulations using the modified RHT parameters and the measurements from the field blast test agree well in terms of damage pattern, crater diameter, and acceleration. Hence, it can be concluded that the RHT model with modified parameters can capture the mechanical behavior of concrete structures well. The validated model can be further used to conduct a parametric study on the influence of key parameters (i.e., compressive strength, fracture energy, and thickness) on blast resistance of concrete structure. Guo Hu, Jun Wu, and Liang Li Copyright © 2016 Guo Hu et al. All rights reserved.