bluuebunny/crossref_metadata_2025 huggingface dataset:
Childhood Cancer near Nuclear Installations
Authors: Fairlie Ian
Published: August 2010

In 2008, the Kinderkrebs in der Umgebung von KernKraftwerken (KiKK) study in Germany reported a 60% increase in solid cancer incidence and a 120% increase in leukaemia incidence among children living within 5 km of all German nuclear power stations. The study has triggered debates as to the cause(s) of these increased cancers. This article reports on the findings of the KiKK study; discusses past and more recent epidemiological studies of leukaemias near nuclear installations around the world, and outlines a possible biological mechanism to explain the increased cancers. In essence, this suggests that doses to embryos/foetuses in pregnant women from environmental emissions from nuclear power plants (NPPs) may be larger than suspected, and that haematopoietic tissues may be considerably more radiosensitive in embryos/foetuses than in children and adults. The article concludes with recommendations for further research.
The Controlled Thermonuclear Fusion Hydrogen Energy—A Permanent Solution to the World's Energy Supply
Authors: Liu Jian-Cheng
Published: August 2010

Fossil fuels (i.e., petroleum, natural gas and coal), which meet most of the world's energy demand today, are being depleted rapidly and will be exhausted in decades or several hundred years. Also, their combustion products are causing global problems, such as the greenhouse effect, ozone layer depletion, acid rain and pollution, which are posing great danger for our environment, and eventually, for the total life on our planet. It is the controlled thermonuclear fusion hydrogen energy system that would overcome all these problems and be the permanent solution of the world's energy supply lasting for billions of years.
Citizens, Politicians and Experts in Energy Policy-Making: The Case of Finland
Authors: Ruostetsaari Ilkka
Published: August 2010

Theoretically, this study debates the issue of technocracy, with the role of representative democracy and expert knowledge in the Finnish energy policy-making as a focus. Policy-making is characterized by several characteristics making it special in international comparison. The study is based on a postal survey conducted among a random sample (N = 4000) representing 18–75-year old Finns in May – October 2007.

Given the expert-centred tradition of Finnish science and technology policy, as well as the characteristics of Finnish political culture, we argued that Finns consider experts and producers of research knowledge to be more legitimate decision-makers than politicians in the energy policy arena. The proposition was tested using three hypotheses. Firstly, we hypothesized that the citizenry do not trust in their chances to influence energy policy-making through political institutions and general elections, and secondly, that people trust more in experts, that is research institutes and authorities as sources of energy-related information than political institutions. According to the third hypothesis, citizens stress more the normative role of experts than that of political decision-makers in the processes of planning and decision-making of energy policy

The hypotheses were mainly verified. Our major finding was that even if people considered political institutions the most powerful actors in energy policy-making they did not trust their own chances to influence energy policy through political institutions. Experts were seen as the more legitimate decision-makers than politicians in energy policy.
Changes in Snowfall in the Southern Sierra Nevada of California since 1916
Authors: Christy John R. , Hnilo Justin J.
Published: August 2010

A time series (1916–2009) of annual snowfall totals for Huntington Lake (HL, elev. 2141 m) in the southern Sierra Nevada of California is reconstructed. A reconstruction is (a) necessary because HL data after 1972 are mostly missing and (b) possible because nearby stations reveal high correlations with HL, two above 0.90. The results show mean annual snowfall in HL is 624 cm with an insignificant trend of +0.5 cm (+0.08%) ±13.1 cm decade−1. Similar positive but insignificant trends for spring snowfall were also calculated. Annual stream flow and precipitation trends for the region again were insignificantly positive for the same period. Snow-water-equivalent comparisons, measured on 1 Apr since 1930 at 26 sites and since 1950 at 45, show similar small, mostly positive, and insignificant trends. These results combined with published temperature time series, which also reveal no significant trends, form a consistent picture of no remarkable long-term changes in the snowfall of this area and elevation of the southern Sierra Nevada of California since the early 20th century.
Sea Level Changes in Bangladesh New Observational Facts
Authors: Mörner Nils-Axel
Published: August 2010

Morphological and stratigraphical observational facts in the Sundarban delta provide data for a novel sea level reconstruction of the area. This sea level documentation lacks traces of a global sea level rise. This implies totally new perspectives for the future of Bangladesh. No longer are there any reasons to fear an extensive sea level inundation in the near future. Sea level estimates based on linear trend analyses of tide gauge data should be avoided and seem often to be directly misleading, as was the case with previous, divergent, claims of a strong global sea level rise component.
The Climate Change Debate Today
Authors: Henderson David
Published: August 2010

The text that follows formed the basis for a talk given in London to the Political Economy Club on 3 February 2010. A post-script takes account of developments in the ensuing month. The writer was formerly Head of the Economics and Statistics Department of the OECD. He is currently a Fellow of the Institute of Economic Affairs in London and Chairman of the Academic Advisory Council of the Global Warming Policy Foundation.
A Null Hypothesis for CO2
Authors: Clark Roy
Published: August 2010

Energy transfer at the Earth's surface is examined from first principles. The effects on surface temperature of small changes in the solar constant caused by the sunspot cycle and small increases in downward long wave infrared (LWIR) flux due to a 100 ppm increase in atmospheric CO2 concentration are considered in detail. The changes in the solar constant are sufficient to change ocean temperatures and alter the Earth's climate. The surface temperature changes produced by an increase in downward LWIR flux are too small to be measured and cannot cause climate change. The assumptions underlying the use of radiative forcing in climate models are shown to be invalid. A null hypothesis for CO2 is proposed that it is impossible to show that changes in CO2 concentration have caused any climate change, at least since the current composition of the atmosphere was set by ocean photosynthesis about one billion years ago.
A Natural Constraint to Anthropogenic Global Warming
Authors: Kininmonth William
Published: August 2010

Computer model projections suggest that unconstrained emissions of carbon dioxide and other greenhouse gases by human activity will cause the global average temperature to rise by at least 2 °C and possibly as much as 4.5 °C toward the end of the 21st century as equivalent concentrations of carbon dioxide in the atmosphere nearly double. A well-specified analysis of the surface temperature response to global warming presented here suggests that global average surface temperature is unlikely to rise beyond 1 °C. This analysis identifies the rate of increase of evaporation (and latent heat exchange) with temperature at the surface as a critical restraining factor that damps surface temperature response to radiative forcing. It is noted that current computer models of the climate system apparently underestimate the rate of increase of surface evaporation with temperature leading to a gross exaggeration of the surface temperature response to radiative forcing.
The Stabilising Effect of the Oceans on the Climate
Authors: Thoenes Dick
Published: August 2010

Based on some simple calculations and a few estimates, it is demonstrated that the oceans have a stabilising effect on the earth's climate. Any additional incoming infrared radiation will be compensated by evaporation of water followed by infrared irradiation from high clouds into space and by heat flow into the deep sea.
The Stable Stationary Value of the Earth's Global Average Atmospheric Planck-Weighted Greenhouse-Gas Optical Thickness
Authors: Miskolczi Ferenc M.
Published: August 2010

By the line-by-line method, a computer program is used to analyze Earth atmospheric radiosonde data from hundreds of weather balloon observations. In terms of a quasi-all-sky protocol, fundamental infrared atmospheric radiative flux components are calculated: at the top boundary, the outgoing long wave radiation, the surface transmitted radiation, and the upward atmospheric emittance; at the bottom boundary, the downward atmospheric emittance. The partition of the outgoing long wave radiation into upward atmospheric emittance and surface transmitted radiation components is based on the accurate computation of the true greenhouse-gas optical thickness for the radiosonde data. New relationships among the flux components have been found and are used to construct a quasi-all-sky model of the earth's atmospheric energy transfer process. In the 1948–2008 time period the global average annual mean true greenhouse-gas optical thickness is found to be time-stationary. Simulated radiative no-feedback effects of measured actual CO2 change over the 61 years were calculated and found to be of magnitude easily detectable by the empirical data and analytical methods used. The data negate increase in CO2 in the atmosphere as a hypothetical cause for the apparently observed global warming. A hypothesis of significant positive feedback by water vapor effect on atmospheric infrared absorption is also negated by the observed measurements. Apparently major revision of the physics underlying the greenhouse effect is needed.
Note on the Miskolczi Theory
Authors: van Andel Noor
Published: August 2010

The Miskolczi theory of our atmosphere is summarized. The main relations of the radiative and non-radiative heat fluxes are derived. The physical control mechanisms that keep the atmospheric fluxes bound to these relations are described. The physical mechanisms of climate change that are published and that are compatible with this theory are mentioned. In an appendix the main analytical derivation of Miskolczi is explained.
The Measurement of Directional Stage Support in a Drama Theatre: Quantifying the Acoustic Effect of a Set
Authors: Cabrera Densil , McCarthy Robin , Bassett John , Gilfillan David
Published: August 2010

The acoustic environment of an auditorium stage can enhance the ability of musicians or actors to hear each other clearly. This is assessed through a set of parameters called ‘stage support‘. Stage support parameters are conventionally measured using an omnidirectional source and microphone separated by 1 m on the stage. Various stage support parameters are derived from energy ratios of the direct and reflected (or reverberant) sound in the impulse response from source to microphone. The present paper examines the possibility of assessing the directional characteristics of the reflected soundfield by using a multidirectional microphone. Measurements were made in the Sydney Theatre Company's ‘Sydney Theatre’ with and without a stage set. The microphone used allows first order spherical harmonic decomposition of the soundfield, which was transformed to cardioid components for orthogonal directions (upstage, downstage, left, right, up and down), as well as for horizontal rotations of the cardioid microphone. These were used to calculate directional stage support values. Results demonstrate the potential of this simple extension of standard stage support measurement by showing the acoustical effect of the set.
Control of Aeolian Noise Generated by the Finned Balustrade of a Freeway Pedestrian Overpass
Authors: Mitchell Andrew , Leclercq Damien , Stead Matthew
Published: August 2010

During construction of a new freeway in Melbourne, it was found that tonal wind-induced noise was being generated by the finned balustrades of architecturally-designed pedestrian overpasses which had been installed at several locations along the route. As the level of wind-induced noise was unacceptable at residences in the vicinity of the overpasses, a solution to reduce or eliminate the noise had to be developed. The solution needed to be practical to retrofit to the existing structure, while satisfying strict project constraints in relation to urban design, design life, and safety in design rules. This paper outlines the investigation that was undertaken to determine the wind-conditions under which the noise occurred, discusses the noise-generation mechanisms that were established to be causing the noise, and presents a summary of the potential solutions that were identified through theoretical analysis, wind tunnel modelling and field trials.
Inelastic Displacement Amplification Factor for Ductile Structures with Constant Strength Reduction Factor
Authors: Zhao Yongfeng , Tong Genshu
Published: August 2010

Based on elastic-plastic time-history earthquake analysis of the single degree of freedom (SDOF) system, the inelastic displacement amplification factor Cd2 of the elastic-perfectly plastic (EPP) model with the same yield strength reduction was investigated for different normalized periods T/TgR, site types, strength reduction factors R, damping ratios, post yield stiffness ratios and second order ( P-Δ) effects. The factor Cd2 can be used to estimate the maximum inelastic response displacement from the elastic displacement under the design seismic conditions. It is found that the probability distribution of Cd2 satisfies the lognormal distribution approximately. The factor Cd2 decreases with decreasing damping (in the medium-long period range) and with increasing post yield stiffness. The existence of the P-Δ effect will increase Cd2 significantly and needs to be considered in future seismic design. Three other hysteretic models: the modified-Clough (MC), shear-slipped (SSP) and bilinear elastic (BIL) models, were analyzed to check the effect of the hysteretic model on Cd2 spectra The results were compared to those of the EPP model and it was found that the Cd2 of the EPP model is the smallest among the four hysteretic models.
Effects of Steel Lap Splice Locations on Strength and Ductility of Reinforced Concrete Columns
Authors: Pam H.J. , Ho J.C.M.
Published: August 2010

Longitudinal steel lap splice is always required in reinforced concrete (RC) columns. Normally, in countries having high seismic risk, lap splices of longitudinal steel must be located around mid-height of the storey. However, in regions of low-medium seismic risk, including Hong Kong, lap splices of longitudinal steel begin right above the beam-column interface to facilitate ease of construction. Such splicing method would undesirably cause the column critical region to move away from the beam-column interface under inelastic deformation. In this paper, the effects of different lap splice locations of longitudinal steel on flexural strength and ductility of RC columns with concrete cube strength around 100 MPa are studied. Four RC column specimens, which contained no lap splice, all lap splices within and outside critical region, as well as lap splices in staggered manner, were tested under simultaneous compressive axial load and reversed cyclic inelastic displacement. It is evident from the results that the column containing lap splices within its critical region had the largest strength but the poorest ductility performance. On the contrary, the column containing lap splices outside its critical region had strength and ductility comparable to those of the column without lap splice. Based on these observations, a recommendation is proposed for positioning longitudinal steel lap splices in RC columns.
Shear Behaviour of RC Beams without Stirrups Made of Normal Strength and High Strength Concretes
Authors: Hamrat M. , Boulekbache B. , Chemrouk M. , Amziane S.
Published: August 2010

The paper describes a study in which sixteen reinforced concrete beams without transverse stirrups were tested to failure to investigate the influences of the shear-span/depth ratio ( a/d), the longitudinal steel ratio (ρ) and the compressive strength of concrete ( f'c) on the global behaviour in shear for beams made of normal strength concrete (NSC) as well as high strength concrete (HSC). Crack development and propagation were studied through continuous monitoring of the shear cracking using digital video recording. The test results show that the shear capacity depends more on the shear-span/depth ratio ( a/d) and the longitudinal steel ratio (ρ) and relatively less so on the compressive strength ( f'c) in the case of HSC.

Based on this study and on data collected from the literature, a proposition for computing the shear stength of concrete beams without stirrups is made; it covers compressive strengths in the range of 40 MPa to 104 MPa. Using the proposed shear formulae, a comparison is made between the different modelling approaches used in the major design codes concerning the contribution of concrete to the shear resistance of beams. In the light of the test results obtained in the present investigation, the applicability of these code approaches to high strength concrete is examined.
Experimental Investigation of Reinforced Concrete T-Beams Strengthened with Steel Wire Mesh Embedded in Polymer Mortar Overlay
Authors: Xing Guohua , Wu Tao , Liu Boquan , Huang Hua , Gu Songlin
Published: August 2010

The application of steel wire mesh (SWM) and polymer mortar composites to the surface of reinforced concrete (RC) members as external reinforcement is a promising and recent new technique for strengthening and rehabilitating damaged concrete elements. Five one-third-scale simply supported RC T-beams were tested during this study. Four-point bending flexural tests were conducted up to failure on one control beam and on four strengthened beams with different load histories. The objectives of this investigation were to study the effectiveness of SWM and polymer mortar composites in increasing the flexural strength of concrete beams and to study the construction technology for further development. The main test parameters included the amount of longitudinal SWM reinforcement and the load history. The results demonstrate the feasibility of rehabilitating and strengthening RC members with SWM composites and indicate that the ultimate strength of RC T-beams, strengthened with SWM composites, is almost the same regardless of the load history at the time of strengthening. A design procedure is presented with aim to predict the flexural strength of T-beams strengthened with SWM composites. Good agreement between experiment and predicted values was achieved.
Behaviour of Concrete Beams Reinforced with Hybrid FRP Composite Rebar
Authors: Cheung Moe M.S. , Tsang Terry K.C.
Published: August 2010

Extensive research has led to a better understanding of the application of various corrosion protection methods in reinforced concrete (RC) structures and the use of fiber reinforced polymer (FRP) rebars is a typical example. However different fibres come along with different deficiencies, such as low elastic moduli and poor alkaline resistance in glass fibre (Saikia et al. 2007); brittle fracture and high cost in carbon fibre. Taking advantages of the strength of different fibres and the cost effectiveness of steel fibre, a hybrid composite rebar was recently developed. Steel fibers and glass fibers are distributed within the core, while aramid and carbon fibers created a shell for strength and corrosion protection. A series of concrete beams reinforced with the proposed hybrid rebars were tested and it was demonstrated that the beams have the ability to undergo large inelastic deformations, and the ductility indexes were found to be similar conventional steel-reinforced beams. Besides, accelerated alkaline ageing tests were performed using concrete pore solutions at different temperatures, and the service life and alkaline resistance of the proposed rebar were proven to be very good.
Structure Damage Detection Using Neural Network with Multi-Stage Substructuring
Authors: Bakhary Norhisham , Hao Hong , Deeks Andrew J.
Published: August 2010

Artificial neural network (ANN) method has been proven feasible by many researchers in detecting damage based on vibration parameters. However, the main drawback of ANN method is the requirement of enormous computational effort especially when complex structures with large degrees of freedom are involved. Consequently, almost all the previous works described in the literature limited the structural members to a small number of large elements in the ANN model which resulted ANN model being insensitive to local damage. This study presents an approach to detect small structural damage using ANN method with progressive substructure zooming. It uses the substructure technique together with a multi-stage ANN models to detect the location and extent of the damage. Modal parameters such as frequencies and mode shapes are used as input to ANN. To demonstrate the effectiveness of this approach, a two-span continuous concrete slab structure and a three-storey portal frame are used as examples. Different damage scenarios have been introduced by reducing the local stiffness of the selected elements at different locations in the structures. The results show that this technique successfully detects all the simulated damages in the structure.
Monotonic Loading Tests on Semi-Rigid End-Plate Connections with Welded I-Shaped Columns and Beams
Authors: Shi Gang , Shi Yongjiu , Wang Yuanqing , Bijlaard F.S.K.
Published: August 2010

8 specimens of beam-to-column bolted end-plate connections with various details and welded I-shaped section columns and beams were tested under monotonic loads. Based on the specification for the end-plate connection rotation proposed, the contribution of the panel zone and the gap between the end-plate and column flange to the joint rotation have been obtained. The influences of both flush and extended types, column stiffeners, end-plate rib stiffeners, bolt sizes and end-plate thicknesses etc on the joint behaviour have been compared. The test results indicate that all these connections tested are typically semi-rigid. For the flush and extended end-plate connection, the joint rotation mainly derives from the relative deformation between the end plate and the column flange and the shearing deformation of the panel zone respectively. Using a special method to measure bolt strain, the bolt tension forces and their development and distribution have been depicted and studied, and two bolt tension force distribution models for end-plate connections using pretensioned bolts are recommended.
Strength and Behaviour of Slender Steel Reinforced Concrete Composite Columns
Authors: Zhao Gentian , Zhang Mengxi , Li Yonghe
Published: August 2010

An experimental study of the behaviour of steel reinforced concrete (SRC) composite columns and the results of a nonlinear numerical analysis are presented. Ten slender SRC composite columns were tested under axial and eccentric loading conditions. The effects of concrete strength, slenderness of columns and eccentricity of the axial load were studied. The load-carrying capacity is reduced with increased slenderness ratio and eccentricity. Concrete strength has a significant effect on the load-carrying capacity of axially loaded columns but has no obvious influence in the case of eccentrically loaded columns. This paper also presents a nonlinear numerical study of pin-ended slender columns. The method is suitable for determining the material failure load or buckling failure load of a slender steel reinforced concrete composite column. In the method both material and geometric nonlinearities are taken into account. The numerical analysis results correlate well with the test results. The test results are also compared with results predicted by ACI 318–05 and Chinese specifications.
Vibration and Stability of an Axially Moving Beam on Elastic Foundation
Authors: Yang Xiao-Dong , Lim C.W. , Liew K.M.
Published: August 2010

The free vibration of an axially moving elastic beam on simple supports resting on elastic foundation is investigated in this paper. Analytical expressions are derived by considering the ordinary differential equations obtained by the Galerkin truncation method. Critical axially moving velocity is computed for different foundation and supporting conditions. The phenomena of divergence and flutter are found beyond the critical velocity. The stability in the vicinity of critical state is studied and instability regions are discussed accounting for the parameters of axial tension and the foundation stiffness. The complex natural frequencies of the system are obtained by considering the governing partial differential equation without truncation. Some numerical examples are presented to illustrate the contributions of axial speed, tension, and the foundation stiffness.
Monitoring Internal Displacements of a Model Dam Using FBG Sensing Bars
Authors: Zhu Hong-Hu , Yin Jian-Hua , Zhang Lin , Jin Wei , Dong Jian-Hua
Published: August 2010

Conventional instrumentation has difficulty to measure displacements inside laboratory-scale physical models. In this paper, an innovative fiber Bragg grating (FBG) sensing bar has been developed to perform high-accuracy and real-time monitoring of internal displacements. According to Euler-Bernoulli beam theory, the strain distribution measured by the quasi-distributed FBG sensors adhered on the bar surface can be used to compute the displacement profile along the sensing bar. The effectiveness of the FBG sensing bar has been verified by calibration tests. In the physical model of the Wudu gravity dam, two FBG sensing bars developed by the authors were installed, together with linear variable displacement transformers (LVDTs) and strain rosettes. The FBG sensing bars successfully captured the variation of internal displacement profiles in the model dam. The monitoring results during the overloading test were presented, based on which the deformation mechanism of the dam-foundation system is explained in details. The displacements measured by the FBG sensing bars are validated by their good agreements with those from LVDTs.
Assessment of the Predictive Performance of Existing Analytical Models for Debonding of Near-Surface Mounted FRP Strips
Authors: Vasquez D. , Seracino R.
Published: August 2010

The near-surface mounted (NSM) strengthening technique, in which pultruded fiber reinforced polymer (FRP) plates or bars are adhesively bonded into grooves cut in the concrete cover, has proven to overcome several of the drawbacks of externally bonded FRP plates on reinforced concrete flexural members. However, as research on the NSM technique is relatively recent, the theoretical foundation for its application is not yet as complete, and some of the debonding mechanisms are not yet fully understood. This paper presents the main findings of a literature review aimed at identifying the existing analytical models to predict the debonding strength of reinforced concrete flexural elements retrofitted with NSM FRP strips, and of a thorough assessment of the adequacy of such models by comparison with all relevant published experimental data. It is concluded that for debonding of NSM FRP strips induced by flexural (or flexural-shear) cracking or the critical diagonal shear crack of the reinforced concrete member, the currently available models capture the behavior of the debonding mechanism and provide reasonably conservative estimations of the debonding strength. However, for debonding induced by stress concentrations at the strip ends, existing models do not fully capture the debonding behavior and as such, are shown to be excessively conservative.
Comparative Study on the Elongation Measurement of a Soil Nail Using Optical Lower Coherence Interferometry Method and FBG Method
Authors: Hong Cheng-Yu , Yin Jian-Hua , Jin Wei , Wang Chao , Zhou Wan-Huan , Zhu Hong-Hu
Published: August 2010

Optical fiber sensor has gained popularity for structural monitoring in recent decades. Studies on the monitoring for geotechnical structures with fully-distributed fiber sensors, however, are quite limited. In this study, the fully-distributed Lower Coherence Interferometry (LCI) sensors and quasi-distributed Fiber Bragg Grating (FBG) sensors are applied for measuring the strain distribution of a soil nail as a slender structure during pullout test. First, this paper introduces an innovative calibration method for the LCI system. Second, the paper describes the procedures of fiber instrumentation on soil nail. Third, the measured results by LCI technology and FBG technology are compared to study the strain distribution and friction resistance of soil nail during pullout test. Comparative study from test results indicates the characteristics of strain distribution and resistance contribution for different parts of soil nail. Through this study, the advantages and limitations of two sensing technologies are examined.
Ultimate Bearing Capacity Analysis of a Super-Long Rock-Socketed Filling Pile Based on Catastrophe Theory
Authors: Yao Wen-Juan , Qiu Yuan-Zhong , Chen Ze-Kun
Published: August 2010

Based on the catastrophe theory of nonlinear science, a cusp catastrophe model of a super-long pile under axially load is established, and the vertical ultimate bearing capacity expression of super-long pile is derived. By fitting pile load-settlement field test data, the coefficients of a hypothetical super-long pile load-deformation curve and the value of ultimate bearing capacity are obtained. The results show that: the cusp catastrophe model is applicable to the determination of ultimate bearing capacity, and can be used to predict the buckling failure of a super-long pile. In addition, a fold catastrophe model is established to investigate the effects of plastic softening on the ultimate bearing capacity. The derived ultimate bearing capacity expression implies that the radius of the elastic and the plastic softening zones are relevant to the ultimate bearing capacity.
Optimal Design of Structures for Earthquake Loading by Self Organizing Radial Basis Function Neural Networks
Authors: Gholizadeh Saeed , Salajegheh Eysa
Published: August 2010

In order to efficiently find the optimal design of structures subjected to earthquake loading two strategies are adopted. In the first strategy, a neural system consisting of self organizing map (SOM) and radial basis function (RBF) neural networks is employed to predict the time history responses of structures. The neural system is termed as self organizing radial basis function (SORBF) networks. To train SORBF, the input-output samples are classified by employing SOM clustering, and then an RBF neural network is trained for each cluster by using the data located. In the second strategy, an improved genetic algorithm, the so-called virtual subpopulation (VSP), is employed to find the optimum design. To improve the performance generality of the SORBF, a VSP based optimal approach is employed. Two structures are designed for optimal weight using exact and approximate time history analyses. The numerical results demonstrate the efficiency and computational advantages of the proposed methodology.
Damage Displacement Estimation of Flexure-Dominant RC Columns
Authors: Jiang Huanjun , Lu Xilin , Kubo Tetsuo
Published: August 2010

A semi-empirical method was developed to estimate lateral displacements of flexure-dominant rectangular RC columns at a number of key seismic damage states. The principal damage states studied here include yielding, crushing of concrete cover, significant concrete spalling, buckling of longitudinal bar, and ultimate limit state. At first, the expressions were derived to estimate the compression zone depth of column section by regression analysis on the results obtained from moment-curvature analysis. Secondly, the strain of the extreme compression fiber of the gross section at the onset of concrete cover crushing and that of the confined core section at significant concrete spalling, longitudinal bar buckling, and ultimate limit state individually were derived on the basis of the plane-section hypothesis, plastic-hinge method, and statistical analysis on the database containing the results of cyclic tests on RC columns assembled at the Pacific Earthquake Engineering Research Center. Then the lateral displacement at individual damage state could be obtained by plastic-hinge analysis accordingly. The proposed method can be used as the basis for displacement-based seismic design and damage evaluation for flexure-dominant RC columns.
Static Strength of Tubular T-Joints with Reinforced Chord under Axial Compression
Authors: Shao Yong-Bo , Lie Seng-Tjhen , Chiew Sing-Ping
Published: August 2010

A typical tubular T-joint is made up of a chord member and a brace member, and the brace member is connected to the chord surface with full penetration welds. As the stiffness of the chord in the radial direction is much weaker than that of the brace member in the axial direction, failure occurs easily at the weld toe on the chord surface when the chord is subjected to static axial load in the brace axial direction. To improve the static strength of a tubular T-joint, the chord near the weld toe can be reinforced locally by increasing its thickness. To study the effect of the chord reinforcement on the static strength of a tubular T-joint, 48 T-joint models with different reinforcements have been analyzed using the finite element method. The effects of the chord thickness and the length of the reinforced chord on improving the static strength of tubular joints have been investigated. It is found that the static strength can be greatly improved by increasing the chord thickness near the intersection. However, the increased chord thickness should not be much greater than the original chord thickness to avoid changing of the failure mode. On the other hand, it is not effective to improve the static strength by increasing the length of the reinforced chord. The effects of the geometrical parameters and the chord thickness on the static strength of the T-joints are also studied parametrically by analyzing another 240 T-joint models. Finally, a parametric equation is presented, and its accuracy in predicting the static strength of the tubular T-joint subjected to axial compression is verified through error analysis against the numerical results.
Design for Moment Redistribution in RC Beams Retrofitted with Steel Plates
Authors: Haskett Matthew , Oehlers Deric John , Ali M.S. Mohamed
Published: August 2010

It is now common practice to retrofit reinforced concrete members by adhesively bonding steel or fibre reinforced polymer plates to their surfaces. However, tests have shown that these plated RC structures tend to have less member ductility, or rotational capacity, than the unplated structure because of premature plate debonding. In this paper, structural mechanics approaches are described for both: quantifying the moment rotation capacity, or member ductility, of steel plated RC flexural members; and quantifying the moment redistribution capacity from the moment rotation capacity. It is shown how the moment redistribution structural mechanics model can be used to design for member ductility directly and, furthermore, it is applied to both externally bonded and near surface mounted steel plates. As would be expected, it is shown that steel plating produces more ductile members than fibre reinforced polymer plating.
Repair of Earthquake Damaged RC Columns with Stainless Steel Wire Mesh Composite
Authors: Kim Sung-Hoon , Choi Jun-Hyeok
Published: August 2010

This paper presents results of an experimental study on a method for repairing earthquake damaged reinforced concrete columns that have inadequate lap splices in longitudinal reinforcement, by the use of stainless steel wire mesh (SSWM) composites. A total of three 1/5 scale model columns were tested under reversed cyclic loading. The columns were then repaired with SSWM composite wraps and re-tested under simulated earthquake loading to validate the effectiveness of the SSWM composite system and to study the feasibility of the repairing method for damaged columns. The results of this study show that the flexural strength, the displacement ductility, and the energy dissipation of the repaired columns were higher than those of the original columns. This indicates that the SSWM composite wraps can be a highly effective repair measure for reinforced concrete columns that have inadequate lap splices.
Structural Performance of Steel-Concrete-Steel Sandwich Composite Structures
Authors: Liew J.Y. Richard , Sohel K.M.A.
Published: August 2010

This paper investigates the structural performance of steel-concrete-steel (SCS) sandwich structures comprising a lightweight concrete core sandwiched in between two steel plates. Different types of mechanical shear connectors such as stud shear connectors and Bi-Steel bar connectors are reviewed and their uses in SCS sandwich construction are discussed. Special J-hook connectors are developed and their uses are not restricted by the concrete core thickness. Direct shear (push-out test) and tension tests have been carried out on J-hook connectors to investigate their performance in transferring shear and tension forces between steel and concrete. The structural performance of SCS sandwich beams and slabs with J-hook connectors subjected to static and dynamic loads is also investigated and test results show that SCS sandwich structures with the J-hook connectors are capable of resisting impact with less degree of damage in comparison with the sandwich structures with overlapping stud shear connectors. The plastic capacity of the sandwich beams and slabs can be predicted with reasonable accuracy using the plastic analysis described in this paper.
Design of Concrete-Filled Stainless Steel Tubular Connections
Authors: Feng Ran , Young Ben
Published: August 2010

A numerical study was performed on concrete-filled stainless steel tubular T- and X-joints using finite element analysis. The specimens were fabricated from square and rectangular hollow sections (SHS and RHS) with concrete-filled in the chord members. The geometric and material nonlinearities of stainless steel tubes as well as the concrete infill were carefully incorporated in the finite element models. The nominal compressive concrete strengths were ranged from 30 to 110 MPa. The numerical results showed good agreement with the experimental results for the concrete-filled stainless steel SHS and RHS tubular T- and X-joints. Therefore, an extensive parametric study was performed using the verified finite element models to investigate the strength and behaviour of concrete-filled stainless steel tubular connections. The joint strengths obtained from the parametric study and tests were compared with the current design strengths calculated using the CIDECT design rules for concrete-filled carbon steel tubular joints, which is the only existing design guideline for concrete-filled tubular joints. It should be noted that the current CIDECT design rules ignore the contribution of the steel tubes in the calculation of the joint strengths. In this study, design formulae of concrete-filled stainless steel tubular T- and X-joints are proposed. The proposed design formulae include the contribution of the stainless steel tubes. A reliability analysis was performed to assess the reliability of the current and proposed design rules. It is shown that the design strengths calculated using the proposed equations are generally accurate and reliable.
Behaviour of Axially Loaded Concrete Filled Stainless Steel Elliptical Stub Columns
Authors: Lam D. , Gardner L. , Burdett M.
Published: August 2010

This paper presents the details of an experimental investigation on the behaviour of axially loaded concrete-filled stainless steel elliptical hollow sections. The experimental investigation was conducted using normal and high strength concrete of 30 and 100 MPa. The current study is based on stub column tests and is therefore limited to cross-section capacity. Based on the equations proposed by the authors on concrete-filled stainless steel circular columns, a new set of equations for the stainless steel concrete-filled elliptical hollow sections were proposed. From the limited data currently available, the equation provides an accurate and consistent prediction of the axial capacity of the composite concrete-filled stainless steel elliptical hollow sections.
Long-Span Shallow Steel Arches Subjected to Fire Loading
Authors: Bradford Mark A.
Published: August 2010

This paper considers the thermo-elastic behaviour of shallow steel arches of long span, which are deployed in large roofing applications such as airport terminals, during a fire. The analysis of shallow arches requires recourse to geometrically non-linear analysis, which is further complicated by the nature of the thermal loading which may occur under a fire and of the degradation of the material properties of steel during a fire. A general technique based on the principle of virtual work is developed, and the analysis results in a formulation in closed form, which includes the stiffness of a tie between the supports of an arch and the supporting columns. It illustrates that these long span structural arch roofing elements are stressed at a low enough level to, in general, preclude considering inelastic effects during a typical fire, so that the simplifying assumptions of elastic behaviour are valid. Guidance is suggested for preliminary design purposes.
Pretension Process Analysis of Arch-Supported Prestressed Grid Structures Based on Member Initial Deformation
Authors: Zhou Zhen , Meng Shao-Ping , Wu Jing
Published: August 2010

Arch-supported prestressed grid structures, composed of steel arches, latticed shells, cables and hangers, are capable of covering large spans with good mechanical performance. Because of the many prestressed cables and hangers, structural analysis of the whole pretensioning process is rather difficult and important. Based on the structural characteristics, this paper develops the stiffness equation, and brings forth mixed influence matrix and iterative approximation methods to determine the initial deformations of cables and hangers. A sequential analysis method is then developed to analyze both batched tension and repeated tension schemes, so as to determine the active and passive forces in the cables and hangers during the pretensioning process. A case study, the Yangtze River Flood-control Model-testing Hall, proves that the proposed methods can efficiently model the whole pretension process for arch-supported prestressed grid structures.
Ductility Design of High-Strength Concrete Beams and Columns
Authors: Kwan A.K.H. , Ho J.C.M.
Published: August 2010

High-strength concrete (HSC) is increasingly used for the construction of tall buildings and long span bridges. However, most engineers just focus on how to better utilize the strength potential of HSC and little attention is paid to ensure that the HSC structures would have sufficient ductility. In this regard, it should be noted that the current design codes, which do not provide any guidelines for ductility design, are not applicable to HSC structures. In recent years, the authors have been conducting research on how the use of HSC would affect the flexural ductility of concrete members. Herein, an overall summary of their research is presented. It will be shown that depending on the reinforcement detailing and loading conditions, the ductility of HSC structures is not necessarily lower than that of normal concrete structures. Finally, guidelines for the ductility design of HSC beams and columns, augmented with design formulas and charts, are given.
Modeling Critical Ground-Motion Sequences for Inelastic Structures
Authors: Moustafa Abbas , Takewaki Izuru
Published: August 2010

The specification of earthquake loads as inputs to engineering structures is a crucial task in earthquake engineering. There are cases, however, where the site under consideration has limited or scarce seismic data, making this process a difficult task. Meanwhile, structural engineers are often concerned with the worst-case scenario that can happen to the structure during its service-life under possible future earthquakes. Repeated ground-motion sequences occurring after short intervals of time, resulting from mainshock-aftershock earthquakes, have been observed in many parts of the world. Such ground motion is capable of creating severe damage in the structure due to accumulation of inelastic deformations from multiple sequences before any structural repair is possible. This paper models ground motions of multiple sequences that produce the maximum damage in the structure. The ground acceleration is represented as Fourier series, with unknown amplitudes and phase angles, modulated by envelope functions. The unknown parameters are optimized to produce the maximum damage in the structure while the ground motion is constrained to the available seismic data at the site. The resulting inverse nonlinear dynamic problem is tackled using optimization techniques, nonlinear time-history analysis and damage indices. Numerical illustrations on modeling critical earthquake sequences for inelastic frame structures are provided. It is shown that critical repeated acceleration sequences produce larger structural damage compared to single critical earthquakes.
Vibration Test and Analysis of An Aircraft Maintenance Hangar under Multi-Support Excitations
Authors: Ye Ji-Hong , Ding You-Liang , Liu Xian-Ming , Huang Zhen
Published: August 2010

Vibration tests on an AMECO (Aircraft Maintenance Engineering Company) maintenance hangar were performed as multi-support excitations in order to verify the effectiveness of the multi-support time history method. The excitation sources represented the three cases of aeroplane taking-off, aeroplane landing and the running in the hangar of the aeroplane engine. Acceleration sensors were installed on the column bases of the hangar structure in order to collect the ground motion records for various excitation cases. The structural dynamic responses were obtained when subjected to the collected ground motions via the multi-support time history method. The calculation results were generally in agreement with those of the test in both the time domain (acceleration peaks) and the frequency domain, which verify the effectiveness of the multi-support time history method. The vibration test can also provide valuable reference data for long-span space structures under multi-support excitations.
Wind Loads and Wind-Induced Responses of Guangzhou New TV Tower
Authors: Zhou Xuanyi , Huang Peng , Gu Ming , Zhu Ledong , Pan Hanming
Published: August 2010

The Guangzhou New TV Tower with a height of about 610 m is presently the tallest TV tower in the world. Wind loads and wind effects are the key factors dictating the design of the structure. A wind-resistance study on the tower has thus been made. The entire tower was divided into 19 sections and models for each section were individually wind tunnel tested using the high-frequency balance technique in specially simulated turbulent wind fields. Descriptions of the sectional tower models, the experimental method and the test results are presented in the paper. The test results were then made use of in computing wind induced responses, including tower displacements, accelerations and internal forces, taking modal coupling effects into account. The whipping effects of the antenna on the responses, especially on accelerations were quantified, can be found. The equivalent static wind loads acting on the structure are also provided in the paper.