bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cracking of concrete cover along anchored deformed reinforcing bars
Authors: Tepfers Ralejs 
Published: October 2009

Synopsis The state of stress in the concrete due to bond forces from deformed reinforcing bars is analysed. For determination of the cracking resistance of the concrete cover, a concrete ring model is used. The stresses are calculated for an elastic stage, a plastic stage, and an elastic stage with internal ring cracks. The appearance of the concrete cover cracks along the deformed bars in the bond zones for normal cover thickness can be determined by using the mean of the values obtained for the two last stages. The partly cracked elastic stage gives cracking loads just on the safe side.
Interaction of casting and mould surfaces in slip-form technology
Authors: Reichverger Z. 
Published: October 2009

Synopsis Friction and adhesion between concrete and form surfaces during the first hours of contact determine the shifting process in slip-form technology and are also of interest in processes involving immediate stripping and in the transportation of ready-mixed concrete. Experimental data are presented on the behaviour of hardening mortar (as a part of concrete obviously coming in contact with mould surfaces) with different mould materials in terms of friction and normal and tangential adhesion, including the aspect of surface cleanliness. These results make it possible to determine the forces required for overcoming adhesion in normal and tangential shifting of the form, and to recommend facing or coating agents for slip-form panels. The results, obtained in small laboratory tests, were then checked by casting 0·15 × l·0 × 2·5 m wall panels in a part of a slip-form.
Biaxial strees–strain relationships for concrete
Authors: Tasuji M. Ebrahim , Nilson Arthur H. , Slate Floyd O. 
Published: October 2009

Synopsis On the basis of experimental results reported more fully elsewhere, a stress-strain relationship is proposed for plain concrete that is applicable to all combinations of biaxial tension and compression. The proposed equation accounts for both non-linear and orthotropic behaviour of concrete. Also based on experimental results, a biaxial ultimate strength criterion is proposed for concrete in the form of a failure stress envelope. The proposed equations are given in a form such that they may be incorporated readily in plane-stress analysis of reinforced concrete using the finite-element approach.
Punching shear strength of concrete slabs subjected to in-plane biaxial tension
Authors: Johnson R. P. , Arnaouti C. 
Published: October 2009

Synopsis It has been found in three tests that in-plane biaxial tensile strains up to 0·0017 cause no reduction in the strength in punching shear of a reinforced concrete slab 90 mm thick. The test results are compared with the predictions of the recent Bridge Code (BS 5400) and of plastic theory.
Thermoluminescence test for fire-damaged concrete
Authors: Placido Francis 
Published: October 2009

Synopsis A new test of fire damage in concrete is proposed based on the technique of thermoluminescence. The thermoluminescence signal remaining in samples of sand extracted from concrete structures is shown to be an indicator of probable fire damage in concrete exposed to temperatures in the range of300°–500°C. The thermoluminescence test is shown to be easy to apply, to require only small samples and to be a more objective test than those in current use where reinstatement is being considered. An important feature of the proposed test is that it is sensitive to the thermal exposure experienced by the concrete rather than just the maximum temperature reached.
Results of a ‘round robin’ thermal conductivity test organized on behalf of the British Standards Institution
Authors: Spooner D. C. 
Published: October 2009

Synopsis A ‘round robin’ series of thermal conductivity tests has been carried out under the auspices of BSI subcommittee RHE 9/2. Three sets of pre-conditioned specimens were circulated to a number oflaboratories with an interest in thermal conductivity testing of masonry materials. The only measurements made at each laboratory were of the dimensions, weights and thermal conductivity of the specimens. Consequently, the results only reflect those sources of variability, specimen preparation and conditioning being deliberately excluded. The measurements of thermal conductivity reported by the laboratories vary quite considerably and, it is suggested, the causes of the variations need further study.
Effect of cover upon the stress–strain properties of concrete confined in steel binders
Authors: Gangadharam D. , Reddy K. Nagi 
Published: October 2009

Synopsis Cover to the stirrups in reinforced concrete structures is one of the important parameters in the theory of confined concrete, On the basis of experimental results, a new term ‘effective confinement index’ is introduced. The expressions for increase in maximum stress and the corresponding strain in terms of effective confinement index are given. Theory is developed to obtain the stress–strain curve of total condtere with confined core and unconfined cover. The experimental and analytical stress–strain curves are compare. Also the maximum stresses and the corresponding strains of shell concrete are compared with the results obtained by the theory of sargin et al.
The strength of the concrete in composite reinforced concrete beams in hogging bending
Authors: Taylor R. , Al-Najmi A. Q. S. 
Published: October 2009

Synopsis The concrete in the compression Zone of a composite reinforced concrete beam loaded in hogging bending is subjected to a complex multi-axial stress system which enables it to withstand much higher longitudinal stresses and strains than is possible in normal reinforced concrete. This paper attempts to assess the ultimate average compressive stresses attained in such beams, the results indicating stresses of the order of three times those in normal reinforced concrete. Hypotheses explaining the confining forces are suggested.
Optimal limit state design with unbonded prestressing tendons
Authors: Marro Piero 
Published: October 2009

Synopsis This paper explores the theoretical behaviour of concrete structures prestressed by means of unbonded tendons according to the CEB-FIP ‘Model Code for concrete structures’. The subject matter is dealt with analytically. The study comprises two parts: the first deals with sections containing unbonded prestressing steel only, the second investigates structures having traditional bonded reinforcement in addition to unbonded tendons. In both cases, diagrams and tables have been provided to facilitate optimal design. To make the scope of the investigation as general as possible, the calculated values have been obtained, or at least presented, in non-dimensional terms. A detailed design example is given in the Appendix.
The conduction of electricity through concrete
Authors: Whittington H. W. , McCarter J. , Forde M. C. 
Published: October 2009

Synopsis This paper examines the relationship between mix proportions, electrical properties of the constituents of concrete and the over-all electrical resistivity for concrete. The mechanisms for the conduction of electricity through the heterogeneous medium of concrete are discussed and an electrical model is proposed. Analysis from a purely theoretical standpoint is also described and the values of electrical resistivity obtained experimentally are shown to compare favourably with the theoretical model.
Discussion: The alkali2–silica reaction2—a model for predicting expansion m mortar
Authors: Hobbs D. W. 
Published: October 2009

Synopsis Data are presented which illustrate the influence that reactive aggregate content, mix proportions and cement alkali content have upon the time to cracking and upon the subsequent expansion of mortar specimens stored in water at 20° C. It is shown that an assumption that the alkali-silica reaction is a two-stage process leads to predictions which are in general agreement with the observed expansion behaviour of mortars.
Concrete coating for submarine pipelines
Authors: Palmer A. C. 
Published: October 2009

Synopsis A submarine pipeline is usually externally coated with reinforced concrete, the function of which is to protect the corrosion coating against impact damage, and give the pipe additional weight to stabilize it on the sea bed. There are unusual requirements in design and application technology. The paper examines the current state of knowledge and practice and the development of more stringent specifications as a result of North Sea experience. It goes on to consider research needs, among them rational design methods and the development of coating concrete with improved resistance to impact, abrasion and bending.
Flexural tests of steel-concrete open sandwiches
Authors: Ong K. C. G. , Mays G. C. , Cusens A. R. 
Published: October 2009

Synopsis A potential method for reducing the weight of the roadway deck on medium- to long-span composite bridges is to use an open steel-concrete sandwich. This consists of a concrete core which is cast against a steel plate, the necessary shear connection being provided by epoxy resin adhesive. Open sandwich beams and slabs constructed in this manner have been appraised by testing over spans of 1·8 and 0·9 m, respectively. Then carried loads equivalent to wheels of an HB vehicle with an adequate safety margin, and current designprocedures generally underestimated both theirflexuraland shear strengths.
FRP-encased concrete as a structural material
Authors: Fardis Michael N. , Khalili Homayoun H. 
Published: October 2009

Synopsis Plastics reinforced with continuous glass fibres have outstanding tensile strength in the fibre direction and excellent corrosion resistance, but are characterized by low modulus and low compressive strength. It is proposed to develop composite members in which a prefabricated FRP (fibreglass-reinforced-plastic) casing is used initially as the form to cast plain concrete, and thereafter to confine the concrete, act as tensile reinforcement and provide corrosion protection. Significant cost savings are possible with the proposed combination of materials, especially in exposed structures, such as bridges. An experimental investigation of FRP-encased concrete cylinders in axial compression and of rectangular FRP-encased beams in bending is presented. The results demonstrate the excellent strength and ductility characteristics of FRP-encased members. The behaviour of circular FRP-encased concrete beam-columns is described also, in terms of analytically obtained moment-axial-load and ductility-axial-load interaction diagrams and moment-curvature relations. The weathering characteristics and the fire resistance of the FRP are discussed, and measures to improve these environmental properties are reviewed.
Long-term deflections of reinforced concrete beams
Authors: Bakoss S. L. , Gilbert R. I. , Faulkes K. A. , Pulmano V. A. 
Published: October 2009

Synopsis Long-term static load tests were carried out on simply supported and continuous reinforced concrete beams at the N.S.W. Institute of Technology, Sydney, Australia. The instantaneous and time-dependent beam deflections were recorded, together with the time-varying strain distributions at selected cross-sections and the redistribution of bending moments due to creep and shrinkage. In this paper, the measured beam deflections are compared with values predicted by British and American design code methods and by finite element methods. The creep and shrinkage properties used in the predictions were obtained from test specimens and were also calculated in accordance with CP 110:1972, AS 1481–1978, ACI 209:1971 and the CEB–FIP 1978 Model Code. For the samples of concretes examined, the applicability of these predictive methods is discussed.
The effect of pfa upon alkali-aggregate
Authors: Gaze M. E. , Nixon P. J. 
Published: October 2009

Synopsis The effect of pulverized-fuel ash (pfa) upon the expansion of mortar bars containing Beltane opal and stored at 38°C has been investigated. The alkali level in the mortar bars was kept constant in order to eliminate the effects of alkali dilution by the pfa. The expansion was found to be reduced ut all levels of pfa substitution and when 20 and 30% pfa was present there was very little expansion at all. The reduction in expansion when the alkali level is reduced was also demonstrated in a parallel series of experiments.
The dependence of punching resistance upon the geometry of the failure surface
Authors: Regan P. E. 
Published: October 2009

Synopsis Punching tests were made on forty concrete slabs with the distances between loads and supports short enough for the shapes of the failure surfaces to be defined by specimen geometry. The results obtained are used to derive a simple empirical expression for punching strength in terms of the geometry of the failure cone. The empirical expression is shown to be similar to the results of a plastic analysis and the relationship of the results to the design of more normal slabs is discussed briefly.
Impact behaviour of prestressed concrete beams in flexure
Authors: Hughes B. P. , Mahmood A. T. 
Published: October 2009

Synopsis Predicting the impact performance of prestressed concrete beams can be greatly facilitated if the energy absorption under impact is related to the energy absorption under static loading. Model beam tests are described which investigate the deformational behaviours under static and impact loads and the total work done bring a member to the same limiting damage or deflection due to either type of load. Design charts, based the model test results, suitable for predicting the performance of beams subjected to flexural impact loads then presented.
Creep and shrinkage in a lightweight-aggregate concrete
Authors: Arnaouti C. , Sangakkara S. R. 
Published: October 2009

Synopsis A model is presented for the determination of the creep and shrinkage of a large reinforced concrete structure from the shrinkage data of a small plain concrete prism. The method is based on the linear relationship between drying creep and concurrent shrinkage and the relationship between drying shrinkage and the exposed area to volume ratio of a concrete specimen. This model was developed to obtain time-dependent properties of concrete slabs for the non-linear finite element analysis of restrained concrete slabs. Results obtained from the creep and shrinkage model and conclusions are also presented.
The influence of lateral pressure upon anchorage bond
Authors: Robins P. J. , Standish I. G. 
Published: October 2009

Synopsis This paper examines the effect of lateral pressure upon the anchorage bond behaviour of both plain and deformed reinforcing bars in lightweight-aggregate concrete. Two common bond tests, the cube pull-out and the semi-beam tests, were modified that lateral pressures could be applied to the bond specimens. The major variables studied were the magnitude of the lateral pressure, the bar diameter. the length of embedment and the concrete strength. The results of over 200 bond tests show that for plain bars the application of lateral pressure can result in an increase in pull-out load of over 250%, whilst for deformed bars of similar size the corresponding increase is about 75%. The different bond mechanisms for plain and deformed bars were highlighted by the failure modes of the bond specimens; this difference in behaviour is rejected in the theoretical work by a frictional bond strength criterion for plain bars and a splitting or shearing criterion f or deformed bars.
Superplasticized flowing concrete: strength and deformation properties
Authors: Dhir Ravindra K. , Yap Andrew W. F. 
Published: October 2009

Synopsis This is the third and final paper from a wide-ranging investigation undertaken into superplasticized high workability concrete. The properties described are those of strictly flowing concrete in the hardened state and include: compressive strength, drying shrinkage, thermal expansion, elastic deformation, creep, creep recovery and post-creep-recovery elastic deformation and strength. It is shown that flowing concretes made with superplasticizers of categories A and B exhibit similar properties. In comparison with the corresponding normal concrete, flowing concrete, for a given strength, is likely to require a slightly higher cement content, it exhibits higher shrinkage, slightly higher elastic modulus and lower creep, whilst its creep recovery and post-creep-recovery elastic deformation and strength properties are generally comparable. With regard to the various mix, curing and testing parameters considered, both normal and flowing concretes appear to respond in a similar manner for the properties studied.
Uniaxial tensile fatigue failure of concrete under constant-amplitude and programme loading
Authors: Cornelissen H.A.W. , Reinhardt H.W. 
Published: October 2009

Synopsis Uniaxial repeated-tension and tension-compression tests on plain concrete are described. The results are presented as S—N diagrams and in the form of a modified Goodman diagram. Stress reversals appeared to reduce life significantly. By a statistical treatment, the influence of scatter in the static strength upon the fatigue results was ascertained. To avoid the effect of this scatter, cyclic creep rate was evaluated to predict life more accurately in constant-amplitude tests as well as in programme loading tests. With this procedure for programme loadings, no significant sequence effect of the loading blocks was observed in the resulting Miner sums. Miner's number M = 1 proved to be a safe failure criterion in general.
Effect of specimen and crack sizes, water/cement ratio and coarse aggregate texture upon fracture toughness of concrete
Authors: Nallathambi P. , Karihaloo B. L. , Heaton B. S. 
Published: October 2009

Synopsis Tests were performed on cement mortar and concrete beams, in two stages, with a view to studying the influence of several specimen and mix variables upon the fracture behaviour of concrete. On the basis of the results from the first stage of tests, in which a single water/cement ratio and type of coarse aggregate were used, a simple formula was established to estimate the fracture toughness of concrete in terms of specimen dimensions, maximum aggregate size and notch depth, together with the mix compressive strength and modulus of elasticity (determined from separate standard cylinder tests). It was found to predict, with sufficient accuracy, the results from the second stage of tests in which, besides variation of the type of coarse aggregate and water/cement ratio, some of the specimen sizes were outside the range used in the first series.
Physical characterization of UK pulverized-fuel ashes for use in concrete
Authors: Dhir Ravindra K. , Jones M. Roderick , Munday John G. L. , Hubbards Frederick H 
Published: October 2009

Synopsis The characteristics of pfa to BS 3892:Part I and their possible effects upon concrete are examined by using supplies from 26 sources in the UK. Fineness identified as giving an over-all measure of ash quality and is used to propose a four-part classification to provide a realistic basis for ash utilization in concrete.
Transient thermal strain of concrete: literature review, conditions within specimen and behaviour of individual constituents
Authors: Khoury Gabriel A. , Grainger Brian N. , Sullivan Patrick J. E. 
Published: October 2009

Synopsis This is the first of three papers presenting the results of an investigation into the effect of material and environmental factors upon the transient thermal strain behaviour of concrete during the first heat cycle under load to 600°C. A literature review of transient thermal creep of concrete is presented. It reveals inadequate understanding of this subject for temperatures above 100°C and a lack of data for conditions pertinent to the analysis of concrete structures during first-time heating. This paper also presents results of preliminary work forming background information for the analysis of the transient thermal strain behaviour of unsealed concrete specimens. The complex temperature, moisture and thermal stress conditions developing during thermal transients in concrete test specimens have, therefore, been investigated experimentally and/or theoretically. The ‘structural’ effects and modification of material behaviour caused by these conditions have consequently been minimized by appropriate design of experiment. Characteristics of the individual aggregate and cement paste constituents have been determined by dilatometry, DTA and TGA tests which showed aggregate thermal stability to be a critical factor.
Application of the highly stressed volume approach to correlated results from different tensile tests of concrete
Authors: Torrent R. J. , Brooks J. J. 
Published: October 2009

Synopsis The highly stressed volume (HSV) approach is considered for relating tensile strength of concrete as determined by a range of test methods and a range of loading configurations with various sizes of specimen. The paper demonstrates that the approach explains the effect of specimen size of geometrically similar specimens upon tensile strength as determined by a given method. However, the HSV approach alone does not correlate the different values of tensile strength as yielded by various methods of test.
Strain of concrete during first heating to 600°C under load
Authors: Khoury Gabriel A. , Grainger Brian N. , Sullivan Patrick J. E. 
Published: October 2009

Synopsis This is the second of three papers presenting the results of an investigation into the transient thermal strain behaviour of concrete during the first heat cycle to 600°C under load. The results during first heating to 600°C under uniaxial compressive load of eight different unsealed concrete andcement paste mixes are presented. The thermal strains were shown to consistof ‘free’ and ‘load-induced’ components which possessed different and distinct properties. The free thermal strains of the unloaded concretes were dominated by the thermal expansion of the constituent aggregate, whilst the load-induced thermal strains (LITS) were identical for temperatures up to about 450°C, irrespective of type of aggregate used, provided certain criteria were met. A ‘master’ LITS curve therefore existed which represented LITS of Portland-cement-based concretes in general. Also LITS was not significantly influenced by the age of the concrete (1 and 9 years) or the initial moisture condition (moist and air-dry). These findings could considerably simplify the analysis of heated concrete structures, particularly since only two strain components are required. Replicate tests were performed to provide a statistical basis for analysis of the results. The effect of aggregate restraint was determined by comparing results from concrete and cement paste specimens. In addition to ‘material’ factors, the effects upon free and load-induced thermal strain of the following ‘environmental’ parameters were examined: temperature level, initial moisture conditioning, preheating, rate of heating and stress level.
Punching shear of steel-concrete open sandwich slabs
Authors: Ong K. C. G. , Mansur M. A. 
Published: October 2009

Synopsis An experimental programme was conducted on simply supported, two-way epoxy-bondedsteel-concrete open sandwich slabs under a central patch load. The major parameters of the study were the method of surface preparation for the steel plate, size of patch load, grade of concrete and thickness of concrete topping. The results of twelve slabs tested in this programme are presented and discussed. On the basis of the test data, a modijication to the existing plastic theory for conventional reinforced concrete is suggested for the design of open sandwich slabs against punching shear failure.