Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains x, 101 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 77-80).

Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains x, 149 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 146-149).

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed May 8, 2007). PDF text: iii, 251 p. : ill. (some col.) ; 2.75Mb UMI publication number: AAT 3237783. Includes bibliographical references. Also available in microfilm and microfiche formats.

One of the major problems in the analysis of beams with Moment of Inertia varying along their length, is to find the Fixed End Moments, Stiffness, and Carry-Over Factors. In order to determine Fixed End Moments, it is necessary to consider the non-prismatic member as integrated by a large number of small sections with constant Moment of Inertia, and to find the M/EI values for each individual section. This process takes a lot of time from Designers and Structural Engineers. The object of this thesis is to design a computer program to simplify this repetitive process, obtaining rapidly and effectively the Final Moments and Shears in continuous non-prismatic Beams. For this purpose the Column Analogy and the Moment Distribution Methods of Professor Hardy Cross have been utilized as the principles toward the methodical computer solutions. The program has been specifically designed to analyze continuous beams of a maximum of four spans of any length, integrated by symmetrical members with rectangular cross sections and with rectilinear variation of the Moment of Inertia. Any load or combination of uniform and concentrated loads must be considered. Finally sample problems will be solved with the new Computer Program and with traditional systems, to determine the accuracy and applicability of the Program.

Single plate connections for steel beams, connected by high strength bolts to the beam web and welded to the column, were investigated to determine their, behaviour. Tests were performed on the connections in the absence and in the presence of shear, and shear was found not to affect the rigidity of the connections. Varying the gauge distance, the weld size, the pitch and the number of bolts in the test specimens, showed that only the pitch and the number of bolts influenced the rigidity of the connections. An increase in the pitch and the number of bolts causes an increase in the rigidity of the connections. In all cases the major slip value was greater than the usually assumed value. Under the action of pure moment the centre of rotation was found to be slightly above the centroid of the connection, whereas under the action of moment and shear the centre of rotation was slightly below the centroid of the connection. The maximum moment developed by the connections varied from 45 kip-inches for the two-bolt connection, to 355 kip-inches for the six-bolt connection. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

The section of highway over the 400 South roadway in Orem, Utah is made up of two separate three span bridges. The bridges were originally constructed in 1960 and were expanded in 2004 to accommodate for one extra lane per bridge. During the fall of 2012 both bridges were scheduled for demolition and four girders were salvaged from the southernmost span of the 2004 expansion. These girders were transported to the Structural Materials And Systems Health Lab (SMASH Lab) where a series of tests were performed to determine the prestressing losses, flexural, shear, and shear-flexure capacity of the girders. The results of these tests were compared to the American Association of State Highway and Transportation Officials Load Resistance Factored Design (AASHTO LRFD) Bridge Design Specifications and an ANSYS Finite Element model. For all test results the AASHTO Bridge Design was conservative for each test setup and was able to predict the type of failure that occurred. The finite element model was developed for the four test conditions and calibrated so as to accurately represent test data. The calibrations were compared to actual tested material properties to determine the difference between the theoretical model and the girders. (120 pages)

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The primary goal of this dissertation consisted of two related parts. The first was to develop an analytical basis for predicting the active control of flexural and extensional power flow in thin semi-infinite and finite beams using piezoelectric actuators and sensors. The second part was to experimentally demonstrate these techniques applied to actual beam systems. In order to maintain total control authority over the system, the control actuators must be able to adequately excite both flexural and extensional motion in the beam. Accurate sensing or estimation of the actual power flow (or variables that can be related to the power flow) in the finite beam in real time is also a requirement. This dictated the development of advanced, new sensing techniques. In order that these overall goals were achieved several tasks were carried out as discussed below. A theoretical model for the excitation of a thin beam by a single piezoelectric actuator mounted on the surface was developed. The model predicts the simultaneous excitation of flexural and extensional motion by a single actuator whose relative amplitudes are functions of beam and actuator parameters. Further, a single pair of axially co-located, symmetrically bonded, and independently driven piezoelectric actuators can excite flexural and extensional motion of variable complex amplitudes. A method for the real time filtering of net positive and negative traveling flexural and extensional waves was developed. The theoretical actuator and sensor models were used to study the control of flexural and extensional power.flow in both finite and semi-infinite beams subjected to point force excitation at the free end. These actuator and sensing techniques when combined with an multiple input/output adaptive controller can simultaneously control flexural and extensional power flow in regions of a beam system over a band of frequencies. The control of flexural and extensional power flow in thin beams was also experimentally investigated for both finite and semi-infinite beams. Power flow attenuations of 30 dB or more downstream of the control actuator location were demonstrated using a single pair of piezoelectric actuators for both resonant and damped beam systems. The experimental and theoretical results demonstrate the effectiveness of piezoelectric actuators and piezoelectric wave vector filters in the control of flexural and extensional power flow in thin beams. / Ph. D.

The object of this investigation was to evaluate and compare four approximate methods of limit analysis as they apply to the calculation of the collapse load, the load versus deflection relationship, and the load versus strain relationship, of a horizontal system of rigidly connected, rectangular beams. The first approximate method considered made use of the stress-strain diagram utilized by Roderick (1948), Luxion and Johnston (1948), Baker (1949), and Roderick and Heyman (1951). The diagram is assumed to be linear until the unit stress reached the value of the upper yield stress in simple tension. The stress was then assumed to decrease to the lower yield stress while the strain remained constant at the value of the elastic limit strain. Thereafter, the strain increased infinitely while the stress remained constant. This first method, being the most exact, served as a basis for comparison of the remaining three methods. Method Two differed from Method One only in that the upper yield stress was neglected. This gave a stress-strain diagram of the type used by Yang, Beedle and Johnston (1951). The third approximate method made use of the simplified moment versus angle change relationship utilized by Van den Broek (1948), and Yang, Beedle and Johnston (1951). In this method, it was assumed that the flexural moment existing on a cross section of a beam varied linearly with the angle change at the same cross section until the moment reached an ultimate value. After reaching this value, the angle change increased infinitely while the moment remained constant. It was assumed in this third method that the ultimate moment was equal to one and one-half times the elastic limit moment for a rectangular beam. The fourth approximate method assumed that the material remained rigid until the ultimate value of moment was developed, and that after this ultimate moment was reached, the angle change increased infinitely while the moment remained constant. It was also assumed in method four that the ultimate moment which can be resisted by a rectangular beam is equal to one and one-half times the elastic limit moment. Each of the approximate methods outlined above was used in the analysis of two structures. The first was composed of two horizontal rectangular beams of unequal lengths which intersect one another at right angles at their midspans. These beams are rigidly connected and are absolutely fixed at their ends. The second structure was similar to the first structure except that the beams in the second structure are of equal lengths. Both structures were loaded by a single concentrated load applied at the intersection of the center lines of the two beams. This load was increased in value until collapse of the structure was imminent. In this manner the collapse load, the load versus deflection relationship, and the load versus strain relationship were determined throughout the entire range of loading. All methods gave identical values for the collapse load. Method one gave the most accurate load versus deflection relationship and load versus strain relationship. Methods two, three, and four gave less accurate results, in that order. It was shown that the theory of elasticity indicated that the structure analyzed in Example Two was the stronger; whereas, the theory of limit analysis indicated that the structure in Example One was stronger. This showed that the elastic theory does not always give a good indication of the load which can be sustained by a redundant structure before collapse. / M.S.