Cyclic Behavior of Smooth Steel Reinforcing Bars: Experimental Analysis and Modeling Issues

This article presents the results of an experimental campaign on the cyclic behavior of smooth steel bars, used as internal reinforcement of existing Reinforced Concrete (RC) structures; the stress-strain relationship is analyzed for different values of L/D ratio, where L is the stirrup spacing and D is the longitudinal bar diameter. Most of the experimental tests concerned smooth bars with L/D ratios ranging between 5 and 100. The analysis of the test results is complemented by some comparisons of the curves obtained by experimental tests on smooth steel bars with those obtained by experimental tests on ribbed steel bars. The theoretical predictions obtained by existing models available in the literature on the cyclic behavior of ribbed steel bars are then discussed. Our review of these formulations underlines their range of applicability as well as their potential to predict the damage and buckling that occur for different L/D ratios of the smooth steel bars.     

Experimental Investigation on the Seismic Performance of Beam-Column Joints Reinforced with GFRP Bars

Glass fiber-reinforced polymer (GFRP) reinforcing bars were used recently as main reinforcement for concrete structures. The noncorrodible GFRP material exhibits linear-elastic stress-strain characteristics up to failure with relatively low modulus of elasticity compared to steel. This raises concerns on GFRP performance in structures where energy dissipation, through plastic behavior, is required. The objective of this research project is to assess the seismic behavior of concrete beam-column joints reinforced with GFRP bars and stirrups. Two full-scale exterior T-shaped beam-column joint prototypes are constructed and tested under simulated seismic load conditions. One prototype is totally reinforced with GFRP bars and stirrups, while the other one is reinforced with steel. The experimental results showed that the GFRP reinforced joint can sustain a 4.0% drift ratio and can recover its deformation without any significant residual strains. This indicates the feasibility of using GFRP bars and stirrups as reinforcement in the beam-column joints subjected to seismic-type loading.     

Gift Exchange and Interpretations of Captain Cook in the Traditional Kingdoms of the Hawaiian Islands

The relationship between the kanaka maoli people of the traditional kingdoms of the Hawaiian Islands and Captain James Cook and his crew is interpreted in the context of a theory of gift exchange. It is argued that interpretations of kanaka maoli behaviour based on an implicit assumption that social relations were structured primarily by property rights leads to error. Instead, sense can be made of kanaka maoli behaviour only if a logic based on rights of person is taken into account.     

Fractal analysis of gravity wave spectra in the middle atmosphere

Wind fluctuations in the middle atmosphere behave like colored noise processes. They have a continuum of scales without dominant features and a power spectrum density (PSD) that often decays with frequency ƒ as ƒ^−β. Spectral index β is generally obtained through least-square fit to PSD estimated by Fourier methods. Graphs of colored noise have fractal plane-filling properties depending on β. An efficient method for finding β using the fractal dimension (D), based on analysis of 1/ƒ noise in galactic X-ray luminosities by McHardy I. and Czerny B., (1987, Nature325, 696), is described. An empirical relation is found between D and β and its validity is confirmed in limiting cases. Then D is obtained from power-law dependence of a length metric L(μ) on scale μ. The method is applied to middle-atmospheric velocity data from the Poker Flat radar in Alaska. Variations of D follow those in β, from an earlier analysis by Bemraet al., (1986, Handbook for MAP20, 216), but show an offset of 0.1–0.2 even after corrections for outliers, gaps, and additive noise. Usefulness of this method for screening data as an aid to spectral analysis is examined.     

Experimental estimates of electron density variations at the reflection height of VLF signals

To study the behaviour of the electron concentration at the reflection level of very low frequency (VLF) waves, two years of phase and amplitude records of the 12.9 kHz signals emitted from Omega-Argentina (43.20°S; 294.60°E) and received at Tucumán (26.90°S; 294.70°E) have been used. The experimental results are compared with values derived from the International Reference Ionosphere model (IRI-79). The experimental data show a seasonal variation not predicted by the model. Differences are explained in terms of changes of night-time atomic oxygen concentration, which control the electron density profile at the base of the night-time D-region, not taken into account in the IRI model. Values of atomic oxygen necessary to explain VLF data are comparable with published data.     

The Coupled Influence of Relative Density,CSR, Plasticity and Content of Fines on Cyclic Liquefaction Resistance of Sands

In this study, stress-controlled cyclic simple shear tests were performed on sand specimens with up to 10% silt or clay contents, and coupled effects of plasticity, fines content (FC), relative density (D_R) and CSR (cyclic stress ratio) were investigated. The results demonstrated that for sands with low fines content, reasonable trends were obtained when the packing index control parameter was selected as D_R. Also, clean sand specimens demonstrated highest liquefaction strength compared with that of sands with fines up to 10% FC. The effect of fines’ plasticity became apparent as the FC increases and CSR reduces in relatively denser specimens.     

Day-to-day variations in nearshore bar patterns on a small sandy beach through a lunar tidal cycle

Nearshore water circulation and bar patterns at Coledale, New South Wales, were surveyed daily over thirty-six consecutive days, from 3 November to 8 December 1978, to identify sequences of changes that might occur in response to spring-to-spring tide cycles of fourteen days, changing barometric and wind conditions associated with the passage of anticyclonic weather systems across the coast, and day to day variation in the nearshore wave regime. During the survey the bar patterns tended to vary from transverse bars, through a composite arrangement incorporating longshore and transverse bars, to a longshore bar pattern as the tide changed from its spring to neap tide phase. However, this sequence was too brief to unequivocally establish variations in nearshore bar pattern that might be attributed to the fourteen day, spring-to-spring tide cycle. Nevertheless, morphologic changes occurring in response to wave regime fluctuation at Coledale were broadly in accord with studies from elsewhere by Dolan et al. (1979, 1982), and Clarke and Eliot (1982, 1983) in that bars and rips were systematically distributed along the beach. At Coledale, bars tended to relocate approximately 0.4 and 0.75 of the distance along the beach from its southern end. The preferred bar spacing closely matches hypothetical standing waves trapped between the headlands of the Coledale embayment. Temporally, the nearshore morphology is highly responsive to wave regime changes such that, as primary breaker heights decrease and remain below H_max=1.0m, the bar pattern changes from longshore through mixed to transverse bar patterns within three to five days. On one occasion the bar pattern switched from a longshore to a transverse bar pattern within twenty-four hours.     

Post‐CO2 injection alteration of the pore network and intrinsic permeability tensor for a Permo‐Triassic sandstone

The aim of this study was to determine the process–structure–property relationships between the pre‐ and post‐CO₂ injection pore network geometry and the intrinsic permeability tensor for samples of core from low‐permeability Lower Triassic Sherwood Sandstone, UK. Samples were characterised using SEM‐EDS, XRD, MIP, XRCT and a triaxial permeability cell both before and after a three‐month continuous‐flow experiment using acidic CO₂‐rich saline fluid. The change in flow properties was compared to those predicted by pore‐scale numerical modelling using an implicit finite volume solution to the Navier–Stokes equations. Mass loss and increased secondary porosity appeared to occur primarily due to dissolution of intergranular cements and K‐feldspar grains, with some associated loss of clay, carbonate and mudstone clasts. This resulted in a bulk porosity increase from 18 to 25% and caused a reduction in mean diameter of mineral grains with an increase in apparent pore wall roughness, where the fractal dimension, D_f, increased from 1.68 to 1.84. All significant dissolution mass loss occurred in pores above c. 100 μm mean diameter. Relative dilation of post‐treatment pore area appeared to increase in relation to initial pore area, suggesting that the rate of dissolution mass loss had a positive relationship with fluid flow velocity; that is, critical flow pathways are preferentially widened. Variation in packing density within sedimentary planes (occurring at cm‐scale along the ‐z plane) caused the intrinsic permeability tensor to vary by more than a factor of ten. The bulk permeability tensor is anisotropic having almost equal value in ‐z and ‐y planes but with a 68% higher value in the ‐x plane (parallel to sedimentary bedding planes) for the pretreated sample, reducing to only 30% higher for the post‐treated sample. The intrinsic permeability of the post‐treatment sample increased by one order of magnitude and showed very close agreement between the modelled and experimental results.     

Fractal analysis of veins in Permian carbonate rocks in the Lingtanchang anticline,western China

Statistical analysis of the thickness distribution of veins in the Lingtanchang structure, southern Sichuan basin, western China, indicates that vein thickness conforms to fractal character and a power‐law distribution, whereas various distributions of veins are indicated by both the spacing distribution and the C_v values. According to geometry and structure, the veins in the Lingtanchang structure can be divided into confined and through‐going veins. The statistical analyses show that confined intralayer veins are consistent with a power‐law distribution in thickness, with D_t values of 1.1–1.7 and a log‐normal distribution in spacing with C_v values of 0.8–0.9. The confined intra‐ to interlayer veins show D_t values of 1.0–1.3 and an exponential distribution in spacing, with C_v values of 0.9–1.0, indicating an unconnected vein network with weak ability for paleofluid flow. However, the through‐going veins show the lowest D_t values of 0.6–0.8 with a power‐law distribution in thickness and power‐law to exponential distribution in spacing with C_v values of 1.5–3.2. Differences in spacing distribution and in the thickness of veins can be explained by different stages of vein growth from confined to through‐going veins. Such processes are dominant with percolating cluster models, which significantly controls spatial distribution of veins and paleofluid flow, and therefore the reservoir conditions in the southern Sichuan basin.     

D-region electron density diurnal changes observed in association with the PCA event of July 1974

Well defined diurnal phase and amplitude deviations of very low frequency radio signals propagation were detected during the solar proton event that occurred from 3 to 8 July 1974. Phase advances observed on signals transmitted from GBR (U.K.), received at Atibaia (Brazil) and at Inubo Radio Observatory (Japan), were compared with simultaneous NWC (Australia) transmissions received at Atibaia, and at Syowa Station (Antarctica). Emphasis was given to the propagation paths NWC-Atibaia and NWC-Syowa, because both propagate completely in the southern hemisphere, crossing regions where the Earth's magnetic field behaves anomalously. The comparison allowed the determination of parameters typical of the D-region at a given height in the lower ionosphere, for geomagnetic regions defined through the McLlwain parameter(L). An exponential model was adopted to fit the vertical distribution of the diurnal electron density. The experimental results showed a delayed contribution to the total ionization observed which was attributed to a slow precipitation of energetic particles in the South Atlantic Geomagnetic Anomaly region.     

Religion,secularisation and nationalism in Quebec and the Basque Country: a comparative approach

This article analyses the relationship between religion, secularisation and nationalism in Quebec and the Basque Country using a comparative approach. I will first outline the ethnic‐religious origin of these nationalist movements. Second, I will examine the extent to which the ‘new’ secular and violent nationalism (Euskadi Ta Askatasuna and Front de Libération du Québec) that emerged in the 1960s was fuelled in its origin by a transfer of sacrality. Third, I will address an aspect that has led some theorists to view religion and nationalism as analogous phenomena, in which nationalism is construed as a religion of blood sacrifice. Fourth, I will examine another aspect that leads to this view of religion and nationalism as analogous phenomena, as the latter also provides a framework of transcendent meaning through an imaginary of continuity between the different generations. The article concludes with a series of general considerations on the relations between nationalism, secularisation and religion.     

Br/Cl signature of hydrothermal fluids: liquid–vapour fractionation of bromine revisited

Br/Cl ratios of hydrothermal fluids are widely used as geochemical tracers in marine hydrothermal systems to prove fluid phase separation processes. However, previous results of the liquid–vapour fractionation of bromine are ambiguous. Here we report new experimental results of the liquid–vapour fractionation of bromine in the system H₂O–NaCl–NaBr at 380–450°C and 22.9–41.7 MPa. Our data indicate that bromine is generally more enriched than chlorine in the liquid phase. Calculated exchange coefficients K_D(Br‐Cl)^{liquid‐vapour} for the reaction Br^vapour + Cl^liquid = Br^liquid + Cl^vapour are between 0.94 ± 0.08 and 1.66 ± 0.14 within the investigated P–T range. They correlate positively with D_Cl^{liquid‐vapour} and suggest increasing bromine–chlorine fractionation with increasing opening of the liquid–vapour solvus, i.e. increasing distance to the critical curve in the H₂O–NaCl system. An empirical fit of the form K_D(Br‐Cl)^{liquid‐vapour} = a*ln[b*(D_Cl^{liquid‐vapour}?1) + e^1/a] yields a = 0.349 and b = 1.697. Based on this empirical fit and the well‐constrained phase relations in the H₂O–NaCl system we calculated the effect of fluid phase separation on the Br/Cl signature of a hydrothermal fluid with initial seawater composition for closed and open adiabatic ascents along the 4.5 and 4.8 J g^?1 K^?1 isentropes. The calculations indicate that fluid phase separation can significantly alter the Br/Cl ratio in hydrothermal fluids. The predicted Br/Cl evolutions are in accord with the Br/Cl signatures in low‐salinity vent fluids from the 9 to 10°N East Pacific Rise.     

DIAPHRAGM ACTION OF SANDWICH PANELS IN PIN-JOINTED STEEL STRUCTURES: A SEISMIC STUDY

The paper focuses on the seismic response of steel pin-jointed frames braced by lightweight cladding panels. In particular, with the aim to investigate the performance of such a structural scheme when acting as a dissipative system, a wide numerical study has been developed. It is based upon available shear tests on screwed sandwich panels, whose experimental cyclic responses are properly incorporated into a scope-oriented, computer program. The goal is firstly to check the possibility of using cladding panels as shear diaphragms in seismic areas and then to assess an appropriate design behaviour factor, accounting for their actual hysteretic response. Key findings from the nonlinear dynamic analyses are: (1) a portal frame steel building in a low-medium seismicity zone may be braced by common cladding panels, completely avoiding the use of other bracing systems; (2) this structural solution, if compared with a conventional one, appears to be more efficient and cost-effective, giving rise to a weight saving which, in the case under examination, reaches a value of about 20%; (3) on the basis of the numerical study a design behaviour factor q _d =2 seems to be realistic for such a structural typology.     

Role of periodic fluctuations in solar wind-magnetosphere coupling

In this paper, the behaviour of the fluctuating component in the solar wind parameters (V, B_z), the auroral electrojet indices (AU, AL), the ring current index (D_st) and the interplanetary electric field (V × B₂) during 10 magnetic storms is analysed to understand the solar wind-magnetosphere coupling. It is found that during the moderate storms (D_st > −100 nT), the fluctuating component of 3–4 h periodicity is clearly discernible in all the parameters, and during the intense storms (D_st < −100 nT) the periodic fluctuations are not well defined.     

Eiscat observations of the ionospheric D-region during auroral radio absorption events

Electron densities in the D-region have been observed with EISCAT during energetic electron precipitation events. Sample results are presented which demonstrate the value of the technique in studying variations of electron density with fine temporal and spatial resolution. Different types of absorption event can be characterized in terms of the changes in the incoming electron spectrum inferred from profiles of electron density. We contrast the D-region behaviour of night- and day-time events in terms of precipitating spectrum and absorption profile. A softening of the electron spectrum during the course of a morning event is clearly seen.     

REGIONAL VARIATIONS IN BLOOMERY SMELTING SLAG OF THE IRON AGE AND ROMANO‐BRITISH PERIODS*

This study highlights regional variation in the composition of iron‐smelting slag produced in England prior to the medieval period and attempts to link slag composition to the type of ore smelted. For many sites, the slag compositions were consistent with the use of limonite ore, but there is evidence that siderite ore was smelted at sites in Sussex in the late Iron Age/Romano‐British periods. A compositional comparison of smelting slags and slag inclusions in Iron Age currency bars, using data from Hedges and Salter (1979 ), illustrates the potential of smelting slag compositional data in provenance studies of early iron objects.     

A FIBRE FINITE BEAM ELEMENT WITH SECTION SHEAR MODELLING FOR SEISMIC ANALYSIS OF RC STRUCTURES

The paper describes the formulation of a non-linear, two-dimensional beam finite element with bending, shear and axial force interaction for the static and dynamic analysis of reinforced concrete structures. The hysteretic behaviour of “squat” reinforced concrete members, in which the interaction between shear and flexural deformation and capacity is relevant for the overall structural performance, is emphasised. The element is of the distributed inelasticity type; section axial-flexural and shear behaviours are integrated numerically along the element length using a new equilibrium-based approach. At section level a “hybrid” formulation is proposed: the axial-flexural behaviour is obtained using the classic fibre discretisation and the plane sections remaining plane hypothesis, the shear response instead is identified with a non-linear truss model and described with a hysteretic stress-strain relationship. The latter contains a damage parameter, dependent on flexural ductility, that provides interaction between the two deformation mechanisms. The element has been implemented into a general-purpose finite element code, and is particularly suitable for seismic time history analyses of frame structures. Analytical results obtained with the model are compared with recent experimental data.     

Dimensional variations of Roman masonry subjected to wetting-drying cycles

Abstract

Many Roman monuments made of opus caementicium are subjected to wetting and drying phenomena caused by water or/and humidity from the ground. The action of water impregnation on the hypothetical dimensional changes in this Roman concrete has not been considered in the literature and no experimental data are available.

The purpose of this work was the evaluation of the effect of wetting and drying cycles in a number of cores taken from an ancient Roman monument (Domus Tiberiana in the Palatine, Rome). The concrete samples were made of a pozzolanic mortar with large pieces of tuff, marble and bricks.

In spite of some differences in their composition, the behaviour of the cores was similar and, generally, quite constant during the experimental cycles. On the average, the length variation was about 3–4%,or 3–4mm for each metre and, when related to high structural walls and monuments, the possible dimensional changes were quite impressive.     

Policy and creative strategies: Hong Kong CEPA films in the China market

Abstract

This article examines the creative strategies of Hong Kong Closer Economic Partnership Arrangement (CEPA) films in engagements with the China market under the framework of CEPA introduced in 2004. One of the aims of CEPA for the film sector is to boost co-production between Hong Kong and the mainland. In the past 10 years, CEPA has dramatically changed Hong Kong cinema’s relationship with China in that major film directors have moved to produce CEPA films to tap into the rapidly growing mainland market. This shift has been considered as part of HKSAR’s overall mainlandization and subsequent disappearance of a distinct local identity. This article revisits this view by presenting two case studies to see if indeed Hong Kong CEPA pictures are devoid of Hong Kong elements. The case studies analyze textual elements of two CEPA blockbuster films, The Mermaid (dir. Stephen Chow, 2016) and The Taking of Tiger Mountain 3D (dir. Tsui Hark, 2014). Citing the intertextual allusions to the directors’ old works seen in these two films, the authors argue that the market advantage granted by the CEPA scheme in effect allowed Hong Kong filmmakers to revive and extend signature creative strategies of Hong Kong cinema, despite censorship constraints.     

An Examination of the Spatial–Temporal Isolation Model in a Nilotic Population: Variation across Space and Time in Nubians Using Cranial Discrete Traits

Nubian biological evolution has come under much scrutiny in preceding years with strong opinions dividing scholars' beliefs as to how it occurred. A new approach is necessary to elucidate subtleties of their population structure in order to shed light on the complex subject. This study employs a spatial–temporal model in an effort to test if in situ biological evolution was the mechanism for biological change. Biological distance was calculated from the phenotype using 20 cranial discrete traits observed in Nubian samples from the sites of Semna South, Kerma, and the islands of Hesa and Biga. The periods represented at Semna South are Meroitic, X‐Group and Christian, whereas the Kerma site yielded skeletal material from the Kerma period, and the islands of Hesa and Biga date to the Christian period. Mahalanobis D² with a tetrachoric matrix was used to calculate biological distances among the samples, and three‐way Mantel tests were applied to the distance, spatial and temporal matrices. Time was not significantly correlated with biological distance. However, an inverse relationship of time and biological distance is expected under the spatial–temporal model. A lack of significant geographic correlations, as found here, is unusual in most populations, but given the spatial construct of the sites along the Nile, this relationship is not completely unexpected. The lack of significant correlation among time, space and biological distance does not support the in situ hypothesis. Copyright © 2011 John Wiley & Sons, Ltd.