bluuebunny/crossref_metadata_2025_split huggingface dataset:
The shear strength of pre-tensioned I beams with unreinforced webs
Authors: Arthur P. D. 
Published: July 2012

Summary This paper presents the results of two-point loading shear tests on 50 pre-tensioned concrete I beams without web reinforcement. Although many of the beams carried a shear load greater than the cracking shear load, the amount of the excess could not be predicted, and it is concluded that failure should be considered to have occurred when the web is cracked in shear. An expression is developed for the diagonal cracking shear force. Test results already published are shown to give satisfactory agreement with this expression, and comparisons are made, for specific cases, between the ultimate shear load predicted by it and by other design equations and code rules.
The deformation of concrete and micro-concrete in compression and tension with particular reference to aggregate size
Authors: Hughes B. P. , Chapman G. P. 
Published: July 2012

Summary The effects of varying the type and size of the aggregate on the stress-strain characteristics of concrete and micro-concrete in compression and tension are described. By applying new experimental techniques, it has been shown that the use of a larger and rounder aggregate yields a concrete which attains a lower maximum strength at a correspondingly smaller deformation.
Some experiments on concrete cubes with non-plane surfaces
Authors: Westley J. W. 
Published: July 2012

Summary After the return of some cube moulds from site early in 1965 and their absorption into the general laboratory stock of moulds, excessive variations were found in the strength of some specimens made from carefully controlled concrete mixes. At the same time cubes coming into the laboratory for testing showed surfaces that were excessively convex and it was found that some of the cube moulds being returned from site were very worn and had surfaces which varied from plane by up to 0·025 in. Several cube moulds were examined and measurements taken to select those with surface variations between 0·001 and 0·015 in. from plane. Cubes were cast in these moulds and, after curing for 7 and 28 days, measured for surface planeness and tested for compressive strength. The results indicate that a 0·010 in. total variation from the plane in the surfaces of a concrete cube can cause a reduction in compressive strength of up to 15 %.
The use of the fineness modulus for the grading evaluation of aggregrates for concrete
Authors: Popovics Sándor 
Published: July 2012

Summary Experimental evidence is used to show that, despite certain weaknesses, the fineness modulus method is applicable within wide practical limits. Then aspects of the fineness modulus and the specific surface not generally known are discussed. These include two mathematical expressionsfor thefineness modulus as afunction of the particle size distribution, which show that the fineness modulus is a measure of the (logarithmic) average particle size of the grading. This, in turn, provides a new interpretation for the relationship between the grading and workability. Similar mathematical expressions are presentedfor the specific surface, and they show that this is also a measure of an average particle size. Specifically, it represents the reciprocal value of the ‘harmonic’ average particle size. However, experimental evidence suggests it is inferior to the fineness modulus where aggregates for concrete are concerned. A further item is the ‘D-m-s method’ in which the fineness modulus and specific surface are both used for grading evaluation, to combine the advantages of the two methods. Finally, an analogy is used in an attempt to explain why the logarithmic average particle size is the parameter which is the most suitable for the grading evalulation of concrete aggregate.
A laboratory test for determining the angularity of aggregate
Authors: Hughes B. P. , Bahramian B. 
Published: July 2012

Summary A convenient and reliable test has been developed for determining the angularity of aggregates. An examination of the existing methods indicated that the determination of the volume of voids in the aggregate when placed in a standard way was the most promising. Two methods, referred to as the flow-rate test and loose bulk density test, were investigated in detail. The latter test was found to be the most satisfactory and can be used in modified forms for both coarse and fine aggregates. It gives satisfactory results for both spheres and natural aggregates.
The influence of CaSO4.2H2O upon the hydration character of 3CaO.Al2O3
Authors: Feldman R. F. , Ramachandran V. S. 
Published: July 2012

Summary This paper presents a quantitative interpretation of results of differential thermal analysis of hydration reactions at 2, 12,23 and 52°C of 3CaO.Al2O3 mixed with 0, 0·25, 2·5, 10 or 20% gypsum, and compares these with length changes obtained from the hydration of compacts of these mixtures. Estimates of the relative reaction rates from d.t.a. peak areas and measurement of length change during these reactions showed marked agreement, although interpretation had to be made with caution. It was concluded that the formation of ettringite (high sulpho-aluminate) had no direct effect upon reaction rate, but that the reactivitv of 3CaO.Al2O3 was reduced by the sorption of (SO4)2− ions on active sites of its surface. Gypsum reduces the rate of conversion of the hexagonal hydro-aluminates to the cubic hexahydrate, probably also by sorption of (SO4)2− ions, and thus is a second mechanism by which they can retard the normal hydration of 3CaO.Al2O3. The degree to which a given addition of gypsum retards the hydration of 3CaO.Al2O3 at a particular temperature is affected by a balance between (1) the concentration of (SO4)2− ions on and around the surface of the 3CaO.Al2O3; (2) the rate of reaction of (SO4)2− ions with the hexagonal hydro-aluminates; (3) the thickness of the hexagonal hydro-aluminate layer around the 3CaO.Al2O3 grain. Reactions at the various temperatures are discllssed in terms of the above parameters.
The influence of testing machine characteristics upon the cube and cylinder strength of concrete
Authors: Sigvaldason O. T. 
Published: July 2012

Summary Although the compression test on cubes and cylinders is used very extensively as a measure of the general quality of concrete, there has been increasing evidence to show that such tests are not as reproducible as has normally been assumed. There are large differences in the strengths obtained from different testing machines, and often a considerable scatter in strengths from one machine. In a series of tests, the influence of such characteristics as spherical seating behaviour, misalinement, homogeneity of specimen, longitudinal stiffness and platen restraint on the strength of cubes and cylinders has been examined. Depending upon the behaviour of the spherical seating, differences of about 6% may be obtained with accurately centred specimens. If such specimens are also misalined, this difference becomes even larger, as enormous reductions in strength are observed with effectively pinned seatings. Cube and cylinder strengths are affected quite differently by the method of end loading, the cylinder/cube strength ratio being lowest when both ends are fixed. Longitudinal stiffness of the machine does not affect strength. Platen restraint, however, has a very significant influence, particularly if the end-blocks are small.
Analysis of tobermorite by the silicate-derivative technique
Authors: Lentz Charles W. 
Published: July 2012

Summary A specimen of natural tobermorite from Crestmore, California, was studied by a new extraction technique. This investigation revealed that tobermorite can be resolved into two fractions. One of them is a soluble species and the other insoluble. The infra-red spectrum of the soluble polysilicate derived from tobermorite is not identical with the infra-red spectrum of the soluble polysilicate derived from a Portland cement paste. The insoluble derivative has the same morphology as the original tobermorite.
Kinematical compatibility problems in yield-line theory
Authors: Janas M. 
Published: July 2012

Summary An attempt is made to classify assumptions made in yield-line theory in connexion with the upper-bound theorem of limit analysis. Both classical theory and theory taking into consideration membrane forces are examined for reinforced concrete slabs. The complete set of generalized stresses and strain rates is considered, and compatibility conditions imposed by the associated flow law are discussed, including those for the configuration of yield lines and for internal compatibility of the cross-section. In the case of Johansen's yield-line theory, the general type of fan pattern generated from the envelope line is considered, and some statical restrictions applied in the upper-bound technique are discussed. Considerations are limited to the case of isotropy, unless otherwise specified, but conclusions can be more or less directly extended to the case of orthotropic slabs.
Some factors affecting the compressive strength of concrete
Authors: Hughes B. P. , Bahramian B. 
Published: July 2012

Summary Abrams's law of compressive strength versus water/cement ratio is well known and many investigators have studied the possible effects of other factors, such as cement content and sand concentration, upon concrete strength. In particular, the British and American literature is often at variance concerning these secondary effects so that a primary aim of the present paper is to reconcile these conflicting views. Any considerations of secondary effects require a very clear definition of what is meant by ‘compressive strength’ and ‘water/cement ratio’. Furthermore, different aggregates can give significantly different results. These considerations are illustrated by presenting data for curves relating compressive strength and water/cement ratio for three distinct criteria for compressive strength and two types of coarse aggregate. The paper then re-examines the effects of varying both the cement content and the sand concentration, for a given water/cement ratio, upon the compressive strength. It is shown that the effects of these secondary factors are in general fairly small and that rational explanations can be given for the often conflicting conclusions obtained by earlier investigators.
Parabolic velaroidal shells
Authors: Chronowicz A. , Dennison A. C. 
Published: July 2012

Summary This paper presents a solution to the differential membrane equation of parabolic velaroidal shells in which a finite polynomial stress function is used. The method of determining stresses and deflexions from the Vlasov-Marguerre differential equations for the bending of such shells by using finite difference techniques is also indicated. Tests conducted on a cement mortar model shell are described and the results are compared with those obtained theoretically.
Creep stability and buckling strength of concrete columns
Authors: Bažant Z. P. 
Published: July 2012

Summary A solution is given for the long-term deflexions of a reinforced concrete column with an initial curvature according to a general theory of linear creep. This is used to produce solutions: (1) according to the Arutyunyan-Maslov theory (using an incomplete gamma function); (2) according to the approximate Dischinger-Whitney law; (3) by the use of an effective deformation modulus. It is shown that, whilst critical long-term loads may be calculated, these are very sensitive to inaccuracies in the creep theory and that it is more convenient to consider the long-term buckling strength of a column. A practical method of analysis is presented in which the long-term buckling strength is assessed by calculating the short-term buckling strength but using a reduced elastic modulus. Graphs are presented to aid analysis.
Allowing for membrane action in the plastic analysis of rectangular reinforced concrete slabs
Authors: Hayes B. 
Published: July 2012

Summary The existing methods for allowing for membrane action in predicting the plastic behaviour of reinforced concrete slabs are reviewed and their limitations outlined. A new equilibrium method is presented and compared with the existing methods. Comparison of the theoretical predictions of the met/1Od with the results obtained/rom tests on model reinforced concrete slabs shows good agreement.
The strengths of cements reinforced with glass fibres
Authors: Grimer F. J. , Ali M. A. 
Published: July 2012

Synopsis Fibrous composite materials utilizing ceramic fibres and inorganic cements offer a potential source of new lightweight, strong and durable materials. Commercial glass fibres now available are not durable in an alkaline medium of the kind present in most hydrating cements; a new alkali-resistant glass has been developed at the Building Research Station to surmount this difficulty. Because this has renewed interest in the subject, and to provide a yardstick for the effectiveness of the new glass, composites made with commercially available glass fibres and various inorganic binders were studied to find suitable methods of fabrication and to establish the behaviour of the material. This paper describes the influence of type of matrix, age and glass content upon the impact, tensile and bending strengths of composites fabricated by a simple spray-suction technique. On the basis of the properties developed before chemical interaction between glass and cement becomes dominant, it can be foreseen that, given a durable glass, the composites will have pronounced advantages over existing sheet materials in respect of impact strength, bending strength and resistance to cracking. As supplies of alkali-resistant fibre become available, the programme will be repeated with this material.
An experimental investigation of the flexural rigidity of T beams for frame design
Authors: Krishnamoorthy C. S. , Yu C. W. 
Published: July 2012

Synopsis Tests conducted on eight T beams subjected to negative moments at the ends and positive moment near midspan are described. The moment-curvature relationships for various sections and the distribution of flexural rigidity, EI, along the beam are discussed. A simplified design procedure is suggested to determine the equivalent EI value for T beams to be used in the limit design of reinforced concrete frames.
A dilatometer for measuring the volume changes of concrete under load
Authors: Spponer D. C. 
Published: July 2012

Synopsis A new apparatus is described which enables the change in volume of cement paste or concrete specimens under load to be monitored continuously. It relies upon the displacement of water from one bellows containing the specimen under load into another, unrestrained bellows. The difference between the magnitudes of the movements of the bellows is proportional to the volumetric strain. The results are shown to be in good general agreement with other volumetric strain measurements. The apparatus has some advantages over current methods.
Model tests to determine the influence of support stiffness upon the distribution of pile loads on an eight-pile cap
Authors: Clarke J. L. , Taylor H. P. J. 
Published: July 2012

Synopsis Tests were carried out on three models, to scales of 1:4, 1:15 and 1:38, of a large pile cap spanning eight piles. The smallest model was tested to determine the effect of the cracking of the pile cap and of varying pile stiffnesses upon the distribution of the applied load between the piles. The results of the tests are presented and are compared with the results of the tests at the larger scales. The use of very small models is shown to be of great value in amplifying the results of more expensive large-scale tests.
A note on an aspect of the variability of deflections
Authors: Beeby A. W. 
Published: July 2012

Synopsis The only property of the concrete normally known to the designer at the calculation stage of a design is its specified characteristic strength. This paper considers the consequence of this fact for the reliability of deflection calculations by investigating the uncertainties introduced by the essential assumption that there are unique relationships between cube strength and modulus of elasticity and between cube strength and tensile strength. It is shown that, for members having low percentages of reinforcement, the likely range of differences attributable to this assumption can be very large under service loads. Some philosophical questions concerning the relationship between ‘research’ and ‘design’ formulae are also raised.
Characteristics and prediction of creep of a saturated mortar under variable temperature
Authors: Illston J. M. , Sanders P. D. 
Published: July 2012

Synopsis In a previous paper it was shown that four strain components can be identified when concrete, stored in an environment with a varying temperature, is subjected to a sustained load. They are: (a) elastic strain; (b) delayed elastic strain; (c) transitional thermal creep; (d) flow. Each component is, in some sense, related to temperature, and the first part of this paper is devoted to the development of explicit functions for each of the components in terms of temperature and time. In particular, it is shown that all the time-dependent strains can be generated from a single curve in which flow is plotted against weighted maturity. The expressions are used in the second part of the paper to predict the strains in mortar tubes under torsional loading, when subjected to severe regimes of temperature change. The predictions show reasonable agreement with experimental results, and a simplified method of prediction, for use in practice, is also demonstrated.
Inferior Alveolar Neurosensory Deficiency Associated With Placement of Dental Implants
Authors: Givol Navot , Peleg Oren , Yarom Noam , Blinder Daniella , Lazarovici Towy Sorel 
Published: July 2012

Background: This study reports and analyzes a large series of patients with neurosensory deficiency related to the placement of dental implants (DIs) and resulting in liability claims (LCs).Methods: From 1998 to 2009, there were 92 LCs related to persistent altered sensation post DI placements in Israel. Patients’ demographics, year and source of LCs, interval between the procedure that resulted in a neurosensory deficiency and the LC, qualifications of the surgeon, preoperative imaging modality, DI length, available alveolar bone for DI placement, placement site, timing of DI placement (immediately after tooth extraction or after socket healing), and treatment after the diagnosis of neurosensory deficiency were recorded and analyzed.Results: There were 21 cases during the first 5 years of the study (mean 4.2/year) and 63 cases (mean 12.6/year) over the following 5 years. Thirty LCs were issued during the second postoperative year and 15 LCs after >5 years. Most LCs (76%) involved procedures that were planned and performed according to radiographs and 24% after computed tomography. Sixty‐five percent of the LCs were performed by general dental practitioners and 35% by specialists. More than one DI was performed during the surgical procedure that resulted in a neurosensory deficiency in 73 LCs (79.3%), and the DI was >10 mm in 55 (59.8%) cases.Conclusions: LCs for DIs that result in a neurosensory deficiency pose a legal risk to the practitioner long after the injury has occurred.
Comparison of Current US Risk Strategy to Screen for Hepatitis C Virus With a Hypothetical Targeted Birth Cohort Strategy
Authors: Tomaszewski Kenneth J. , Deniz Baris , Tomanovich Peter , Graham Camilla S. 
Published: July 2012

Objectives. We compared the theoretical performance of a 1-time, birth cohort strategy with the currently recommended risk strategy for screening for hepatitis C virus (HCV) infection, which is undetected in an estimated 75% of 4 million affected people in the United States. Methods. We applied current American Association for the Study of Liver Disease risk screening guidelines and a targeted birth cohort strategy to National Health and Nutrition Examination Survey data from 2003 to 2006 to estimate their performance in identifying HCV cases. Results. Risk guidelines would recommend testing 25% of the US population aged 20 years or older and, if fully implemented, identify 82% of the projected HCV-exposed population. A targeted birth cohort (1946–1964) strategy would test 45% of the same population and identify 76% of the projected HCV population. Conclusions. In this ideal-world simulation, birth year and risk screening had similar theoretical performances for predicting HCV infection. However, actual implementation of risk screening has not achieved its theoretical performance, and birth cohort screening might increase HCV testing rates.
Renal Dysfunction and Elevated Blood Pressure in Long-Term Childhood Cancer Survivors
Authors: Knijnenburg Sebastiaan L. , Jaspers Monique W. , van der Pal Helena J. , Schouten-van Meeteren Antoinette Y. , Bouts Antonia H. , Lieverst Jan A. , Bökenkamp Arend , Koning Caro C.E. , Oldenburger Foppe , Wilde James C.H. , van Leeuwen Flora E. , Caron Huib N. , Kremer Leontien C. 
Published: July 2012

Summary

Background and objectives
Little is known about renal function and blood pressure (BP) in long-term childhood cancer survivors. This cross-sectional study evaluated prevalence of these outcomes and associated risk factors in long-term childhood cancer survivors at their first visit to a specialized outpatient clinic.

Design, Setting, Participants, & Measurements
Estimated GFR; percentages of patients with albuminuria, hypomagnesemia, and hypophosphatemia; and BP were assessed in 1442 survivors ≥5 years after diagnosis. Multivariable logistic regression analyses were used to estimate effect of chemotherapy, nephrectomy, and radiation therapy on the different outcomes.

Results
At a median age of 19.3 years (interquartile range, 15.6–24.5 years), 28.1% of all survivors had at least one renal adverse effect or elevated BP. The median time since cancer diagnosis was 12.1 years (interquartile range, 7.8–17.5 years). High BP and albuminuria were most prevalent, at 14.8% and 14.5%, respectively. Sixty-two survivors (4.5%) had an estimated GFR <90 ml/min per 1.73 m2. Survivors who had undergone nephrectomy had the highest risk for diminished renal function (odds ratio, 8.6; 95% confidence interval [CI], 3.4–21.4). Combined radiation therapy and nephrectomy increased the odds of having elevated BP (odds ratio, 4.92; 95% CI, 2.63–9.19), as did male sex, higher body mass index, and longer time since cancer treatment.

Conclusion
Almost 30% of survivors had renal adverse effects or high BP. Therefore, monitoring of renal function in high-risk groups and BP in all survivors may help clinicians detect health problems at an early stage and initiate timely therapy to prevent additional damage.