bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two‐layer concrete bridge beams as composite elements
Authors: Iskhakov Iakov , Ribakov Yuri 
Published: October 2013

AbstractTwo‐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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractThis 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

AbstractConsidering 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

AbstractMost 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

AbstractUsing 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

AbstractStaggering 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

AbstractConservation 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

AbstractEngineers 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

AbstractThe 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

AbstractThis 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

AbstractThe 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

AbstractThe 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.
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

AbstractSeveral 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

AbstractWe 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.