bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural systems for protection against extreme events
Authors: van Breugel Klaas
Published: October 2013

Typical for extreme events is their multidisciplinary nature, and, consequently, solutions for protection against extreme events should mirror their inherent characteristics. This article discusses different types of hazards and extreme events in order to illustrate the complexity and scale of the problem. Concepts for judging hazards and associated risks are dealt with. Some features of the traditional risk concept are discussed, followed by a proposal for an extended risk concept, to be applied when dealing with extreme hazards. The emphasis will be on aspects that are typical of “low‐probability/high‐consequence risks”, particularly industrial risks. The potential role of structural (concrete) protective systems for mitigating the consequences of industrial accidents is emphasized. Throughout this article, the role of structural designers and their possible contribution to the debate on adequate protection against extreme events is addressed.
Application of performance‐based environmental design to concrete and concrete structures
Authors: Kawai Kenji
Published: October 2013

The environmental impact and the effect of its reduction must be assessed quantitatively if we are to show clearly the effect of lowering the environmental impact of concrete and concrete structures. One of the quantitative evaluation methods is to regard and verify the environmental impact of concrete and concrete structures as an environmental performance in accordance with the performance‐based design method. This article briefly describes the performance‐based environmental design method prepared by fib Commission 3 TG3.6 and shows an example of the application of the design method applied to a concrete structure.
Minimizing environmental impact and maximizing performance in concrete recycling
Authors: Noguchi Takafumi , Kitagaki Ryoma , Tsujino Masato
Published: October 2013

The sheer amount of concrete in use and in stock compared with other building materials throws up environmental issues such as the huge amount of CO2 emitted when cement and concrete are produced and transported and the enormous amount of waste generated when concrete is disposed of. In addition, we are beginning to deplete aggregate resources at a fast rate. Concrete has conventionally been regarded as being difficult to recycle. The construction industry has addressed these problems and carried out research and development regarding the recycling of concrete since the 1970s. Recycling technology has been shifting from simple crushing into scrubbing with some preparations to produce high‐quality recycled aggregate for structural concrete, and recycling of concrete in a completely closed loop has now become technically feasible. This paper reviews the development history of recycling technologies in Japan from the viewpoint of the properties of recycled aggregate and recycled aggregate concrete as well as the environmental impact such as CO2 emissions and waste generation in recycling. The paper also presents the outline of completely recyclable concrete, with which closed‐loop circulation of component materials is realized.
Reorganization of the ACI 318 Building Code
Authors: Poston Randall W. , Dolan Charles W.
Published: October 2013

In 2008, ACI 318 initiated a six‐year task of reorganizing the format of the ACI Building Code for Concrete Structures. This is the first major reorganization of the code in nearly 40 years. The reorganization effort moves the code from a behaviour‐based to a member‐based design approach. This article presents the philosophy of the code development, efforts leading up to the reorganization and an outline of the 2014 code format.
Base‐isolated super high‐rise RC building composed of three connected towers with vibration control systems
Authors: Nishimura Akira , Yamamoto Hiroshi , Kimura Yasuhiko , Kimura Hideki , Yamamoto Masashi , Kushibe Atsumichi
Published: October 2013

The Island Tower Sky Club is a super high‐rise RC apartment block constructed in Fukuoka City, Japan, which makes inventive use of the most advanced building technologies. The building is 145 m tall with 42 storeys. It is composed of three similar, slender towers with three‐fold rotational symmetry. The towers are connected at three different levels by aerial gardens and contain various vibration control devices to assure a high level of safety. The aerial gardens are connected to the towers by vibration control dampers to reduce the overturning effects of the towers caused by seasonal winds and large earthquakes. An elaborate control system can reduce the storey acceleration response by 30 %. At the upper two storeys of each tower, super‐plastic zincaluminium alloy dampers are also used. To reduce the storey acceleration response, the base of the building is isolated using a hybrid system of bearing supports and dampers. The validity of the control system implemented is confirmed by human power vibration tests conducted at the aerial gardens.
Formwork pressure induced by highly flowable concretes – design approach and transfer into practice
Authors: Graubner Carl‐Alexander , Boska Erik , Motzko Christoph , Proske Tilo , Dehn Frank
Published: October 2013

An analytical model for the calculation of the pressure of concrete on vertical formwork has been developed on the basis of experimental tests on highly flowable concretes in the fresh state (see companion paper “Material investigations and large‐scale tests”). The model takes into account the time‐dependent material parameters of the fresh concrete, the specific properties of the highly flowable vibrated concretes and self‐compacting concretes (SCC) as well as operational aspects. A proposal for the design of formwork was developed based on the experimental tests and the semi‐probabilistic safety concept. It was found that the design load is often lower than the hydrostatic concrete pressure – even for highly flowable concretes. On construction sites, the pressure can be best controlled by limiting the casting rate. Insufficient experience of personnel in the handling of highly flowable concretes increases the uncertainties with respect to the design values and the safety risk.

Further investigations into construction management‐related aspects regarding the use of highly flowable concretes cover the risk assessment during concreting, design of the processes on the construction site and the development of the basis for a documentation system.
Statistical comparison of data from concrete families in ready‐mixed concrete plants
Authors: Caspeele Robby , Taerwe Luc
Published: October 2013

Data has been collected from several European ready‐mixed concrete plants in order to analyse some data‐based statistical aspects of the concrete family concept. Concrete strength records of concrete families were obtained from seven different concrete plants. This data is used to investigate the presence of autocorrelation in the transposed data of concrete family strength records. Further, strength records from two Belgian concrete plants are investigated in more detail and used to investigate how the concrete family concept, the applied transformation method and the family composition guidelines influence the general quality of accepted batches.
Behaviour of steel prestressing wires under extreme conditions of strain rate and temperature
Authors: Gálvez Francisco , Atienza Jose Miguel , Elices Manuel
Published: October 2013

The purpose of this paper is to provide information on the behaviour of steel prestressing wires under likely conditions that could be expected during a fire or impact loads. Four loadings were investigated: a) the influence of strain rate – from 10–3 to 600 s–1 – at room temperature, b) the influence of temperature – from 24 to 600 °C – at low strain rate, c) the influence of the joint effect of strain rate and temperature, and d) damage after three plausible fire scenarios.

At room temperature it was found that using “static” values is a safe option. At high temperatures our results are in agreement with design codes. Regarding the joint effect of temperature and strain rate, mechanical properties decrease with increasing temperature, although for a given temperature, yield stress and tensile strength increase with strain rate. The data provided can be used profitably to model the mechanical behaviour of steel wires under different scenarios.
The levels‐of‐approximation approach in MC 2010: application to punching shear provisions
Authors: Muttoni Aurelio , Ruiz Miguel Fernández
Published: October 2013

In order to address how new knowledge influences design expressions, design codes have in most cases become significantly more complex over the last decades. However, this tendency is leading to codes that are too complicated for preliminary design but still not sufficiently accurate for assessing existing structures (where even more realistic models of behaviour are sometimes required). An alternative code strategy is that proposed by codes based on a levels‐of‐approximation (LoA) approach. This approach is based on the use of theories based on physical parameters where the hypotheses for their application can be refined as the accuracy required increases. The approach proposes adopting safe hypotheses during the first stages of design, leading to relatively quick and simple analyses. In cases where such a degree of accuracy is not sufficient (e.g. design of complex structures, assessment of existing structures, significant potential economic savings), the hypotheses can be refined in a number of steps, leading to better estimates of the behaviour and strength of members. This approach, recently adopted in the first complete draft of Model Code 2010 for a number of design issues, is discussed within this paper with reference to punching shear provisions.
Behaviour of tilt‐up precast concrete buildings during the 2010/2011 Christchurch earthquakes
Authors: Henry Richard , Ingham Jason
Published: October 2013

The Christchurch region of New Zealand experienced a series of major earthquakes and aftershocks between September 2010 and June 2011 which caused severe damage to the city's infrastructure. The performance of tilt‐up precast concrete buildings was investigated and initial observations are presented here. In general, tilt‐up buildings performed well during all three major earthquakes, with mostly only minor, repairable damage occurring. For the in‐plane loading direction, both loadbearing and cladding panels behaved exceptionally well, with no significant damage or failure observed in panels and their connections. A limited number of connection failures occurred due to large out‐of‐plane panel inertia forces. In several buildings, the connections between the panel and the internal structural frame appeared to be the weakest link, lacking in both strength and ductility. This weakness in the out‐of‐plane load path should be prevented in future designs.
Design procedure and simplified equations for the flexural capacity of concrete members reinforced with fibre‐reinforced polymer bars
Authors: Torres Lluis , Neocleous Kyriacos , Pilakoutas Kypros
Published: October 2013

The predominant failure mode of concrete members reinforced with fibre‐reinforced polymer (FRP) bars is flexural, due to either concrete crushing or FRP rupture. Many design tools have been developed for the flexural design of FRP‐reinforced concrete. These tools are sufficiently accurate, but an iterative procedure is required when dealing with flexural failure due to FRP rupture. In addition, despite the fact that the design concepts involved are similar to those used for conventional steel‐reinforced concrete, the changes in the design philosophy and the linear behaviour up to rupture of the FRP bars lead to the sectional properties having a different influence on the design, which not everyone may be familiar with. Therefore, this study proposes a general methodology for evaluating the design flexural capacity of FRP‐reinforced concrete sections. This methodology is based on the design provisions of Eurocode 2 and comprises non‐dimensional, closed‐form equations, derived independently of the concrete and FRP characteristics. The proposed methodology can be used to derive universal dimensionless design charts as well as tables. The accuracy of the proposed design tools has been verified by comparing the predictions with the experimental results of 98 beams, which are available in the published literature.
Precast concrete structures: the lessons learned from the L'Aquila earthquake
Authors: Toniolo Giandomenico , Colombo Antonella
Published: October 2013

This paper examines the problems of the seismic design of precast concrete structures as indicated by the effects of the L'Aquila earthquake of 2009. The behaviour of such structures on that occasion is analysed on the basis of detailed surveys performed on site on a relevant number of buildings just after the earthquake.

Following this analysis, which points out the inadequacy of the cladding panel connections, the paper presents a systematic definition of the problem, examining the behaviour of the whole system of structure + panels. Proposals are made for the typology of one‐storey buildings for industrial uses, some possible alternative solutions that ensure the stability of all the construction elements. Specific calculations for a typical precast building give the order of magnitude of the forces and/or displacements for which the connections are to be designed.
Stress‐strain behaviour of self‐compacting concretes containing limestone fillers
Authors: Desnerck Pieter , De Schutter Geert , Taerwe Luc
Published: October 2013

Knowledge of the stress‐strain relationship of concrete under uniaxial compression is crucial for the design of concrete members. This study focuses on the stress‐strain behaviour under compression and especially the strain‐softening of self‐compacting concretes produced with limestone fillers. Four self‐compacting concretes (SCC) and three conventional vibrated concretes (VC) were used to produce cylindrical test specimens with an h/d ratio of 3. The σ‐ϵ diagram at five different ages (3–91 days) was recorded during uniaxial compressive tests. The peak strain of the SCC cylinders was shown to be higher than the ones recorded for VC concretes. However, the specific toughness of both concrete types turned out to be comparable.
Deterioration model and input parameters for reinforcement corrosion
Authors: Beck Matthias , Burkert Andreas , Harnisch Jörg , Isecke Bernd , Osterminski Kai , Raupach Michael , Schießl Peter , Tian Wei , Warkus Jürgen
Published: October 2013

The paper presents the damage model of German Research Unit 537 which was used as a working hypothesis for the development of a user‐friendly design model. Excerpts from the laboratory experiments and numerical calculations processed in project A of the research unit are presented here. The excerpts include the quantification of self‐corrosion, geometrical effects in the macrocell corrosion, development of corroding steel surface and pit depth as well as the quantification of the resistivity of the concrete and the corrosion of steel in cracked concrete.
Experimental evaluation of large circular RC columns under pure compression
Authors: Lee Tai‐Kuang , Chen Cheng‐Cheng , Pan Austin D.E. , Hsiue Kai‐Yuan , Tsai Wei‐Ming , Hwa Ken
Published: October 2013

Eight sets of large, circular, short reinforced concrete columns were tested under monotonic axial compression. The primary variables are type of transverse reinforcement (spiral vs. circular tie), type of splice, end hook length and staggered length of adjacent circular ties. The tests confirmed the acceptable performance of the circular tie newly proposed in ACI 318M‐11. In addition, the circular tie scheme in which the ends terminate with hooks that engage with a longitudinal steel bar and bend into the concrete core is acceptable for performance and ease of construction. The effectiveness of its end hook length and the staggered length of adjacent circular ties is also investigated.
Reliability‐based non‐linear analysis according to fib Model Code 2010
Authors: Cervenka Vladimir
Published: October 2013

The fib Model Code 2010 for Concrete Structures introduces numerical simulation as a new tool for designing reinforced concrete structures. The model of resistance based on non‐linear analysis requires adequate model validation and a global safety format for verifying designs. The numerical simulations combined with random sampling offer the chance of an advanced safety assessment. Approximate methods of global safety assessment are discussed and compared in a case study. An example of a bridge design supported by non‐linear analysis is shown.
Compressive, tensile and bending basic creep behaviours related to the same concrete
Authors: Tailhan Jean‐Louis , Boulay Claude , Rossi Pierre , Le Maou Fabrice , Martin Eric
Published: October 2013

This paper concerns the relationship between compressive, tensile and flexural creep behaviours related to the same concrete. Experimental tests and a numerical simulation are performed in the scope of this work. The main conclusion of this study is that due to the strong scale effect related to the tensile and bending creep behaviours of a “standard” concrete mix design, it is not possible to simulate numerically (with classical Kelvin‐Voigt chains) the bending creep behaviour of that type of concrete knowing the compressive and tensile creep behaviours obtained using the specimen geometries normally used in laboratories.
Design for punching of prestressed concrete slabs
Authors: Clément Thibault , Ramos António Pinho , Fernández Ruiz Miguel , Muttoni Aurelio
Published: October 2013

Prestressing in flat slabs helps to control deformations and cracking under service loads and allows the required slab thickness to be reduced, thus leading to more slender structures and an economic solution for long spans. However, as a consequence of the limited thickness of these members, punching typically governs at the ultimate limit state. Studies of the punching shear strength have shown that the presence of prestressing in flat slabs has a number of potential beneficial effects, namely the vertical component (force) carried by inclined tendons, the in‐plane compression stresses and the bending moments developed near the supported region. However, the approach provided by codes of practice for punching design in the presence of prestressing may differ significantly. Some codes neglect the influence of the bending moments introduced as a result of prestressing and the sections at which the deviation forces of the tendons are considered may be located at different distances from the edge of the supported region. The influence of prestressing on the punching shear strength of members without shear reinforcement is investigated in this paper by using the fundamentals of the critical shear crack theory. Using that as a basis, and also taking into account 65 tests available in the scientific literature, the suitability and accuracy of a number of design codes, e.g. Model Code 2010, Eurocode 2 and ACI 318‐11, are investigated and compared.
Normal impact of hard projectiles on concrete targets
Authors: Khazraiyan Najmeh , Liaghat Gholam Hossein , Khodarahmi Hossein
Published: October 2013

This research study involves obtaining an analytical model for the perforation of unreinforced concrete targets by a hemispherical hard projectile. Dynamic cavity expansion theory and the reflection of compressive waves from the end of the concrete targets are used for developing the analytical model. The effect of the friction coefficient is also investigated in the analysis. Numerical modelling of the problem has been performed in LS‐DYNA code for validating the analytical results. Johnson‐Holmquist concrete and rigid material models have been employed for the concrete and the projectile respectively. The impact velocity range considered in this work is between 250 and 850 m/s. No projectile erosion is considered in this range. The analytical results have been compared with numerical results and show good agreement with numerical simulations.
Highlights of the design and construction of a 12 km elevated APM bridge project in Saudi Arabia
Authors: Ayoub Essam , Malek Charles , Helmy Gamal
Published: October 2013

The automated people mover (APM) bridge project constructed at Princess Nora University (PNU) in Saudi Arabia and inaugurated in May 2012 is a major project with many challenges in design and construction due to its strict time‐frame compared with the big scale of the project. Therefore, the design had to be such that it ensured simplicity, time‐savings, lowest costs, aesthetics and the high quality required for bridge project elements. For aesthetic reasons, a box section was chosen for all the APM bridge sections for the bridge project, including straight, bifurcation and curved parts. This paper highlights the efficiency of the precast concrete techniques used in the design and construction of big projects such as this elevated APM bridge project at PNU in Saudi Arabia.
Two‐layer concrete bridge beams as composite elements
Authors: Iskhakov Iakov , Ribakov Yuri
Published: October 2013

Two‐layer high‐performance RC beams can be used in the traffic (longitudinal) direction of long‐span bridges. The beam section consists of two parts: a bottom part made of normal‐strength concrete (NSC), which has a U‐type section, and an upper one made of steel fibre‐reinforced high‐strength concrete (HSC), which has a rectangular section. Using two‐layer beams is logical because as the beam span becomes longer and the service load increases, so a higher concrete strength is required in the beam's compression zone to withstand rather large bending moments. As concrete in the tension zone of the section contributes little to the beam's loadbearing capacity, this zone is made of NSC. This is an important economical advantage of two‐layer beams. Steel fibres are only used in the compression zone made of HSC. The addition of steel fibres results in a higher ductility for the HSC layer, allowing proper design of two‐layer bridge beams for dynamic loads. The design parameters for such beams include the HSC class, where the HSC layer depth is known and is equal to the depth of the rectangular section (above the U‐section). The bottom NSC part (U‐section) of a long‐span beam is usually prestressed. Taking into account this circumstance, the total beam section depth should be checked for the serviceability limit state.
Performance‐ and displacement‐based seismic design and assessment of concrete structures in fib Model Code 2010
Authors: Fardis Michael N.
Published: October 2013

The scope of fib Model Code for Concrete Structures 2010 includes the fully fledged performance‐ and displacement‐based seismic design of new structures and assessment of existing ones. This part of fib Model Code 2010 covers buildings, bridges or similar concrete structures and aims to provide well‐defined performance levels for specific seismic hazard levels. Detailing of members for ductility is not based on opaque prescriptions, as in current codes, but on transparent, explicit verification of inelastic deformation demands against capacity limits. The reference analysis method is non‐linear dynamic, but under certain conditions inelastic deformation demands may be estimated from linear analysis and the 5%‐damped elastic response spectrum; in that case force demands on force‐controlled, brittle failure modes are estimated from the plastic mechanism through equilibrium. In order to predict the seismic deformation demands with some confidence, the analysis should use realistic values for the member secant stiffness up to the yield point. The paper explains the background to the expressions given for this property in fib Model Code 2010 as well as of those for the deformation limits used when verifying seismic deformation demands. The modifications to the shear resistance approach of fib Model Code 2010, which takes cyclic loading into account, are also explained and justified.
Non‐linear analysis of statically indeterminate SFRC columns
Authors: Abbas Ali A. , Mohsin Sharifah M. Syed , Cotsovos Demetrios M.
Published: October 2013

The structural behaviour of steel fibre‐reinforced concrete (SFRC) has been studied using non‐linear finite element analysis (NLFEA) and ABAQUS software. An interesting feature of this work is the consideration of statically indeterminate SFRC columns. Most of the SFRC specimens studied in the literature are simply supported beams, and information on statically indeterminate columns is sparse. In addition, both axial and lateral loads were considered in order to allow for compression and flexural effects on the columns. The aim of the work was to examine the potential for using steel fibres to reduce the amount of conventional transverse steel reinforcement without compromising ductility and strength requirements. To achieve this, the spacing between shear links was increased while steel fibres were added as a substitute (spacing between shear links increased by 50 and 100 % with fibre volume fraction Vf increased to Vf = 1, 1.5, 2 and 2.5 %). The numerical model was carefully calibrated against existing experimental data to ensure the reliability of its predictions. Parametric studies were subsequently carried out, which provided insight into how the steel fibres can help reduce the number of conventional shear links.
Strengthening the 100‐year‐old reinforced concrete dome of the Centennial Hall in Wrocław
Authors: Onysyk Jerzy , Biliszczuk Jan , Prabucki Przemysław , Sadowski Krzysztof , Toczkiewicz Robert
Published: October 2013

The Centennial Hall, a reinforced concrete structure with an auditorium for 10000 people, was opened in Wrocław, Poland (then Breslau, Germany), in 1913 after two years of construction. Its dome, covering the whole building, has a diameter of 65.0 m and in the year it was completed was the largest reinforced concrete dome in the world. This broke the previous record, held by the dome of the Pantheon in Rome (43.3 m), which had lasted for 1787 years. This paper describes the structure of the building, its condition after 100 years of use and the renovation works carried out in 2009–2011. An important part of the renovation was strengthening the lower (tension) ring of the ribbed dome by way of external prestressing. Details concerning the assessment of the technical condition of the hall, numerical calculations and the proposed system of strengthening are presented. In 2006 the monumental Centennial Hall was listed as a UNESCO World Heritage Site for its pioneering reinforced concrete structure, designed in the style of modernism.
Cracking performance of SCC reinforced with recycled fibres – an experimental study
Authors: Groli Giancarlo , Pérez Caldentey Alejandro , Soto Alejandro Giraldo
Published: October 2013

This paper presents an experimental campaign aiming to assess the cracking behaviour of flexural members made with self‐compacting concrete (SCC) and reinforced with both rebars and steel fibres recycled from end‐of‐life tyres (ELT). The characteristics, constructability and performance of this new type of fibre are first discussed. The results of the tests carried out are then presented and discussed. The parameters that have been investigated are: ϕ/ρs,ef, concrete cover and fibre content. The results obtained show improvement in cracking behaviour, especially for low reinforcement ratios and large covers. Results are compared with the predictions of the recently published fib Model Code for Concrete Structures 2010. The main objective of this investigation is to evaluate the efficiency of a new type of fibre technology for crack width control of RC elements, with advantages in sustainability from the point of view of recycling and durability.
Sustainability in fib Model Code 2010 and its future perspective
Authors: Sakai Koji
Published: October 2013

Considering the depletion of resources and energy and the risks of climate change on a global scale, a thoughtless increase in the use of resources and energy in the construction sector is obviously unacceptable. The sector has until now constructed a system of technology focused on safety and comfort, with priority given to economic and social benefits. Such demands remain extremely important; however, in the future we ought to give additional consideration to the depletion of resources, energy consumption and other, ensuing environmental issues. This means that the sector needs to incorporate sustainability – including the environmental, economic and social aspects – into its systems of design and technology. The fib decided to incorporate a “concrete sustainability” concept in its new fib Model Code for Concrete Structures 2010. This paper explains sustainability as expressed in this code together with the background to it. In addition, the essence of sustainability with respect to future Model Codes is discussed.
Fibre‐reinforced polymer reinforcement enters fib Model Code 2010
Authors: Triantafillou Thanasis , Matthys Stijn
Published: October 2013

Most applications of fibre‐reinforced polymers (FRP) deal with externally bonded reinforcement as a means of repairing and strengthening reinforced concrete (RC) structures or retrofitting RC structures in seismic regions. As internal reinforcement, FRP rebars or (more rarely) prestressing elements are used in special projects, combining material strength and durability characteristics. Over the last years, several national and international design guidelines have become available specifically for the design and application of FRP‐strengthened or FRP‐reinforced concrete structures. These efforts clearly demonstrate the interest in FRP as a novel reinforcing material for concrete construction. Hence, the time had come to introduce FRP reinforcement into the new fib Model Code for Concrete Structures 2010 as well. The main contributions to the fib Model Code 2010 relate to sections 5.5 “Non‐metallic reinforcement” and 6.2 “Bond of non‐metallic reinforcement”. The material presented in those two sections is further elaborated in this article.
Early‐age behaviour of precast concrete immersed tunnel based on degree of hydration concept
Authors: Liu Xian , Jiang Wei , De Schutter Geert , Yuan Yong , Su Quanke
Published: October 2013

Using the Hong Kong–Zhuhai–Macao Link project as an example, the focus of this research is to describe the early‐age behaviour of a precast immersed tunnel using a constitutive model based on the degree of hydration concept. In this way, the effect of both age and temperature on the early‐age behaviour can be taken into account simultaneously. Special attention is also paid to early‐age creep under varying stress levels combined with the degree of hydration concept. Numerical procedures are proposed to predict the early‐age behaviour of immersed tunnel segments during the entire fabrication process. The engineering factors related to early‐age cracking are analysed and discussed. This in‐depth study results in a better understanding, and further appropriate practical measures can be employed to control early‐age cracking in the actual project.
Staggered lap joints for tension reinforcement
Authors: Cairns John
Published: October 2013

Staggering lapped joints increases the complexity of detailing and steel fixing, and may require additional resources and slow construction on site. Major design codes encourage staggering lapped joints in tension by imposing a penalty on lap length depending on the proportion of bars lapped at the same section. There are, however, inconsistencies in the value of the coefficients to be applied, and little evidence is available for validation. A programme of 17 physical tests found no evidence of an increase in strength when laps were staggered, and when allowance is made for increases in transverse spacing, staggering was found to reduce lap strength. Differences in the distribution of bond stress through a lap joint and in the share of the tension force taken by continuous and lapped bars are demonstrated to be responsible for the reduction.
Conservation of concrete structures according to fib Model Code 2010
Authors: Matthews Stuart , Bigaj‐van Vliet Agnieszka
Published: October 2013

Conservation of concrete structures forms an essential part of the fib Model Code for Concrete Structures 2010 (fib Model Code 2010). In particular, Chapter 9 of fib Model Code 2010 addresses issues concerning conservation strategies and tactics, conservation management, condition surveys, condition assessment, condition evaluation and decision‐making, making interventions and the recording of information for through‐life management.

Chapter 9 incorporates the overall philosophy adopted in the development of fib Model Code 2010, which introduces a new integrated life cycle perspective into the design of concrete structures. Accordingly, Chapter 9 provides a response to concepts introduced earlier within fib Model Code 2010 relating to the service life design process, which requires the structure and its component parts to be allocated to a condition control category at the time of design. Different condition control categories are defined depending on factors such as the importance of the structure, its function, design service life, impact on third parties, environmental conditions, ease of maintenance and cost. The condition control levels and inspection regimes are defined in conjunction with these requirements. A through‐life management process, outlined in Chapter 9, provides feedback for service life design and allows the associated theoretical model employed to be updated, in turn facilitating the assessment of compliance with the original design objectives.

An example of concrete structure conservation according to the fib Model Code 2010 concept is also presented.
Sensitivity analysis of the early‐age cracking risk in an immersed tunnel
Authors: Liu Xian , Yuan Yong , Su Quanke
Published: October 2013

Engineers know only too well that early‐age cracking accounts for the decrease of long‐term serviceability for a majority of infrastructure. In immersed tunnels, early‐age cracks may leave paths for aggressive media, which lead to deterioration and thus compromise durability. On the other hand, the cracking risk in concrete structures depends on a number of factors, such as material properties, construction methods, curing measures, etc., which make decisions complex.

This work presents the results of a sensitivity analysis of early‐age behaviour for an immersed tunnel cast in situ. Numerical modelling and local sensitivity methods are employed to evaluate the sensitivity of early‐age cracking to casting temperature, formwork conductivity, formwork removal time, curing temperature and ambient temperature. The numerical results indicate that the casting and curing temperatures appear to be the most dominant factors with regard to the whole fabrication period.

This study provides a realistic method for determining the uncertainty analysis of concrete structures at an early age, and identifies the most important factors during the fabrication of immersed tunnel segments, which is beneficial for further decisions related to the control of early‐age cracking.
N,N′‐Homopiperazinebis(methylenephosphonic Acid) and its Use in the Synthesis of the new Copper Phosphonate ­[Cu(HO3P–CH2–NC5H10N–CH2–PO3H)]
Authors: Schilling Lars‐Hendrik , Stock Norbert
Published: October 2013

The new aminomethylphosphonic acid H2O3P–CH2–NC5H10N–CH2–PO3H2 (H4L2) was synthesized and characterized in detail. Its reaction with Cu(NO3)2·3H2O under hydrothermal conditions led to the formation of the copper phosphonate [Cu(H2L2)], which was structurally characterized by single‐crystal X‐ray diffraction [space group P21/n, a = 8.4754(17), b = 16.903(3), c = 9.0787(18) Å, β = 106.58(3)°, R1 = 0.0296, wR2 = 0.0728]. In the crystal structure each Cu2+‐ion is chelated by one ligand molecule forming tetragonal planar CuO2N2 polyhedra. Coordination by an oxygen atom from an adjacent second ligand molecule leads to [Cu(H2L2)]2 dimers, which contain tetragonal pyramidal CuO3N2 polyhedra. These dimers are linked by hydrogen bonds to one‐dimensional chains, which are further connected by van der Waals interactions. The compound was further characterized by powder X‐ray diffraction (PXRD), elemental analysis, IR spectroscopy, Raman spectroscopy, and magnetic measurements.
Nitro Derivatives of Parabanic Acid as Potential Explosives: A Theoretical Study
Authors: Türker Lemi , Variş Serhat
Published: October 2013

This work deals with certain parabanic acid (PA) derivatives because they possess great calculated density (>1.8 g·cm–3) and high content of nitrogen (26 %). Computed ballistic properties of eight different parabanic acid derivatives are presented. The structures were optimized at the B3LYP/6‐31G(d, p) level. The calculated data for PA are found to be compatible with the experimental X‐ray data. The detonation performance analyses were done using empirical Kamlet‐Jacobs equations. Additionally, detonation products were assigned and power index were calculated. All the compounds considered are powerful candidates for high energy materials.
A New Tricarboxylate‐Terbium(III) Compound: Synthesis, Structure, and Luminescent Property
Authors: Chen Yan‐Xue , Chen Bing‐Yi , Yang Jin‐Hui , Qin Guo‐Qiang
Published: October 2013

The TbIII compound [Tb(tci)(H2O)]n·n(DMF) (1) [H3tci = tri(2‐carboxythyl)isocyanurate, DMF = N,N′‐dimethylformamide] was synthesized by the reaction of terbium oxide, H3tci, and two drops of concentrated nitric acid in the presence of DMF and H2O. Single crystal X‐ray analysis reveals that it features a three‐dimensional (3D) framework based on infinite –Tb–COO–Tb– chains. The tci ligand in 1 links six different TbIII ions with its two carboxylate groups in μ2‐κ1O;κ2O,O′ mode and the third in μ2‐κ1O;κ1O′ mode. Thermal analysis reveals that it remains high thermal stability until 390 °C. Luminescence investigation shows that it emits characteristic green light of TbIII ions.
Synthesis and Characterization of Pentanuclear Complexes Composed of Pairs of Macrocyclic Ni2L and Zn2L Complexes Linked by cis‐[PtCl2(dppba)2] and trans‐[RhCl(CO)(dppba)2] [dppba = (4‐Diphenylphosphanyl)benzoate, L = Macrocyclic Ligand]
Authors: Golecki Matthias , Kersting Berthold
Published: October 2013

The ability of the square‐planar complexes cis‐[PtCl2(Hdppba)2] (4) and trans‐[RhCl(CO)(Hdppba)2] (5), where Hdppba represents 4‐(diphenylphosphanyl)benzoic acid to act as bridging metalloligand for dinuclear macrocyclic [Ni2L]2+ and [Zn2L]2+ complexes is demonstrated (L2– is a 24‐membered hexaazadithiophenolate macrocycle). Pentanuclear Ni4Pt and Zn4Pt complexes of composition [(M2L)2(μ‐dppba)2PtCl2]2+ [M = Ni (7a) or Zn (8a)] could be obtained either from substitution reactions between 4 and the corresponding [M2L(μ‐Cl)]+ compounds (M = Ni, Zn) or by treatment of [PtCl2(NCMe)2] with the [M2L(μ‐dppba)]+ complexes (M = Ni, Zn). The pentanuclear Ni4Rh and Zn4Rh complexes of composition [(M2L)2(μ‐dppba)2RhCl(CO)]2+ [M = Ni (9a) or Zn (10a)] were obtained by treatment of [Rh2Cl2(CO)4] with the [M2L(μ‐dppba)]+ complexes. The new complexes were characterized by elemental analyses, ESI mass spectrometry, IR and UV/Vis spectroscopy, and by 1H, 13C, and 31P NMR (for Zn). The Pt and Rh dppba complexes in 7a–10a act in all cases as quadridentate bridging ligands linking two bioctahedral LNi2 (or LZn2) units by μ1, 3‐bridging carboxylate functions. The 31P chemical shifts and the 1J(P, Pt) and 1J(P, Rh) coupling constants further show that the cis and trans stereochemistry of the mononuclear starting materials 4 and 5 is maintained in the pentanuclear products. It is also demonstrated that the terminal Cl– ligands can be substituted by Br– and I– without affecting the pentanuclear nature of the complexes.
Formative assessments in medical education: a medical graduate’s
perspective
Authors: Abu-Zaid Ahmed
Published: October 2013

None
Albuminuria associated with CD2AP knockout mice is primarily due to dysfunction of the renal degradation pathway processing of filtered albumin
Authors: Russo Leileata M. , Srivatsan Subhashini , Seaman Matthew , Suleiman Hani , Shaw Andrey S. , Comper Wayne D.
Published: October 2013

Here we address the assumption that the massive intact albuminuria accompanying mutations of structural components of the slit diaphragm is due to changes in glomerular permeability. The increase in intact albumin excretion rate in Cd2ap knockout mice by >100‐fold was not accompanied by equivalent changes in urine flow rate, glomerular filtration rate or increases in dextran plasma clearance rate, which demonstrates that changes in glomerular permeability alone could not account for the increase in intact albumin excretion. The albuminuria could be accounted for by inhibition of the tubule degradation pathway associated with degrading filtered albumin. There are remarkable similarities between these results and all types of podocytopathies in acquired and toxin‐induced renal disease, and nephrotic states seen in mice with podocyte mutations.
PPARalpha regulates the production of serum Vanin‐1 by liver
Authors: Rommelaere Samuel , Millet Virginie , Gensollen Thomas , Bourges Christophe , Eeckhoute Jérôme , Hennuyer Nathalie , Baugé Eric , Chasson Lionel , Cacciatore Ivana , Staels Bart , Pitari Giuseppina , Galland Franck , Naquet Philippe
Published: October 2013

The membrane‐bound Vanin‐1 pantetheinase regulates tissue adaptation to stress. We investigated Vnn1 expression and its regulation in liver. Vnn1 is expressed by centrolobular hepatocytes. Using novel tools, we identify a soluble form of Vnn1 in mouse and human serum and show the contribution of a cysteine to its catalytic activity. We show that liver contributes to Vanin‐1 secretion in serum and that PPARalpha is a limiting factor in serum Vnn1 production. Functional PPRE sites are identified in the Vnn1 promoter. These results indicate that serum Vnn1 might be a reliable reporter of PPARalpha activity in liver.
Different sling procedures for stress urinary incontinence: A lesson from 453 patients
Authors: Luo De‐Yi , Wang Kun‐Jie , Zhang Han‐Chao , Dai Yi , Yang Tong‐Xing , Shen Hong
Published: October 2013

Several midurethral sling (MUS) procedures, such as tension‐free vaginal tape (TVT), TVT obturator (TVT‐O), tension‐free vaginal tape SECUR (TVT‐S), and pubovaginal sling (PVS), have been used for the treatment of female stress urinary incontinence (SUI); however, which method is best for a particular patient group is not known. This study aimed to identify the best rationale for choosing the optimal MUS procedure for each patient. In total, 453 consecutive female patients with SUI who were treated with MUSs in West China Hospital of Sichuan University from September 2003 to September 2011 were enrolled in this study. All the patients underwent comprehensive pre‐, intra‐, and postoperative evaluations, including collection of demographic information, pelvic examination, and urodynamic testing, and operation‐related complications were recorded. The Incontinence Quality of Life questionnaire was also completed. Under local or general anesthesia, 105 cases were treated with TVT, 243 with TVT‐O, 90 with TVT‐S, and 15 with PVS. Patients with different profiles in terms of age, symptom duration, concomitant procedures, urodynamic parameters, and pelvic organ prolapse (POP) quantification score were treated successfully; the body mass index did not differ significantly among the various treatment options. The cure and improvement rates were similar among the treatment groups: 97.14% (102/105) in TVT, 100% (243/243) in TVT‐O, 98.89% (89/90) in TVT‐S, and 100% (15/15) in PVS. Only minor complications were experienced by the patients. In conclusion, each MUS procedure was observed to be safe and effective in different subpopulations of patients, and the results suggest that appropriate patient selection is crucial for the success of each MUS procedure.
Large-eddy simulation of three-dimensional dunes in a steady, unidirectional flow. Part 2. Flow structures
Authors: Omidyeganeh Mohammad , Piomelli Ugo
Published: October 2013

We performed large-eddy simulations of the flow over a series of three-dimensional (3D) dunes at laboratory scale. The bedform three-dimensionality was imposed by shifting a standard two-dimensional (2D) dune shape in the streamwise direction according to a sine wave. The turbulence statistics were discussed in Part 1 of this article (Omidyeganeh & Piomelli,J. Fluid Mech., vol. 721, 2013, pp. 454–483). Coherent flow structures and their statistics are discussed concentrating on two cases with the same crestline amplitudes and wavelengths but different crestline alignments: in-phase and staggered. The present paper shows that the induced large-scale mean streamwise vortices are the primary factor that alters the features of the instantaneous flow structures. Wall turbulence is insensitive to the crestline alignment; alternating high- and low-speed streaks appear in the internal boundary layer developing on the stoss side, whereas over the node plane (the plane normal to the spanwise direction at the node of the crestline), they are inclined towards the lobe plane (the plane normal to the spanwise direction at the most downstream point of the crestline) due to the mean spanwise pressure gradient. Spanwise vortices (rollers) generated by Kelvin–Helmholtz instability in the separated shear layer appear regularly over the lobe with much larger length scale than those over the saddle (the plane normal to the spanwise direction at the most upstream point of the crestline). Rollers over the lobe may extend to the saddle plane and affect the reattachment features; their shedding is more frequent than in 2D geometries. Vortices shed from the separated shear layer in the lobe plane undergo a three-dimensional instability while being advected downstream, and rise toward the free surface. They develop into a horseshoe shape (similar to the 2D case) and affect the whole channel depth, whereas those generated near the saddle are advected downstream and toward the bed. When the tip of such a horseshoe reaches the free surface, the ejection of flow at the surface causes ‘boils’ (upwelling events on the surface). Strong boil events are observed on the surface of the lobe planes of 3D dunes more frequently than in the saddle planes. They also appear more frequently than in the corresponding 2D geometry. The crestline alignment of the dune alters the dynamics of the flow structures, in that they appear in the lobe plane and are advected towards the saddle plane of the next dune, where they are dissipated. Boil events occur at a higher frequency in the staggered alignment, but with less intensity than in the in-phase alignment.