bluuebunny/crossref_metadata_2025 huggingface dataset:
A genetic analysis of body size in pink salmon (Oncorhynchus gorbuscha)
Authors: Beacham Terry D. , Murray Clyde B.
Published: April 2011

Two small-sized and two large-sized male pink salmon (Oncorhynchus gorbuscha) were mated to each of four females, producing eight families sired by small males and eight sired by large males. The juveniles were reared for 500 d after fry emergence. Juvenile weight in the two male size classes was similar until the spring of the year of maturity, when juveniles sired by large males grew faster than those sired by small ones. Heritability estimates of weight based upon the dam component of variance increased during 500 d of rearing from 0.4 to 0.8. Heritability of weight based upon the sire component of variance generally ranged between 0.1 and 0.3. The large variation in male body size in spawning pink salmon populations may have resulted from different male breeding strategies.Key words: heritability, salmon, body size.
G-banding in plant chromosomes
Authors: Wang H. C. , Kao K. N.
Published: April 2011

G-banding was successfully demonstrated in chromosomes of cultured Vicia hajastana cells using a simple and reproducible technique. The factors considered important in achieving successful banding were (i) the omission of HCl hydrolysis or enzymatic digestion during the process of making the chromosome preparations; and (ii) the treatment with a weak NaHCO3 solution at pH 9.0–9.5 prior to staining with Giemsa. The G-banding in prophase and prometaphase chromosomes was of better quality and more consistent than that in metaphase chromosomes.Key words: Vicia hajastana, cell line, G-banding.
DNA content and chromosome evolution in the shrubby Oxalis
Authors: Azkue Daniel de , Martínez Arturo
Published: April 2011

The amount of DNA varies widely in 20 shrubby Oxalis species analyzed, ranging from 1.76 pg in O. alstonii to 33.00 pg in O. dispar. This wide variation in DNA content coincided with a wide variation in chromosome size and shape. Numerical taxonomy methods showed that this variation in chromosome size and shape in shrubby Oxalis is mainly due to extra DNA. It was also possible to arrange the 20 species examined in six different groups on the basis of karyotypic similarities.Key words: Oxalis, DNA content, chromosome evolution, multivariate analysis.
Molecular analysis of an alcohol dehydrogenase (Adh) gene from chromosome 1 of wheat
Authors: Mitchell L. E. , Dennis E. S. , Peacock W. J.
Published: April 2011

We have cloned and determined the nucleotide sequence of a gene encoding alcohol dehydrogenase (Adh) from Triticum aestivum cv. Millewa. Southern analysis using cv. Chinese Spring nullisomic–tetrasomic and ditelosomic lines established that the cloned gene mapped to the long arm of chromosome 1A and does not correspond to any previously identified wheat Adh locus. Southern analysis also provided evidence for triplicate copies of this Adh gene on the homoeologous group 1 chromosomes, while Northern blots indicated that the homoeologous group 1 Adh genes, like several other plant Adh genes, are transcribed under anaerobic conditions. Sequence analysis indicates that the cloned gene has a structure similar to both monocot and dicot Adh genes with an open reading frame encoding a polypeptide of 379 amino acids. Sequences important for eucaryotic gene expression such as the TATA box, polyadenylation signal, and intron splice sites were found in the expected positions. The open reading frame is interrupted by 8 introns which are in identical positions with 8 of the 9 introns in maize and pea Adh genes, suggesting that during evolution there are processes occurring that result in the loss of introns. Sequence analysis also revealed that the cloned wheat Adh gene shared extensive homology with the barley Adh3 gene not only in the coding region but also in the noncoding regions. However, this homology is discontinuous as a result of a 1.8-kbp insertion (TLM), which is present in the cloned wheat Adh gene and absent in the barley Adh3 gene. Sequence analysis of this insertion reveals features characteristic of the short terminal inverted repeat class of eucaryotic transposable elements. We have no evidence for the transposition of the TLM element. However, Southern blots reveal multiple copies of sequences related to TLM in the wheat genome and in other closely related species, suggesting that transposition may once have played an important role in the evolution of the Gramineae family.Key words: Triticum aestivum, alcohol dehydrogenase, Adh, chromosome 1, anaerobic induction, insertion element, transposable element.
Cytology, fertility, and origin of Elymus abolinii (Drob.) Tzvelev and its F1 hybrids with Pseudoroegneria spicata, E. lanceolatus, E. dentatus ssp. ugamicus, and E. drobovii (Poaceae: Triticeae)
Authors: Jensen Kevin B.
Published: April 2011

Chromosome pairing and hybrid fertility provide a direct measure of phylogenetic relationships between different taxa. Five accessions of Elymus abolinii (Drob.) Tzvelev were studied to (i) determine their reproductive characteristics; (ii) describe phylogenetic relationships and genomic affinities through chromosome pairing and fertility in the species and species hybrid complex with closely related taxa; (iii) evaluate the morphological variation between related taxa; and (iv) propose a possible origin for E. abolinii. Interspecific and intergeneric hybrids with E. abolinii were obtained from the following "analyzer" parents: Pseudoroegneria spicata (Pursh) A. Love, E. lanceolatus (Scribn. &Smith) Gould, E. dentatus (Hook, f.) Tzvelev ssp. ugamicus (Drob.) Tzvelev, and E. drobovii (Nevski) Tzvelev. The results showed that E. abolinii is an allotetraploid forming 14 bivalents in 95% of the cells, and it is self-fertilizing. Chromosome pairing within the species hybrid complex demonstrated that E. abolinii comprises the S and Y genomes, with close affinities to other eastern Chinese taxa that comprise the S and Y genomes. Multivariate analysis of morphological characters supports the hypothesis that E. abolinii originated from a natural hybridization between E. dentatus ssp. ugamicus and E. gmelinii Ledeb.) Tzvelev, followed by a possible backcross with E. dentatus ssp. ugamicus.Key words: genome, meiosis, chromosome pairing, morphology, hybrid, Triticeae.
Simple methods for evaluating the population of naidids in drinking water treatment plants
Authors: Beaudet Jean-François , Prévost Michèle , Niquette Patrick , Clément Bernard , Coallier Josée , Arcouette Normand
Published: April 2011

The use of biofiltration ozonation followed by biofiltration in drinking water to improve the physicochemical and biological qualities of drinking water can promote the development of macro-invertebrates in filters colonized by bacteria. The passage of invertebrates in filtered water should be avoided both from an aesthetic point of view and from the potential of bacteria growth support on their surface. This paper focuses on the development of two simple methods to estimate the population of members of the naidid family from the class of oligochaetes in biofilters and in water. The first method involves a naidid column trap used to concentrate naidids present in the effluent of biofilters. During the study, the concentrations of naidids recorded in the biofilter effluent studied varied from 0 naidid per m3 in cold water (1°C) to 20 naidids per m3 in warm water (22°C). The second method enumerates naidids in a sample of biofilter media taken using a core sampler. Typical naidid densities encountered ranged from the limit of detection (1 naidid per 4 mL) in cold water (1°C) to 25 naidids per mL in warm water (25°C) at the surface of the biofilter. Statistical analyses done on the second method have shown that samples taken at the surface of the filter media at depths between 0 and 200 mm were statistically different from those taken at deeper levels and represented the maximum naidid densities measured in the biofilter studied.Key words: drinking water, biofiltration, population of naidids.
Méthode générale d'identification paramétrique : application a l'étude thermophysique de quelques matériaux locaux utilisés dans la construction au maroc (platre - liège - brique creuse)
Authors: Bakkouri A El , Boussaid S , Ezbakhe H , Ajzoul T , Bouardi A El
Published: April 2011

The research for habitat comfort conditions goes through a better knowledge of the thermal behavior of materials for building surfaces subject to thermal perturbations. This paper presents a general method for the simultaneous identification of the thermal diffusivity a and of the surface transfer coefficients, one for the irradiated face h0 and one for the non-irradiated face he, of a single-layer or multi-layer building surface. The experimental technique used, which is called box method, is based on the exploitation of the experimental thermograph of the non-irradiated face. The results of the identification are given for several construction materials (hollow brick, plaster, cork). The noteworthy influence of the number of parameters to identify is also exposed.Key words: Construction and insulation materials, measure and identification, thermal diffusivity, thermal loss coefficients.
Real-time daily flow forecasting using black-box models, diffusion processes, and neural networks
Authors: Lauzon N , Rousselle J , Birikundavyi S , Trung H T
Published: April 2011

The purpose of this study is to compare three modeling approaches used for the prediction of daily natural flows 1-7 days ahead. Linear black-box models, which have been commonly used for modeling flows, constitute the first approach. The second approach, a linear type in the context of our application, is less known in the water resources field and is identified by the term diffusion process. The third approach uses models called neural networks, which have gained interest in many fields. All these approaches were tested on 15 watersheds from the Saguenay - Lac-Saint-Jean hydrographic system, located in the province of Quebec, Canada. Because the watersheds possess different physical characteristics, the models were tested under several runoff conditions. In this article, the focus is on results; all approaches along with their conditions of use have been detailed elsewhere in the literature. The results obtained showed that neural networks constitute, for almost all the watersheds studied, the best approach to forecast daily natural flows. The more flexible structure of neural networks allows a best reproduction of complex runoff conditions. However, neural networks are more sensitive to outliers present in observed natural flow series, which are used as inputs in the three models tested. In practice, to model flows at specific periods of the year, it seems preferable to establish seasonal models. If a neural network has an inadequate structure for the period under consideration, then it may produce less convincing results than the other two modeling approaches tested in this study.Key words: forecasts, flows, black-box model, diffusion process, neural network.
Suspended sediment concentration and deformation of riverbed in a frazil jammed reach
Authors: Sui Jueyi , Wang Desheng , Karney Bryan W
Published: April 2011

The presence of ice in rivers affects hydrodynamic conditions through changes in both the river's boundary conditions and its thermal regime. Therefore, the characteristics of sediment transport and the deformation of the river channel in ice-covered rivers are quite different from those experiencing conventional open channel flow. The variables of ice behavior, ice jamming extent, sediment transport, and deformation of the riverbed during ice periods are interrelated on the basis of both physical arguments and field experiments of river ice jams in the Hequ Reach of the Yellow River. The characteristics of sediment concentration in water, frazil ice, and ice cover are described. Analyses have been made on the mechanism of the evolution of frazil jam and the associated adjustments in the riverbed. It has been found that the evolution of the ice jam and the deformation of the riverbed reinforce each other. The interrelationship between the particular features of evolution of ice jam and deformation of riverbed is summarized here in the form of regression relationships relating the hydraulic parameters of water under ice jams to the deformation-extent of the riverbed and the jamming-extent.Key words: deformation of riverbed, evolution of frazil jam, frazil jam, suspended load, sediment concentration.
Truss plate reinforced bolted connections in parallel strand lumber
Authors: Hockey B , Lam F , Prion H GL
Published: April 2011

This paper summarizes the results of an investigation into the behaviour of truss plate reinforced single and multiple bolted connections in parallel strand lumber (PSL) under static tension loading. Sixty single-bolt connections were tested with bolt and PSL size combinations of 12.7 mm bolts in 38×140 mm specimens, 15.9 mm bolts in 89×140 mm specimens, and 22.2 mm bolts in 133×191 mm specimens. Another sixty multiple-bolt specimens were tested, using the above-mentioned PSL size and bolt combinations. The multiple-bolt connections consisted of two rows of five bolts in the 38×140 mm and 89×140 mm specimens and two rows of two bolts in the 133×191 mm specimens. Each connection was configured according to the Canadian Standard for Engineering Design in Wood (CAN/CSA 086.1-94) in terms of bolt spacing, edge distances, and end distances. All reinforced single-bolt connections had average ultimate strength increases, compared to unreinforced connections, of 3% for the 133×191 mm, 12% for the 89×140 mm, and 37% for the 38×140 mm specimens. Reinforcement had little effect on the strength of multiple-bolt connections in both the 38×140 mm specimens and the 89×140 mm specimens. The reinforced four-bolt connections in the 133×191 mm specimens had a 7% increase in average ultimate strength. Reinforcement significantly improved the ductility in all the connections tested. Key words: timber connections, parallel strand lumber, multiple bolts, reinforcement, truss plates, ductility, composite wood products, testing, experimental, composite structural lumber.
Traitement des eaux usées par coagulation-floculation avec recirculation des boues chimiques : Performance générale et stabilité du procédé
Authors: Monette Frédéric , Brière François G , Létourneau Michel , Duchesne Marc , Hausler Robert
Published: April 2011

Six series of tests were carried out to have a better understanding of the stability and efficiency of a coagulation-flocculation process with chemical sludge recycling. The tests consisted in sequential sludge recycling in 100-L pilot reactors. Other tests were performed to examine the stability following wastewater loading variations. Results showed that stability was reached immediately during the first recycling sequences. Furthermore, to obtain improved results compared with those of a classical coagulation-flocculation process, the flocculant concentration must be increased according to the sludge recycling load. Results also revealed that recycling sludge does not absorb wastewater load variations. Consequently, the implementation of sludge recycling in a wastewater treatment plant would not cause effluent degradation or entail major changes in a normal plant operation routine. The predominant coagulation-flocculation mechanisms that explained the increase in efficiency, in comparison with the classical process, were identified as enmeshment and sweep flocculation. Finally, the recycled sludge produced were conditioned and dewatered in a fashion similar to that of a classical process.Key words: recycling, sludge, preformed flocs, coagulation-flocculation, treatment, wastewater, stability.
Le mûrissement à l'eau de chaux des échantillons de béton en laboratoire est-il adapté au cas des bétons contenant des cendres volantes?
Authors: Duchesne J , Marchand J , Lajnef-Edwards M
Published: April 2011

In order to study the influence of the maturation type on the behavior of concrete containing fly ash, specimens of mixtures and mortars have been made with a water/binder ratio of 0.40. In all cases, the proportion of fly ash has been constant and equal to 20%. Different maturation types have been studied: the confinement in an aluminum foil, the immersion in a lime saturated solution and the immersion in an NaOH and KOH solution simulating the interstitial solution that is found in concrete. At different times, the composition of the interstitial solution, the resistance to compression, the content of chemically bound water as well as the quantity of portlandite have been measured in order to evaluate the maturation effect. The results show that the maturation type has an influence on the fly ash hydration rate. The data also indicate that it is essential that the specimens have enough water to hydrate themselves. In the case of the confinement of samples, evaporation must absolutely be avoided. In order to qualify mineral additions representatively, and to measure their properties on representative specimens of the conditions usually found in the concrete structure mass, the alkalinity of the interstitial solution must be preserved. Immersion of samples in an NaOH and KOH solution at a concentration simulating that of the interstitial solution is suggested. The maturation in lime water provides enough water for hydration but pulls down the alkalinity of the interstitial solution too rapidly, which reduces the fly ash hydration rate.Key words: maturation, fly ash, cement, lime water, interstitial solution, chemically bound water, resistance, portlandite.[Journal translation]
A physical model study of ice passage at the Soo Locks
Authors: Tuthill Andrew M
Published: April 2011

A physical model study investigated alternatives to improve ice passage at the Soo Locks in Sault Ste. Marie, Michigan. This paper describes the ice problems at the Soo Locks and the solutions developed in the study. Model tests were conducted to evaluate the performance of high-flow air curtains to deflect ice pushed ahead of vessels entering the 366-m-long Poe Lock. A series of air curtains and an array of point source bubblers were also tested to break ice jams in the upper approach of the adjacent MacArthur Lock. In addition, an array of high-flow point source bubblers was developed in the model to relieve ice congestion in front of the downstream miter gates of the Poe Lock. A model water cannon was also found effective for clearing ice in front of miter gates and breaking jams in the upper lock approach.Key words: Soo Locks, physical model study, ice passage, winter navigation, Great Lakes, high-flow air curtain, point source bubbler, miter gate, water cannon.
De nouvelles approches pour quantifier le risque de rupture d'une retenue d'eau
Authors: Lavallée Daniel , Marche Claude , Quach Tung
Published: April 2011

Construction of dams on streams allows multiple beneficial uses to the population. But in the advent of extreme floods, the structures may fail and free the stored water. Recently built structures respond to more and more demanding design standards. Older structures, which were deemed safe at the time of their construction, might sometimes no longer satisfy these new standards. To evaluate the necessity, the importance and the urgency of works that would make these structures conform again, one of the more and more used approaches consists in resorting to a risk analysis. A risk analysis has been applied a posteriori on a site where a failure was observed in order to determine whether this approach would have brought the managers to undertake corrective works. This application shows the limited capacity of the conventional risk analysis for dams. Two alternative approaches are presented and discussed as a tool to evaluate the risk of a site.Key words: risk analysis, dam break, dam, public safety.[Journal translation]
Un système de prévision appliqué aux crues subites de la rivière Châteauguay
Authors: Lavallée Daniel , Roy Luc , Marche Claude
Published: April 2011

Increasing occupation of flood plains augments the number of residents affected with flashfloods. Temporary protection measures can be considered as long as the authorities are warned soon enough before the occurrence of a flood. A simple forecasting system is presented in this technical note. It is based on the coupling of one hydrological model with one hydraulic model, and on a data acquisition and result analysis module. A case study is also presented.Key words: flashfloods, civil protection, flood, warning.[Journal translation]
Special purpose simulation templates for tunnel construction operations
Authors: Ruwanpura Janaka Y , AbouRizk Simaan M , Er K C , Fernando Siri
Published: April 2011

Simulation is a powerful tool for decision making. It provides an appealing approach to analyze and improve repetitive processes such as tunnelling. Notwithstanding this appeal, application of simulation to real-life construction projects has been minimal. This paper describes the design, development, and application of a special purpose simulation tool for actual tunnel construction operations performed by the City of Edmonton Public Works Department. The implementation of this tool in industry was successful and serves as a model for others to follow. The decision-making process adopted by the model developers and the construction industry personnel during the design, development, and implementation of the simulation are described. The cost-planning tool in the tunnel template is very useful in making decisions and evaluating the feasibility of tunnel construction projects. The real-life application of various alternatives compared to the conceptual estimates prepared for a proposed tunnel project to be constructed in Edmonton is presented in three stages. The basic costs, operational costs, support costs, productivity, duration, and resources utilization data are presented for different alternatives for the proposed tunnel project. Future modifications required by the engineering staff of the City of Edmonton, and the proposed research for modelling uncertainties in tunnel construction are identified. The successful application of the simulation for actual construction project highlights the interactive collaborative research work between academia and industry.Key words: simulation, tunnelling, construction, modelling, planning.
Construction bid price evaluation
Authors: Salem Hiyassat Mohammed A
Published: April 2011

To overcome the disadvantages of the low bid price policy in open competitive contracts, many are advocating the average bid method for bid evaluation. However, as elucidated in this study, this method has some disadvantages. The purpose of this paper is to propose an alternate statistical procedure for bid evaluation. Such procedure applies simple statistical analysis to identify unrealistically low-priced bids, based on either the t-distribution or the normal distribution of a previously established database of similar bids. In this procedure, the ratio of a contractor's bid to owner cost estimate is used to eliminate the distorting effect of the project size. The unrealistically low-priced contracts are then excluded and the bid with the lowest price among the remaining bids is accepted. The procedure requires establishing a database of previous bids.Key words: bid evaluation, competitive bidding, contractor qualification, tender evaluation, contract administration, contract management, bid management.
Seismic analysis of hydraulic structures affected by alkali-aggregate reaction: a case study
Authors: Parvini M , Pietruszczak S , Gocevski V
Published: April 2011

This paper describes the results of numerical analysis of a hydraulic structure subjected to seismic load. The paper is divided into two main parts. First, a numerical procedure for the description of mechanical effects of alkali-aggregate reaction in concrete structures is briefly outlined. Subsequently, a single unit of the Beauharnois power plant, situated in Quebec (Canada), is analysed in the context of seismic excitation. The numerical simulations are aimed at assessing the dynamic stability of this unit and investigating the evolution of damage associated with inception of macrocracks.Key words: alkali-aggregate reaction, plasticity, seismic analysis, hydraulic structures.
Physical, mechanical, and durability properties of gypsumPortland cementnatural pozzolan blends
Authors: Çolak Adnan
Published: April 2011

This paper deals with the effect of gypsumPortland cement and gypsumPortland cementnatural pozzolan ratios on the physical, mechanical, and durability properties of gypsumPortland cementnatural pozzolan blends. The results indicate that the setting time of these paste decreases with the increase of gypsum content in the mixture, ranging from 8 to 11 min. The addition of superplasticizer increases the setting time from approximately 11 to 35 min. This increase is greatly dependent on the plasticizer admixture dosage. These blends show a kinetic of capillary water absorption very similar to that of the Portland cement binder. Sorptivity is strongly influenced by the type of binder, binder composition and waterbinder ratio. Porosity of blended gypsum binders ranges from 12% to 37%. Their water absorption is high, reaching 27% in the blends with a greater proportion of gypsum. The gypsumPortland cement blends themselves possess good water resistance, which is further enhanced by the addition of natural pozzolan and superplasticizer. The water-cured blends with the composition of 41:41:18 (gypsum : Portland cement : natural pozzolan) and 41:41:18S1 (gypsum : Portland cement : natural pozzolan : 1% superplasticizer) offer a compressive strength of approximately 20 MPa at room temperature. These blends give excellent properties retention after aging in water at 20°C for 95 days. Their good resistance to water decreases as the gypsum content in the mixture is raised. However, the strength loss for the gypsumPortland cementnatural pozzolan blends is generally less than that observed for the gypsum binder.Key words: gypsum, Portland cement, natural pozzolan, physical, mechanical, durability.
Design flood estimates in mountain streams  the need for a geomorphic approach
Authors: Jakob Matthias , Jordan Peter
Published: April 2011

Estimates of design flood frequencies are routinely required for engineering purposes on ungauged streams and streams with a limited period of streamflow record. In these cases, the design flood is determined either by rainfall frequencyduration analysis, regional analysis of streamflow data, or by extrapolation of a short record from a gauged stream. Although these types of analyses are valuable in a first approximation of peak discharges for different return periods, there is increasing evidence that geomorphic processes such as debris flows, landslide dam failures, glacial outburst floods, and even snow avalanches in the watershed can significantly exceed these estimates. This paper highlights the problem of a purely hydrologic approach for design flood estimates using several case studies, and suggests procedures to routinely include geomorphic processes in standard flood frequency studies.Key words: debris flows, debris floods, landslide dams, flood hazards, outburst floods, frequency analysis.
A GPS-based monitoring program of land subsidence due to groundwater withdrawal in Iran
Authors: Mousavi S Morteza , Shamsai Abolfazl , Naggar M Hesham El , Khamehchian Mashallah
Published: April 2011

Land subsidence, lowering of the land surface by mass movement, has been caused by human activities in many countries all over the world. The full economic impact of man-induced subsidence is large, yet difficult to estimate. Groundwater withdrawal is one of the most important causes of land subsidence that has caused extremely expensive damages to buildings, walls, roads, railroads, pipelines, and casings of the water wells. A necessary step to perform a proper analysis of land subsidence is to obtain accurate measurements of actual subsidence at certain intervals. The objective of this paper is to evaluate land subsidence using global positioning system (GPS) technique. One example of subsiding areas is the Rafsanjan plain, which has had the most subsidence in Iran. First, the latest situation of land subsidence in the Rafsanjan plain as well as the geological, hydrogeological conditions and groundwater utilization are explained. Next, the monitoring program and engineering works for its implementation are discussed. Finally, the results of two successive measurements carried out recently as the first attempt in Iran to monitor land subsidence by using GPS are presented and interpreted. Based on the results obtained, it was found that the relationship between the decline of groundwater level and land subsidence is not exactly or necessarily linear at every point. Also, the response of different points of the soil body within the plain would not be the same due to the groundwater withdrawal and the change in groundwater level. The ground behavior is influenced by many other factors such as the thickness of aquifer, soil structure, and interlaying manner of sublayers.Key words: land subsidence, groundwater, monitoring, GPS, Iran.
Effect of foundation flexibility on seismic response of reinforced concrete TV-towers
Authors: Halabian Amir M , Naggar M Hesham El
Published: April 2011

The analysis of tall reinforced concrete TV-towers is commonly simplified by assuming a fixed base and ignoring the effect of soilstructure interaction. However, the foundation flexibility affects the dynamic characteristics of tall structures and influences their dynamic behaviour. To design these towers for dynamic loading, the fundamental natural periods, base bending moment, and base shear force as the most important parameters are needed and must be evaluated properly. In the current study, a finite element formulation for the response analysis of TV-towers subjected to earthquake ground motion accounting for soilstructure interaction is presented. The effects of foundation flexibility on the dynamic behaviour of TV-towers were evaluated for two different types of foundation, shallow footing and deep foundation, and various soil profiles. A typical example for these towers is analysed and the results for a range of soil dynamic parameters are presented. It was found that the foundation flexibility increases the natural periods, alters the natural mode shapes, and decreases the base bending moment. It was also concluded that the effect of soilstructure interaction may have a large effect on the base shear of the tower and should be considered in the analysis, especially for the design of horizontal reinforcement.Key words: soilstructure interaction, TV-towers, natural period, base forces, foundation flexibility.
Minimum thickness of concrete members reinforced with fibre reinforced polymer bars
Authors: Ghali Amin , Hall Tara , Bobey William
Published: April 2011

To avoid excessive deflection most design codes specify the ratio (l/h)s, the span to minimum thickness of concrete members without prestressing. Use of the values of (l/h)s specified by the codes, in selecting the thickness of members, usually yields satisfactory results when the members are reinforced with steel bars. Fibre reinforced polymer (FRP) bars have an elastic modulus lower than that of steel. As a result, the values of (l/h)s specified in codes for steel-reinforced concrete would lead to excessive deflection if adopted for FRP-reinforced concrete. In this paper, an equation is developed giving the ratio (l/h)f for use with FRP bars in terms of (l/h)s and (εs/εf), where εs and εf are the maximum strain allowed at service in steel and FRP bars, respectively. To control the width of cracks, ACI 318-99 specifies εs = 1200 × 106 for steel bars having a modulus of elasticity, Es, of 200 GPa and a yield strength, fy, of 400 MPa. At present, there is no value specified for εf; a value is recommended in this paper.Key words: concrete, cracking, deflection, fibre reinforced polymers, flexural members, minimum thickness.
Scale model testing and calibration of City of Ottawa sewer weirs
Authors: Bettez J , Townsend R D , Comeau A
Published: April 2011

This paper reports the results of a laboratory study of the effects of (i) manhole proximity to installation site, (ii) pipe slope (i.e., approach velocity), (iii) upstream head measurement location, and (iv) submergence on the "hydraulics" of two types of sewer weirs used by the City of Ottawa. The City's streamlined form of broad-crested weir and its compound-shaped sharp-crested weir were initially calibrated for a "pipe straight"-arrangement (no upstream manhole is present) for a wide range of flow conditions at 0.2%, 0.4%, and 1.0% pipe slopes. The calibration tests were then repeated with the weirs positioned immediately downstream of a model manhole structure ("manhole"-arrangement). Corresponding data sets were compared to determine the effects of (i) approach velocity and (ii) manhole proximity (for two different shapes of manhole "benching") on the respective weir discharge coefficients.Key words: sewer weirs, broad-crested weir, compound sharp-crested weir, calibration, sewer benching, discharge coefficients.
User costs at the work zone
Authors: Najafi Fazil T , Soares Roberto
Published: April 2011

The objective of this technical note is to discuss the implications related to evaluating work zone user costs. It discusses the work zone dilemma existing among the agency, users, and contractors, and presents different strategies that have been conducted to minimize delay and maximize the number of vehicles that can travel safely throughout the work zone. It further discusses the implication of using five of the most used tools in the process of evaluating the work zone: (i) the Manual on Uniform Traffic Control Devices (MUTCD); (ii) the Highway Capacity Manual (HCM); (iii) computerized software; (iv) delay models; and (v) work zone user costs models.Key words: work zone, user costs, HCM, MUTCD, accident, delay, delay costs.
Behaviour of steel and (or) composite girders with corrugated steel webs
Authors: Sayed-Ahmed Ezzeldin Yazeed
Published: April 2011

Composite beams with corrugated steel webs represent a new innovative system which has emerged in the past decade for short and medium span bridges. The new system usually combines the usage of corrugated steel plates as webs and reinforced/prestressed concrete slabs as flanges for plate or box girders. Bridges that have been recently built with this hybrid system are outlined in this paper, which focuses on the advantages of using corrugated steel webs as opposed to traditional flat webs. The flexural behaviour and bearing resistance of girders with corrugated steel webs is briefly discussed. The flanges of the new system solely provide the flexural strength of the beam with no contribution from the corrugated web. On the other hand, the corrugated web provides the shear capacity of the system. Thus, the shear behaviour of girders with corrugated webs is explicitly discussed focusing on the different failure and (or) buckling modes that affect the design of the corrugated steel web plates. Design charts for such webs are constructed based on the different interaction equations of failure. The torsion-warping behaviour of composite box girders with corrugated steel webs is also discussed.Key words: bridges, composite beams, corrugated steel webs, global buckling mode, interactive buckling, local buckling.
Inelastic seismic response of concrete shear walls consideringPdelta effects
Authors: Tremblay R , Léger P , Tu J
Published: April 2011

The inelastic response of a typical 12-storey ductile reinforced concrete flexural wall is examined under strong earthquake ground motions to determine the importance of Pdelta effects and assess the seismic demand in shear and flexure. According to the stability factor approach of the National Building Code of Canada (NBCC) to account for Pdelta effects, the flexural strength of the wall has to be increased by as much as 29%. However, the inelastic dynamic analyses indicate that Pdelta effects on lateral deformations and curvature ductility demand are negligible for walls that meet the 2% NBCC interstorey drift requirement. The current NBCC stability factor approach to consider Pdelta effects is thus overly conservative for shear wall structures, which respond significantly in their second and higher modes of vibration. The analyses also indicate that the magnitude and distribution of shear forces and bending moments in the wall are different from those obtained using the NBCC static design procedure. Plastic hinges can occur above the base of the wall, although the probable moment resistance diagram exceeds the assumed moment envelope after plastic hinge formation at the base. Dynamic amplification of shear forces due to higher mode effects was also observed, which must be accounted for in design. Dynamic shear amplification factors proposed for wall structures in the commentary to the current standard for design of concrete structures in Canada compared well with the results of this study.Key words: seismic, flexural wall, Pdelta effects, stability coefficient, inelastic response, National Building Code of Canada, dynamic shear force amplification, higher mode effects.
Un modèle thermo-plastique couplé à l'endommagement pour le béton à hautes températures
Authors: Nechnech Wahid , Reynouard Jean-Marie , Meftah Fekri
Published: April 2011

In this paper a new thermoplastic damage model for plain concrete subjected to combined thermal and cyclic loading is developed using the concept of plastic-work hardening and stiffness degradation in continuum damage mechanics. Two damage variables are used: one for mechanical action and the other one for thermal action. Further, thermomechanical interaction strains have been introduced to describe the influence of mechanical loading on the physical process of thermal expansion of concrete. The constitutive relations for elastoplastic responses are decoupled from the degradation damage responses by using the effective stress concept. This method provides advantages in the numerical implementation. Efficient computational algorithms for the proposed model are subsequently explored and performance of this model is demonstrated with numerical examples.Key words: damage theory, plasticity, thermal, unilateral phenomenon, thermomechanical interaction.
Integrating CAD and schedule for identification and resolution of work space conflicts between subcontractors
Authors: Guo Sy-Jye
Published: April 2011

Numerous workers, equipment, material, temporary facilities, and permanent structures share the limited space during construction. Since space constraints may affect productivity and the critical path, it is essential to organize the available space efficiently and minimize space conflicts. This study considers space availability due to time and scheduling, productivity loss due to space constraints and path interference, as well as the possibility of alternative space to resolve these conflicts and optimize space usage. Herein CAD is integrated with scheduling software for dynamic identification of space conflicts on the job site. Follow-up supplemental decision criteria are then provided for conflict analysis and resolution. A prototype decision support system, which combines the criteria, was developed to solve this significant and complex problem more efficiently and precisely. A case study demonstrates the use and development of this system, which is very helpful to engineers and project management.Key words: space, conflict, resolution, CAD, schedule.
Fatigue reliability assessment of tubular joints of existing offshore structures
Authors: Aghakouchak A A , Stiemer S F
Published: April 2011

Tubular joints of offshore structures are prone to fatigue damage. Because of uncertainties involved in quantifying the fatigue process in this type of structure, a reliability approach may be adopted to assess the risks of failure. In-service inspections of structures produce additional information, which may be taken into consideration in order to update the reliability. The paper reviews the methods for carrying out such reliability analyses based on principles of linear elastic fracture mechanics and applies them to a sample tubular joint. The results of this type of analyses may be used for inspection, planning, and (or) decision making regarding repairs or modification of the service life of a structure.Key words: fatigue, reliability, tubular joints, offshore structures, condition assessment.
Seismic response of structural walls: recent developments
Authors: Paulay T
Published: April 2011

It is postulated that for purposes of seismic design, the ductile behaviour of lateral force-resisting wall components, elements, and indeed the entire system can be satisfactorily simulated by bilinear forcedisplacement modeling. This enables displacement relationships between the system and its constituent components at a particular limit state to be readily established. To this end, some widely used fallacies, relevant to the transition from the elastic to the plastic domain of behaviour, are exposed. A redefinition of stiffness and yield displacement allows more realistic predictions of the important feature of seismic response, component displacements, to be made. The concepts are rational, yet very simple. Their applications are interwoven with the designer's intentions. Contrary to current design practice, whereby a specific global displacement ductility capacity is prescribed for a particular structural class, the designer can determine the acceptable displacement demand to be imposed on the system. This should protect critical components against excessive displacements. Specific intended displacement demands and capacities of systems comprising reinforced concrete cantilever and coupled walls can be estimated.Key words: ductility, displacements, reinforced concrete, seismic design, stiffness, structural walls.
A structure for government requirements in publicprivate partnerships
Authors: Abdel-Aziz A M , Russell A D
Published: April 2011

A spectrum of requirements for the procurement of public infrastructure under various publicprivate partnership arrangements has been communicated by governments to the private sector participants. This paper suggests a structure for these requirements and demonstrates how they have been realized in publicprivate partnership projects. Government requirements are categorized and described under a structure of three dimensions: rights, obligations, and liabilities. Each dimension is further defined and explained through a number of attributes. The structure provides insights as to the basis for the different modes under publicprivate partnerships such as buildoperatetransfer, buildownoperatetransfer, and buildtransferoperate. The structure is used to examine government requirements in a number of publicprivate partnership transportation projects. The results show that, for each dimension and its related attributes, comprehensive and clear articulation of government requirements is generally needed. This will reduce the amount of supplemental materials issued for the request for proposals, help consortiums in responding with proposals that can fit the requirements and reduce the amount of time spent in negotiations and (or) the need for contract amendments to reflect marketplace realities missed earlier.Key words: publicprivate partnerships, concessions, development agreements, franchise agreements, transportation projects.
Mesure du développement durable : une évaluation semi-quantitative du volet environnemental pour le cas du traitement des effluents d'une papetière
Authors: Boudreau Julie , Leduc Roland , Wilson James R
Published: April 2011

Since the beginning of the 1990s, many researchers and several organizations concerned with development- and environment-related issues have devised methods to evaluate sustainable development at national and international scales. To that effect, they have identified sustainable development indicators. To date, however, very little work has focused on industrial activities. This paper presents a semi-quantitative method allowing evaluation of the environmental aspect to sustainable development, with an application on the environmental performance of the effluent treatment procedure of a paper mill. Eight environmental indicators for sustainable development are considered for evaluation. These indicators are linked to the strategic requirements for sustainable development as stated in the Bruntdland Commission. They are also acknowledged by many authors and organizations. The environmental performance evaluation on the effluent treatment procedure of the paper mill under study shows that this activity meets a relative degree of sustainability. This evaluation allows the identification of the strengths and weaknesses of the effluent treatment with respect to sustainable development.Key words: indicators, sustainable development, measure, environmental performance, biologic treatment, effluents, paper mills.[Journal translation]
Utilisation d'éléments structuraux en aluminium dans les ponts routiers : Étude économique et structurale
Authors: Roy Carol , Beaulieu Denis , Bastien Josée
Published: April 2011

The study presented in this paper is part of a project aiming at evaluating the potential use of aluminum in structures. The types of intervention could range from a simple repair or a reinforcement involving structural aluminum, the replacement of a used bridge deck by an aluminum deck, to the construction of a new bridge made in full or in part of aluminum. It is this latter type of intervention that justified a research project, the results of which are presented in this article. The first step involves identifying the most advantageous type of aluminum structural system from a structural standpoint as well as an economic standpoint. This step includes the analysis and partial design of 40 girder- or truss-type road bridges, spanning 15 and 35 m, supporting either an active concrete slab or an aluminum deck. These studies have shown that bridges built using a Pratt-type truss and an active concrete slab provided the best results. It is also shown that some calculation criteria, such as vibration, deflection, and fatigue criteria limited the extensive use of aluminum in bridges. In the second step, nine bridges are more comprehensively analysed and designed, based on the standards used in North America, and three are fully designed, including the connexions, in order to realize a cost analysis study that is as accurate as possible. Special attention is given to vibration and fatigue problems as well as to the details related to connexions calculation. The study concludes that the development of an aluminum-only medium span road bridge system is a non-viable project in the short to mid term from a structural standpoint as well as an economic standpoint, and it makes recommendations on the use of aluminum decks and on the continuation of the work.Key words: aluminum, analysis, bridges, connexions, design, fatigue, standards, vibration.[Journal translation]
Analyse dynamique de l'interaction pont-véhicules pour les ponts routiers. I. Aspects numériques
Authors: Henchi Kamel , Fafard Mario , Talbot Martin
Published: April 2011

In this paper, a general and efficient procedure for the dynamic analysis of road bridges is presented, that takes into account bridge-vehicle interaction and the road profile in a realistic way. With this approach, the bridge structure can be modeled with a tridimensional finite element method using shell and beam elements. The vehicle model is represented using a discrete method based on Lagrange equations. This method uses the modal superposition technique for the bridge components, with a correction for the displacement based on the method of modal acceleration. The Newmark- beta method is used to solve the movement equations of each bridge and vehicles system and the solution is obtained through an iterative process of the interactive forces between the bridge and the vehicles. A simple academic example is presented to show the validity of the proposed algorithm.Key words: shell, dynamics, finite elements, interaction, bridge, roughness, vehicle.[Journal translation]