Reinforced concrete structures were originally designed on the elastic behavior of the materials by the "Working Stress Design Theory". As reinforced concrete structures became more widely used, another theory based on the inelastic behavior of materials was developed and is commonly known as the “Ultimate Strength Design Theory.” Recently, the attention has been focused on another design theory known as “Limit Design Theory.” This theory is based on the redistribution of moments at high loads. This thesis presents the comparison of these three theories of reinforced concrete. The members of an interior panel of a continuous framed structure are designed by the working stress design method and then a few members are analyzed by the above three design methods. The comparison has been made on the basis of the live load as a common denominator. The results of the analyses show that the overall increase in live load is 13 percent by ultimate strength analysis and 52 percent by limit design analysis. This further shows that limit design is a more efficient method for statically indeterminate structures. / Master of Science

Deterioration of reinforced concrete bridge decks has gained widespread public attention and concern in recent years. Much of the damage can be attributed to corrosion of steel reinforcing bars. Numerous solutions have been suggested, one of which is the replacement of steel with a non-corroding reinforcement, such as fiberglass-reinforced plastic materials. Much of the current research focuses on the applicability of FRP as the main tensile reinforcement in the slab. The nature of FRP presents many obstacles to its use in this capacity. This investigation aims to capitalize on the strengths of both steel and FRP by combining them. Traditional steel rebar should be used where it will provide strength and ductility to the deck --in the bottom layer of reinforcement. The FRP is placed where it will provide strength and non-corroding reinforcement where it is needed: the top layer. Recent research has shown that minimal negative moment is created over supports in bridge decks, suggesting that the use of the non-ductile FRP as the top reinforcement would not be detrimental. A review of prior and current research in this area was conducted. Based on this information, four different FRP reinforcing materials were obtained. Simple-beam test specimens were designed and built. The procedure is described, and experimental results are presented and analyzed. Conclusions are drawn and recommendations for future work are outlined. This investigation provides first-hand data on the behavior ofFRP reinforced concrete and will serve as the basis for future work. / Master of Science

This study investigates the effects of typical construction details on the strength of steel deck reinforced concrete composite slabs. Past research on composite slabs has been centered primarily around single span, single panel width slabs with unrestrained ends. The test specimens in this study are more representative of actual slab construction. The effects of multiple spans, multiple panels, end restraint from pour stops, and deck anchorage from shear studs and welds are investigated. The results of this experimental study are analyzed using methods given in the Steel Deck Institute Composite Deck Design Handbook. The models were found to conservatively predict the strength of the composite slabs. Recommended modifications to the calculation methods are given. / Master of Science

The purpose of this study is to investigate the effects of tension stiffening and softening of concrete in reinforced concrete beams and beam-columns. Analytical models of beams and beam-columns are prepared and the results compared to experimental results previously conducted by Berwanger et al. (1960) A layered model of the beams is developed and strains and stresses at various layers are computed. Moment-curvature relationships are then obtained from these. The stress-strain curves adopted are from El-Metwally and Chen (1989). The effects of tension stiffening and softening are included by adopting realistic stress-strain curves in both compression and tension. / Master of Science

Adjacent voided slab bridges (AVSB) are economical systems for short spans. They provide the advantages of having low clearances due to their small section depths, accelerated construction times, and high torsional stiffness. The current longitudinal connection detail, a partial depth grouted shear key, has been known to fail in many of these bridges. The failure leads to reflective cracking in the wearing surface which allows chloride laden water to seep down through the joint, where it corrodes the reinforcement and prestressing strand. Ultimately, the failed keys lead to costly repairs and bridge replacements sooner than their proposed lifespan. This research project aimed to develop a more durable longitudinal connection detail by using sub-assemblages to test five alternate connections. The objective was to find a connection that abated all cracking in the shear key, thus removing the need for transverse post-tensioning. The tested connections employed alternate connection shapes and two different mix designs of fiber reinforced high strength concretes. The results showed that each tested connection outperformed the current detail. The findings of this research indicate that the longitudinal connection detail of adjacent member voided slab bridges should be modified. The modified version should be a blockout with lap splice connection detail utilizing a nonproprietary fiber reinforced high strength concrete. / Master of Science

This thesis is a product of the U.S. Army Corp of Engineer's desire to develop a more accurate procedure for estimating the load capacity of an in-service T-beam bridge. A bridge type that is a stumbling block for U.S. Army field engineers due to the unknown amount and placement of the flexural reinforcement in the T-beam girder cross-sections. Personnel from the U.S. Army Corp of Engineer's Waterways Experiment Station in cooperation with personnel from Virginia Tech conceived a procedure that is potentially more accurate, can be quickly executed in the field, and is relatively easy to use by field engineers. In general, the procedure provides a method for transition between the quantity of flexural reinforcement in a reinforced concrete T-beam and the member's actual moment of inertia. Specifically, the goal of this thesis is to evaluate the accuracy of selected, effective moment of inertia models as a component in the proposed analysis procedure. The accuracy of the selected models is evaluated with test data generated from a testing program detailed herein, which load tested full-scale reinforced concrete T-beams. The test specimens were subjected to a closely-spaced, tandem-axle load configuration, a load configuration typical of military equipment. / Master of Science

Under sustained loads plain concrete and concrete members experience the phenomenon known as creep. Creep varies in rate and magnitude depending upon the nature and magnitude of load and upon the physical characteristics of the concrete. From a review of the literature, creep coefficients are studied as to how the values are affected by mixes, loadings, time, curing, and quality of aggregates and materials. Within the allowable working stress range of concrete, creep strain can be considered proportional to the induced stress. Assuming known stress - creep strain - time relations, a series of equations have been derived analytically to calculate the stress changes in both the steel and concrete in reinforced concrete beams of rectangular cross-section due to creep relaxation. The data has been tabulated and graphed. Extensive use of the digital computer has been made to thoroughly investigate these stress changes within a wide range of parameters including these stress changes within a wide range of parameters including magnitude of load, strength of concrete, geometric proportion of the beams, and the amount and type of reinforcing steel. / Master of Science

Master of Science

Approximately fifty percent of the bridges in the United States are considered deficient. The deterioration of the concrete components is a leading cause of the problem. The deterioration of concrete bridge decks is due primarily to corrosion of the reinforcing steel in the concrete. A promising solution to the problem is the use of fiber reinforced plastics (FRP) as a replacement for reinforcing steel. The use of FRP as reinforcement has the following advantages of lightweight, high tensile strength, corrosion resistance, flexibility, and electromagnetic resistance. This paper looks at the use of FRP as reinforcement in concrete beams and compares the information from deflection measurements of different configurations. Also, a material cost comparison is made to determine the cost of using the FRP reinforcement over standard steel reinforcement. Concrete bridge deck systems are designed using steel and fiber-reinforced plastics and allowable stress and load resistance factor methods. Recommendations for further study and uses of FRP are made. / Master of Science

In the opening years of the 20th century, a furor of new and experimental techniques swept the architectural field. The materials and methods of building altered so rapidly that standards of architectural representation and the acts of construction they choreographed appeared for a time to exist without history or precedent. In chaotic times chaos seems all consuming; yet standards are soon established and modes of practice formalized. So it was with the advent of architectural modernity. The beginning of the century was a time of great experimentation and innovation, not only in architectural materials but in the tools and representations of architects, and the methods of building they described. In this exploration of the relationship between material innovation and architectural representation, we examine the case of the Pennsylvania artisan-scholar Henry Chapman Mercer (1856-1930), and his development of a unique method for construction in reinforced concrete and ceramic tiles of his own design. In the years between 1907 and 1916, Mercer built three buildings of increasing complexity and scale, using methods of fabrication he developed over the course of these constructions. His approach was experimental, innovative, and yet quite different from the prevailing currents in engineering and industry at that time. While Mercer has been studied as a decorator of tiles, as an archaeologist, and as a curator of one the first and finest collections of early American material culture, very little work has been completed on Mercer as architect-builder. In Mercer's building projects we see a scientific mind and an artistic maker explore and experiment freely, building a bridge between his seemingly disparate worlds: from the Arts and Crafts-inspired Moravian Pottery he founded, to the archaeologically rigorous collection of pre-industrial tools. Mercer focused with great intensity on implements and evidences of traditional craft activities, and it is his particular sensitivity to the traditions and forms of craft activity that renders his architectural activity unique, and pertinent to the question of innovation in method. At the center of his architectural activities, Mercer's construction notebooks, in which he worked out plans, details, and many of his most unique procedural innovations, illustrate a novel comportment of architect to architectural representation, and offer a story of how the making of architecture is, itself, made. / PHD / In the opening years of the 20th century, a furor of new and experimental techniques swept the architectural field. The materials and methods of building altered so rapidly that standards of architectural representation and the acts of construction they choreographed appeared for a time to exist without history or precedent. In chaotic times chaos seems all consuming; yet standards are soon established and modes of practice formalized. So it was with the advent of architectural modernity. The beginning of the century was a time of great experimentation and innovation, not only in architectural materials but in the tools and representations of architects, and the methods of building they described. In this exploration of the relationship between drawing and building, we examine the case of the Pennsylvania artisan-scholar Henry Chapman Mercer (1856-1930), and his development of a unique method for construction in reinforced concrete and ceramic tile of his own design. Mercer has been studied as a decorator of tiles, as an archaeologist, and as a curator of one the first and finest collections of early American tools. Yet very little work has been completed on Mercer as architect-builder. In Mercer’s building projects we see a scientific mind and an artistic maker explore and experiment freely, building a bridge between his seemingly disparate loves: from the Arts and Crafts-inspired Moravian Pottery he founded, to the archaeologically rigorous collection of pre-industrial tools. Mercer focused with great intensity on implements and evidences of traditional craft activities, and it is his particular sensitivity to the traditions and forms of making that renders his architectural activity unique, and pertinent to the question of innovation in method. At the center of his architectural activities, Mercer’s construction notebooks, in which he drew plans and worked out many of his most unique procedural innovations, illustrate a novel comportment of architect to drawing, and offer a story of how the making of architecture is, itself, made.