bluuebunny/crossref_metadata_2025_split huggingface dataset:
Die deutsche Arbeitsverwaltung im Generalgouvernement und die Juden
Authors: Lehnstaedt Stephan 
Published: July 2012

Vorspann
Dass die polnischen Juden von der deutschen Besatzungsmacht nicht nur ermordet, sondern auch in großem Maßstab ausgebeutet wurden, erfuhr die Öffentlichkeit erstmals durch ein Buch und einen Film: Schindlers Liste. Über die Geschichte dieser Zwangsarbeit und ihre Bedingungen ist indes nur wenig bekannt. Wie groß die Defizite noch immer sind, zeigte sich erst vor wenigen Jahren, bei den deutschen Prozessen über die Verrentung jüdischer Zwangsarbeiter, die den Holocaust überlebt hatten. Umso wichtiger scheint dieser Aufsatz, der auf der Basis deutscher und polnischer Quellen erstmals präzise nachzeichnet, wie diese Zwangsarbeit organisiert war und welche Konsequenzen dies für die Betroffenen hatte.
The Indigenous Andean Concept of Kawsay, the Politics of Knowledge and Development, and the Borderlands of Environmental Sustainability in Latin America
Authors: Zimmerer Karl S. 
Published: July 2012

Kawsay in Colonial and Postcolonial BorderlandsThe personage of Huatya Curi, the “Baked Potato Gleaner,” figured prominently in an early colonial account of the landscape and religious mythology of the Andean people of Huarochirí, a province in the mountainous interior of Lima in the Viceroyalty of Peru. The Huarochirí manuscript, a sixteenth-century Quechua document, introduces Huatya Curi with these words: “Chay pacha cay huatya curi ñisca huacchalla micuspapas huatya cuspalla causaptinsi sutiachircan huatya curim ñispa …” ‘At that time Huatya Curi, a poor potato eater, was accustomed to living from gleaning baked potatoes, and for that reason people named him Huatya Curi …‘ (Salomon and Urioste 163; my trans.; see also Taylor 32–33). While poor, Huatya Curi was powerful; in the same passage he goes on to vanquish a mighty Andean lord, Tamta Ñamca. The demise of Tamta Ñamca sets the stage for the ascendance of Paria Caca, Huatya Curi's father, who emerges as the chief Andean deity. Huatya Curi's existence is earthly yet linked to his supernatural lineage.
Yield-line theory for reinforced concrete slabs at moderately large defiexions
Authors: Morley C. T. 
Published: July 2012

Summary Conventional yield-line theory for reinforced concrete slabs is extended to allow for membrane effects and moderately large dejfexions, by isolating those membrane displacement rates 0/ the rigid slab portions which do not affect yield-line positions, and developing a method of choosing these rates so that the load estimate from the work-rate equation is stationary. For a slab with an assumed pattern of yield lines, the relationship between load-carrying capacity and deffexion can then be obtained. A number of examples are worked, with different shapes of slab and boundary conditions.
The composition of alite (tricalcium silicate) in a Portland cement clinker
Authors: Midgley H. G. 
Published: July 2012

Summary The composition of the alite (tricalcium silicate) phase in a Portland cement clinker has been determined by using an electron probe microanalyser. The molar proportions of the ions based on the unit cell are Ca 103·54 Fe 1·43, Mg 1·75, Na 0·80, K 0·18, Mn 0·02, Al 0·28 (in caldum sites); Al 0·23 (in interstitial sites); Si 34·48, Al 1·41, Ti 0·11 (in silicon sites); O 180. A comparison has been made with two other chemical analyses of tricaldum silicates and also with synthetic preparations.
A direct tensile test for concrete under long- or short-term loading
Authors: Elvery R. H. , Haroun W. 
Published: July 2012

Summary This paper describes details of a method of testing concrete in uniaxial tension. This method was devised to suit the requirements of a research programme started in 1965 to study the tensile creep andfailure of concrete. Details of the p.v.c. moulds for the manufacture of the specimens are given and a description of the arrangements for loading the specimens includes details of end attachments and a frame in which up to 30 specimens can be loaded in tension simultaneously. Typical experimental results of strain behaviour and strength are presented to indicate the performance of the method in the laboratory.
The bearing strength of concrete loaded through flexible plates
Authors: Hawkins N. M. 
Published: July 2012

Summary Approximate expressions are developed for the bearing strength of concrete axially loaded by a punch covering a limited area of the bearing plate. Depending on their stiffnesses, plates are characterized as flexible, semi-flexible or rigid. It is shown that for a flexible plate the ultimate capacity increases linearly with the plate thickness, whereas for a semi-flexible plate the rate of increase rises continuously until a maximum value is reached corresponding to the capacity for a rigid plate. The expressions predict the results for eight series of tests on concrete blocks loaded through plates ranging in thickness from 1/32 in. to 1 in.
The analysis of belite in Portland cement clinker by means of an electron-probe micro analyser
Authors: Fletcher K. E. 
Published: July 2012

Summary It is believed that the rate of hydration of dicalcium silicate in a Portland cement clinker will depend upon the type and amount of stabilizing agent present in the crystal lattice. Complete analyses are given for a belite grain in a normal British Portland cement clinker and in a sulphate-resisting Portland cement clinker. Lattice substitutions are suggested which are consistent with the analyses obtained. Belite grains in the normal and sulphate-resisting Portland cement clinkers differed in the relative proportions of Al and Fe present. The ratio of Al to Fe in the belite grains corresponded closely to the ratio of Al to Fe in the cement clinker. Difficulties which arise in the electron-probe microanalysis are discussed.
Shear in reinforced concrete beams
Authors: Regan P. E. 
Published: July 2012

Synopsis Generally acceptable compatibility and ultimate strength precepts are used in this paper to establish a physical theory of shear in reinforced concrete. Account is taken of the shear resistances of both un cracked concrete and shear reinforcement. The theory is used as the basis for the development of a simpler, but still analytic rather than empirical, design method, and the adequacy of the accuracies of both the basic and the simplified approaches is established by comparison with more than a thousand published test results.
A partial failure of limit analysis for slabs, and the consequences for future research
Authors: Wood R. H. 
Published: July 2012

Synopsis A brief discussion of the essential differences between yield-line theory and limit analysis is followed by an examination of whether or not it is possible to prove the existence or otherwise of exact solutions in all cases in limit analysis, in the light of considerable new evidence. It is maintained that the evidence is now strong enough to eliminate the possibility of exact solutions for most slabs governed by the ‘square’ yield criterion, especially continuous and encastered slabs commonly dealt with in yield-line theory. The changes that this would entail in the future direction of reinforced concrete research, and the immediate practical consequences, are discussed. It is suggested that the nodal-force theory of Johansen is a general technique which could well find application in many other branches of science.
Destructive tests on rationally designed slabs
Authors: Muspratt M. A. 
Published: July 2012

Synopsis Destructive tests on prototype reinforced concrete slabs designed by Johansen's yield-line method and Hillerborg's strip method are described. All the slabs were square, simply supported and uniformly loaded. The yield and failure characteristics of these slabs are then compared with those obtained from slabs designed by an optimum lower-bound approach. The optimum slabs contained 37 % and 16 % less reinforcing steel than the slabs designed by Johansen's and Hillerborg's methods respectively.
The effect of lead compounds in aggregate upon the setting of Portland cement
Authors: Midgley H. G. 
Published: July 2012

Synopsis Lead compounds may occur in rocks used as aggregates in concrete and those soluble in lime water will affect the rate of hardening of the concrete. The set will be delayed for 7 days by 0·8 % lead soluble in limewater, for 1 day by 0·15 %. Smaller amounts will delay the set and lower the early strength, but subsequent strengths will be as good as or better than for concretes with an equivalent aggregate without the lime-soluble lead.
Limit-state design for shear in rectangular and T beams
Authors: Regan P. E. , Placas A. , Baker A. L. L. 
Published: July 2012

Synopsis The four major modes of shear failure—diagonal tension, shearing, shear-compression and web crushing—are discussed briefly and equations are given for predicting resistances to them. The larger part of the paper is devoted to two other design criteria. An analytical approach to shear cracking at vertical web-flange junctions is outlined and its predictions are compared with the results of a limited group of tests by the authors. A semi-empirical equation is derived for the calculation of limit state of local damage resistance as determined by widths of shear cracks, and is compared with more extensive test data for various types of beam tested by the authors and others.
Some tests on the transmission length and ultimate strength of pre-tensioned concrete beams incorporating Dyform strand
Authors: Mayfield B. , Davies G. , Kong F. K. 
Published: July 2012

Synopsis Tests were carried out on 24 beams pre-tensioned with Dyform strand and 6 beams pre-tensioned with standard strand, to determine and compare transmission length, flexural strength and behaviour. It was found that the transmission length was greater for specimens incorporating Dyform strand than for those with standard strand, both at transfer and after a period of some months. Ultimate load tests indicated that the flexural behaviour of the two types of specimen was similar.
Further consideration of a mathematical model for progressive fracture of a heterogeneous material
Authors: Dougill J. W. 
Published: July 2012

Synopsis Uniaxial stress-strain curves are derived for a mathematical model designed to represent a heterogeneous material that fails in tension by progressive fracture. These results show qualitative agreement with the behaviour of real materials including mortars and concretes. The results suggest that the behaviour that occurs, after the peak stress has been achieved in a deformation-controlled test, is dependent upon the energy required to fracture the material. If this is sufficiently high, stable fracture propagation occurs. However, if the energy required for fracture is low, failure occurs by instability under reducing stress. The conditions for the occurrence of this instability are obtained in terms of the properties of the model material and the implications of this behaviour, for materials testing and the derivation of failure criteria, are briefly discussed.
Stress-strain-time relationships for concrete
Authors: Spooner D. C. 
Published: July 2012

Synopsis A pilot study has been made of the effects of strain rate upon the compressive stress-strain behaviour of prism specimens made from one particular concrete mix. The specimens were cured either in water or in air in the laboratory and tested when approximately three months old. The stress at failure was strain-rate dependent for the specimens cured in water, and the strain at failure was strain-rate dependent for the specimens cured in air.
Time-dependent strains in sealed concrete under systems of variable multiaxial stress
Authors: Jordaan I. J. , Illston J. M. 
Published: July 2012

Synopsis Sealed concrete cubes were subjected to sustained systems of uni-, bi- and triaxial stress. The uniaxial stress and one of the principal stresses in the bi- and triaxially loaded specimens were set initially at the same nominal value, and later cycled between this and a higher level while the orthogonal stresses remained constant. The strains resulting from the stress cycle were essentially the same for all three stress systems; the strains in a direction orthogonal to the stress change were found to be fully recoverable but those in the direction of the stress included an irrecoverable component. The creep Poisson's ratio was approximately the same for all stress increments. The Poisson's ratio for creep recovery rose with time from the removal of load. It is concluded that, in engineering analysis, the time-dependent strain of concrete under constant multiaxial compressive stress can be found by using a constant value of creep Poisson's ratio, equal to the static elastic value. Under variable stress, Boltzmann superposition (or a similar principle) can be applied to sum the effects of a succession of changes in stress.
Incremental deformations of under-reinforced concrete beams
Authors: Gerstle Kurt H. , Tulin Leonard G. 
Published: July 2012

Synopsis Existing ultimate strength theories for reinforced concrete structures are not sufficient to describe behaviour under cyclic loading. In particular, the phenomenon called ‘incremental collapse’ or its converse, ‘shake-dow’, must be considered. An elastic-perfectly-plastic theory has been developed, but its applicability has been questioned. If the material properties show evidence of strain-hardening, the system will shake down under cyclic loads up to and greater than the perfectly plastic limit load. This paper applies strain-hardening concepts to the theoretical response of reinforced concrete structures and verifies the predictions so obtained by comparing results with experimental responses of a set of reinforced concrete continuous beams.
The plastic flow law for reinforced concrete beams under combined flexure and torsion
Authors: Jackson Neil , Estañero Romeo A. 
Published: July 2012

Synopsis The possible application of plastic analysis to reinforced concrete structures, the members of which are subjected to both bending and twisting moments, depends not only upon their ductility but also upon a knowledge of the associated plastic flow law. An experimental investigation to determine the flow law for rectangular reinforced concrete beams under combined flexure and torsion is described in this paper. Bending and twisting rotations measured during the pseudo-plastic stage occurring near maximum load are reported for 80 beams, which included both symmetrically and unsymmetrically placed reinforcement. Typical interaction curves with their associated incremental rotation vectors are presented and the corresponding flow law is stated. The complete interaction curve is considered and the implications of this and the plastic flow law are discussed in relation to the applicability of current methods of plastic analysis to concrete structures.
Modes of failure of concrete panels exposed to high temperatures
Authors: Dougill J. W. 
Published: July 2012

Synopsis The occurrence of a mode of general spalling, in which a concrete wall panel or floor slab may be completely destroyed shortly alier the start of a fire test, is examined. Examples are given to suggest that this may be a form of compression failure, caused by strain softening, which has much in common with behaviour observed in a standard compression test. A method of analysis for the structural behaviour of a plain concrete panel is formulated in general terms. This analysis demonstrates the effects of strain softening, suggests that there are two possible modes of instability causing compression failure and shows that instability is not possible under conditions of high axial and flexural restraint. These conclusions are independent of the precise form of the stress-strain relationship but are primarily a direct consequence of the existence of a descending branch in the stress-strain curve of concrete in compression.
The effect of mix proportions upon the ultimate air-drying shrinkage of mortars
Authors: Dougill J. W. , Hobbs D. W. 
Published: July 2012

Synopsis Values are given for the ultimate air-drying shrinkage of 25 mm square mortar and paste prisms moist-cured for one week and dried at 65% R.H. and 20°C. The mortars, of water/cement ratios 0·35, 0·47, 0·59 and 0·71 and aggregate volume concentrations ranging from 40 to 70%, were made from one hatch of all ordinary Portland cement and Thames Valley flint aggregate of 5 mm maximum size. The ultimate shrinkages of the mortars are plotted as contours on a ternary diagram of mix proportions by weight and it is shown that ultimate shrinkage of the mortars is approximately proportional to water content by weight in the original mix. A comparison is made between theoretical predictions of shrinkage and the experimental values.
Determining the water content of concrete panels by using a microwave moisture meter
Authors: Figg J. 
Published: July 2012

Synopsis Sections of 1 × 2 m, sawn from full-size commercial concrete panels, were tested with a microwave moisture meter to establish calibration curves for different types of concrete cladding panel. The tests confirmed that the relationship between microwave attenuation and percentage of absorhed water for such panels was linear, but it was also found that the slope of the curve depended upon the particular construction of the concrete panel. With 10% absorbed water, the microwave attenuation varied between approximately 10 and 20 dB. Anomalous results were obtained during freezing weather and these were attributed to molecular orientation of the water in the concrete.
Moment redistribution in continuous prestressed concrete beams
Authors: Priestley M. J. N. , Park R. 
Published: July 2012

Synopsis In a previous paper relationships between moment and average curvature were developed for prestressed sections subjected to constant moment. The variation of stiffness due to concrete tension between cracks was taken into account. These relationships are now used to determine the moment-load and load-deflection curves for continuous beams up to the onset of concrete crushing. The results of an experimental programme on two-span continuous beams are presented and show close agreement with theoretical results.
Steel-fibre-reinforced mortar: a technique for producing composites with uniaxial fibre alignment
Authors: Hannant D. J. , Spring N. 
Published: July 2012

Synopsis A technique is described by which short steel fibres can be aligned parallel to the direction of tensile stress in mortar beams to be subjected to flexural loading. A combination of vibration and mechanical alignment enables the load carried by the beam to be doubled in comparison with that achieved by using vibration alone.
The use of lighter-weight blastfurnace slag as dense coarse aggregate in concrete
Authors: Gutt W. , Teychenné D. C. , Harrison W. H. 
Published: July 2012

Synopsis The use of imported iron ores has led, in recent years, to a lowering in the bulk density of some blastfurnace slags produced in the United Kingdom. To take account of this change, it was decided to examine the properties of this lighter-weight slag and its suitability as dense coarse aggregatefor concrete. Accordingly, studies have been made of three slag aggregates having bulk densities below the minimum of 1250 kg/m3 specified in British Standard 1047:1925, which governs the use of dense coarse slag aggregates for concrete. This investigation, which included chemical and mineralogical examination of the aggregates and concrete durability studies up to five years from casting, has now been completed. It has been established that the strength and durability of concretes made with the lighter-weight slags did not differ significantly from those of control concretes made with flint gravel, crushed limestone and normal density slag, provided that adequate cement content and workability levels were ensured by appropriate mix design techniques. The investigations carried out included examination of reinforcing steel takenfrom the concrete. These findings could lead to a lowering of the bulk density minimum in BS 1047, andfurther encourage the utilization of blastfurnace slag as dense coarse aggregate for concrete.
Plastic analysis of shear in reinforced concrete
Authors: Bræstrup Mikael W. 
Published: July 2012

Synopsis The square yield condition and associated flow rule for concrete are postulated. The state of stress in a kinematical discontinuity (crack) in plain concrete is derived and it is shown that interface shear transfer occurs when the relative displacement rate is not normal to the crack. This is used to analyse the shear of an orthogonally reinforced concrete disc element, including the case when the reinforcement in one direction does not yield. This is also the case for reinforced concrete beams subjected to shear, and the shear strength of a beam with compression flange is derived. The solution is compared with test results, and with the British and the Danish Codes of Practice.
Apparatus for testing concrete under multiaxial states of stress
Authors: Newman J. B. 
Published: July 2012

Synopsis The paper describes the equipment and techniques for applying multiaxial stress states to specimens of concrete, and accurately measuring the deformation at small and large strains. Particular attention is given to inducing uniform and definable states of stress, together with ease and accuracy of control during the various loading regimes. Details of the construction of the apparatus and principles of operation are given.
Estimating long-term creep and shrinkage from short-term tests
Authors: Brooks J. J. , Neville A. M. 
Published: July 2012

Synopsis From experimental results on a range of mixes made with two lightweight and two normal-weight aggregates and from an analysis of numerous data of other investigators, it is proposed that creep and shrinkage at one year can be predicted from measured values at between 7 and 28 days by means of linear and power equations. Equations for the prediction of longer-term values are also given.
Time-dependent and steady-state stresses in concrete structures with steel reinforcement, at normal and raised temperatures
Authors: England G. L. , Jordaan I. J. 
Published: July 2012

Synopsis Stresses and displacements in concrete structures are influenced by the creep of concrete. When loads and temperatures are sustained, stresses tend to limiting or steady-state values which are influenced by the presence of steel reinforcement and concrete shrinkage. The paper describes the influence of these two factors in symmetrically reinforced concrete columns. It is shown that two steady-state solutions are possible: an elastic steady state in which all the column load is carried by the reinforcement and the steel remains in the elastic range, and a yield steady state for which there is a shared load between the steel and concrete, but the reinforcement is in a yield condition. The inclusion of shrinkage leads to more rapid stress changes towards the steady state and to an earlier state of yield in some cases.
Fibre bond strengths in cement and concrete
Authors: Hughes B. P. , Dougill J. W. 
Published: July 2012

Synopsis The bond strength between fibre and matrix in cement-based fibre-reinforced composites is usually low and the more successful fibres tend to have some form of mechanical anchorage. However, since the bond strength between fibre and matrix also depends upon the degree of damage sustained by the matrix, the satisfactory prediction of fibre efficiencies is very difficult, and bond test results for single fibres have shown poor correlation with the corresponding tensile properties of the composites. The paper describes an improved form of bond test for single or grouped fibres of various shapes, diameters, lengths and distributions.