bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a Transformable Three‐wheeled Lunar Rover: Tri‐Star IV
Authors: Aoki Takeshi , Murayama Yuki , Hirose Shigeo
Published: October 2013

The Japanese government is planning to send a rover to investigate the moon's surface in the near future, and it has been carrying out a considerable amount of research and making significant developments to make this possible. Toward that end, we have been developing and proposing expandable three‐wheeled rovers. This paper proposes a new concept for a three‐wheeled rover, namely the Tri‐Star IV, and its mechanical design is described herein. Tri‐Star IV has two arms that can rotate around horizontal shoulder axes and connect the rover's main body, and two rear wheels with off‐centered crank‐type axles that can expand from a storage posture. The two arms can be adjusted to adapt to traversing over sloped terrain, including recovery from rollover. The new wheels for traveling on the moon's surface, which is covered with regolith, are composed of a spring spoke and canvas cloth. In this project, two types of Tri‐Star IV were developed and field‐tested. The first was designed for mobility over rough sloped terrain. The other rover had a new front wheel installed that was designed for tethered descent/climbing over steep slopes. This paper reports on the mobilities of Tri‐Star IV, which were verified in experiments conducted on real sand and a test bed and in a field test at the Nakatajima sand dune in Japan.
Design and implementation of a monitoring system applied to a long‐span prestressed concrete bridge
Authors: Sousa Helder , Félix Carlos , Bento João , Figueiras Joaquim
Published: October 2013

Currently, long‐term monitoring systems are mandatory for major civil engineering structures such as bridges, tunnels and dams. Generally, they monitor a set of physical, chemical and mechanical parameters in critical sections of the structure by incorporating appropriate sensors. The set of data collected demonstrates great potential in the prevention of damage and contributes to more efficient maintenance of the structures monitored. This work presents the long‐term monitoring system installed on the new Lezíria Bridge over the River Tagus in Portugal. The system was developed to control some aspects of the construction process and to survey the service life of the structure. A set of structural, durability and environmental parameters defining the bridge condition are remotely assessed in real‐time via a fibreoptic network. Aspects such as architecture, installation and functionality of the monitoring system are discussed and the innovative aspects of the implementation are highlighted. In this context, the main goal of this work is to present the long‐term monitoring system of Lezíria Bridge, sharing the experiences, the solutions and the procedures adopted, given their potential usefulness in the implementation of similar projects.
Three‐dimensional FE analysis of reinforced concrete structures using the lattice equivalent continuum method
Authors: Ahmad Syed Ishtiaq , Tanabe Tada‐aki
Published: October 2013

The lattice equivalent continuum model (LECM) has proved to be very effective in analysing reinforced concrete structures in two‐dimensional cases. That model is extended here to three dimensions and is fitted to a finite element formulation for analysing three‐dimensional reinforced concrete structures. In any of the three principal directions, the stress–strain behaviour of concrete will be affected by the stress state in the other two directions. Consequently, stress‐strain curves for concrete will shift from a uniaxial pattern. This phenomenon is considered in this work by selecting concrete peak stresses in three alternative approaches. The effectiveness of those approaches is also evaluated. The results of the calculations show good reproduction of the test data, which indicates the validity of this proposed 3D modelling of reinforced concrete.
A deformation criterion for fatigue of concrete in tension
Authors: Thun Håkan , Ohlsson Ulf , Elfgren Lennart
Published: October 2013

A deformation criterion is proposed for the fatigue failure of concrete in tension. According to the criterion, a fatigue failure is imminent when the total deformation approaches the deformation at maximum stress in a corresponding static test. This criterion was originally proposed for bond slip by Balázs in 1991. It is tested on two series of new and old concrete cylinders loaded in cyclic tension. How the criterion may be used to predict the number of load cycles to failure for existing structures under cyclic tensile loading is also shown.
History and overview of fabric formwork: using fabrics for concrete casting
Authors: Veenendaal Diederik , West Mark , Block Philippe
Published: October 2013

The concept of casting concrete in fabrics, fabric formwork technology, has resurfaced at various times and in different forms throughout the past century. The following paper traces developments that have used fabrics for concrete formwork, including different types of flexible formwork, controlled permeability formwork and pneumatic formwork. This paper presents a comprehensive historical overview of fabric formwork, listing key innovators, technological developments and their advantages, and offering examples of structures built with these methods. The information gathered is used to present a taxonomy of these related formwork technologies as well as a formal definition of the term “fabric formwork” that encompasses them. The paper is intended to introduce readers to these technologies and offer readers already familiar with these methods additional historical background.
Effects of cross‐sectional shape on the reliability of RC columns
Authors: Baji Hassan , Ronagh Hamid R.
Published: October 2013

This paper studies the effects of cross‐sectional shape and rebar configuration on the reliability indices of concrete columns. Three sections with rectangular, square and circular shapes are selected. Using the Monte Carlo simulation technique, the statistical parameters for reinforced column resistance are calculated along several load eccentricities using the most recent statistical data available in the literature. The statistical parameters show that the magnitude and the variation of bias factors and the coefficients of variation are not similar for the sections selected. The coefficients of variation of the square and circular sections are greater than that of the rectangular section. The results of reliability analysis indicate the importance of sectional shape, especially at low load eccentricities. In some cases, the effect of cross‐sectional shape or reinforcement configuration is found to be more important than the effect of the compressive strength of the concrete. It is recommended to include the shape factor and the reinforcement configuration in the code calibration process for the capacity reduction factors.
An innovative design concept for improving the durability of concrete bridges
Authors: Berger Johannes , Bruschetini‐Ambro Sebastian Zoran , Kollegger Johann
Published: October 2013

It is proposed to build concrete bridges with tendons fully encapsulated in plastic ducts and without the use of reinforcing steel. In this case the durability of the proposed bridge depends only on the durability of the concrete because corrosion is no longer a determining factor regarding the lifetime of the structure. The requirements of the serviceability and ultimate limit states are fulfilled by providing post‐tensioned tendons with strands fully encapsulated in plastic ducts and watertight anchorages. Since the proposed bridge does not contain any steel, which would be endangered by material‐related corrosion, there is no need for insulation to the deck. Consequently, there is also no need for pavement and edge beams. This concept of building bridges represents a breakthrough with regard to sustainability and durability of concrete bridges and is applicable to small and mediumsized bridges. The method has already been implemented for the design of the Egg‐Graben Bridge in the Großarl valley in the province of Salzburg, Austria. Prior to the actual construction of the bridge, large‐scale tests were performed to obtain practical values for the serviceability, ductility and loadbearing capacity of this structural system.
Ultimate strength of curved strand tendons
Authors: Kollegger Johann , Gmainer Susanne , Lehner Klaus , Simader Josef
Published: October 2013

In a bridge construction process, where large concrete elements are rotated with the aid of strand lifting units (lowering of arch halves, balanced lift method), the tendons have to be deviated over saddles with small radii of curvature. Since information on the ultimate strength of curved strand tendons was not available at the time, a test programme was carried out in order to determine the ultimate strength as a function of radius of curvature (R = 0.5 m, R = 1.0 m, R = 3.0 m, straight tendons), number of strands (1 to 55) and type of strand (0.5″ and 0.6″). The results of the full scale experiments showed almost no decrease in efficiency with regard to single strand tendons and only moderate losses regarding multistrand tendons. Based on the experimental results and a biaxial failure criterion, an analytical model was developed which is able to predict the ultimate strength of curved tendons.
Improvements to the Eurocode 2 shrinkage model for concrete using a large experimental database
Authors: Raphael Wassim , Faddoul Rafic , Geara Fadi , Chateauneuf Alaa
Published: October 2013

Shrinkage plays an important, sometimes crucial, role in the design of many types of concrete structures as well as in their behaviour after construction. However, the uncontrolled strains are often larger than the expected values. As a matter of fact, there is as yet no perfectly satisfactory physical explanation for shrinkage. In this work, a large database has been set up for shrinkage testing performed by several research centres in Europe. On the basis of the statistical analysis of this database and by observing real structural behaviour, it becomes possible to investigate the current codes of practice regarding the computation of time‐dependent shrinkage strains. As comparison with experimental tests has shown that predictions are often inaccurate, a correction factor is proposed in this work to improve the European Code, Eurocode 2, and lead to more satisfactory results.
Considerations for the design of doubly unsymmetrical precast pretensioned beams used for box girder construction
Authors: Ayoub Essam , Malek Charles , Helmy Gamal
Published: October 2013

Many box girder bridges are constructed with doubly unsymmetrical precast beam units. The aim of this paper is to present special considerations for the optimum arrangement of pretensioned strands in a simply supported precast pretensioned beam with a doubly unsymmetrical section. The goal of the optimum arrangement is to minimize the distortion (lateral sway phenomenon) caused by the doubly unsymmetrical characteristic of the beam section at transfer. The study shows that the distortion of the unsymmetrical section is minimized when the resultant stresses at transfer are constant over all of the top flange and over all of the bottom flange of the precast beam for most of the sections within the beam length. In this case, the neutral axes of these sections will be horizontal with respect to the beam section. This approach is verified with the help of two different finite element models. In the first model, the beam is modelled as one‐dimensional space frame elements; in the second model, the beam is modelled using three‐dimensional solid elements. A practical example of a box girder bridge made from doubly unsymmetrical precast pretensioned beams in the APM (Automated People Mover) elevated bridge project in Saudi Arabia is also presented.
Façade damage assessment of concrete buildings in the 2011 Christchurch earthquake
Authors: Baird Andrew , Palermo Alessandro , Pampanin Stefano
Published: October 2013

The magnitude 6.3 earthquake that struck Christchurch on 22 February 2011 caused widespread damage throughout Christchurch's central business district (CBD), where a large proportion of the building stock consists of reinforced concrete (RC) buildings. Damage to the façades of these buildings was a clear contributor to overall building damage. This paper presents the damage assessment of the façade systems of these RC buildings. A survey of 173 RC buildings in the Christchurch CBD is conducted here, focusing on the damage to the façade systems of the buildings. The survey covers only buildings greater than three storeys in height, excluding the majority of unreinforced masonry façades, the damage to which has been well documented. The façade type and modularity is classified for each system, as well as the connection type where possible. The level of damage to each façade is determined in terms of the following performance levels: Operational, Immediate Occupancy, Life Safety and High Hazard. Further investigation is also made into three precast concrete panel systems. These case studies examine the damage, detailing and construction practice of each particular system.
The seismic performance of RC buildings in the 22 February 2011 Christchurch earthquake
Authors: Kam Weng Yuen , Pampanin Stefano
Published: October 2013

The 22 February 2011 Mw 6.2 Christchurch (Lyttelton) earthquake was a particularly severe test for both modern seismically designed and existing non‐ductile reinforced concrete (RC) buildings. Some 16.2 % of 833 buildings with RC systems within the Christchurch central business district (CBD) were severely damaged. There were 182 fatalities, 135 of which were the unfortunate consequences of the complete collapse of two medium‐rise RC buildings. As with the post‐Northridge 1994 earthquake, the design performance of “modern” structures is being scrutinized – with the inevitable question: is “life safety” but irreparable damage still a valid performance target? This brief paper presents a summary of RC building damage from a broad performance‐based earthquake engineering perspective. Several preliminary lessons, not all of them surprising, and the issues that have arisen will be discussed using case study buildings, with suggestions for urgently needed research areas.
Behaviour of grouted dowels used in precast concrete connections
Authors: Aguiar Eduardo Aurélio Barros , Bellucio Ellen Kellen , El Debs Mounir Khalil
Published: October 2013

This research deals with the behaviour of grouted dowels used in beam‐to‐column connections in precast concrete structures. The research focuses primarily on the theoretical and experimental analysis of the resistance mechanism of the dowels. The experimental programme included 15 models for analysing the following variations in dowel parameters: a) dowel diameters of 16, 20 and 25 mm, b) dowel inclinations of 0° (i.e. perpendicular to the interface), 45° and 60°, c) compressive strength of classes C35 and C50 for the concrete adjacent to the dowels, and d) the absence or presence of compressive loads normal to the interface. The experimental results indicate that the ultimate capacity and shear stiffness of the inclined dowels are significantly higher than those of the perpendicular dowels. Based on these results, an analytical model is proposed that considers the influence of the parameters studied regarding the capacity of the dowel.
Design model for reinforcement corrosion
Authors: Osterminski Kai , Schießl Peter
Published: October 2013

The performance‐based durability design of reinforced concrete structures for corrosion of reinforcement is currently limited to the initiation period. That includes modelling the transport processes of chlorides and carbon dioxide into the concrete structure. Up to now, the subsequent time period after depassivation of the reinforcement, in which corrosion propagates, could not be modelled in a comparable manner. The task of the research project presented here, which was part of German Research Unit 537, was to develop a design model that enables a reinforced concrete structure to be designed against reinforcement corrosion for its entire service life. Therefore, a physically well‐defined damage model for corrosion propagation was chosen as a basis. All system parameters in the damage model were investigated on the basis of numerical and laboratory studies carried out in the subprojects of the research unit. Statistical analysis allowed the simplification of the complex damage model into a user‐friendly design model. This paper presents the working steps, the basic results of the analysis and the user‐friendly full‐probabilistic design model for reinforcement corrosion.
Design and optimization of skew reinforcement in concrete shells
Authors: Bertagnoli Gabriele , Giordano Luca , Mancini Simona
Published: October 2013

Nowadays, it is more and more often necessary to design two‐dimensional reinforced concrete elements to satisfy both architectural demands and to comply with traffic safety requirements in the design of road and railway infrastructures. In fact, the demand for non‐regular structural geometry is increasing in both cases.

As a consequence, the use of finite element analyses to model structures and calculate internal actions is constantly growing because closed‐form solutions are generally unavailable for irregular shapes. Therefore, the problem of reinforcement design needs our attention because steel bars, in general, should be placed in non‐orthogonal directions and can vary over the structure.

Consequently, there are two different kinds of design problem: choice of reinforcement direction and evaluation of the reinforcement ratio between the chosen directions, with the aim of minimizing the total amount.

Such problems can be easily overcome by generalizing a mechanical model consolidated in the literature for orthogonal reinforcement for skew directions. The model is set up according to the ultimate plastic behaviour of the elements. An optimization technique based on genetic algorithms is then applied to the new model to reduce the amount of reinforcement.

This paper describes both the ultimate resisting mechanism with generic reinforcement directions and the way genetic algorithms are employed to optimize the amount of reinforcement.
Time‐dependent analysis during construction of concrete tube for tower high‐rise building
Authors: Jiang Wei , Gong Jian , De Schutter Geert , Huang Yulin , Yuan Yong
Published: October 2013

Vertical and differential deformations in super‐high‐rise buildings are extremely important during construction. In order to be able to adjust the construction process accurately, taking the deformations into account, such deformations must be calculated exactly. The analysis of the vertical deformations of the high‐rise Shanghai World Financial Centre building is illustrated in this paper. The prediction models of CEB‐FIP 90 are used for calculating shrinkage and creep. The fictitious degree of hydration method has been applied for calculating the creep behaviour of the early‐age concrete. The influence of steel bars on the vertical deformations has been analysed based on the macroscopical modulus method. Calculation of the vertical deformations includes the pre‐construction and the post‐construction deformations. Finally, the differential deformation between the concrete and the mega‐structure column is determined. Theoretical results for the vertical displacement of this super‐high‐rise building agree very well with field monitoring data.
Crack healing of cementitious materials using shrinkable polymer tendons
Authors: Isaacs Ben , Lark Robert , Jefferson Tony , Davies Robert , Dunn Simon
Published: October 2013

This paper presents an experimental study on autogenous healing in a recently developed shrinkable polymer cementitious material system. Small‐scale hollow prismatic mortar beams with unbonded shrinkable polymer tendons were loaded until a crack of predefined width had formed. The specimens were then subjected to a range of combined heating/curing regimes to activate the shrinkable polymer and to promote autogenous healing of the cementitious material prior to reloading to failure. Upon reloading, specimens loaded with the shrinkable polymer tendons remaining after heating and curing achieved between 120 and 195% of their initial peak loads, whereas specimens tested with the shrinkable polymer tendons removed after the heating and curing stages recovered on average 80% of their initial peak loads. The overall conclusion was that, provided a supply of water is present and sufficient heat is applied for polymer activation, the material system is effective at not only closing cracks and applying a prestress, but also at enhancing the self‐healing of cracks in cementitious materials.
The influence of aggregate fracture on the shear strength of reinforced concrete beams: an experimental and analytical research project
Authors: Sagaseta Juan
Published: October 2013

High‐performance concretes such as high‐strength concrete (HSC) or lightweight aggregate concrete (LWAC) are generally used to reduce member sizes and self‐weight, and to optimize the construction of reinforced concrete structures. The bond between the aggregate particles and the cement paste can be strong enough in HSC and LWAC to cause the aggregate to fracture at cracks, which in turn reduces the shear stress that can be transferred across cracks by means of aggregate interlock. Relatively smooth cracks can also develop in self‐compacting concrete due to the low coarse aggregate content. The contribution of aggregate interlock to the shear strength of RC beams is uncertain and depends on parameters such as the amount of shear reinforcement or the contribution of arching action for loads applied close to the support. Existing tests on slender RC beams without shear reinforcement have shown that shear strength is reduced by aggregate fracture. However, there is a lack of similar test data for members with stirrups and for members with varying shear span/effective depth ratios. This paper reviews the findings and contributions in this area from the experimental and analytical research of the author's PhD thesis, which was awarded the fib Achievement Award for Young Engineers in 2011.
Development of a mix design methodology for high‐performance geopolymer mortars
Authors: Ng Tian Sing , Foster Stephen J.
Published: October 2013

This paper presents the development of a mix design method for geopolymer mortar mixes with a principal focus on compressive strength. The method is based on the hypothesis that the overall strength of geopolymer mortar depends on the strength of the geopolymer binder materials, the packing density of the aggregates in the mortar and the amount of geopolymer binder. First, the strength of the binder was evaluated experimentally. Fly ash obtained from two different sources and ground granulated blast‐furnace slag were used as the main ingredients in the production of the geopolymer binder. Correlation between the packing density of the aggregates in the mortar and their influence on the binder demand and compressive strength were investigated. Finally, a conceptual framework for a geopolymer mortar mix design approach is proposed. In addition to describing the mortar mix design methodology in a rational way, it is hypothesized that the approach can also be extended to the development of a geopolymer concrete mix.
Design for service life: implementation of fib Model Code 2010 rules in the operational code ISO 16204
Authors: Helland Steinar
Published: October 2013

CEB/FIP Model Code 1990 (MC‐1990) did represent the technology and focus some 20 years ago. However, it soon became evident that the document had some notable lacunas. In 1995 the general assemblies of the two organizations endorsed CEB/FIP bulletin No. 228, extensions to MC 1990 for high‐strength concrete, and in 2000 a similar extension to MC 1990 for lightweight aggregate concrete as bulletin No. 4.

The fib approved bulletin No. 34 Model Code for Service Life Design (MC SLD) in 2006. All these three additions have since matured and are now incorporated in the new fib Model Code for Concrete Structures 2010 (MC‐2010).

The main purpose of an fib Model Code is to act as a model for operational standards. The obvious counterpart for a body such as fib operating worldwide is ISO. The initiative taken by MC SLD has therefore further matured in ISO TC‐71/SC‐3/WG‐4 and it was accepted as ISO 16204 “Durability – Service Life Design of Concrete Structures” during the summer of 2012.

According to the obligations given in the WTO Agreement on Technical Barriers to Trade, it is hoped that these principles will be further implemented in national and regional standards.

This article describes the need for a transparent methodology when dealing with service life design, and the process – originating from a group of enthusiasts one decade ago – through fib and finally reaching international consensus in ISO.
Behaviour of concrete in a stress continuity region after cracking under restrained drying shrinkage
Authors: Seo Tae‐Seok , Kim Jung‐Chul
Published: October 2013

Some studies have investigated the time‐dependent characteristic of concrete for predicting stress under restrained shrinkage. However, these studies investigated the shrinkage behaviour of concrete in restrained conditions before cracking, and no study has yet investigated the behaviour of concrete due to restrained shrinkage in the stress continuity region after cracking. Therefore, this study investigates the shrinkage behaviour of concrete in the stress continuity region after cracking in uniaxial restrained specimens and analyses the restrained tensile stress of concrete in this region by way of a bond analysis. The results show that the effective tensile Young's modulus considering tensile creep is approx. 22–26% of the static modulus of elasticity. Moreover, the analytical results of the restrained tensile stress of concrete considering the effective tensile Young's modulus were in accordance with the experimental results.
Resistance of reinforced concrete members with hollow circular cross‐section under combined bending and shear – Part II: New calculation model
Authors: Völgyi István , Windisch Andor
Published: October 2013

Part II analyses the applicability of current shear design models for RC members with a hollow circular cross‐section on the basis of experimental results introduced in Part I of this paper. A new calculation model is proposed which assigns the contribution of the concrete zone in compression to shear resistance. The proposed model takes into account how the flexural and shear reinforcement, the load‐to‐support distance and the shape of the cross‐section affect the shear resistance.

The model is based on the analysis of potential failure sections subjected to bending and shear, and applies a compatibility criterion that considers how the member carries the load. The analogy between the failure of the concrete compression zone and the failure of the soil along a sliding surface are presented as well as the conditions for the development of the failure section.
Residual compressive and flexural strength of a recycled aggregate concrete following elevated temperatures
Authors: Xiao Jianzhuang , Fan Yuhui , Tawana M.M.
Published: October 2013

A recycled aggregate concrete (RAC) with different replacement percentages of recycled coarse aggregates (RCAs) (i.e. 0, 30, 50, 70, 100%) was investigated experimentally at elevated temperatures. The residual compressive strength as well as the residual flexural strength of the RAC following elevated temperatures was studied and evaluated. A relationship between the residual compressive flexural strength of RAC and the elevated temperature was proposed. Furthermore, the relationship between the residual flexural strength and the compressive strength of the RAC was compared and analysed. It was found that both the residual compressive strength and the residual flexural strength of the RAC decrease with a rise in temperature, and the effect of the RCAs replacement percentage on the residual flexural strength and the residual compressive strength of RAC was found to be obvious.
A physical approach for considering how anchorage head size influences the punching capacity of slabs strengthened with vertical steel bolts
Authors: Silva Ricardo , Faria Duarte M. Viúla , Ramos A. Pinho , Inácio Micael
Published: October 2013

The introduction of new vertical steel bolts is an easy, practical and common solution for retrofitting and strengthening slabs for punching. Although a common option where punching strengthening is concerned, few studies exist regarding how the bolt's anchorage dimensions and its embedment in the concrete slab affect the strengthening efficiency. This work presents an analytical approach that is able to predict the punching capacity of slabs strengthened with post‐installed vertical steel bolts, taking into account the anchorage dimensions and positioning plus the material properties. This approach results from the combination of two physical models: one provided in the fib Model Code for Concrete Structures 2010 regarding the punching capacity estimation, and another that allows the deformation (crushing) of the concrete beneath the head of the anchorage to be taken into account. The predicted values are compared with experimental results, showing that the analytical approach is able to simulate correctly the anchorage behaviour and its influence regarding a slab's loadbearing capacity. A parametrical analysis is carried out in order to study the importance of different factors such as concrete compressive strength, longitudinal reinforcement ratio and steel bolt length, always accompanied by the effect of anchorage head size and embedment.
Design for SLS according to fib Model Code 2010
Authors: Balázs György L. , Bisch Philippe , Borosnyói Adorján , Burdet Olivier , Burns Clare , Ceroni Francesca , Cervenka Vladimir , Chiorino Mario A. , Debernardi Piergiorgio , Eckfeldt Lars , El‐Badry Mamdouh , Fehling Ekkehard , Foster Stephen J. , Ghali Amin , Gribniak Viktor , Guiglia Matteo , Kaklauskas Gintaris , Lark Robert J. , Lenkei Peter , Lorrain Michel , Marí Antonio , Ozbolt Josko , Pecce Marisa , Pérez Caldentey Alejandro , Taliano Maurizio , Tkalcic Damir , Torrenti Jean Michel , Torres Lluis , Toutlemonde François , Ueda Tamon , Vitek Jan L. , Vráblík Lukáš
Published: October 2013

This paper provides an overview of serviceability specifications given by the fib Model Code for Concrete Structures 2010 (fib MC2010 [1]). First, the reasons behind crack control and deflection control are discussed, then specific design rules are provided. Simple rules as well as detailed models are also presented. Numerical examples are provided in order to assist in the application of the design recommendations for crack control and deflection control (reinforced and prestressed concrete elements).

Simple rules mean indirect control of cracking or deflections without calculations. Indirect crack control may include limitation of stresses and selection of maximum bar diameter or maximum bar spacing. Indirect deflection control normally means limiting the span‐to‐depth ratio.

Detailed models are based on physical and mathematical approaches to cracking and deflections. The design crack width is expressed as the maximum bond transfer length multiplied by the mean strain between cracks. Deflection analysis can be provided by integrating curvatures or by using a simplified or refined method. Vibrations and numerical modelling of cracking are also briefly discussed.
Bilateral loading experiment on and analysis of concrete piers using mortar‐jointed ultra‐high‐strength fibre‐reinforced concrete precast formwork
Authors: Yamanobe Shinichi , Saito Kimio , Ichinomiya Toshimichi , Kanamitsu Yoshihisa
Published: October 2013

The seismic performance of a reinforced concrete pier structure depends greatly on the plastic hinge region at the base of the pier. To improve the plastic hinge region of the structure, we propose using ultra‐high‐strength fibre‐reinforced concrete (UFC) formwork for the concrete cover at the base of the pier. This study describes the structural characteristics of a pier with a base cast using mortar‐jointed UFC formwork.

To investigate the structural characteristics, a bilateral circular cyclic loading experiment and a simulation analysis using a fibre model were conducted. The results show that the flexural strength remained stable under a large rotation angle. Even at the rotation angle at the ultimate limit state, crushing failure of the mortar did not occur and the ultimate limit state did not result from mortar damage, because the tensile strength of mortar‐filled joints is close to zero, and thus excellent flexural crack distribution performance can be achieved.
fib Model Code for Concrete Structures 2010: mastering challenges and encountering new ones
Authors: Walraven Joost
Published: October 2013

The Model Code for Concrete Structures 2010 is a recommendation for the design of structural concrete, written with the intention of giving guidance for future codes. As such, the results of the newest research and development work are used to generate recommendations for structural concrete at the level of the latest state of the art. While carrying out this exercise, areas are inevitably found where information is insufficient, thus inviting further study. This paper begins with a brief introduction to the new expertise and ideas implemented in fib Model Code 2010, followed by a treatment of areas where knowledge appeared to be insufficient or even lacking and where further research might be useful.
Design recommendations for interface shear transfer in fib Model Code 2010
Authors: Randl Norbert
Published: October 2013

Interface shear transfer between differently aged concretes is a topic that crops up frequently and in different situations in structural design. In the fib Model Code for Concrete Structures 2010 the fundamental basics of concrete‐to‐concrete load transfer are given in section 6.3 and the corresponding design rules in 7.3.3.6. The different potential mechanisms contributing to the shear resistance along the interface, i.e. adhesive bond, aggregate interlock, friction and dowel action, are thus combined and their relationship taken into account by interaction factors. This article summarizes the most important results from past and ongoing studies and presents the background to the theory forming the design basis of fib Model Code 2010, the “extended shear friction theory” (ESF).
Reliability analysis of RC beams strengthened for torsion with carbon fibre composites
Authors: Souza Osvaldo Luiz de Carvalho , Sánchez Filho Emil de Souza , Vaz Luiz Eloy , Silva Filho Júlio Jerônimo Holtz
Published: October 2013

Two sets of reliability analyses for two beam series strengthened with carbon fibre composites (CFC) in different ways and subjected to torsional moments are described in this paper. The analyses consider three failure functions and the system is regarded as a series system formed by these three limit state modes.

Five random variables are taken into account in the first set of analyses. The analyses are performed for different torsional moment ratios, defined as the ratio of the torsional moment due to live loads to the total torsional moment. The system reliability indexes and the factors of importance associated with each random variable are obtained. In the second set of reliability analyses, only the two most relevant random variables selected in the first set of analyses according to the values of their factors of importance are considered, and new reliability indexes are determined. The examples show that despite the constant value of the total torsional moment, the increase in the torsional moment ratio leads to a decrease in the system reliability levels. The fact that the values of the reliability indexes obtained in both sets of reliability analyses are very similar validates the efficiency of the sensitivity analyses.
Shear in concrete structures subjected to dynamic loads
Authors: Magnusson Johan , Hallgren Mikael , Ansell Anders
Published: October 2013

Shear failures in reinforced concrete structures under intense dynamic loads are brittle and limit the structure's energy‐absorbing capabilities. This paper comprises a review of the literature dealing with the problem of dynamic shear of reinforced concrete elements, with a focus on parameters that control flexural shear and direct shear. In this context, dynamic loads refer to intense events due to explosions and impacts. For this reason, the initial response is also highlighted. Experimental investigations and calculations show that shear force and bending moment distributions in dynamic events are initially significantly different from the distributions under slowly applied loads. Therefore, structural wave propagation, geometrical properties of elements, strain rate effects and dynamic load characteristics need to be considered when analysing shear. The review also indicates that arch action in the shear span soon after the load has been applied has a large influence on the shear capacity of an element. This action is of particular importance in intense loading events. Finally, suggestions for further research are identified.
Structural behaviour and deformation patterns in loaded plain concrete ground‐supported slabs
Authors: Alani Amir M. , Rizzuto Joseph , Beckett Derrick , Aboutalebi Morteza
Published: October 2013

The work presented in this paper is considered to be an attempt to contribute towards a better understanding of the structural behaviour of plain concrete slabs under step loading conditions. The Concrete Society Technical Report TR34 “Concrete Industrial Ground Floors” is in its 3rd edition (2003) and is currently under review. TR34 covers the design of concrete ground‐supported slabs containing fibres, both steel and synthetic, as an alternative to mesh reinforcement. This work reports on tests carried out at different critical loading locations, including the centre, edges and corners of a 6.0 × 6.0 × 0.15 m deep plain concrete slab. The test results are compared with theoretical values derived using available design codes and other information sources. The results show a notable difference between the test results and the theoretical values.
Prenatal unilateral cerebellar hypoplasia in a series of 26 cases: significance and implications for prenatal diagnosis
Authors: Massoud M. , Cagneaux M. , Garel C. , Varene N. , Moutard M.‐L. , Billette T. , Benezit A. , Rougeot C. , Jouannic J.‐M. , Massardier J. , Gaucherand P. , Desportes V. , Guibaud L.
Published: October 2013

Objective

To define imaging patterns of unilateral cerebellar hypoplasia (UCH), discuss possible pathophysiological mechanisms and underline the etiology and prognosis associated with these lesions.

Methods

In this retrospective study we reviewed the charts of 26 fetuses diagnosed between 2003 and 2011 with UCH, defined by asymmetrical cerebellar hemispheres with or without decreased transverse cerebellar diameter. The review included analysis of the anatomy of the cerebellar hemispheres, including foliation, borders and parenchymal echogenicity, and of the severity of the hypoplasia. Data from clinical and biological work‐up and follow‐up were obtained.

Results

Our series could be divided into two groups according to whether imaging features changed progressively or remained constant during follow‐up. In Group 1 (n = 8), the progression of imaging features, echogenic cerebellar changes and/or hyposignal in T2*‐weighted MR images were highly suggestive of ischemic/hemorrhagic insult. In Group 2 (n = 18), imaging features remained constant during follow‐up; UCH was associated with abnormal foliation in three proven cases of clastic lesions, a cystic lesion was noted in three cases of PHACE (posterior fossa anomalies, hemangioma, arterial anomalies, cardiac abnormalities/aortic coarctation, eye abnormalities) syndrome and, in the remaining cases, UCH remained unchanged, with no imaging pattern typical of hemorrhage. In 24 cases the infant was liveborn and follow‐up was continued in 23, for a mean period of 3 years. Among these, neurological complications were identified in seven (in one of seven (at a mean of 46 months) in Group 1 and in six of 16 (at a mean of 35 months) in Group 2). The surface loss of cerebellar hemisphere was > 50% in 19/24 fetuses and the vermis was clearly normal in appearance in 19/24. Predisposing factors for fetal vascular insult were identified in eight cases: these included maternal alcohol addiction, diabetes mellitus, congenital cytomegalovirus infection and pathological placenta with thrombotic vasculopathy and infarctions.

Conclusion

UCH is defined as a focal lesion of the cerebellum that may be secondary to hemorrhage and/or ischemic insult, suggesting a clastic origin, particularly when imaging follow‐up reveals changes over time. UCH may also be a clue for the prenatal diagnosis of PHACE syndrome. The amount of surface loss of cerebellar hemisphere does not correlate with poor prognosis. UCH with normal vermis is often associated with normal outcome. Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd.
Synthesis of the Benzoate Intercalated Layered Double ­Hydroxide of Nickel and Aluminum: Application of Mering's Rule
Authors: Manohara G. V. , Vishnu Kamath P.
Published: October 2013

Homogeneous precipitation from a mixed metal nitrate solution using benzamide as a hydrolysis agent results in the formation of a benzoate‐intercalated layered double hydroxide of nickel and aluminum with a basal spacing of 15.6 Å. The alternation in the line widths of the basal reflections has been shown to arise by the random interstratification of a 8.8 Å phase with an altered orientation of the benzoate ions. This work is an illustration of the application of Mering's rules to model disorder in layered double hydroxides.
Formation and Decomposition of Metastable α′′‐Fe16N2 from in situ Powder Neutron Diffraction and Thermal Analysis
Authors: Widenmeyer Marc , Hansen Thomas C. , Niewa Rainer
Published: October 2013

In order to gain more information on the formation and decomposition behavior of metastable α′′‐Fe16N2 from different starting materials in situ neutron diffraction and thermal analysis in different gas atmospheres and heating rates were carried out. Under inert conditions a direct conversion of α′′‐Fe16N2 in α‐Fe and N2 was observed using higher heating rates, while with lower heating rates the decomposition occurs via the formation of γ′‐Fe4Ny. The changes in c/a ratio of the α′′‐phase are related to a subsequent transformation into martensitic α′‐Fe8N during the decomposition. In situ neutron diffraction data were collected in high quality, due to an optimized experimental setup with a time resolution of two minutes on D20 (Institut Laue‐Langevin, ILL) allowing for detailed Rietveld analyses. Thermal analyses support the proposed metastable nature of α′′‐Fe16N2. For all phase transition temperatures within the investigated system a strong dependency from heating rate, thermal history of the sample, gas flow conditions, and particle size exists. Particularly, for bulk α′′‐Fe16N2 the synthesis conditions from reaction of in situ produced fine iron particles and ammonia were improved and a high purity sample [93(2) wt %] was achieved.
New Acyclic Neutral Phosphorus Sulfides and Sulfide Oxides
Authors: Schönberger Stefanie , Jagdhuber Christoph , Ascherl Laura , Evangelisti Camilla , Klapötke Thomas M. , Karaghiosoff Konstantin
Published: October 2013

A great number of binary neutral phosphorus sulfides was discovered and investigated. However all stable representatives of this family of compounds adopt a polycyclic structure in contrast to their lighter homologues, the nitrogen oxides. Acyclic representatives can be stabilized by adduct formation with a nitrogen base. The bis(pyridine) adduct py2P2S5 of the unstable acyclic phosphorus sulfide P2S5 is readily obtained stirring P4S10 in pyridine at ambient temperature. X‐ray diffraction studies on single crystals of py2P2S5·0.5 py (1b) show a N2O5 like structure for the P2S5 framework. The long P–N distances of 1.86 Å indicate only weak coordination of the pyridine molecules to phosphorus. Single crystal X‐ray diffraction studies on py2P2S4.34O0.66 (2) reveal the presence of py2P2S4O (3) together with py2P2S5 in the crystal. Compound 3 contains the mixed phosphorus oxide sulfide molecule P2S4O stabilized as bis(pyridine) adduct. It is readily obtained from pyP2S5 by oxidation with KMnO4 in pyridine. The oxygen atom occupies the bridging position between the two phosphorus atoms. Quantum chemical calculations at the MPW1PW91 level of theory as well as DTA/TG thermal analyses confirm the weak coordination of the pyridine molecules in py2P2S5, py2P2S4O, and py2P2S7 to phosphorus.
The Formation of Hemiacetal Complexes of Rhenium(V) by Degradation of a Schiff Base
Authors: Barandov Ali , Abram Ulrich
Published: October 2013

Mono‐ and dinuclear oxidorhenium(V) complexes with hemiacetal ligands were isolated from a reaction of (NBu4)[ReOCl4] with a potentially tetradentate Schiff base prepared from (1R,2R)‐cyclohexane‐1, 2‐diamine and (2‐formylphenyl)diphenylphosphine in methanol. The hemiacetal is formed by solvolysis of first one imine functionality of the Schiff base, whereas the second remains intact. The resulting amine/iminophosphine coordinates as a tridentate N,N, P ligand in a dinuclear compound. Ongoing degradation of the Schiff base gives more hemiacetal (HL1a) and the final product, the monomeric complex [ReOCl(L1a)2] is formed. Cleavage of the organic framework is not observed during the reaction of (NBu4)[ReOCl4] with a related Schiff base derived from ethylene‐1, 2‐diamine and (2‐formylphenyl)diphenylphosphine. The Schiff base reacts as a bis‐bidentate N, P ligand and a dinuclear oxorhenium(V) compound with a central ethylene bridge is formed.
Synthesis of Palladium and Platinum Complexes with an NH, NEt‐substituted Benzimidazolin‐2‐ylidene Ligand
Authors: Hervé Alexandre , Jahnke Mareike C. , Pape Tania , Hahn F. Ekkehardt
Published: October 2013

The compound 2‐chloro‐N‐ethylbenzimidazole 1 was synthesized and was reacted with complexes of type [M(PPh3)4] (M = Pd, Pt) in the presence of NH4BF4 as proton source. This reaction leads via an oxidative addition to complexes of type [MCl(NH, NEt‐NHC)(PPh3)2]BF4 (M = Pd, [3]BF4; M = Pt, [4]BF4). In case of M = Pd, only compound trans‐[3]BF4 was obtained, while for M = Pt two isomeric platinum complexes cis‐[4]BF4 and trans‐[4]BF4 were obtained in a ratio of 78:22. The molecular structures of the square‐planar complexes trans‐[3](BF4) and cis‐[4]BF4 were determined by X‐ray diffraction.
State of the Art of Robotic Pancreatic Surgery
Authors: Milone Luca , Daskalaki Despoina , Wang Xiaoying , Giulianotti Pier Cristoforo
Published: October 2013

More than a decade has passed since robotic technology was adopted for abdominal surgery, and virtually every gastrointestinal operation has since been shown to be feasible, safe, and reproducible using the robotic approach. Robotic pancreatic surgery had been left behind at the beginning, because they were technically challenging, requiring not only being very familiar with the robotic technology but also having a perfect knowledge of the anatomical variations, very frequent in this area. Nonetheless in the last few years many authors have approached the robot for pancreatic surgery with very promising results in terms of surgical and oncological outcomes. The aim of this article is to review the literature on robotic pancreatic surgery and to define the state of the art use of the robotic approach for pancreatic disease.