Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1982. / Microfiche copy available in Archives and Barker. / Includes bibliographical references. / by Peter David McQuade. / M.S.

Prefabricated and pre-stressed reinforced concrete beams and girders are integral components of many highway structures, including those built by rapid construction techniques. Concerns exist regarding the development of cracks during curing, form removal, detensioning, transport, installation, and operation. Non-destructive, Acoustic Emission (AE) sensing techniques have the potential for detecting and locating cracking in prefabricated, pre-stressed concrete girders used as Prefabricated Bridge Elements and Systems (PBES) used in rapid construction practices as part of a Quality Assurance/Quality Control (QA/QC) program. AE sensing records transient elastic waves produced by the release of stored elastic energy resulting in plastic deformations (i.e., crack nucleation and growth) with an array of point sensors. The AE instrument system is relatively portable which can allow for it to be an option for both off-site fabrication QA/QC as well as on-site field QA/QC. This thesis presents a multi-stage research initiative on acoustic emission monitoring of prefabricated and pre-stressed reinforced concrete beams used in highway bridge construction during detensioning, craned removal from formwork and transport to bridge sites, along with supporting laboratory tests and numerical analysis. The specific objectives of this research were to: 1. Identify suitable instruments to monitor pre-stressed and/or post-tensioned concrete girders for cracking activity; 2. Design and develop a reusable instrumentation package; 3. Measure performance and condition of concrete girders during fabrication and transport; and 4. Identify test protocols and possible accept/fix/reject criteria for structural elements based on information from monitoring system. Presented are results from laboratory, full-scale girder fabrication, and transport monitoring, along with overall conclusions and recommendations for future research.

The inclusion of trapezoidal types of steel decking in the shear connection of composite beams has been found to significantly reduce their maximum strength and ductility by causing premature concrete-related failure modes. In order to investigate the complex behaviour and various load-transfer mechanisms that can occur in composite beams incorporating this type of connections, a total of 91 carefully-designed push-out tests were performed. Specific failure modes in conventionally reinforced specimens were initially induced by varying critical parameters. Specimens incorporating specific stud reinforcing devices were subsequently tested to suppress the undesirable failure modes. The concrete reinforcing and stud performance-enhancing devices, which included novel waveform-type reinforcement elements and spiral wire or ring components surrounding individual studs in secondary composite beams and special haunch reinforcement in primary beam applications, significantly delayed the onset and reduced the effect of the premature concrete-related failure modes. Hence, they increased the ultimate strength and ductility of the shear connection. The findings of the small-scale push-out tests were also verified in two full-scale composite beam tests which showed good agreement in shear connection behaviour and failure mode. Most of the design approaches currently used around the world take into account the weakening effect of trapezoidal types of decking by applying a reduction factor to the nominal strength that the same connection would have in a solid slab. From the test results, it is evident that not every shear connection incorporating steel decking, and within the limits of the associated standards, can be classified as ductile. A new and more reliable design approach is proposed which also incorporates the application of the various stud reinforcing devices. The key element of this design approach is to classify the anticipated connection behaviour, in regards to its deformation capacity, into ductile or brittle connections, hence ensuring satisfactory shear connection behaviour where the new types of trapezoidal steel decking are used. A reliability analysis of the new proposal is presented which enables the application of this new approach in accordance with AS 2327.1 (Standards Australia 2003). It is calibrated to provide a reliability index similar to stud applications currently in use. Simple strength reduction factors for the types of trapezoidal steel decking available in Australia are also provided which can be applied to the current solid slab shear connection strength for a fast and simplified design. / Doctor of Philosophy (PhD)

Bridges and other coastal structures in Georgia and throughout the Southeast are deteriorating prematurely due to corrosion. Numerous corrosion initiated failures have occurred in precast prestressed concrete (PSC) piles and reinforced concrete (RC) pile caps, leading to the costly repair and replacement of either the entire bridge or the affected members. With the Federal Highway Administration's goal of a 100-year bridge service life and recent legislative action such as the Bridge Life Extension Act, new emphasis has been placed on the development and implementation of new corrosion mitigation techniques. This thesis involves the mechanical testing, and proposed future test program of high-strength stainless steel (HSSS) prestressing strand to be used in prestressed marine bridge piles. The metallurgy for two types of HSSS strand was selected from a previous study of the corrosion resistance, mechanical properties, and feasibility of 6 candidate HSSS drawn wire samples. Duplex stainless steel (DSS) grades 2205 and 2304 were selected for production of 7-wire 1/2" diameter prestressing strand. DSS wire rod was drawn, stranded, and heat-treated using the same production methods and equipment as used for standard of practice, high carbon prestressing strand. The production process was documented to analyze the problems facing this production method and suggest improvement and optimization. After production, the strands were subjected to a series of mechanical tests. Tension testing was performed to provide a stress-strain curve for the strands and related mechanical properties. Wire samples were also taken at varying points in the drawing process to give more information about the work hardening of the stainless steels. Stress relaxation testing was performed on both strand and wire samples to assess the overall losses and to provide comparisons between strand and wire test results as well as drawn wires before and after heat-treatment. An experimental program for future study was designed to assess the HSSS prestressing strand behavior in precast piles. This testing involves assessment of pile driving performance, pile flexural and shear behavior, strand transfer and development length, long-term prestressing force losses, and material durability.

The use of composite steel-concrete columns and beam-columns in many structural systems is increasing globally due to the intrinsic synergy when these materials are designed and detailed together properly. However, limited test data are available to justify the structural system response factors and comprehensive design equations in current design specifications. This research, through the testing of 18 full-scale, slender concrete-filled steel tube (CFT) beam-columns, attempts to address the latter need. The circular and rectangular CFT specimens tested for this research are by far the longest and the most slender full-scale CFT members tested worldwide. These CFT specimens were subjected to a complex load protocol that includes pure compression, uniaxial and biaxial bending combined with compression, pure torsion, and torsion combined with compression. In addition, data from the hydrostatic pressure on the steel tubes due to the fresh concrete at casting was evaluated. The single most important contribution of this research is the clarification of the interaction between strength and stability in slender composite concrete-filled columns and beam-columns. Parallel to the experimental study, advanced computational analyses were carried out to calibrate material and element models that characterize the salient features of the observed CFT response, such as steel local buckling and residual stresses, concrete confinement, stability effects, strength, and stiffness degradation, among others. Based on the observed behavior, simplified guidelines for the computation of the strength and stiffness parameters for CFT columns and beam-columns are proposed for design purposes.

No description available.

This thesis compares the consumption of primary superstructure material in a conventional single span CPCI system with those of double-T alternatives. The CPCI system is currently the preferred bridge type for short and medium spans in Canada, despite its relatively inefficient use of materials due to imperfect live load sharing among multiple parallel girders. The double-T alternatives utilize slender double-T cross-sections, fully precast segments, and post-tensioning in both longitudinal and transverse direction. The economy of the CPCI and double-T systems is compared within the framework of four sample designs. The results indicate that the double-T systems are in general more efficient than the CPCI system and have the potential to achieve better economy.

This thesis compares the consumption of primary superstructure material in a conventional single span CPCI system with those of double-T alternatives. The CPCI system is currently the preferred bridge type for short and medium spans in Canada, despite its relatively inefficient use of materials due to imperfect live load sharing among multiple parallel girders. The double-T alternatives utilize slender double-T cross-sections, fully precast segments, and post-tensioning in both longitudinal and transverse direction. The economy of the CPCI and double-T systems is compared within the framework of four sample designs. The results indicate that the double-T systems are in general more efficient than the CPCI system and have the potential to achieve better economy.

This thesis evaluates the use of High Strength Lightweight Concrete (HSLW) in bridge girders for the I-85 Ramp "B" Bridge crossing SR-34 in Cowetta County, Georgia. This bridge consisted of four spans; all girders were constructed using lightweight expanded slate aggregate. Spans 2 and 3 had a design strength of 10,000 psi, and span 2 was chosen for this research. The BT-54 girders were 107 ft 11½ inches in length. The prestressing strands used in these girders were 0.6 in diameter, grade 270, low relaxation strands. Material properties and member properties were tested. All 5 girders of span 2 were instrumented with vibrating wire strain gages at midspan, as well as with DEMEC inserts for transfer length measurements and with a deflection measurement system. Transfer length measurements found the transfer length of the girders to be 23% less than the values suggested by AASHTO and ACI equations. The deflection measurements showed 4.26 inches of camber at 56-days while the girders were stored at Standard Concrete Products. The camber measurements matched theoretical predictions within 5%. Mechanical property tests found the concrete to be within all design requirements. A stiffness, load test was performed on each of the 5 girders at Standard Concrete Products. The average stiffness value of 8.428 x 106 kip ft2 is recommend for use by GDOT engineers in designing the deck and road profile. This thesis discusses all short term findings from construction to the end of storage. A later report will address long term issues such as creep and shrinkage, as well as the performance of the girders as part of the bridge.

Thesis(M.S.)--Auburn University, 2005. / Abstract. Includes bibliographic references.