bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of Hydrated Fly Ash as a Flexible Base Material
Authors: Senadheera Sanjaya P. , Jayawickrama Priyantha W. , Rana A. S. M. Ashek
Published: August 2018

Common uses for fly ash, such as soil stabilization and cement replacement, account for less than 20 percent of the fly ash produced in the United States. Therefore, finding other bulk uses for fly ash is important. One such potential application is hydrated fly ash as a base material. The Texas Department of Transportation (TxDOT) is working to produce specifications to incorporate hydrated fly ash as a flexible base material. High-calcium Class C fly ash has a self-hydrating capability in the presence of moisture. Class C fly ash produced from coal power plants using lignite and subbituminous coal is mixed with water, dumped in large pits, and left to hydrate for a period of 3 to 6 weeks. The result is a hard, homogeneous mass of hydrated fly ash that can be mined to produce a construction aggregate much like limestone. TxDOT has used this material on several test projects. It has a desirable compressive strength, but in some instances its adhesion to seal coats has been a problem. Laboratory studies indicate that hydration water content has a significant influence on its strength. Microscopic investigations on hydrated Class C fly ash indicate that the hydration products may depend on the curing conditions. Hydrated Class C fly ash has a potential as a flexible base material provided that the curing process is carefully managed.
Sulfate-Bearing Soils: Problems with Calcium-Based Stabilizers
Authors: Kota Prakash B. V. S. , Hazlett Darren , Perrin Les
Published: August 2018

Several roads, airfield pavements, and parking lots in Texas and other states in the western United States have suffered severe pavement damage due to expansive minerals formed from the reactions of calcium-based materials used to stabilize sulfate-bearing soils. Remediation costs for projects that suffer sulfate-induced heave damage are very high, because often the entire pavement may have to be removed and reconstructed. Observations from several projects are described to illustrate the phenomenon of sulfate-induced heave and the current methods to predict the problem. Two recent projects described include one using cement as a replacement for lime and a second using a double application of lime. The discussion also includes limitations of the present methods for determining the so-called soluble sulfate levels in soils. The practice of a double application of lime and several other alternative methods and their limitations are discussed. Although research has clearly identified the expansive minerals as being calcium bearing, no published investigations of non-calcium-based stabilizers that could effectively stabilize sulfate-bearing soils were found.
Phosphogypsum as a Component of Flowable Fill
Authors: Gandham S. , Seals R. K. , Foxworthy Paul T.
Published: August 2018

Phosphogypsum (PG) is a by-product of the production of phosphoric acid, a key ingredient in the manufacture of fertilizers. Large amounts of PG have been stockpiled in Florida, Louisiana, and Texas, as well as other parts of the world. The means of using and disposing of this by-product with minimal environmental impact have been developed in research spanning almost 20 years. A study was conducted to investigate PG as a potential component of flowable fill materials along with Class C fly ash. Both Class F and Class C fly ashes have been used successfully to provide flowability and strength characteristics to flowable fill. A number of mix proportions of PG and fly ash were tested for flowability, time of setting, and unconfined compressive strength in a preliminary test series. Using the results of these preliminary tests, three final design mixtures were developed. These mixtures were then subjected to different physical and engineering property tests, including flowability, time of setting, unconfined compressive strength, flexural strength, dimensional stability, and permeability. Tests were also conducted to evaluate the environmental effects of the individual mixtures. These tests included the toxicity characteristic leaching procedure and radon emission testing. The results of this study indicated that PG can be used successfully as a component of flowable fill.
Load and Resistance Factor Design of Driven Piles
Authors: Goble George G.
Published: August 2018

A load and resistance factor design (LRFD) bridge specification has been accepted by the AASHTO Bridge Committee. This design approach is now being implemented for highway bridges in the United States, including the design of driven pile foundations. To test the new specification's practicality and usefulness, an example problem has been solved using it. In the example, a pipe pile was designed to be driven into a granular soil to support a bridge column subjected to a factored axial compression load of 10 MN. The nominal strength selected for the pile was 1.58 MN with an estimated length of 25 m. Since the resistance factors are defined by the specified quality control procedures, the number of piles required in the foundation also depends on the quality control. In this example, the number of piles required varied from 15 to 8 with improved quality control, for a savings of almost half of the piles. This example indicated that the new AASHTO LRFD specification for driven pile design can be used effectively to produce a more rationally designed foundation. Some modifications should be made to include additional serviceability limit states, and additional research may indicate that changes should be made in some of the resistance factors.
Moisture Accumulation and Pore Water Pressures at Base of Pavements
Authors: Eigenbrod K. D. , Kennepohl G. J. A.
Published: August 2018

A unique mechanism based on extensive field and laboratory studies is presented to account for certain premature failures of flexible pavements in cold areas like those in Scandinavia and in northern parts of Canada and the United States. Water condensing at the interface between pavement and granular base accumulates at subzero temperatures resulting in excess moisture in this zone. During the thaw period of the uppermost base layer, the excess water in the aggregate is trapped between impervious layers of frozen ground to the sides and below as well as an impervious layer of asphalt pavement above. Because of this containment, high pore water pressures can occur, leading to loss in shear strength of the base material and thus to failure of the pavement structure itself. It was found that under special conditions, excess moisture can accumulate in granular base with a silt content greater than 20 percent and very high pore water pressures can develop during initial thaw at the pavement-soil interface. With silt contents of less than 2 percent, excess pore water pressures can be avoided during thaw. It was also shown that when a clean open gravel is placed below the pavement on top of a silty base material, moisture accumulation near the pavement-base interface can be prevented, and thus also the development of high pore water pressures.
Shrinkage and Suction Properties of Pledger-Roebuck Alluvial Clay
Authors: Clarke Christopher R. , Nevels James B.
Published: August 2018

The behavior of clays on drying leads to undesirable consequences with regard to high-plasticity clay subgrades and embankments. The soil suction and shrinkage properties of an alluvial clay soil were characterized. The CLOD shrinkage test procedure was found to be very effective in developing the experimental shrinkage curves. At the McCurtain County, Oklahoma, site, three types of samples were analyzed: undisturbed samples taken with thin-walled tubes, hand-augured soil chunks, and compacted standard Proctor samples. Results of the CLOD shrinkage tests for this site indicate consistent results regardless of the sample type and well-defined normal and residual segments of the shrinkage curve. Shrinkage limits estimated from the CLOD shrinkage curves were comparable with shrinkage limit test values. The effect of overconsolidation is reflected in the characteristic curves for different depths in the soil profile. A large suction range was calculated at the general air entry moisture content.
Influence of Aggregate Properties on Performance of Heavy-Duty Hot-Mix Asphalt Pavements
Authors: Ahlrich Randy C.
Published: August 2018

Because approximately 85 percent of the total volume of hot-mix asphalt (HMA) mixtures consists of aggregates, the performance of HMA mixtures is greatly affected and influenced by properties of the aggregate blend. The angularity, shape, and texture of the aggregate particles have a significant effect on the performance of HMA mixtures by controlling the mixture's strength and rutting resistance. Rough, angular aggregates have been proved to produce higher-quality HMA pavements than smooth, round aggregates. Current aggregate tests are primarily based on experience and empirical characterization tests. A study was conducted to evaluate test methods that could be used to characterize aggregate properties that are related to HMA rutting potential of heavy-duty pavements. Specifically, FAA aggregate properties and aircraft loading conditions were addressed. The aggregate particles were characterized with the particle index (ASTM D3398), uncompacted void content for fine aggregate (ASTM C1252), modified ASTM C1252 for coarse aggregate, and unit weight and voids in aggregate (ASTM C29). The HMA mixtures were evaluated for rutting potential using the confined repeated load deformation (dynamic creep) test. The laboratory investigation indicated that the tests for particle index, uncom-pacted void content for fine and coarse aggregates, and unit weight and voids in aggregate could be used to characterize the shape and texture of aggregate particles. The study also indicated that the confined creep test could differentiate between HMA mixtures with different aggregate properties in terms of their rutting potential.
Aggregate Characteristics Governing Performance of Seal Coat Highway Overlays
Authors: Abdul-Malak Mohamed-Asem U. , Fowler David W. , Constantino Cesar A.
Published: August 2018

A study was undertaken to identify the engineering properties of aggregates that explain the variability in the frictional performance of seal coat highway overlays. The frictional performance data of 72 test sections and section replicates collected over a period of 8 years were used in the formulation of statistical models that incorporate the significant variables. The effects of traffic, construction, and environmental variables were also considered. Formulated models were of two types: general and individual. The former type attempts to describe frictional performance using the observations collected on all aggregate materials used. The latter describes the performance of individual aggregate groups. Laboratory properties found to be significant included the polish value, impact and abrasion, and soundness properties. The coating of aggregate particles, gradation, and construction placing rates of aggregate and asphalt were also shown to be significant in explaining performance variability. The influence of traffic and region was found to be interactive with the type and properties of aggregates. The formulated models can be used as a tool for predicting the frictional performance of seal coat aggregates, thus providing a better means for the proper selection of aggregates and for the planning of future seal coat construction projects.
Evaluation of Laboratory Procedures for Aggregate Polish Test
Authors: Won Moon C. , Fu Chien N.
Published: August 2018

Years of polish value testing at the Texas Department of Transportation have revealed that the test results are highly sensitive not only to aggregate textures, but also to other factors, resulting in large variabilities in test results. For the test results to be purely indicative of aggregate textures, other factors need to be tightly controlled. The primary objectives of the study were to address those factors and to improve the testing procedures to minimize variability. All possible factors were identified and pilot tests were conducted to eliminate factors with nonsignificant effects. Detailed tests were conducted to evaluate the effects of the remaining factors. Among the factors investigated that were found to be significant in this study were curvature of the coupons, the length of the slider contact path, slider rubber characteristics, aggregate particle arrangement, normal slider load, and aggregate selection technique. To minimize the variability, the following emphasis is recommended: (a) measure the coupon curvature before testing, (b) control the length of the slider contact path, (c) maintain the normal slider load between 2500 and 2600 g, and (d) select aggregate particles by splitting, rather than handpicking, for mineralogically heterogeneous aggregates.
Coarse Aggregate Effects on Elastic Moduli of Concrete
Authors: Choubane Bouzid , Wu Chung-Lung , Tia Mang
Published: August 2018

The results of a laboratory testing program carried out to investigate the effect of coarse aggregate types on the elastic modulus of typical pavement concretes are presented. The elastic modulus was determined in both flexure and compression using static and dynamic means. Three different mixes, made using three different aggregates, were compared. The water-cement ratio was kept at 0.53 throughout the test program. The results showed that within the tested range, the aggregate type significantly affected the studied properties of concrete. Calera aggregate (a dense limestone) with its rough-textured surface and angular shape produced a concrete with higher strength and stiffness than those of concretes made with Brooksville aggregate (a porous limestone) and river gravel. In addition, the measured dynamic modulus in compression was significantly different from that in flexure. Also, in flexure, the dynamic modulus was higher than the static modulus by an average of 23 percent, whereas in compression, the dynamic modulus appeared to be in the same range as the static modulus. The change in frequency from 1 to 7 Hz did not have a significant influence on the dynamic modulus.
Evaluation of Frost Resistance Tests for Carbonate Aggregates
Authors: Koubaa Amir , Snyder Mark B.
Published: August 2018

D-cracking is a progressive distress associated primarily with the use of coarse aggregates that deteriorate when they are critically saturated and subjected to repeated cycles of freezing and thawing. The present study was undertaken to consider better acceptance criteria for concrete aggregates and to allow for the use of more local Minnesota aggregates through selected aggregate beneficiation techniques. Condition surveys of concrete highway pavements were performed to document the field freeze-thaw performance of selected aggregate sources representing a range of frost resistance. Cores were obtained from these sections for laboratory testing and evaluation, and coarse aggregates were obtained from the original sources for use in performing environmental simulation tests [i.e., variations of ASTM C666 and the Virginia Polytechnic Institute (VPI) single-cycle slow-freeze test] and correlative tests (i.e., absorption and bulk specific gravity, Portland Cement Association absorption and adsorption tests, Iowa pore index test, acid insoluble residue test, X-ray diffraction analysis, X-ray fluorescence analysis, thermogravimetric analysis, and the Washington hydraulic fracture test). The tests that provided the best correlation with field performance included a modification of ASTM C666 Procedure B (specimens prepared with salt-treated aggregates), the VPI single-cycle slow-freeze test, and the Washington hydraulic fracture test. Other test procedures were correlated with field performance to lesser extents. It was noted that petrographic examination of pavement cores can help to distinguish between D-cracking and other conditions that can produce distresses with similar appearances (e.g., distresses caused by secondary mineralization, embedded shale, poor mix design, and alkali-aggregate reaction).
Testing Methodology for Resilient Modulus of Base Materials
Authors: Nazarian S. , Pezo R. , Melarkode S. , Picornell M.
Published: August 2018

Resilient moduli of base and subgrade materials are important parameters in the new pavement design method adopted by AASHTO and many state agencies. Several testing protocols for determining the resilient moduli of subgrade soils have been proposed and evaluated in the technical literature. Unfortunately, less effort has been focused on developing protocols appropriate for base materials. The main objective was to describe a resilient modulus testing procedure that has been developed for the Texas Department of Transportation. The proposed procedure contains the main steps of the AASHTO T294-92 procedure, with several exceptions. Namely, the loading sequence of the T294-92 procedure was modified to avoid subjecting the specimens to high devi-atoric stresses at low confining pressures. The conditioning cycles were replaced by a procedure in which the specimen was grouted to the platens to minimize disturbance to the specimen during stage testing. The effects of end restraint on the vertical strains were minimized by measuring the deformations of the middle one-third of the specimen. To avoid well-known problems with mounting linear variable differential transformers on the specimen, noncontact probes were used to measure deformations. To maximize the amount of information gained, the lateral deformations were also measured with noncontact probes to determine the Poisson's ratio. On the basis of tests on nine synthetic specimens with known properties and nine different base materials from different parts of Texas, it was concluded that the proposed methodology yields accurate and repeatable results.
Influences on Permanent Deformation Behavior of Unbound Granular Materials
Authors: Lekarp Fredrick , Richardson Ian Reginald , Dawson Andrew
Published: August 2018

The results of a research program aimed at characterizing the permanent deformation behaviors of different types of unbound aggregates under repeated loading are summarized. Tests were performed in a triaxial or hollow-cylinder apparatus, depending on the grading of the materials. The scope of the research was to assess the relationship between total permanent axial strain and both the number of load applications and the stress level. The test results were used to verify a model recently developed in France in which attempts are made to predict the long-term behaviors of granular materials. The French model is examined with particular reference to its validity on the effect of stress level on permanent deformation of unbound granular materials. The results of the study indicate that the French model is generally successful in predicting the permanent strain for a given number of load applications. For one of the materials, however, the model did not seem to fit the data well. The French model also suggests that the variation in total permanent strain with stress level is related to the static failure line and could be determined by comparing the maximum shear stress ratio with the slope of the estimated failure line. This is discussed and shown to be questionable because it results in either unreasonable failure parameters or a very low level of correlation with the observations. An attempt was made to modify the French model, but that also proved to be unsuccessful. The concept of relating the permanent deformation behavior to the static failure condition of the material is therefore questioned.
Shakedown of Subgrade Soil under Repeated Loading
Authors: Radovsky Boris S. , Murashina Natalie V.
Published: August 2018

A new model for predicting the performance of a subgrade during soil compaction by rollers as a function of contact pressure and the strength characteristics of soils was developed. The model can be used to develop improved methods of pavement design, considering that the accumulation of plastic strains may continue under additional load repetitions or may cease to increase with time, indicating adaptation or shakedown conditions. To develop the mechanistic model of a subgrade, the homogeneous semi-infinite elastoplastic half-space under repeated loading was considered. By using a Mohr-Coulomb failure criterion, the boundary loads for which shakedown conditions or the steady state will be attained were determined. The residual horizontal normal stresses in the half-space were calculated and were shown to be in agreement with the measured distribution with depth. The theoretical and experimental results as they apply to soil compaction and pavement design problems are discussed. The required compaction contact pressure and the thickness of the compacted zone are estimated. The structural pavement design approach, considering residual normal stresses in a subgrade, is presented.
Lincoln Avenue Reclaimed Asphalt Pavement Base Project
Authors: Garg Navneet , Thompson Marshall R.
Published: August 2018

Pavement rehabilitation and reconstruction operations have generated large supplies of reclaimed asphalt concrete (RAC). In Illinois crushed RAC generally called recycled asphalt pavement (RAP) supplies are not 100 percent recycled into hot-mix asphalt concrete production. RAP acceptance as a pavement base material has been limited because of the lack of laboratory testing information, information on structural behavior, and field performance data. Limited preliminary laboratory testing and isolated commercial and local road agency paving experience in Illinois indicate that RAP has significant potential as a pavement base. RAP base potential was evaluated by constructing the Lincoln Avenue (Urbana, Illinois) demonstration project during late September and early October 1993. The pavement section is a 305-mm (12-in.) lime-modified, fine-grained subgrade, a 203-mm (8-in.) compacted RAP base, and a 76-mm (3-in.) dense-graded asphalt concrete surface course. The construction, structural response, and performance of the Lincoln Avenue RAP base project were monitored as part of a cooperative study (Illinois Department of Transportation, City of Urbana, and University of Illinois). The accumulated construction, field testing and evaluation, and laboratory testing data and information are summarized. The field construction experience, field control test data, laboratory testing results, falling weight deflectometer results, and Lincoln Avenue performance data indicate that RAP can successfully be used as a conventional flexible pavement base material. The performance of the Lincoln Avenue RAP base pavement (to date) is comparable with that of a crushed stone base.
Measurement of Soil Resilient Properties Using Noncontacting Proximity Sensors
Authors: Maher M. H. , Papp W. J. , Gucunski N.
Published: August 2018

The utility of noncontacting proximity sensors for the measurement of small strains in resilient modulus tests is evaluated. The proximity sensor measurements of resilient modulus were compared with those obtained from linear variable differential transformers. The important issue of granular soil sample preparation and its effect on the magnitude of resilient modulus was evaluated. Two methods were proposed to facilitate sample preparation and to provide good contact between the soil and the loading platen. The effect of conditioning sequence on sample integrity was also investigated for the two proposed methods of compaction. In addition to the experimental program, a number of constitutive models, used for prediction of resilient modulus of granular soils, were examined; and model predictions were compared with the test data.
Radial Strain Measurements in Resonant Column and Torsional Shear Tests
Authors: Gupta Ayushman , Shao Lisheng , Borden Roy H.
Published: August 2018

During resonant column and torsional shear tests using a Stokoe device, conventionally only the change in height of the specimen is measured. To obtain the change in diameter of the specimen, a relationship between radial strain and longitudinal strain is assumed. In this study, the Stokoe device was modified to enable the measurement of change in diameter of the specimen along with the change in its height during resonant column and torsional shear tests. The diameter change measurement system comprises three proximity probes, coaxial cables, proximitor conditioners, and DC power supply. The probes (7.9 mm diameter) are capable of making noncontact displacement measurements with a resolution of 0.025 mm using a metallic target. These probes are fixed along the circumference of the outer chamber at equal 120 degree spacing. The vertical location of these probes is such that they correspond to the midheight of the specimen. Each probe is mounted on a micrometer to enable accurate adjustment of the probe. This system gives a linear output for a distance range of 0.38 to 2 mm between the probe tip and the metallic target. During the tests, the targets (circular copper foils 26 mm in diameter) are fixed on the soil specimen, and output voltage from each of the three proximity probes is recorded directly by a computer. The average readings of the three probes are used to calculate the change in diameter of the specimen. This paper will present the results of tests on seven residual soil specimens.
Characterization of Granular Systems by Digital Signal Processing of Low Strain Wave Response
Authors: Romero Salome , Pamukcu Sibel
Published: August 2018

The characterization and quality assessment of composite materials, particularly those constructed of residual materials such as slags, ashes, and crumb rubber, are difficult because of chemical and physical inhomogeneity and inconsistency at the time of their production. The characterization of granular systems, constructed of a mixture of geological and residual materials, may provide inconclusive information when tested by existing methods. The proposed nondestructive evaluation uses low-strain, low-frequency dynamic excitation as a means to better evaluate such materials. The applied excitation results in a sample response characterized by wave patterns. The wave pattern response is analyzed by digital signal processing and an artificial neural networks (ANN) system to facilitate characterization of the material. Dynamic excitation of representative samples was accomplished using a longitudinal-torsional resonant column. Nondestructive testing was conducted at low strain levels applying a torsional oscillatory motion. The resulting sample response wave forms were recorded. The shear modulus values obtained at the resonant frequency of each sample were used to train an ANN system to characterize sample wave responses measured at random frequencies. The recorded sample response wave forms were analyzed to identify the embedded dominant frequencies, which were unique signatures of the tested materials. These signatures were then submitted to the previously trained ANN to predict the material shear modulus. The samples tested were composed of dry Ottawa sand (0.85 to 0.6 mm), Ottawa sand and crumb rubber modifier, and soda-lime spheres compacted at various densities and tested under different confining pressures. Distinctive patterns, unique to the granular sample composition, were obtained. These are termed the signature patterns. A fast Fourier transform algorithm was used to convert collected data to the frequency domain. ANN analysis was applied to enhance pattern recognition and characterize the samples according to their shear moduli
Displacement during Progressive Failure Estimated from Microseismic Activity
Authors: Dai Shongtao , Labuz Joseph F.
Published: August 2018

An acoustic emission (AE) system with eight channels of recording was used to monitor progressive failure of a weak sandstone in plane-strain compression. The recorded waveforms were analyzed for event location and source mechanism. In the quantitative assessment of acoustic emission, a localized event is idealized as a point source of displacement discontinuity. The point source can be modeled as the combination of body forces that would produce the same elastic wave-field as the defect. The assumed condition of self-equilibrium requires each body force to be paired with an equal and opposite force to form a dipole of forces called a seismic moment tensor. In this study, the seismic moment tensor of each event was evaluated and the source mechanisms were determined through a calibration of the sensors, where the first peak of the signal recorded by an AE sensor was assumed to correspond to the first peak of the normal displacement at the sensor. The microseismic events generated during progressive failure of the sandstone were characterized as being caused predominantly by shear slip. Within a certain portion of the post-peak regime where 110 events were captured, the slip displacement was 0.0217 mm from the seismic estimate and 0.0335 mm from the global measurement. This suggests that the acoustic emission technique could be used to estimate displacement along a localized zone of failure where microseismic activity takes place.
Soil Particle Size Analysis Using X-Ray Absorption
Authors: Vitton Stanley J. , Nesbitt Carl C. , Sadler Leon Y.
Published: August 2018

The hydrometer method is the standard method of grain size analysis used in geotechnical engineering. Although the hydrometer method provides accurate grain size distributions and is relatively easy to conduct, it takes a minimum of 2 days to complete and is subject to operator error. In studies where small-magnitude changes or more rapid results are required, an alternative method to hydrometer testing is to use an automated particle size analysis instrument employing X-ray absorption. This technique passes a finely collated X-ray beam through a suspension of settling particle in a fluid. Because the intensity of the X-ray is directly related to the percentage mass of soil in a suspension, Stokes' law can be used to calculate the grain size distribution of a soil assuming an equivalent particle diameter for the soil grains. X-ray absorption has been found to produce accurate grain size distributions in the 75 μm to 1 μm size range when sample preparation adheres to AASHTO T88-90 specifications and suspension concentrations are approximately 2 percent by volume. Testing for particles sizes down to 1 μm takes approximately 20 min per sample. Technical concerns remaining involve obtaining representative samples of the soil in the 75 μm, to 1 μm size range suspension for testing. One method being evaluated is injection flow analysis, which is an inexpensive method of obtaining representative samples used with a variety of inorganic, industrial, and environmental materials in which direct sampling of fluid is required.
Instrumentation for Laterally Loaded Model Piles
Authors: Caliendo Joseph A. , Anderson Loren R. , Winward Renέ F. , Dapp Steve , Musser Samuel C.
Published: August 2018

Utah State University is involved with a research project funded by the Utah Department of Transportation and the Mountain Plains Consortium. The reaction of model piles subjected to lateral loading is the subject of ongoing research. The measured response of laterally loaded model pile is compared with predicted results. The model piles are 1524 mm (60 in.) long with approximately 1219.2 mm (48 in.) embedded in a soft clay soil. The piles consist of 1-in. Schedule 40, 33.40 mm (1.315 in.) OD aluminum tubes, with a wall thickness of 8.407 mm (0.331 in.). To measure the pile response to the lateral loads, each pile is instrumented with 14 pairs of foil strain gauges mounted at 91.875mm (3.75-in.) spacings. The gauge pairs were mounted on the inside wall of the seamless tube. A special installation tool was designed and fabricated at Utah State University for this purpose. A wedge-scissors device was used to mount the gauges to the inside wall. The strain gauges (CEA-13-250UW-120) are each wired into a ¼ Wheatstone bridge circuit with a dummy temperature gauge. The 28 two-wire leads along with linear variable deformation transform leads are routed through a multiplexer to a 21X data logger. The pile calibration and load test results are discussed. The measured moments compared favorably with those predicted by LPGSTAN and COM624P.
Behavior of Shaft-Sand Interface from Local Measurements
Authors: Sakhawy Nagwa R. El , Edil Tuncer B.
Published: August 2018

The load-displacement response of axially loaded structural inclusions in soil, which transfer the load to the soil along their shafts, is of growing interest in geotechnical engineering. The load-displacement response of a shaft interface is characterized by nonlinear and inelastic behavior. Surface roughness of the inclusion and stresses and deformation characteristics (stress-strain response, dilation, or contraction) of the soil element surrounding the inclusion are significant aspects of the interface mechanism. Localized shear displacement at the soil-shaft interface necessitates use of a constitutive model specifically developed for the interface. To verify theoretical models and modify and improve them, laboratory tests are performed. In recent years, there has been increasing emphasis in measurement of small-magnitude local strains to define stiffness at low strains similar to those encountered in the field in stress-path testing. To verify the theoretical model of the shaft-soil interface, a special test rig was developed that uses a cylindrical soil specimen with an inclusion in its center. The specimen represents a soil element surrounding a structural inclusion. The shaft-sand interface was investigated by small-magnitude local measurement of interface strains and thereby interface stresses and displacements during axial loading of the inclusion. The results are compared with those inferred from global measurements of interface variables. The advantages of the small-magnitude local strain measurements in determining the interface model parameters are presented. The use of the measured quantities in an elasto-plastic interface model is demonstrated by capturing the effects of confining stresses and boundary conditions of the soil specimen surrounding an axially loaded inclusion as well as the surface roughness of the inclusion.
Small- and High-Strain Measurements of in Situ Soil Properties Using the Seismic Cone Penetrometer
Authors: Burns Susan E. , ayne Paul W. M
Published: August 2018

Seismic cone penetration tests provide an economical and expedient means of assessing small-strain properties (low-amplitude shear modulus, GMAX) and large-strain behavior (shear strength, τmax) of soil deposits from a single sounding. That measurements are taken at complete opposite ends of the strain spectrum permits development of the entire stress-strain-strength representation of soil layers with depth. A modified hyperbola is shown to be appropriate in a modulus degradation scheme for application to static monotonic loading of soils. Also, a global correlation of mass density (ρ) with shear wave velocity (Vs) for all types of geomaterials is presented, which facilitates the calculation of GMAX = ρVs2.
Aesthetic Design for Akashi Kaikyo Bridge
Authors: Fujikawa Hiroyuki , Kishimoto Yoshitaka , Nasu Seigo
Published: August 2018

The Akashi Kaikyo Bridge, part of the Honshu-Shikoku bridge project, is a suspension bridge with a center span of 1990 m. When completed in the spring of 1998, it will be the longest suspension bridge in the world. The bridge is expected to be an attractive addition to the highly urbanized area of Kobe. Therefore, the aesthetic design needed careful consideration. A suspension bridge consists of horizontal stiffening trusses, gently curving main cables, a pair of vertical towers, and anchorages. Aerodynamic stability is important in its structural design. For the Akashi Kaikyo Bridge, five types of towers were compared using 1:500 scale models. Given the fabrication and erection work for the structure, a basic truss-type design was chosen. Structural concerns dictated the shape of the stiffening trusses and the main cables. In the selection of color, the surrounding environment was studied. Further research using computer graphics and scale models and site appearance tests was carried out. Greenish-gray was finally chosen from among 30 candidate colors. To lessen the impact of the immense concrete anchorages, light and shadow effects were utilized, and vertical and horizontal indentation was adopted on the surface. The result will be structural beauty and optimum harmony of the bridge with its surroundings.
Washington, a City of Beautiful Bridges: Paradigms to Emulate
Authors: Myer Donald B. , Lichtenstein Abba
Published: August 2018

Washington enjoys a unique international focus as a city planned for beauty. It incorporates a monumental baroque plan superimposed on a topography bordered by rivers and hills. Marble monuments and governmental structures carefully range a tree-lined formal landscape in the city's core. Fiercely protected height limits assure as a centerpiece the Capitol dome and monument-lined Mall. Conscious planning and architectural aesthetic effort have resulted in bridges that are an integral part of the nation's capital in 1996. Its structures reveal history, engineering excellence, and undeniable aesthetic import. Six bridges defend this thesis: Arlington Memorial Bridge, sculpture and arches formally carrying the Mall across the Potomac River; Francis Scott Key Bridge, high concrete arches whose silhouette are a major feature of the Potomac Palisades; William Howard Taft Bridge, engineering tour de force (largest unreinforced concrete structure in the world), carrying one of the city's main avenues across Rock Creek Park on multiple arches; Dumbarton Bridge, integrating architecture and sculpture in the parkscape while solving a street misalignment across Rock Creek Park; Connecticut Avenue Bridge over Klingle Valley, Art Deco steel-arched structure; and John Phillip Sousa Bridge, early 20th century axial connection of Pennsylvania Avenue, S.E., over the Anacostia River. Steel, concrete, arches, and trusses make up the aesthetic components of these structures, each in a unique visual context.
Aesthetic Design of Haneda Sky Arch
Authors: Shiomi Masaki , Nakamura Yoshio
Published: August 2018

The Haneda Sky Arch, located in front of the new passenger terminal of Tokyo International Airport (Haneda Airport), consists of a pair of steel-cable-stayed girder superstructures supported by a main arch pylon. In the construction of the new terminal, two design concepts were given priority, recognizability and architectural harmony. To help achieve such a goal, this unique arch bridge was designed to become the symbol for the newly enlarged airport. The three-dimensional arrangement of the cables lends an elegant grace to the Sky Arch when viewed from various vantage points, and its unique structural form makes it readily identifiable. The Sky Arch integrates numerous interesting features, including (a) slender main girder superstructures that suggest the lines of an airplane's wing, (b) interesting stainless steel details, (c) smooth cold-worked curves on arch rib corners, and (d) field-welded splices to minimize the use of mechanical fasteners. These features are in complete harmony with the architecture of the other facilities. Fulfilling both functional and decorative purposes, the remarkable design of the Haneda Sky Arch enhances the overall attractiveness of the new airport facilities.
Aesthetic Guidelines for Older Bridges
Authors: DeMond Gregory F.
Published: August 2018

As the nation's infrastructure ages, many older bridges face rehabilitation or replacement. Many of these structures have historical significance, and others have become community landmarks. Distinctive metal truss bridges and various concrete arch bridges still grace the nation's highways, but they are rapidly disappearing because they cannot meet the safety requirements of modern highway usage. As a result, where roadway and river crossings were once defined by expressive, sometimes monumental spans that made the passage truly an experience, travelers now speed efficiently over unobtrusive structures, often unaware they were ever on a bridge. Engineers are becoming increasingly aware of the undercurrent of public sentiment for preserving these links to the past. Opposition to replacement can delay needed improvements for months and even years, but it can be overcome by incorporating the existing bridge into alternative solutions that meet both the functional needs and the aesthetic desires of the community. When an older bridge is to be part of the new crossing solution, what are the aesthetic considerations for the bridge designer or the project manager? The aesthetic impact of various alternative solutions involving older bridges is discussed, including compatibility of parallel structures when different bridge types are involved, importance of viewpoints, and aesthetic impact of various preservation measures such as cathodic protection. In addition, guidelines are provided and examples of various solutions are shown.
Objectivity and the Aesthetic Design Process
Authors: Petzold Ernst H. , Carlson Brian E.
Published: August 2018

The aesthetic design process is sometimes limited to dealing solely with personal likes and dislikes, creating a totally subjective situation that leads to significant design decisions made on the basis of the strength of individual personalities rather than on any fundamental aesthetic content. A bridge type selection case study is provided to illustrate and discuss a technique to develop a logical process and bring some objectivity into aesthetic decisions. The case study involves a major 10-lane bridge 815 m (2,670 ft) long through an urban park. Because of the controversial nature of the project, a citizens' design committee was established to provide design oversight. Broad underlying issues such as land use, form and circulation, and scale and proportion were presented to the committee to form a baseline for subsequent activities. Open discussions with the committee were used to focus on the relative importance of each issue. On the basis of these discussions, aesthetic design criteria were developed in order to rank various alternatives. Conceptual designs, which were developed after preliminary discussions with the committee, were ranked by the committee according to how well each satisfied the previously established aesthetic design criteria. The recommended alternative, from an aesthetic standpoint, was simply the one with the highest ranking. Although aesthetic considerations will always involve questions of individual taste and opinion, the technique described can be used to bring a degree of objectivity to decisions about aesthetics.
Glenwood Canyon Tunnel Aesthetic Design
Authors: Frey Craig A. , Danielson Scott L. , Slakey Douglas M.
Published: August 2018

As a growing and increasingly mobile population demands the construction of new transportation facilities, often in environmentally sensitive areas, the significance of quality transportation aesthetics cannot be overemphasized. Given the associated costs, impact, and permanence of these facilities, it is imperative that citizen advisory groups, public agencies, and design professionals work together in striving to improve the design and construction of transportation facilities. The Glenwood Canyon Tunnel in western Colorado is testimonial to the successful corroboration of these groups. Designed by Parsons Brinckerhoff and completed in 1993, the Glenwood Canyon Tunnel transports Interstate 70 traffic through one of the most scenic areas in the United States while preserving its natural features, vistas, and associated recreational opportunities. Architectural aesthetics and environmental concerns were driving forces in the design of the tunnel, in addition to life safety, tunnel ventilation, and surveillance. This study elaborates on the emphasis given to aesthetics and environmental concerns in the design of the tunnel, the Shoshone and amphitheater portals, and the Cinnamon Creek ventilation and control complex, as well as on the coordinated efforts of all those involved in making the Glenwood Canyon Tunnel state of the art and an aesthetically pleasing reality that has gained recognition throughout the United States.
Aesthetics and Other Community Values in the Design of Roads
Authors: Passonneau Joseph
Published: August 2018

The Interstate highway system was designed to handle large volumes of high-speed traffic. It has been one of the most successful public works projects of the century. But in the design of roads, aesthetics and other community values have been increasingly, and unnecessarily, neglected. This study provides a brief history of the Interstate highway acts and of agency responses to conflict. Discussion of the aesthetics of streets and roads follows, which examines the “fit” between roads and the physical and social landscapes through which they pass. It shows that parkways have been successful in fitting roads to their surroundings and in minimizing the area of concrete. Also parkway safety appears adequate. Several examples are cited of typical cases in which highway guidelines are modified to save money. The processes that have led to successful conflict resolution are described, and necessary conditions for constructive citizen participation are examined. This study's aim is to provide support for professionals and citizens attempting to resolve such conflicts.
Fusion of Creativity in Rail Transit Stations: A Retrospective and Critique
Authors: Kivett Hanan A.
Published: August 2018

The past, present, and future provide a framework for this discussion of the fusion of creativity among artists, architects, and engineers represented in the design of urban rail transit stations. The fusion of talent has a highly recognized past. Washington's Union Station, built early in this century, was restored to its original grandeur and is a major tourist attraction in the nation's capital. The power of the state is exploited in the Moscow subway, where stations take on a decorative quality found in the great monuments of Europe during the Gothic and High Renaissance era of architectural history. Transit stations designed in the late 1960s and 1970s in this country have had limited involvement by artists. Washington's Metro has a unique image created by architects and engineers dominating the underground stations. The power of nature in architecture was realized in Atlanta's Peachtree Station, where a rock cavern became an integral part of the station. The most successful fusion of art, architecture, and engineering in the 1970s was realized in the Stockholm Metro's underground stations, where artists were involved in every aspect of the design. The present is represented by five stations in the Seattle Underground completed in 1990—a gallery of art and architecture. Five stations operational on the Los Angeles Metro Red Line and eight more under construction will bring to reality the fusion of creativity. The future may once again see artists, architects, and engineers combining their talents to produce landmarks that will endure through the twenty-first century as Washington's Union Station has done in this century.