| Dynamic Strength Enhancement of Conventional Concrete |
30 JUN 1999 |
23 pages |
| Authors:
H. D. Kang; Y. S. Roh; K. J. Willam; Y. Xi; COLORADO UNIV AT BOULDER DEPT OF CIVIL ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING
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 | In order to investigate the performance of conventional concrete at different loading rates, experimental results of strength enhancement were obtained under tension and compression tested under different loading speeds. G- mix specimens prepared at the Tyndall Air Force Base were used to determine the range of loading rates of the servo-hydraulic equipment at hand and to obtain experimental results with a series of indirect tension and uniaxial compression tests. For ... |
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| A System Reliability Approach to the Lifetime Optimization of Inspection and Repair of Highway Bridges |
97 |
420 pages |
| Authors:
Allen C. Estes; COLORADO UNIV AT BOULDER DEPT OF CIVIL ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING
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| The objective of this study is to develop and demonstrate a methodology for evaluating the system reliability of a highway bridge over time and to develop an optimum inspection and repair strategy for that bridge that can be updated as new information becomes available. This study neglects uncertainty associated with human error in design, construction, or testing. It suggests a method of incorporating inspector error into the assessment of visual ... |
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| Development of a 400 G-Ton Geotechnical Centrifuge |
10 NOV 86 |
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| Authors:
Hon-Yim Ko; COLORADO UNIV AT BOULDER DEPT OF CIVIL ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING
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 | This report summarizes the development of a large 400 g-ton centrifuge facility at the University of Colorado. The $1,800,000 facility is being funded by the Univ. of Colorado as well as by several federal agencies, including AFOSR, and industry. At the time of this report, the installation of the centrifuge is almost complete. A February, 1987 start-up date is being scheduled. The centrifuge is capable of taking a 2-ton payload ... |
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| Development of a 10,000-PSI Multiaxial Cubical Soil Test Cell with Pore Pressure Measurement Facilities |
MAY 86 |
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| Authors:
Hon-Yim Ko; Stein Sture; Vincent C. Janoo; COLORADO UNIV AT BOULDER DEPT OF CIVIL ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING
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| This report deals with the development of a high pressure, multiaxial cubical test cell for the testing of soil specimens up to 10,000 psi. The equipment is capable of measuring pore water pressure generated during testing. The report describes a multiaxial cubical cell which consists of a 9,900-in. cubical main frame with a central 4,070-in. cubical cavity. Six walls, each made up of a sealing disk, a main wall, and ... |
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| Finite Elements and Localized Failure |
31 DEC 85 |
141 pages |
| Authors:
Kaspar J. Willam; Stein Sture; COLORADO UNIV AT BOULDER DEPT OF CIVIL ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING
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| This project was comprised of research on three different levels: 1) Experimental Work: Stroke controlled post-peak experiments on plain concrete specimens which were subjected to direct tension, triaxial compression and direct shear; 2) Constitutive Work: Homogenization of localized failure cure to tensile cracking and frictional slip in the form of the Composite Fracture Model which describes the degradation of strength within an elementary volume of a fracture energy equivalent continuum; ... |
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| Centrifugal and Analytical Modeling of a Buried Flexible Culvert |
31 OCT 85 |
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| Authors:
Jim C. Ni; COLORADO UNIV AT BOULDER DEPT OF CIVIL ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING
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| This report summarizes one phase of the research on the modeling of buried structures by centrifuge testing and by numerical methods. Testing in the centrifuge makes it possible to simulate the gravity-induced overburden pressure effects that dictate the soil stiffness which in turn determine the soil- structure phenomena. Scaled model testing in the centrifuge is used in the project to validate analytical methods commonly used to analyze soil-structure interaction problems. ... |
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| The Bank of Westminster and Hyland Park Construction Contracts as Engineering Student Classroom Projects; Construction Phase |
13 DEC 84 |
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| Authors:
Robert J. Bossa; COLORADO UNIV AT BOULDER DEPT OF CIVIL ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING
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| Within the scope of the undergraduate and graduate Civil and Architectural engineering programs is the need to relate information from textbooks and classrooms to the actual construction industry. The report will attempt to bridge the gap between real world situations and the world of academics. Walters Construction Management has agreed to let their organization and one of the current projects serve as a model for this report. The Bank of ... |
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| Identification of Strain-Softening Properties and Computational Predictions of Localized Fracture |
01 MAR 1984 |
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| Authors:
K. J. Willam; S. Sture; N. Bicanic; J. Christensen; B. Hurlbut; COLORADO UNIV AT BOULDER DEPT OF CIVIL ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING
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| The main objective of the present investigation is to evaluate strain-softening formulations for contained fracture in cementitious materials such as concrete and geo-materials. This report includes two principal developments: a rational approach to identify softening properties due to tensile cracking and frictional slip from displacement controlled material testing, and a systematic verification of contained fracture computations from small-scale structural testing. To this end, a composite damage model is proposed to ... |
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| The Strength and Behavior of Steel Fiber-Reinforced Concrete under Combined Tension-Compression Loading |
MAY 1983 |
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| Authors:
R. W. Meier; H. Y. Ko; S. Sture; C. C. Feng; COLORADO UNIV AT BOULDER DEPT OF CIVIL ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING
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| The addition of steel fibers to concrete-type materials has been shown to improve many of the engineering properties of those materials. Notable among them is an enhancement in the tensile strength of an otherwise weak and brittle material. Although much is known about the tensile strength of steel- fiber reinforced concrete (SFRC) under one-dimensional state of stress, little is known with regard to the strength behavior under multi-dimensional tension- compression ... |
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| Constitutive Properties of Steel Fiber Reinforced Concrete in Multiaxial Loading, |
MAY 1983 |
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| Authors:
Hon-Yim Ko; Roger W. Meier; Daniel E. Egging; Stein Sture; Chuan C. Feng; COLORADO UNIV AT BOULDER DEPT OF CIVIL ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING
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| The constitutive properties of steel fiber reinforced concrete (FRC) are being studied experimentally in a unique fluid cushion multiaxial cubical test cell at the University of Colorado. In the first phase of the program, the behavior of FRC was tested under three-dimensional compressive loading. The strength and stress-strain properties are analyzed by using constitutive models available in the literature. In the second phase, a modification to the existing test apparatus ... |
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| Experimental Modeling of Strength and Deformation Behavior of Concrete in Direct Shear, |
MAY 1983 |
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| Authors:
Stein Sture; COLORADO UNIV AT BOULDER DEPT OF CIVIL ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING
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| Direct shear experiments on large prismatic specimens of plain concrete were conducted in a large capacity servo-controlled and structurally stiff test apparatus in order to assess the predictive capabilities of nonlinear computational analysis techniques. The objective in these experiments was not to obtain material properties but rather to investigate load-deformation response behavior and strength characteristics of a mini-structure subjected to the complex states of nonproportional loading imposed by the direct ... |
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| Finite Element Analysis of Concrete Failure in Shear, |
MAY 1983 |
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| Authors:
James Christensen; Kaspar Willam; COLORADO UNIV AT BOULDER DEPT OF CIVIL ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING
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| The main purpose of this study is to assess the current computational methods for predicting the failure behavior of concrete and geomaterials in the form of tensile cracking and frictional slip. The paper concentrates on the peak and post-peak response of plain concrete in shear which is modeled by the smeared finite element approach in which localized failure zones are distributed over a finite material region with softening material properties. ... |
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| Comparison of the Hollow Cylinder and the Truly Triaxial Test Apparatuses for the Study of Anisotropic Clays |
1983 |
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| Authors:
F. R. Smith; COLORADO UNIV AT BOULDER DEPT OF CIVIL ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING
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| The test results presented and the discussion of the mechanism for development of shear strength make it clear that the undrained strength of anisotropic clays is dependent on both the magnitude and the direction of the principal stresses with respect to the principal material axes. The proper test system for investigation of the effects of anisotropy must be capable of applying relatively uniform and well-defined three-dimensional states of stress and ... |
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| Constitutive Relations of Randomly Oriented Steel Fiber Reinforced Concrete under Multiaxial Compressive Loadings |
DEC 1981 |
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| Authors:
Daniel E. Egging; Hon-Yim Ko; COLORADO UNIV AT BOULDER DEPT OF CIVIL ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING
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| A review of the state-of-the-art research on steel fiber reinforced concrete (SFRC) is given and a review of the behavior and strength of plain concrete subjected to multiaxial stresses is presented. Two series of tests on SFRC were conducted. The first preliminary series, provides results of some basic tests on concrete randomly mixed with each of five types of commercially available steel fibers. This information allowed the determination of the ... |
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| Statistical Variation of the Compliance of Coal |
JUN 1976 |
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| Authors:
Richard Henry Atkinson; Hon-Yim Ko; COLORADO UNIV AT BOULDER DEPT OF CIVIL ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING
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| The recent advances in the application of numerical analysis techniques to geomechanics problems require detailed knowledge of the constitutive relations of the geologic materials involved. The properties of most geologic materials, however, cannot be characterized by a single deterministic value, but rather exhibit a considerable scatter of experimentally determined values about the mean. The extent and nature of the distribution of these values constitutes an important characterization of the material. ... |
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| Stress Analysis of Strain-Softening Materials |
JUN 1976 |
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| Authors:
Stein Sture; Hon-Yim Ko; COLORADO UNIV AT BOULDER DEPT OF CIVIL ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING
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| Many engineering materials, notably geologic materials, exhibit strain-softening, or work-softening behavior in which the complete stress-strain curve exhibits a peak strength level followed by a portion with a negative slope leading to a residual strength plateau. Such behavior could best be measured in stiff testing machines or in machines with servo-controls. Analyses of structures made up of materials having such characteristics were investigated by means of various techniques, invariably utilizing ... |
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