bluuebunny/crossref_metadata_2025 huggingface dataset:
Population Growth the Scapegoat? Rethinking the Neo-Malthusian Debate
Authors: Collins Patrick
Published: October 2002

In the last thirty years of the twentieth century we saw a resurrection of the writings of Matlhus. In their new guise we are told that instead of war, pestilence and famine, the earth has decreasing biodiversity, loss of species, loss of natural resources and water shortages, to name but a few, to look forward too. Population growth today, as it was two hundred years ago, is portrayed as Public Enemy number one. There is little doubt that the Neo-Malthusian argument has made an impact on policy, indeed, probably moreso than did its namesake. The newly clad argument shares much with its namesake, not least, its significant faults.

The argument is two hundred years old, and the inaccuracies share that age. Malthus' predictions never reigned true because he made the fundamental error of not taking account of technical progress, or the ability of human ingenuity to adapt to change. This paper looks at the evolution of both sides of the population argument, and argues that this year's World Summit in Johannesburg should not fall foul to the dangerous generalisations invoked by the Neo-Malthusian school of thought. This paper is an attempt to lay the blame for environmental degradation not on the increasing population of the Third World, but on the consumption patterns and lifestyles of the First World. Affluence consumes energy and produces waste at a far higher rate than poverty. In looking at the environmental debate only an integrated approach, and not one that is concerned solely with ‘demonising’ population growth, can result in success.
How Can the European Community Fulfil the Kyoto Protocol? the Wise-Man Approach
Authors: Kübler Knut
Published: October 2002

The decisions taken at the 7th session of the Conference of the Parties to the UNFCCC make it likely that sufficient Parties will proceed with ratification of the Kyoto Protocol to result in its entry into force before the Johannesburg summit in 2002. Can the European Community fulfil the obligations of the Kyoto Protocol? The answer is yes and easily, if it follows the wise-man approach, taking advantage of the flexible mechanisms, using the option to absorb CO2 emissions by proper “land-use-change”, exploiting the greenhouse gas reduction potential outside the energy sector and implementing some of the current proposals in the area of energy and transport policy. Quantitative analysis lead to the result that there is no need to develop new measures to meet the obligations of the Kyoto Protocol. The coming years can be used to facilitate the transition to a new energy system and to start exploring policies beyond 2012.
Environmental Effects of Increased Atmospheric Carbon Dioxide
Authors: Soon Willie , Baliunas Sallie L. , Robinson Arthur B. , Robinson Zachary W.
Published: October 2002

A review of the literature concerning the environmental consequences of increased levels of atmospheric carbon dioxide leads to the conclusion that increases during the 20th century have produced no deleterious effects upon global climate or temperature. Increased carbon dioxide has, however, markedly increased plant growth rates as inferred from numerous laboratory and field experiments. There is no clear evidence, nor unique attribution, of the global effects of anthropogenic CO2 on climate. Meaningful integrated assessments of the environmental impacts of anthropogenic CO2 are not yet possible because model estimates of global and regional climate changes on interannual, decadal and centennial timescales remain highly uncertain.
Climate Change in the Arctic and its Empirical Diagnostics
Authors: Adamenko V.V. , Kondratyev K. Ya , Varotsos C.A.
Published: October 2002

The Hypothesis that global climate warming observed during the last century is due to anthropogenically induced carbon dioxide concentration growth, has provoked controversy. In this context, general considerations are discussed which support the view that the ‘greenhouse’ global warming hypothesis is doubtful. Numerical climate modelling data ‘predicts’ that there must be an enhancement of the ‘greenhouse signal’ with latitude. Some results of surface air temperature (SAT) observations in the Arctic during the last 20–30 years demonstrate, however a reduction in SAT in several Arctic regions. Some dendroclimatic data fot the last 200–300 years relevant to tree growth near the northern forest boundary reveals that not ony the conclusoin about polar enhancement of climate warming is wrong but the warming itself could hardly be real. It is concluded that no uncontroversial information exists to support the hypothesis of global ‘greenhouse’ warming.
Speech Intelligibility Improvement by Sound Recording Techniques
Authors: Ruiz Robert , Faiget Laurent
Published: October 2002

Speech intelligibility studies have modelised the influences of the acoustical features of the room and/or the properties of the voice signal and/or the electroacoustical characteristics of the loudspeakers on scores. A complementary element is added here: the sound recording system. The purpose of this paper is to demonstrate that sound recording microphone techniques can modify intelligibility scores: monophonic techniques (with an omnidirectional and a cardioïd microphones) and a stereophonic O.R.T.F one. The sense and the extent of the variation are discussed: scores are increased when recordings are listened. The experimental conditions are recalled [1] but new results are obtained leading to a new detailed analysis. A discussion is started up concerning the reliability of intelligibility tests in an auralization approach.
Field Measurement and Criteria for Sound Insulation between Dwellings in Europe
Authors: Sheridan Linda , Maluski Sophie
Published: October 2002

Airborne and structure-borne sound transmission are the dominant noise paths in terraced, semi-detached houses and in multi-storey buildings, often causing annoyance when heard. They usually are controlled by applying building regulations before, during and after the construction of the dwellings. As part of a comparative study of the control and promotion of quality in housing in Europe, the acoustic quality in dwellings have been investigated for France, Norway, Sweden, the Netherlands, Germany, Switzerland, Italy and the United Kingdom. The study highlights many differences in regulations, criteria and methods of measurement.

The conclusion drawn from this comparison is that there is no uniformity in the regulations for the acoustic quality of dwellings in Europe and much work is needed to establish uniformity.
A Computer Investigation of the Performance of Virtual Reflectors: Part 1 - Development of the Method
Authors: Oldham D J , El-Zeky L
Published: October 2002

In a companion paper [1] a technique for improving acoustic conditions in open stage auditoria by means of virtual reflectors has been proposed. Possible methods of testing the application of a virtual reflector system were discussed and it was concluded that computer simulation was the most appropriate. However, before employing a commercially available package it was necessary to devise suitable procedures.

The need for both a directional loudspeaker and a directional microphone is an essential requirement for the virtual reflector system but most computer simulation packages only allow for source directivity. Hence a method of incorporating the effect of microphone directivity using the principle of reciprocity was developed. The basis of establishing the gain factor has been devised and it is proposed that the convolution of echograms rather than the convolution of true impulse responses can be employed to predict system performance.

The action of the virtual reflector system has been investigated using a model of an open stage theatre. Both system microphone and system loudspeaker were selected from a catalogue of available modern commercial sound equipment. The resulting STI contours demonstrated that the effect of the virtual reflector over the audience area to the rear of a human speaker was to raise the speech intelligibility to be approximately equal to that to the front of the speaker.

It has been shown that the STI at the rear of a speaker with the virtual reflector system in operation does not increase significantly with gain. This is due to the Modulation Transfer Functions which determine the STI value being determined by the convolution of two impulse responses multiplied by a gain factor and added to a third impulse response. The resulting impulse response therefore consists of many ‘reflections’ and hence the MTF's and STI values will be adversely affected if excess gain is applied.
Prediction Models of Impact Sound Insulation on Timber Floor Structures; A Literature Survey
Authors: Brunskog Jonas , Hammer Per
Published: October 2002

To develop new types of lightweight wall and floor structures it is important to increase the knowledge of the transmission and radiation processes for such structures. To do so, detailed models based on deterministic and statistical assumptions may form a valuable tool. In lightweight floor structures, impact sound insulation is perhaps the most important factor to consider. This paper gives an overview of various solution strategies that may be useful in finding a prediction model for impact sound insulation.
Acoustical Design and Measurement of a Circular Hall for Improved Spatial Factors at Each Seat
Authors: Takatsu Akio , Sakai Hiroyuki , Ando Yoichi
Published: October 2002

A round-shaped multi-purpose event hall (ORBIS Hall, Kobe, Japan) was designed based on the subjective-preference theory of sound fields [Y. Ando, Architectural Acoustics -Blending Sound Sources, Sound Fields, and Listeners-, AIP Press/Springer-Verlag, New York, 1998]. To avoid acoustical problems produced by round-shaped walls, and to maximize the total scale value of the subjective preference at each seat, acoustical features including several kinds of reflectors were carefully designed. The IACC calculated for the design phase, however, did not include all the installed features because these have complicated scattered reflection characteristics. After construction of the hall, therefore, the IACC measurements were conducted using two different music motifs. Results indicate that the values of the IACC are much improved due to these features. Also, the SPL-dip in the low frequency range in the area close to the stage is effectively improved by the inclusion of a perforated floor.
Acoustic Emissions from Construction Equipment
Authors: Waddington D. C. , Lewis J. , Oldham D. J. , Gibbs B. M.
Published: October 2002

This paper examines the various source data commonly used for the prediction of construction site noise immissions, i.e. the total amount of noise from all contributing sources at a given position. A series of analyses are presented of the noise emission data from over 400 measurements of various powers and types of construction and open site plant. The sound power level data was obtained from on-site measurements performed by consultants, and from ISO tests performed for manufacturers. Comparisons are made of the sound power level data obtained from ISO tests with guaranteed sound power levels, and with the permissible sound power levels of plant specified in the EC Regulations. It is seen that manufacturers' data measured using established ISO test codes introduces less uncertainty to sound field predictions than does the permissible sound power level of the plant or the guaranteed sound power level of the machine. Comparisons are also made with additional data from the British Standard BS5228. Consideration is given to the utilization of each sound power data source for the prediction of construction site generated noise.
Technical Note: Absorption Coefficients of Common Construction Materials for Use in Computer Modelling of Enclosed Spaces
Authors: Dance S. , Shield B.
Published: October 2002

Absorption coefficients, which have been shown to give accurate predictions using a number of computer models, each using a different modelling technique, are presented. The types of room simulated were various, as were the room acoustic parameters predicted. For highly absorbent materials it has been shown that the use of Millington based absorption coefficients gives improved prediction accuracy and hence Millington coefficients are also presented. With this data it is now possible to introduce limited standardisation when using computer models to predict room acoustics parameters.
Technical Note: Field Survey of Noise Generated by Elevator Installations
Authors: Romeu J. , Jiménez S. , Salueña X. , Capdevila R.
Published: October 2002

A study is carried out to determine the sound sources in typical elevator devices used in domestic buildings in Spain. The analysis consists of measurements in more than 50 different buildings, including vibration analysis. Surveys have shown that the main sound sources are: the machine itself, the controller, the doors and the blocking device. Noise measurements have been taken inside the adjacent parts of residential buildings, showing values in excess of 50 dBA, caused by faults in the vibration isolation of the machine and the controller in electromechanic elevators. On the other hand, hydraulic elevators showed a greater variability in results, depending on the machine.
Frequency and Time Numerical Solutions of 3D Sound Propagation in Open and Closed Spaces
Authors: Tadeu António , António Julieta , Godinho Luís
Published: October 2002

Problems in acoustics can often be solved with the aid of formulas or expressions known as Green's functions. These functions, or fundamental solutions, relate the field variations (such as pressures) in an acoustic medium caused by sound sources placed elsewhere in the medium. The two fundamental solutions most often used are for harmonic point loads in a three-dimensional, infinite, homogeneous space, and for a harmonic line load acting within two-dimensional spaces. These are chosen because their solutions are known in closed-form and they are relatively simple in structure. This paper presents a set of three-dimensional solutions applied when the space domain is modeled with plane barriers placed together to reproduce spaces that vary from a simple half-space to a parallelepiped closed space. It is assumed that the homogeneous three-dimensional space is subjected to 3D point sources and spatially sinusoidal, harmonic line sound loads.

The resulting expressions are implemented to evaluate the field inside a rectangular space, whose walls allow different absorption coefficients. The time responses are obtained by means of Inverse Fourier Transforms. Complex frequencies are used to attenuate the response at the end of the time window. The effect of this attenuation is taken into account by re-scaling the time response.
Scale Model Investigation on the Influence of Boundary Conditions on the Airborne Sound Insulation of Lightweight Double Walls
Authors: Astolfi G. , Garai M. , Secchi S.
Published: October 2002

Sound reduction index measurements were performed inside a 1:10 scale model of two adjoining rooms of a test facility in an acoustic laboratory, with the aim of investigating the influence of the boundary conditions on the acoustic performance of lightweight double walls. The model was built entirely of polymethyl methacrylate (PMMA). The specimen double walls were built using the same acrylic material. At first, measurements were performed on a single homogeneous panel, in order to check the reliability of the whole procedure and the repeatability of the measurements. A good correspondence was found between theoretically calculated values and measured values of the sound reduction index above the critical frequency. A second set of measurements was carried out on model double walls comprising two leaves, connected to each other only by a border frame running along the whole wall perimeter. It was found that the effect of the border frame is a reduction of the performance of the double wall, to under that of a single plate with the same total surface mass. A third set of measurements was carried out inserting vertical studs to connect the two leaves. It was found that the presence of the studs causes a general decrease of the sound reduction index values and a decomposition of the critical frequency. A fourth set of measurements was carried out on the same double wall using border frames made of different materials. The experimental results show that damped materials (wood, rubber) give a better performance than rigid materials (acrylic, aluminium).
A Comparison of the Predicted Dynamic Stiffness of Resilient Layers with Calculated Values Obtained from the Measured Acceleration Response
Authors: Stewart Michael A. , Mackenzie Robin. K.
Published: October 2002

Obtaining the dynamic properties of resilient materials is a subject that has been extensively researched by other workers using a variety of techniques; many of these techniques use detailed numerical methods. In this paper a simplified approach has been adopted which allows the dynamic stiffness of resilient layers to be predicted at higher frequencies where wave effects across the thickness of the layer are important. The method is a development of the technique used in the ISO Standard 9052-1. However, the ISO Standard method will only give the stiffness at one frequency whereas the method in this paper gives the stiffness across a frequency range. Reasonable agreement with measurements is shown.
Technical Note: Influence of the Frame on the Sound Reduction Index of a Window
Authors: Cervera Francisco , Uris Antonio
Published: October 2002

The Sound Reduction Index of 1.2 × 1.2 m windows composed of two identical pivoting leaves of three different thickness of laminated glass and inserted in two different frames (aluminium and PVC) had been measured using pressure and sound intensity techniques. The Sound Reduction Index has been also predicted. These results have allowed us to compare the relative importance of the frame acoustic isolation effectiveness against the glass pane effectiveness in order to achieve an overall window Sound Reduction Index.
Technical Note: Shock Testing Using a Vibrator
Authors: Gerges Samir N. Y.
Published: October 2002

In recent years there has been an increasing tendency to use shakers rather than shock devices, for shock testing. The advantage of using the same transducers and fixtures for both vibration and shock tests, is that not only does this reduce initial equipment costs; it also complements the sophisticated digital control systems currently available and significantly reduces set-up and breakdown time in the laboratory. This paper presents a review of the state of art on testing by simulating a shock environment with shakers.
Air-Borne Sound Insulation of Single Walls at Low Frequencies: A Discussion on the Influence of Boundary and Mounting Conditions
Authors: Ljunggren S
Published: October 2002

A theoretical analysis of the air-borne sound transmission through a single wall at low frequencies is presented. The wall is assumed to be surrounded by orthogonally mounted partitions. The results are compared with those presented previously for a wall mounted in a baffle. The comparison shows that the presence of the orthogonal partitions can substantially increase the transmission due to the forced response at frequencies around and below the critical frequency. The magnitude of this effect depends on how the wall is mounted to surrounding constructions; it can be large for certain cases. The analysis also shows that the transmission due to the resonant response increases by 6 dB at frequencies below the critical frequency in the region where the edge radiators are predominant.
The Acoustic Properties of Expanded Clay Granulates
Authors: Asdrubali F. , Horoshenkov K. V.
Published: October 2002

The purpose of this work is to characterise experimentally and theoretically the acoustic performance of mixes of loose expanded clay granulates. The surface acoustic impedance is obtained from measurements in the impedance tube and predicted using the Pade approximation approach. The random incidence absorption coefficient is measured using the ISO 345/85 method. Experimental data for the surface acoustic impedance are used to deduce the porosity, tortuosity and the statistical pore size distribution; these parameters are difficult to obtain directly, because of the relatively low density of the loose granulates and the fact that the granular base contains 5–30% of the closed, unconnected pores. Good agreement between the theory and the results is found; 50–100 mm layers of expanded clay granulates can be used efficiently for noise control over a broad frequency range.
Measurement of the Acoustic Properties of Resilient, Statically Tensile Loaded Devices in Lightweight Structures
Authors: Brunskog Jonas , Hammer Per
Published: October 2002

Resilient devices are commonly used in lightweight structures to decrease sound transmission in a broad frequency band. Applications of such devices may be found in e.g. resilient mounted ceilings in aeroplanes, ships and buildings. A measurement method to characterise the frequency dependency of the transfer stiffness and the input stiffness of the resilient device is presented. The mechanical characteristics of the measurement method are investigated. In addition, some resilient devices used in buildings are analysed with respect to acoustic properties. Parameters such as static load and mountings for the devices are considered and handled by means of statistical analysis.
Subjective Evaluation of Acoustical Environments for Solo Performance
Authors: Chiang Wei-Hwa , Huang Jan-Chun
Published: October 2002

A subjective experiment was conducted involving assessment of acoustical environments for solo performance by two different instruments, the cello and the xylophone. The sound fields were produced by digital convolution of binaural impulse responses with recorded “dry” music. A group of professional listeners and a group representing the general public were asked to evaluate simulated music via headphones. A forced-choice comparison was used. Participants picked their preferred sound field for each of 66 pairs of test signals. Multiple regression analyses yielded 3 orthogonal measures. They were early level (G80), reverberation time (RT) or early decay time (EDT), and treble ratio of early level (T(G80)) according to their respective significance of correlation with preference score. The minimum acceptable overall level (G) was 5.6 dB and the preferred reverberation time (RT) was 1.4 sec. Both groups of listeners preferred a 0.19-sec longer reverberation time for the cello music than for the xylophone music.
Impact Sound Insulation of Timber Floors: Interaction between Source, Floor Coverings and Load Bearing Floor
Authors: Scholl W. , Maysenhölder W.
Published: October 2002

It is well known that prediction of impact sound of timber floors contains large uncertainties. They partly originate from the dynamic interaction of impact sources and floor elements which makes it difficult to characterise the performance of the elements of a floor in the right way. First results of a project recently started at the Fraunhofer-Institut für Bauphysik on this subject are presented. Calculations reveal strong influences of impact source and load bearing floor on the acoustical performance of the floor coverings. There are considerable deviations between concrete and timber floors. The standard ISO tapping machine and human walkers interact quite differently with floors and coverings, thus modifying the impact sound improvement “of the floor covering”. To clearly separate performance of the floors, floor coverings and impact sources detailed information about their dynamic properties is necessary. Non-linear effects are expected especially with carpets.

The results of the project should be helpful to design a laboratory measuring method for the impact sound improvement on lightweight (timber joist) floors and to design floors with a better impact sound insulation.
Technical Note: A Simple Tool for Classifying the Acoustical Performance of Permeable Materials
Authors: Kleinschmidt Klaus
Published: October 2002

Development work leading to improved sound absorbing qualities of concrete blocks led to the creation of an extremely simple tool for assessing the acoustical potential of permeable materials including concrete aggregates, insulation and acoustical panels with either a hard or open backing. Acoustical panels and curtain fabrics, whose sound absorption values have been determined by standardized tests in reverberation chambers can serve as reference points for the simple tool. Certain advantages and disadvantages of standardized material testing in reverberation chambers and impedance tubes as well as of flow resistance tests are discussed.
Application of Total Loss Factor Measurements for the Determination of Sound Insulation
Authors: Meier A. , Schmitz A.
Published: October 2002

The influence of the total loss factor of building elements on their sound insulation is well known, although the problem of measuring this value was up to now not solved completely.

This article describes an improved measuring method for total loss factors of building products especially for heavy elements. Furthermore, the principle of conversion of different results for transmission loss of the same type of wall under different mounting conditions using the total loss factor is presented. Measurement results in a transmission suite were examined and corrected with values derived from the improved measuring method.
Structure-Borne Sound Transmission in Rib-Stiffened Plate Structures Typical of Wood Frame Buildings
Authors: Bosmans Ivan , Nightingale Trevor R.T.
Published: October 2002

Structure-borne sound transmission at a subfloor/joist connection typical of wood frame buildings is investigated experimentally and theoretically. The first part of this paper investigates the influence of the fastener spacing on the vibration attenuation across a joist. For this purpose, measurements were carried out on a small floor section for various coupling conditions of the joist. The experimental results suggested the existence of an effective coupling area characterizing the screwed joist/floor connection. In the second part of this study, a calculation model is developed based on Statistical Energy Analysis (SEA) and plate strip theory for the idealized case of a rigid line connection. The presented model is verified experimentally on a Plexiglas structure and a subfloor/joist connection. The experimental validation showed fair agreement between measured and calculated data, but revealed that more work is required to improve the prediction accuracy in realistic situations.
Accuracy of CEN-Prediction Models Applied to German Building Situations
Authors: Metzen Heinrich A.
Published: October 2002

The accuracy for the simplified and detailed models described in EN 12354, parts 1 and 2, was investigated for 31 building situations with mainly heavy separating and flanking elements. For the weighted apparent sound reduction index R'w the absolute mean deviation with standard deviation between the measured and the calculated results was found to be (2.0 ± 1.8) dB for the simplified model, (2.1 ± 1.8) dB for the detailed model, and (2.5 ± 1.8) dB for the detailed model with correction of structural reverberation time. Detailed correction of geometry is not of major influence on the final result for the simplified and the detailed model. The detailed editing of the coupling conditions compared with a situation with a maximum number of couplings does not improve the accuracy of the detailed model.
Inter-Laboratory Test of Sound Insulation Measurements on Heavy Walls: Part I — Preliminary Test
Authors: Schmitz A. , Meier A. , Raabe G.
Published: October 2002

The intention of sound reduction index (SRI) measurements in transmission suites is to obtain more reliable values of the specific test element's sound insulation properties. Unfortunately, these values are influenced by the mounting of the test element itself and the construction design of the test facility. Both the mounting of the test element and, in part, the design of the test facility can effect the damping of the test element. From previous studies a suggested solution has been to take into account the damping in terms of the test element's loss factor. By incorporation of the loss factor in SRI measurements, of heavy walls, it has been suggested that this could reduce the deviations in SRI values due to laboratory influences.

To determine the variance of sound transmission measurements in test facilities for a heavy wall, an inter-laboratory test (ILT) was performed in twelve different institutes. This ILT study included the measurement of sound reduction index, velocity levels and damping.

In this first part, of a two part paper, a review concerning the principle previous studies is given. Furthermore, decisions regarding the choice of the test element, principal measurements and participating laboratories are reported.
Measurement of the Vibration Reduction Index, Kij on Free-Standing Masonry Wall Constructions
Authors: Hopkins C.
Published: October 2002

In the determination of coupling parameters between concrete/masonry walls in the laboratory there are potential advantages in using free-standing test constructions instead of flanking laboratories. To assess this potential, free-standing masonry walls were built in the laboratory to test two common types of rigid T-junction. The measured modal overlap factors were typically less than unity over the frequency range 50Hz – 1kHz. In this range, empirical rules imply that it is not possible to state with statistical confidence that there is any significant difference between the two types of junction connection. Below 1kHz many solid concrete/masonry separating elements are likely to have modal overlap factors less than unity in both the laboratory and the field. This is problematic for laboratory measurements because the vibration reduction index, Kij is unlikely to be a ‘situation invariant’ parameter when determined with elements that have low modal overlap.
Evaluation of EN 12354 Part 1 and 2 for Nordic Dwelling Houses
Authors: Pedersen Dan Brøsted
Published: October 2002

Standardised prediction models for airborne and impact sound insulation in buildings are described in EN 12354 part 1 and 2. These models have been evaluated by comparing the predicted and measured sound insulation for common building constructions used in Nordic dwelling houses. In total, more than 200 comparisons were carried out. The standard includes informative annexes on calculation of input data for the prediction models (the sound reduction index of monolithic elements, the normalised impact sound pressure level of homogeneous floor constructions, the vibration reduction index for junctions, etc.). The annexes as well as alternative calculation principles have been evaluated. Calculations based on a few modifications of the informative annexes are recommended for application of the standard in the Nordic countries. For some types of construction like lightweight double leaf walls, floating floors, etc., results of measurements in Nordic laboratories are in most cases used as input data. The obtained accuracy of the predictions is satisfactory for airborne sound insulation and for impact sound insulation of heavy floors vertically.
Vibration Response of Lightweight Wood Frame Building Elements
Authors: Nightingale T.R.T. , Bosmans Ivan
Published: October 2002

Direct and indirect measurements of the vibration response of several wood-framed walls and floors were made. The data indicate that these building elements do not behave like a homogeneous and isotropic system but rather exhibit a response typical of a periodic plate/beam structure. There is localization of energy near the excitation point and very strong attenuation with distance in the direction normal to the framing members. This region of high attenuation is followed by one of considerably reduced attenuation. A systematic study of a floor/ceiling assembly indicated that the onset of this second attenuation region was caused by the presence of a butt joint in the plate. It is speculated that the weak bending-to-bending coupling caused by the butt joint reduced the bending energy enough so that wave conversion from in-plane to bending at each plate/beam joint accounted for the presence (and in some cases near-constant level) of bending energy after the butt joint.
Utilisation of Test Data for Column Bases When Assessing Overall Frame Response: A Review
Authors: Hensman J. , Nethercot D.A.
Published: October 2002

Previous studies of the behaviour of steel column base connections are reviewed; attention is concentrated on the results from programmes of laboratory testing. Nominally pinned bases are shown to provide significant rotational restraint and to be capable of transferring quite large moments into the foundations. Ways of representing these effects in frame analysis are investigated and, based on sample studies, a recommendation is provided.
Softening of Normal Strength and High-Strength Concrete Frames
Authors: Mendis Priyan
Published: October 2002

In the 21st century, computing facilities will make it possible to opt on a regular basis for more accurate rigorous methods of analysis. A rigorous collapse load analysis requires a knowledge of the behaviour of plastic hinges up to advanced curvatures. Concrete sections characteristically soften, that is the bending moment capacity decreases with increasing curvatures after the end of the plastic plateau while steel sections undergo a hardening phase. Consideration of softening is essential in a rational analysis. In this paper, the important aspects of softening of concrete frame structures are reviewed.

High-strength concrete (f'c>50 MPa) is a more brittle construction material than normal strength concrete. High-strength concrete sections show a steeper softening slope when compared with similar normal strength concrete sections. An example is presented to demonstrate that a HSC frame structure with steeper softening slopes will have a lower collapse load.
Aeroelastic Model Investigation and Spectral Analysis of a Tall Lattice Tower
Authors: Lou W.J. , Sun B.N. , Tang J.C.
Published: October 2002

The aerodynamic responses of a tall steel lattice transmission tower are examined using a 1:100 full aeroelastic model in a boundary-layer flow with adequate turbulence intensities. Since the structure modelled is composed of 583 thin wall steel tubes, it is difficult to construct a perfect aeroelastic model. In this study, an equivalent scattered stiffness method was developed to overcome the difficulties. The results presented and discussed include the aerodynamic force coefficients, acceleration responses and wind load factors at various wind velocities and wind attack angles. It is revealed that the wind load factors increase with wind mean velocity and along the model height. The wind-induced dynamic responses in two sway directions are approximately equal for any wind attack angle. In other words, across-wind vibration is evident. Spectral analysis based on the Kaimal spectrum and F.E.M., which takes into account wind-structure coupling effects, was also developed for calculating the wind-induced dynamic responses. The numerical results of along-wind responses show good agreement with the experimental results.
Inelastic Dynamic Response of RC Bridges Subjected to Spatial Non-Synchronous Earthquake Motion
Authors: Tzanetos N. , Elnashai A.S. , Hamdan F.H. , Antoniou S.
Published: October 2002

The assumption that earthquake response of extended structures, of which bridges is one example, may be studied ignoring the possibility of out-of-synch motion of various supports is examined in this paper. The purpose is to assess whether the reduction of dynamic response is sufficient to offset the increase in relative displacements, due to independent motion of different supports.

The paper starts with a review of possible damage patterns due to asynchronous motion. Thereafter, a brief literature review is undertaken, followed by an assessment of the status of seismic design codes concerning this issue. Advanced inelastic analysis, using sophisticated material models and analysis techniques, is then employed to explore characteristics of input motion and structural configuration, which may lead to unconservative results from conventional (synchronous) analysis. Natural and artificial earthquake records are applied, representing travelling wave as well as geometric incoherence effects. Two model structures of medium span RC bridges are studied, subjected to different boundary conditions that influence the mode contributions. This is undertaken under transverse, longitudinal and vertical earthquake motion. The large volume of results, represented as displacement and force time-histories as well as Fourier amplitude spectra of the acceleration response, are distilled and used to assess the balance between dynamic de-tuning and static relative displacements. It is concluded that the conventional synchronous case provides conservative results for vertical vibrations. However, unconservative results, of up to 30%, are obtained for transverse and longitudinal response of short periods of structural vibrations, as well as cases where the higher modes of response are likely to be excited.
Analysis of Progressive Interface Failure under Cyclic Shear Loading
Authors: Shen Xinpu , Mroz Zenon
Published: October 2002

Based on the so-called “ shear beam model”, an analytical study is presented on interface failure under the joint action of constant compression and cyclic anti-plane shear. Analytical solutions are presented for the evolution and distributions of shear stress and displacement along the entire length of the shear beam during unloading and reloading processes. Results indicate that, owing to the existing of a damage process zone ahead of the crack tip, both unloading and reloading are inelastic and are accompanied by friction and damage dissipation. Furthermore, “ stress locking” will occur if an unloading process can not erase the damage zone left by its neighboring loading process. Analysis of structural response presented at the end of the paper clarifies two different kinds of structural responses: 1) contact plastic shakedown and 2) progressive failure.
Refined Plastic Hinge Analysis of Steel Frame Structures Comprising Non-Compact Sections I: Formulation
Authors: Avery P. , Mahendran M.
Published: October 2002

Application of “advanced analysis” methods suitable for non-linear analysis and design of steel frame structures permits direct and accurate determination of ultimate system strengths, without resort to simplified elastic methods of analysis and semi-empirical specification equations. However, the application of advanced analysis methods has previously been restricted to steel frames comprising only compact sections that are not influenced by the effects of local buckling. A concentrated plasticity formulation suitable for practical advanced analysis of steel frame structures comprising non-compact sections is presented in this paper. This formulation, referred to as the refined plastic hinge method, implicitly accounts for the effects of gradual cross-sectional yielding, longitudinal spread of plasticity, initial geometric imperfections, residual stresses, and local buckling.
Damping Formulae for Reinforced and Partially Prestressed Concrete Beams
Authors: Chowdhury S. H. , Loo Y. C. , Fragomeni S.
Published: October 2002

A full-size test program was carried out on 26 simply-supported and continuous reinforced and partially prestressed concrete beams to study the cracking behaviour and damping characteristics of concrete beams. The beams were subjected to free vibration tests and logarithmic decrement values corresponding to each load level were measured. Separate regression analyses on the reinforced and the partially prestressed beams were undertaken. These analyses resulted in two separate empirical formulae for predicting the logarithmic decrement of damping in reinforced and in partially prestressed beams. Comparison with test results from all 26 beams indicates that the predictions are accurate. It is also found that the damping formula for reinforced beams is applicable to both single and continuous spans. The proposed damping formulae predict damping from the residual crack widths of the beams. As such, formulae developed for predicting residual crack widths from given variables defining the beams and their deflection-span ratios are also reported.
Tests on Concrete Filled Steel Tubular Columns with High Slenderness Ratio
Authors: Han Lin-Hai
Published: October 2002

The behavior of very slender concrete filled tubular columns and hollow tubular columns with circular sections subjected to axial load was investigated experimentally. A total of fifteen specimens including eleven concrete filled steel tubular columns and four hollow tubular columns were studied. The main objectives of these tests were twofold: first, to describe a series of tests on very slender composite columns; and secondly, to compare the accuracy of the predictions by using the recommendations of LRFD, AIJ, EC4 and DL/T 5085. Experimental results indicate that the concrete infill increases the compressive load capacity of the steel tube. The loading capacity of the concrete filled steel tubular columns can be conservatively predicted by using LRFD, AIJ, EC4 and DL/T 5085 recommendations for normal length columns.
A New Formula for Prediction of Crack Widths in Reinforced and Partially Prestressed Concrete Beams
Authors: Chowdhury S. H. , Loo Y. C.
Published: October 2002

A new formula for predicting the average crack widths in reinforced and partially prestressed concrete beams has been developed incorporating four governing parameters. The performance of the proposed formula is checked using the authors' test results which includes crack spacing and crack width measurements from 18 reinforced and 12 partially prestressed concrete beams. Also included in the comparison are published data on 76 beams from other laboratory investigations. The comparative study indicates that the predictions are accurate. The performance of the proposed formula is also compared with three major code formulas, viz those recommended in the ACI Building Code, the British Standard and the Eurocode. It is concluded that better correlation with test data is achieved by the proposed formula.
Stresses in Elastically Supported Cylindrical Shells under Wind Load and Foundation Settlement
Authors: Pircher M. , Guggenberger W. , Greiner R.
Published: October 2002

Thin-walled shell structures of a circular cylindrical shape are widely used in structural engineering to serve in applications such as silos, tanks or chimneys. The design of such structures poses some considerable challenges to structural engineers as the load carrying behaviour of cylindrical shells is quite complex, especially for non-axisymetric load cases. Very often a comprehensive analysis causes considerable expenses and the vast amounts of results which are typically generated make it hard to understand the underlying load-carrying principles of the structure. The introduction of an engineering method to handle two typical non-axisymetric load cases on circular cylindrical thin-walled shell structures is the goal of this paper. The proposed method offers a quick way to generate critical section forces and displacements. The load cases discussed herein are wind-loading and foundation-settlement. Ground support for many cylindrical steel structures is often realised by anchoring the lower shell boundary to a concrete foundation. This is accomplished by steel bolts that can be looked at as spring elements providing elastic support for the shell structure. The influence of this type of support on the section forces and displacements under wind loading can be modelled by combining the two abovementioned load cases via an interaction diagram also given in this paper.
Torsional Buckling of Steel Members: The Flexural Buckling Analogy
Authors: Van Impe Rudy
Published: October 2002

A substantial body of literature exists on the flexural elastic buckling problem for prismatic members. The contribution made by this paper is to show how this knowledge can be immediately exploited to solve torsional buckling problems, made analogous if the correct kinematic and boundary conditions are applied.
A Boundary Integral Transformation for Bending Analysis of Thick Plates Resting on Bi-Parameter Foundation
Authors: Rashed Youssef F.
Published: October 2002

In this work an efficient boundary element analysis for plates resting on bi-parameter foundation is presented. The present formulation mainly deffers from previously published formulations in the way of the treatment of body forces. Domain integrals due to uniform loading are transformed to equivalent boundary integrals. The Reissner plate bending theory is used to model the bending behavior of the plate and the Pasternak (bi-parameter) foundation model is used. Unlike, common techniques of the transformation, which are based on the Green second identity, the present formulation employs the Green first identity which gives more smooth and simpler transformed kernels. The necessary particular solutions are derived and the kernels for the computation of stress resultants at the internal points are derived and given in explicit forms. A general technique for avoiding the appearance of jump terms in the transformed boundary integrals is presented. Three numerical examples are presented to demonstrate the accuracy and the validity of the present formulation.
A Model for the Post-Buckling of Thin-Walled Silos and Tanks under Axial Load
Authors: Pircher Martin , Bridge Russell Q.
Published: October 2002

Steel silos and tanks are constructed from plates which are rolled to the correct curvature and welded together to form strakes. Several strakes of curved plates, placed on top of each other then form the completed structure. At each circumferential weld, a slight hourglass depression occurs essentially forming axisymmetric imperfections which are known to be most deleterious. The detrimental influence of this particular type of imperfection on the buckling of axially compressed cylindrical shells such as silos and tanks is well known. Axial compression onto silos or tanks is commonly generated by roof structures, snow loads or, in the case of silos, by friction forces generated by the content. However, very little is known about the post-buckling of thin-walled cylinders with a circumferential weld imperfection. A post-buckling load bearing model was developed and the influence of weld imperfection amplitude, weld-induced residual stress-fields, different boundary-conditions and elastic–plastic material behaviour was studied. Different modelling techniques, taking into account various symmetries of the problem, are also discussed.
Load-Bearing Capacity of Masonry Arch Bridges Strengthened with Fibre Reinforced Polymer Composites
Authors: Chen J. F.
Published: October 2002

This paper presents a new mechanism analysis method to calculate the ultimate load-bearing capacity of masonry arch bridges strengthened by externally bonding fibre reinforced polymer (FRP) composites on the intrados. The M– N relationship of a strengthened arch ring cross section is analysed and fully considered in the mechanism analysis. The Complex Method of nonlinear programming is used to perform a constrained minimisation of the load function to obtain the minimum collapse load and its corresponding hinge positions. This has advantages because the arch ring does not need division into many discrete blocks as in traditional mechanism analysis and the solution process is fully automatic. Some initial results are presented, which show that significant strength increases can be achieved by bonding a small amount of FRP composites to the intrados of masonry arch bridges.