bluuebunny/crossref_metadata_2025 huggingface dataset:
Soil-Pollution Effects on Geotextile Composite Walls
Authors: Fang H-Y , Pamukcu S , Chaney RC
Published: March 2009

For designing or selecting proper types or porosity of the geotextile to be used in a composite wall, it is necessary to know the grain size distribution of the surrounding soil under consideration. This determination becomes especially critical when the engineered facility is exposed to various biological and chemical stresses overtime. A series of laboratory investigations were conducted to examine the effects of pore fluid pH, soil adsorption of particulate matter and also particle volume change on the grain size distribution of soils. The results showed that the particle size distribution curve shifted to finer scales as water pH increased for non-dispersive clays. For a dispersive clay, the trend of the particle size distribution curve was opposite, shifting to the finer sizes with decrease in water pH. Surrounding water pH was also found to correlate with volume change of soil particles and soil matrix which subsequently would affect particle size distribution.
Effects of Construction of a Diaphragm Wall Very Close to a Masonry Building
Authors: Chan SF , Yap TF
Published: March 2009

Observations were made to study the settlement behavior of an old 4 story masonry building during the construction of a 25m deep diaphragm wall. The adjacent building, which was only 1.2m to 1.5m from the wall, was supported on shallow footings founded on weak deposits of loose sand and soft clay. A preliminary assessment before construction in the critical area indicated that settlement would be excessive if conventional construction procedures were followed. This led to the adoption of several settlement control measures in the construction process. It was found that these measures were effective in restricting the average settlement of the adjacent building to only 7.2mm and there was no visible sign of cracking.
Design and Construction of Cement-Bentonite Cutoff Wall for S.A. Murray Jr. Hydroelectric Station
Authors: Ramachandra K , Swan CH
Published: March 2009

The Sidney A. Murray Jr. Hydroelectric Station is the largest, low-head run-of-river hydroelectric facility in the United States. Located near Vidalia, Louisiana, the plant generates 192 MW of electric power from eight 24 MW units. The powerplant structure and abutment dams are subjected to differential hydraulic heads of up to 8m (26 ft) under the project flood conditions and up to 12m (39 ft) under extreme, emergency conditions. Plastic concrete cutoff was installed utilizing cement-bentonite mixes placed by the slurry trench method to control seepage and uplift under the structures. This paper presents design concepts, mix design, field installation procedures and test data of the cores from the installed cutoff. Permeability, Modulus of Elasticity and Pinhole erosion criteria were used as the main control parameters for acceptance of the work.
Slurry Wall Performance Adjacent to Historic Church
Authors: Winter E , Nordmark TS , Tallard G
Published: March 2009

Underpinning and conventional sheeting and shoring using soldier beams and wood lagging was substituted with a slurry wall adjacent to a historic Washington, D.C. church. This church was badly damaged in 1970 due to ground movement from a building excavation to the west. Understandably there was concern regarding a proposed new excavation on the east side for an office building planned only a few metres away. The church hired consultants to review all design and construction measurement data independently. This paper presents the measurement data on the slurry wall from readings on slope inclinometers embedded in the wall, survey of surface points and observations on the church itself. Readings at the various stages of construction are shown. The work was completed without any significant movement or damage to the church.
Quality Control of Slurry Cutoff Wall Installations
Authors: Bell RA , Sisley JL
Published: March 2009

A predominantly sandy levee embankment along an 18 km portion of the Sacramento River had a history of heavy seepage during river flood stages. A seepage cutoff wall keyed into clayey layers in the foundation soils was chosen by the U.S. Army Corps of Engineers to remedy the seepage problems. A test cutoff program utilizing 4 different methods (backhoe, trencher, mix-in-place and vibrated beam) of installing a cement-bentonite cutoff wall was undertaken as a performance type of contract to evaluate the methods and results of installing cutoffs with specified minimum width, depth, strength, and maximum hydraulic conductivity. This was followed by a Phase I contract to install 3.2 km of cutoff wall (27,870 m2) with essentially the same performance type specification as used in the test program. The quality control programs involved sampling and molding specimens of cutoff wall materials and sampling of the hardened materials with drilled borings, in situ packer permeability testing, and numerous sampling methods. Test results raised questions of the representativeness and degrees of disturbance caused by the various sampling and testing methods and they indicated the cutoff walls did not always meet the required minimum unconfined compressive strength of 103 kPa or the maximum hydraulic conductivity of 1 × 10-6 cm/sec. The paper presents the test results and discusses the quality control methods, procedures and problems encountered in both the test program and Phase I contract.
Design, Construction and Performance of a Soil-Bentonite Cutoff Wall Constructed in Two Stages
Authors: Khoury MA , Fayad PH , Ladd RS
Published: March 2009

Soil-bentonite seepage cutoffs constructed by the slurry-trench method in earth embankments present serious design and construction concerns that need to be adequately addressed in order to assure overall embankment safety. The paper describes the various phases of the installation and performance monitoring of a 1,500 m (4,900 ft) long S-B cutoff wall in a dam and dike constructed of sandy material. The cutoff wall extended to a maximum depth of 23 m (75 ft) and had a width of 0.9 m (3 ft), except for a 305 m (1,000 ft) long section where the width was increased to 1.5 m (5 ft) to accommodate hydraulic heads in excess of 9 m (30 ft). Construction of the wall was performed in two stages. The lower stage was constructed when the dam reached about 75 percent of its maximum height while the upper stage was constructed when the dam was close to its final height. This is believed to be the first use of an S-B cutoff constructed in two stages as the main barrier in a new embankment. The paper also discusses the lessons learned from this two-stage construction and post-construction performance based on the collected instrumentation data.
State of the Art in Bio-Polymer Drain Construction
Authors: Day SR , Ryan CR
Published: March 2009

A common feature of civil engineering design is the “french drain,” a trench intended to intercept and collect groundwater and transfer it laterally to a sump. The environmental marketplace has created a larger demand for these drains for the purpose of the collection of contaminated groundwater. Traditional construction methods that use trench boxes or shoring, sometimes in combination with dewatering systems, present a number of problems, particularly if the trenches have depths in excess of about five meters.

The Bio-Polymer Slurry Drain (BP Drain) has provided a new method for constructing deep drains that eliminates shoring and dewatering. It does not require a wide excavation, reducing spoil disposal and does not require trench entry by workers, improving safety.

The system uses basic slurry trench technology but, instead of bentonite clay slurry, a guar-gum based slurry is used to maintain the open trench. Once the trench is dug to full depth, it is backfilled with a pervious material such as gravel. Wells can be inserted, pipe laterals can be placed and filter fabric inserted, all under slurry. When the trench is filled, the slurry is chemically and biologically “broken”, allowing the slot to collect water.

This paper reviews the current practice as illustrated by these case studies: a collection trench for oil, another for a chemical containment, and a drain constructed inside a slurry wall at a landfill site. The authors believe that this methodology will be subject to wide application once all of its features and advantages are fully realized.
Post Office Square Garage Project — A Case History of Instrumented Slurry Wall Performance
Authors: Schoenwolf DA , Whitman RV , Abbott EL , Becker JM
Published: March 2009

This paper presents the results of the monitored performance of a reinforced concrete diaphragm wall (slurry wall) while making a seven-level, 24.4 m (80 ft) deep excavation in downtown Boston for the construction of an underground garage using the “top-down” construction technique. In developing the design and construction methodology, ground movement control was considered to be an important aspect in design of the excavation support system. Finite element analyses were performed to model the anticipated soil and adjacent building movements. Observed movements during construction were compared to the values generated during design to judge the performance of the excavation support system. Modifications to the construction sequence were made to help reduce future movements. The owner's commitment of resources necessary to support the program played an important role in achieving the desired goals.
Synergistic Effects of Acid Deposition and Road Salts on Corrosion
Authors: Baboian R
Published: March 2009

The interaction of our natural environment (rain, snow, humidity) with chemicals introduced to the environment (road salts, emissions) provides a complex chemistry. During the past three decades, this chemistry throughout the world has changed drastically. Use of sodium chloride and calcium chloride for ice and snow removal has increased to an extremely high level. Emissions of SO2 and NOx have also risen to such levels. These emissions convert to sulfuric and nitric acids and are deposited over large areas by precipitation. The combination of protective film disruption on metals by chlorides and the deposition of reducible hydrogen ions by acid precipitation provides a synergistic effect on corrosion of infrastructure metals. Results of laboratory and field tests show that steel is much more susceptible to corrosion in this type of environment.
Wetness Monitoring on the Exterior of Infrastructures
Authors: Hechler J-J
Published: March 2009

The ASTM G-84 time-of-wetness sensor was used to study the moisture deposition on the exterior of a large building for an autumn and a winter period. It was possible to detect the presence of all types of moisture deposition and to measure the time-of-wetness at any location on the building. The influence of such parameters as orientation, design, and temperature on the moisture deposition is discussed.
Utilization of Electrochemical Impedance Techniques to Estimate Corrosion Damage of Steel Infrastructures
Authors: Homma K , Goto N , Matsuoka K , Ito S
Published: March 2009

Infrastructures such as bridges, highways, pipelines and harbor piers sometimes suffer from corrosion damage during their service life. To diagnose deterioration of infrastructures and secure effective maintenance, in-situ corrosion monitoring methods based on electrochemical impedance techniques have been developed. This paper reports three examples of new corrosion monitoring sensors: 1) a sensor for detecting corrosion of marine steel structures in seawater, 2) a sensor for detecting corrosion of reinforcing bars in concrete, and 3) a sensor for detecting coating deterioration of painted steel structures in the atmosphere. The effectiveness of these sensors has been verified by experiments both in the laboratory and in the field.
A Theoretical Analysis for the Residual Strength of Corroded Gas and Oil Transmission Pipelines
Authors: Kanninen MF , Pagalthivarthi KV , Popelar CH
Published: March 2009

The current regulations governing the integrity of corroded gas and oil pipelines are empirical. In many cases the guidelines are very conservative, but even so they are not reliably conservative in all instances. To improve upon this situation, a theoretical approach was taken within elastic shell bending theory. Preliminary results developed using a maximum hoop stress criterion in an axisymmetric approximation of the metal loss provided a relation for the failure pressure for a pipe with axial direction metal loss. It was found that the form assumed in the existing empirical approach is essentially correct in so far as the axial extent of the damage governs. However, the extension of the shell bending theory approach to the plane strain case indicates that it may be the circumferential dimension of the damage that actually governs the failures of corroded pipes. While this important finding must be confirmed by further analyses and experimentation, this result indicates the usefulness of the type of approach described in this paper. The use of even simple mechanics models where only empirical approaches currently exist can surely be useful to address corrosion-related problems associated with a variety of infrastructural components.
Recent Developments in Inspection Techniques for Corrosion Damaged Concrete Structures
Authors: John G , Hladky K , Gaydecki P , Dawson J
Published: March 2009

Improved procedures for inspecting both reinforced concrete and prestressed concrete structures, with regard to determination of the embedded steel components are discussed. Prototype ultrasonic procedures recently developed to determine the condition of prestressed pretensioned tendons in concrete will be discussed. The application of electrochemical surface mounted systems for estimating the rate of corrosion of reinforcing steel and other embedded steel components in large concrete structures will also be described. In particular, the ability to obtain rate of corrosion data over the concrete surface and presenting it as iso-corrosion rate contours will be highlighted.
Prediction and Control of Sulfide Induced Corrosion in Concrete Sewer Infrastructure and Rehabilitation Techniques
Authors: Jeyapalan JK
Published: March 2009

Most cities, counties, and sanitary districts have used concrete pipe for sewer construction during the past 100 years. Many of these pipelines under certain site conditions have been corroded by sulfuric acid formed from sulfide gas. Despite this track record, many design engineers are still selecting concrete pipe with some allowance for corrosion using the somewhat outdated sacrificial wall thickness method. There are numerous agencies which do not even include sulfide corrosion prediction and control as part of the sewer structure material selection process. Even when sulfide corrosion studies are undertaken, no engineering considerations are given for the potential of corrosion in structures such as wet wells, manholes, drop structures, and metering stations. Deteriorated concrete pipe in some cases is replaced with new concrete pipe with no provisions for corrosion and such practices will lead to premature failure of the sewer system and excessive rehabilitation budgets. This paper presents the state-of-the-art of prediction and control of sulfide corrosion in sewers and rehabilitation methods available for repairing such sewer systems.
Corrosion-Related Deterioration of Reinforced Concrete Structures at Oil Refineries in the Persian Gulf Region
Authors: Novokshchenov V
Published: March 2009

This paper cites specific examples of corrosion-related distress of reinforced concrete exposed to aggressive environments of the Persian Gulf region. Several case histories are described involving structures at various oil refineries situated along the Gulf coast. The paper outlines major factors affecting the development of a particular failure and depicts repair techniques implemented to eliminate the damage and to prevent the future occurrence of the failure.
Aquatic Community Response to Stress: Prediction and Detection of Adverse Effects
Authors: Pratt JR
Published: March 2009

General ecological principles have been used to hypothesize community stress responses. A review of responses of microcosms, mesocosms, and ecosystems to chemical stressors indicated that changes in taxonomic and standing crop measures of community structure were usually reliable and sensitive indicators of stress responses. Changes in process rates showed less frequent response to chemical stressors. Ecosystem experiments have not demonstrated some predicted changes even at extreme levels of stress. Problems in demonstrating community and ecosystem responses may be a result of present methodologies or may identify failures of ecologists to accurately predict stress effects. Many ecosystem processes are substrate limited and robust even under severe stress. Although additional information is needed on the natural variability of measures of both structure and process, stress measures based on the composition of biological communities seem to have the greatest promise for evaluating ecosystem conditions.
Aquatic Test Systems for Studying the Fate of Xenobiotic Compounds
Authors: Cripe CR , Pritchard PH
Published: March 2009

A variety of test systems, including microcosms, have been developed to provide information on the environmental fate of test compounds in aquatic ecosystems. As the overall strategy for development of tests has been less than logical and only vaguely chronological, we believe that some degree of categorization and guidance in the application of these test systems is appropriate. Our approach is based on four criteria: environmental inocula, sediment, generation of degradation rates, and intact water/sediment cores. Test systems either (1) provide basic biodegradability/rate information (Screening Tests) or (2) answer research questions about biodegradation rates and their controlling factors in the environment (Investigative Tests). Examples of each system type are cited with their respective advantages and disadvantages.

Criteria are suggested for selection of test systems with emphasis on the simplest system that can provide the most relevant and necessary information. Shake-flask tests are recommended for degradation rate information and assessment of significance of environmental factors on degradation. Intact core microcosm systems are useful to study a limited number of processes that cannot be examined in shake-flasks and, with a mathematical model, to verify biodegradation rates obtained from simpler test systems using conditions more reflective of natural conditions.
Review of Chemical Fate Testing Conducted under Section 4 of the Toxic Substances Control Act: Chemicals, Tests, and Methods
Authors: Walker JD
Published: March 2009

Since the implementation of Section 4 (testing chemical substances and mixtures) of the Toxic Substances Control Act (TSCA), the U.S. Environmental Protection Agency (EPA) has received numerous environmental effects, chemical fate, or health effects testing recommendations for several hundred chemicals. This paper provides information on the types and numbers of Federal Register (FR) notices that EPA has published in response to these testing recommendations. In addition, this paper provides detailed discussions of the chemicals and tests for which chemical fate testing has been conducted under TSCA Section 4 and the methods used to conduct those tests. As of 31 December 1988, 182 TSCA Section 4 FR notices (including 65 TSCA Section 4 FR notices mentioning chemical fate testing, and 15 TSCA Section 4 FR notices requesting chemical fate testing) had been published by EPA in response to numerous testing recommendations. For the 51 chemicals in the 15 TSCA Section 4 FR notices requesting chemical fate testing, test data for 105 of the requested 120 chemical fate tests had been received by 31 December 1988. The 28 test methods used for the 105 chemical fate tests were evaluated; modifications were proposed for a few test methods to improve test data reliability.
Use of the Blue Mussel, Mytilus edulis, in Water Quality Toxicity Testing and In Situ Marine Biological Monitoring
Authors: Nelson WG
Published: March 2009

An effort was undertaken at the Environmental Protection Agency's (EPA) Environmental Research Laboratory, Narragansett (ERL-N), Rhode Island, to evaluate the integration of in situ biological monitoring with the blue mussel, Mytilus edulis L., into EPA's Complex Effluent Toxicity Testing Program. The scope for growth (SFG) index, an instantaneous measure of energy balance in an organism, was used to assess the physiological condition of the mussels. The initial step in this program, assessing the sensitivity of M. edulis to several known toxicants in the laboratory, indicated that the SFG of the mussel is comparable in sensitivity to those of other endpoints and test species currently used for assessing receiving waters. A second step involved using the mussel in situ to assess the impact of a municipal sewage outfall on receiving water quality in Greenwich Cove, East Greenwich, Rhode Island. This was completed twice; once before the initiation of an upgrade of the facility, and once when the upgrade was about half complete. Mussels were deployed along a dilution gradient from the sewage outfall to a control station for a period of one month. Subsets of mussels were collected after a 7-day and 30-day exposure period. The results of the first deployment, prior to the upgrade, indicated a significant decline in SFG after 7 days at stations located proximal to the sewage outfall. A similar spatial and temporal pattern was observed in mussels deployed for 30 days. The results of the second deployment, after a portion of the upgrade, indicated that there were no effects after the 7-day exposure and only a slight gradient in mussel SFG after 30 days, suggesting that the upgrade had a positive effect on water quality in Greenwich Cove. These data indicate also that in situ biological monitoring with mussels can be an effective method for assessing receiving water toxicity, including the evaluation of sewage treatment plant improvements, and that short-term tests (7-day) can be reflective of longer-term (30-day) chronic impacts.
The Aquatic Toxicity of the Sensory Irritant and Riot Control Agent Dibenz(b,f)-1,4-Oxazepine (CR)
Authors: Johnson DW , Haley MV , Landis WG
Published: March 2009

The aquatic toxicity of dibenz(b,f)-1,4-oxazepine (CR) was examined using organisms from three trophic levels. The compound is a peripheral sensory irritant which produces an immediate irritation of the eyes, nose, mouth, skin, and respiratory tract in man. The compound is comprised of a double benzene ring with a shared oxygen molecule and a doublebonded carbon, nitrogen group. The intended use of the compound is for the control of civil disturbances. Acute bioassays were performed using Ankistrodesmus falcatus, Daphnia magna, and Pimephales promelas. A 21-day static renewal test was performed using D. magna.

A 24-h EC50 of 1.48 mg/L and 48-h EC50 of 0.94 mg/L were calculated for daphnids. Significant differences in reproductive output and body length were observed at 0.50 mg/L using ANOVA in the 21-day chronic assay with D. magna. The 96-h algal growth inhibition test yielded an IC50 in the range of 1.95 to 3.55 mg/L. An LC50 of 2.6 to 2.8 mg/L was determined for the fish. An enhancement compared to controls in reproductive output was observed for both the algae and daphnia at low concentrations of CR. Dose response curves and comparisons of linear and exponential regressions are presented for several of the toxicity tests.
Short-Term Amphibian Toxicity Tests and Paraquat Toxicity Assessment
Authors: Linder G , Barbitta J , Kwaiser T
Published: March 2009

Changes in agricultural practice may alter agrichemical effects on nontarget wildlife. Because of routine practice in various forms of conservation tillage, paraquat (1,1′-dimethyl-4,4′-bipyridinium dichloride) has increasingly been used for weed control in agricultural fields and in supporting management practices. Though highly adsorbed by soil and foliage, paraquat may gain increased notice as an agrichemical potentially impacting wetlands which surround much of the farmland across the country; consequently, amphibian toxicity evaluations may be incorporated into wildlife hazard assessments conducted for chemicals finding increased use in conservation tillage. Using amphibians representative of two anuran families, early life stage toxicity tests (96-h modified FETAX) were performed. Acute and subacute exposures were completed, and toxicity endpoints (mortality and teratogenicity) were evaluated for exposures to technical-grade and formulation-grade paraquat. These preliminary toxicity assessments suggested that acute and subacute endpoints for each form of paraquat may be significantly different, since the commercial formulation was three times as acutely toxic as the technical-grade chemical. Furthermore, it appeared that species and familial differences must be regarded with increased caution until a comparative toxicity data base is developed for amphibians.
Reducible Dye 2-(p-lodophenyl)-3-(p-Nitrophenyl)-5-(Phenyl)-2H-Tetrazolium Chloride (INT) for Use in Aquatic Toxicology: Notes on Chemical Structure, Electrochemistry, and Toxicity
Authors: Catallo WJ , Gale RJ , Wong RL , Bender ME
Published: March 2009

Studies of 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-(phenyl)-2H-tetrazolium chloride (INT) chemical structure and aqueous electrochemistry at Hg, C, and Pt electrodes were conducted to address conceptual difficulties in published literature and questions arising from INT behavior in our bioassay systems. Data presented include nuclear magnetic resonance spectra and consistent chemical structures for INT, INT formazan, and an extract from INT-treated Escherichia coli cells. Results from normal and differential pulse polarography, cyclic voltammetry, and spectrochemical determination of minimum potentials for INT reduction on Pt are reported and given mechanistic interpretations. The results of experiments with INT on C and Pt electrodes suggested interfering electrode reactions involving hydrogen. An expanded reaction scheme is proposed based on these observations. Preliminary mutagenicity testing on INT and its reduction products was conducted using the Ames/Salmonella assay. The results of these assays are presented.
Use of Hazard Models in Evaluating the Effect of Exposure Duration on the Acute Toxicity of Three Pesticides
Authors: Moore DW , Schluchter MD , Scott GI
Published: March 2009

Renewal toxicity tests (96 h) were conducted with the emulsifiable concentrates of three pesticides: azinphosmethyl, endosulfan, and fenvalerate. A second test design, which incorporated a 6-h period of exposure followed by 90 h of observation, was also conducted on these three pesticides.

Toxicity results from the two test types were then compared using different hazard models to test a series of null hypotheses. These comparisons indicated: (1) while the effect of concentration was constant across time, hazard changed for each of the test types; and (2) when the effect of concentration was the same for the initial periods of exposure (6 and 24 h) in the two test designs, the average hazard was significantly lower for 6 h of exposure than for 24 h.

This study may have significant implications for relating results from laboratory toxicity tests to mortality among organisms exposed in situ. The 6-h exposure test design provides information on delayed effects due to short-term exposures, while hazard analysis can be used to estimate the underlying time/concentration relationship from standard laboratory toxicity test data.
The Response of Diploid and Polyploid Rainbow Trout Cells Following Exposure to Genotoxic Compounds
Authors: Powell DB , Kocan RM
Published: March 2009

Polyploid cells have been associated with malignant neoplasms in many animal species. Recent advances in the genetic engineering of aquatic vertebrates have made it possible to produce healthy rainbow trout (Oncorhynchus mykiss, formerly Salmo gairdneri) that are completely triploid (3n) or tetraploid (4n). The objectives of this study were to compare the effects of direct- and indirect-acting carcinogens on DNA repair and measure the relative binding of benzo[a]pyrene (B(a)P) to DNA in diploid and polyploid cells.

The level of DNA repair was measured in diploid and polyploid cells following an in vitro exposure to the direct-acting carcinogen N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) or the indirect-acting carcinogen B(a)P. A DNA repair assay was used to compare the effects of MNNG and B(a)P on nucleated erythrocytes and hepatocytes.

Diploid and polyploid hepatocytes responded more strongly to MNNG than to B(a)P. DNA repair activity per haploid genome in polyploid fish hepatocytes was found to be greater than in diploid hepatocytes. Tetraploid cells consistently exhibited slightly more than twice the unscheduled DNA synthesis of the diploid cells. Rainbow trout erythrocytes were completely refractory to MNNG and B(a)P in the DNA repair assay.

The 32P-postlabeling assay, which measures DNA-bound compounds, indicated that at least five distinct DNA adducts are formed in rainbow trout liver cells following exposure to B(a)P. Diploid and tetraploid cells were found to contain significant differences in the relative number of specific adducts. No adducts were detected in the DMSO solvent controls.
Reduction in the Numbers of Antibody-Producing Cells in Rainbow Trout, Oncorhynchus mykiss, Exposed to Sublethal Doses of Phenol Before Bath Immunization
Authors: Anderson DP , Dixon OW , van Muiswinkel WB
Published: March 2009

The numbers of splenic antibody-producing cells were reduced in groups of fish given a 2, 5, or 30 min bath exposure to 10 ppm phenol before immunization by bath with the bacterin, Yersinia ruckeri O-antigen. The lethal time of 50% (LT50) for the 10 ppm phenol bath was 45 min. The passive hemolytic plaque assay was used to monitor the numbers of antibody-producing cells in the phenol-pretreated and sham-treated fish 14 or 21 days after contaminant exposure and 5 min bath immunizations at 10 or 100 μg/mL. These results, documenting a suppression of the immune response to bath immunization following a brief exposure to a toxicant, may help to explain delayed mortalities where pollution is implicated.
Stress Proteins: Their Detection and Uses in Biomonitoring
Authors: Bradley BP
Published: March 2009

The synthesis of stress proteins is induced by a wide variety of stressors and occurs in virtually every organism. Which proteins are synthesized depends on the stressor, and the amount of protein synthesized seems to depend on the level of stress.

Stress proteins can be detected quite easily autoradiographically or immunologically. A field immunoassay is feasible, allowing early warning of environmental problems as well as routine in situ monitoring. More sophisticated laboratory assays are also available, combining gel electrophoresis, autoradiography, immunoassays, and densitometry to confirm the field assessment and perhaps to suggest the physical or chemical stressor or stressors causing the problem.

The tests can be done on live, fresh, or preserved specimens. Assaying preserved specimens allows samples from different areas and times to be tested simultaneously.
DNA Damage as an Indicator of Pollutant-Induced Genotoxicity
Authors: Shugart LR
Published: March 2009

Biological monitoring is an approach of considerable interest to scientists in the field of environmental genotoxicity who are investigating the effects of hazardous substances on the biota. In essence the technique involves an evaluation of various types of responses in living organisms for their potential to identify exposure to dangerous substances and to define or to predict subsequent deleterious effects. The rationale for the selection of DNA damage as an indicator of exposure to genotoxic agents is based mainly on the mechanisms of action of chemicals that are known mutagens and carcinogens. An alkaline unwinding assay that detects excess strand breakage within the DNA polymer was applied to sunfish in a local stream as a biological monitor for environmental genotoxicity due to industrial pollution. The study was conducted over a period of 15 months, and the temporal and spatial aspects of the data were evaluated for the effect of remedial action.
Contextual Intervention/Technical Invention
Authors: Smith AD
Published: March 2009

The focus of the paper is the design, development, and construction of exterior walls on three recent projects: (1) Rowes Wharf Project (Boston, MA); (2) the NBC Tower (Chicago, IL); and (3) FC-2 (at Founders Court, London, England). The best definition of value engineering is the ability of new technology to provide a cost- and time-effective construction process, which provides the opportunity to develop a richer building of higher quality. The key is the relationship between all of the members of the design and construction team. The relationship has to be established at the beginning of the design process in order to be contextual with (integrated into) the process. The three case studies presented represent how value engineering and the relationship between members of design and construction enrich the tradition of building in the urban context.
Curtain Wall Caveats, or How to Help the Architect/Engineer and/or Construction Manager Be Wary
Authors: Zinn P
Published: March 2009

Facade design on paper by a competent designer-draftsman is often an exercise in artistic license, a flight of fancy, so to speak. This article is an attempt by one who has participated in the full gamut of experience in this field to impart his experience to those who have never dealt with the mechanic in the shop or on the open building frame.
The Use and Preparation of Curtain Wall Structural Design Drawings
Authors: Tawresey JG
Published: March 2009

The concept of curtain wall structural design drawings is introduced. What are structural design drawings? How are they used and how are they prepared? These questions are discussed.

Curtain wall structural design drawings apply to either the design-then-bid or the bidder design construction format. They are analogous to the structural design drawings for a building structural frame and can be used for design team review and building department approvals.

The structural engineer's involvement in curtain wall design goes beyond conformance with prescription in the form of codes, standards, or specifications. There are few curtain wall prescriptions. Instead, the involvement relies on hands-on experience with the materials, judgment, customized testing, and analysis. The results of these efforts must be clearly communicated to the rest of the design team, and the curtain wall structural design drawing is a method to accomplish this task.
Innovations in Structural Sealant Glazing
Authors: Francis GV
Published: March 2009

Structural silicone glazing—sometimes called flush glazing, stopless glazing, or just structural glazing—is a method of fixing glass to its supporting framework by an adhesive. This fixing method results in a smooth, uninterrupted surface of glass, which significantly improves the appearance of glass walls.

Use of the method has grown considerably since it was introduced in the early 1970s. Currently, nearly 30% of all commercial glazing in the United States is fixed in place using silicone on at least two edges of the glass.

Many people, however, are concerned about the safety aspects of the method. The industry has responded with improved materials, improved quality control procedures, and improved designs.

One of the most recently designed systems which addresses the safety issue uses a special insulating glass unit with a recessed channel around all four edges of the lite. The recess is then used to hook or clip the unit to the supporting mullion. The installation then gives the appearance of structural silicone glazing without relying entirely upon a silicone tensile bead.

The evolution and growth of structural sealant glazing, safety aspects, and the design, testing, and safety of the new method are presented.
Insulated Concrete Sandwich Walls
Authors: Sauter JE
Published: March 2009

Durability, fire resistance, relatively low cost, and availability makes concrete a natural choice for wall construction. The insulating properties of concrete, however, greatly reduce its effectiveness. Concrete sandwich panels were developed in response to the need for more efficient concrete wall systems.

The first forms of sandwich walls used steel and/or concrete connections to hold two layers of concrete together with insulation sandwiched between. Steel and concrete traversing the insulation layer, however, can reduce the insulating value of a wall by 20 to 40% or more due to a phenomenon known as thermal bridging. A method for determining loss due to the thermal bridging has been developed by ASHRAE called the isothermal planes (series parallel) calculation method. A modern personal computer and spreadsheet can be used to easily perform these calculations.

Composite materials (reinforcing fibers and binding resins) developed for the aerospace industry have recently been adapted to take the place of steel and metal connections in concrete sandwich walls. The result is the ability to manufacture insulated concrete sandwich panels with no loss in thermal energy. The composite connections are stronger than steel, will not corrode, are flexible to withstand thermal cycling, and are cost competitive. Modern technology has provided concrete panel manufacturers with the ability to produce concrete panels that are almost 100% thermally efficient.
Glass Fiber Reinforced Concrete Cladding Panels
Authors: Knowles ES
Published: March 2009

Glass fiber reinforced concrete (GFRC) panels are a lightweight cladding panel. They are used as facia panels for building structures. GFRC panels support their own vertical load and the vertical load from the glazing system.

The GFRC skin is reinforced (stiffened) by a steel stud frame. The stud frame is attached to the GFRC skin by means of flex anchors.

The gravity load of the GFRC skin is transferred to the stud frame by two methods: (1) flex anchors only and (2) gravity anchors in addition to flex anchors. The stud frame is attached to the structure, and the loads of the panel are carried through the stud frame to the panel connection points on the structure.
Reflections on the Development of Test Methods for Advanced Composites
Authors: Whitney JM
Published: March 2009

The importance of analyzing failure modes in conjunction with the development of test methods is discussed. Illustrations are chosen from four classic areas of interest: flex testing of unidirectional composites exposed to moisture, the short beam shear test, the edge delamination test, and two configurations of the Illinois Institute of Technology Research Institute (IITRI) compression test method. In each of these tests, the failure mode is an important consideration in accepting and interpreting the resulting data.
Open Hole and Postimpact Compressive Fatigue of Stitched and Unstitched Carbon-Epoxy Composites
Authors: Portanova MA , Poe CC , Whitcomb JD
Published: March 2009

This investigation evaluates the fatigue performance of a stitched uniweave fabric composite and a toughened tape composite. It also addresses the effects of stitching on compression fatigue life. Postimpact compressive fatigue and open hole fatigue tests were run on an AS4/3501-6 uniweave with stitching and a toughened IM7/8551-7 tape without stitching. Stitching was found to increase the thickness and, consequently, the weight of the composite material. The two materials were compared on an equal carbon content basis as well as on an equal weight basis. The excess thickness in the stitched uniweave composite was responsible for the lower fatigue life, on an equal carbon basis, compared to the toughened resin tape composite. Comparison of fatigue lives on an equal carbon fiber areal weight basis indicated that puncture or crimp damage from stitching has very little effect on compression failure. Postimpact fatigue tests showed that, although the damage area in the stitched uniweave composite was twice that of the toughened tape composite, the fatigue lives of the stitched composite were significantly longer than those of the toughened composite. Thus, it appears that the increase in thickness from stitching is much more of a penalty than crimped fibers or puncture damage from stitching.
Thermomechanical Testing of High-Temperature Composites: Thermomechanical Fatigue (TMF) Behavior of SiC(SCS-6)/Ti-15-3
Authors: Castelli MG , Bartolotta P , Ellis JR
Published: March 2009

Thermomechanical testing techniques recently developed for monolithic structural alloys were successfully extended to continuous fiber-reinforced composite materials in plate form. The success of this adaptation was verified on a model metal-matrix composite (MMC) material, namely SiC(SCS-6)/Ti-15V-3Cr-3Al-3Sn. The effects of heating system type and specimen preparation are also addressed. Cyclic lives determined under full thermomechanical conditions were shown to be significantly reduced from those obtained under comparable isothermal and in-phase bithermal conditions. Fractography and metallography studies of specimens subjected to isothermal, out-of-phase, and in-phase conditions revealed distinct differences in damage/failure modes. Isothermal metallography revealed extensive matrix cracking associated with fiber damage throughout the entire cross section of the specimen. Out-of-phase metallography revealed extensive matrix damage associated with minimal (if any) fiber cracking. However, the damage was located exclusively at surface and near-surface locations. In-phase conditions produced extensive fiber cracking throughout the entire cross section, associated with minimal (if any) matrix damage.
Hot/Wet Testing of Celion 3000/PMR-15 Coupon Specimens
Authors: Kinman EB
Published: March 2009

Mechanical properties testing of a graphite/polyimide (Celion 3000/PMR-15) fabric was performed in primarily four environments: -54°C (-65°F) as fabricated, room temperature as fabricated, 204°C (400°F) after moisture conditioning, and 316°C (600°F) after moisture conditioning. Specimens that had been moisture conditioned before testing were considered “wet.” To accomplish this hot/wet testing, special strain-gaging techniques were developed to improve strain measurement in the severe environments. Heating techniques were also developed to heat the specimens quickly to retain sufficient moisture at the time of failure. This test program demonstrated that moisture, temperature, and specimen geometry can each dramatically affect test results. The program also demonstrated the need for industry standards for hightemperature testing and moisture level requirements. Without such standards, data thought to be hot/wet test data may actually be hot/dry test data. Such a discrepancy appears to have significant ramifications according to this program's test results.
A Scientific Approach to Composite Laminate Strength Prediction
Authors: Hart-Smith LJ
Published: March 2009

A new method of predicting the strength of cross-plied fibrous composite laminates is based on expressing the classical maximum-shear-stress failure criterion for ductile metals in terms of strains. Starting with such a formulation for classical isotropic materials, the derivation is extended to orthotropic materials having a longitudinal axis of symmetry to represent the fibers in a unidirectional composite lamina. The only modification needed to represent those same fibers with properties normalized to the lamina rather than fiber is a change in axial modulus. A mirror image is added to the strain-based “lamina” failure criterion for fiber-dominated failures to reflect the cutoffs caused by the presence of orthogonal fibers. It is found that the combined failure envelope is now almost identical with the well-known maximum-strain failure model in the tension-tension and compression-compression quadrants, but is truncated in the shear quadrants. The new predictions refer only to fiber-dominated failures of efficient, well-interspersed, laminate patterns. This restriction permits the laminate strengths to be defined by only half as many material properties as were used in the past. Premature matrix failures are excluded from consideration for conventional fiber/polymer composites. The new failure envelope is compared with published biaxial test data.
Deformation and Failure of Longitudinally Loaded Brittle-Matrix Composites
Authors: Lee J-W , Daniel IM
Published: March 2009

A modified shear lag analysis is proposed for a unidirectional brittle-matrix composite under longitudinal tensile loading. It is assumed that the matrix, having a lower ultimate strain than the fiber, fails by transverse cracking. The analysis was conducted for a cylindrical element of matrix with a single fiber with various boundary conditions. Closed form solutions were obtained for stress distributions in the matrix and fiber as a function of applied stress and constituent properties in each case. In addition, the matrix crack density, debonded length, and reduced axial stiffness of the damaged model of two matrix cracks were obtained in closed form as a function of applied stress and constituent properties. The shear lag parameter is only a function of geometry and shear moduli of the constituents. The basic assumptions used in the analysis are that the shear stress in the fiber varies linearly and in the matrix varies according to an inverse function of a second-degree polynomial in the radial direction. The analysis can take into account residual stresses in the material.

The predicted stress-strain and stress versus matrix crack density curves were compared with experimental results for a silicon carbide/glass ceramic (SiC/CAS) composite subjected to monotonic loading. The predictions in general are in good qualitative agreement with experimental results. In particular, the saturation crack density measured is very close to the predicted value.
Analysis and Test Techniques for Composite Structures Subjected to Out-of-Plane Loads
Authors: Paul PC , Saff CR , Sanger KB , Mahler MA , Kan H-P , Kautz EF
Published: March 2009

The ability to predict stresses and failures caused by out-of-plane loads has gained importance as airframe manufacturers begin to use integral (co-cured or bonded) composite structures to minimize weight and maximize performance. Rapid and accurate analysis methods are needed to reduce the amount of testing required to ensure confidence in integral composite structures. Recently, simple two-dimensional analysis methods were developed to predict the out-of-plane failure strengths of composite airframe structures. These analyses were primarily derived to address induced stresses in laminate corner radii, direct stresses as a result of fuel pressure loads, induced stresses as a result of panel buckling, and induced stresses as a result of stiffener runouts or other load path changes.

The development and verification of analyses for out-of-plane failures have shown the need for out-of-plane material properties and strength allowables that are not traditionally determined for composite laminates. Accurate stress and failure predictions depend heavily on these experimentally determined values. The test methods and experience gained in this program indicate the need for new techniques to determine the interlaminar properties required for accurate stress and failure predictions. Test techniques are suggested for determining some of the values necessary for these predictions.