The general area of investigation was first suggested by the problem of designing a plug to block off a tunnel that was to be filled with water. The specific purpose of this project was to determine if the shear stress along the edge of a plug in a circular hole could be considered uniform when the hole on one side of the plug was subjected to hydrostatic pressure. Three mathematical solutions were attempted using the theory of elasticity, but none yielded a simple solution. The problem was then attacked experimentally by plane photoelasticity and 32 configurations of six plane models were examined. The results showed that the shear stress was not uniform, but rose to a high peak and then declined rapidly. Three-dimensional photoelastic techniques were also used and the results of five "stress-freezing" models confirmed this conclusion. Other significant conclusions concern the variation of stresses with plug thickness; the use of fillets to strengthen the plug; and the dissipation of shear stress with distance from the plug. Some discussion is also made of the optimum design for a plug. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

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We analyze plane strain thermomechanical deformations of a prenotched rectangular plate impacted on one side by a prismatic body of rectangular cross-section and moving parallel to axis of the notch. Both the plate and the projectile are made of the same material. Strain hardening, strain-rate hardening and thermal softening characteristics of the material are modeled by the Johnson-Cook relation. The effect of different material parameters, notch-tip radius, impact speed and the length of the projectile on the maximum tensile principal stress and the initiation and propagation of shear bands at the notch-tip is analyzed. It is found that for high impact speeds or enhanced thermal softening, two shear bands, one at and the other at to it propagate from the notch tip. Otherwise, only one shear band nearly parallel to the notch-ligament initiates at the notch-tip. The notch-tip distortion for high strength materials is quite different from that for low strength materials. The maximum tensile principal stress occurs at a point on the upper surface of the notch-tip and for every set of values of material parameters and impact speeds studied equals about 2.3 times the yield stress of the material in a quasistatic simple tension or compression test. We assume that the brittle fracture occurs when the maximum tensile principal stress equals twice the yield stress of the material in a quasistatic simple tension test and a shear band initiates when the effective plastic strain at a point equals 0.5. The effect of material and geometric parameters on the time of initiation of each failure mode is computed. It is found that for low impact speeds (< 30 m/s), a material will fail due to the maximum tensile principal stress exceeding its limiting value, and at high impact speeds due to the initiation of a shear band at the notch-tip. Results are also computed for a C-300 steel with material parameters given by Zhou et al. For an impact speed of 50 m/s, the shear band speed and the maximum effective plastic strain-rate before a material point melts are found to be 350 m/s and 5 x /s respectively. / Master of Science

Full-depth precast deck panels are a promising alternative to the conventional cast-in-place concrete deck. They afford reduced construction time and fewer burdens on the motoring public. In order to provide designers guidance on the design of full-depth precast slab systems with their full composite strength, the horizontal shear resistance provided at the slab-to-beam interface must be quantified through further investigation. Currently, all design equations, both in the AASHTO Specifications and the ACI code, are based upon research for cast-in-place slabs. The introduction of a grouted interface between the slab and beam can result in different shear resistances than those predicted by current equations. A total of 29 push off tests were performed to quantify peak and post-peak shear stresses at the failure interface. The different series of tests investigated the surface treatment of the bottom of the slab, the type and amount of shear connector and a viable alternative pocket detail. Based on the research performed changes to the principles of the shear friction theory as presented in the AASHTO LRFD specifications are proposed. The proposal is to break the current equation into two equation that separate coulomb friction and cohesion. Along with these changes, values for the coefficient of friction and cohesion for the precast deck panel system are proposed. / Master of Science

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Full-depth precast panels are used in concrete bridges to provide several benefits such as faster construction, lower cost and reduced constructional hazard. However, one construction drawback is that connectors are required to transmit horizontal shear across the interface between the girder and deck. Shear connector performance is characterized by a series of experiments performed on part of a bridge system that mimics a full-depth precast deck on concrete girder with a pocket-connector-haunch system. Following initial breakaway of the adhesive bond within the haunch region, the specimens slide with frictional resistance provided by the clamping force of the anchor bolt. This leads to bolt yield with an observed sliding friction coefficient of 0.8 (+/- 20%) with lower values occurring at higher displacements. It is concluded that for a viable connector system to be developed a key feature is to have sufficient stirrups in the neighborhood of the anchor bolt to form a non-contact splice and to ensure the high pull-out force can be sustained without leading to premature beam failure. The successful implementation of a full-depth precast deck-panel system requires the use of a viable design methodology that properly accounts for system behavior. The design of a deck-haunch-girder system uses a truss modeling approach to design for the shear forces created by service loading. The truss model approach is considered more suitable for a concrete member due to the premise that the member will be substantially cracked at an ultimate limit state and that traditional beam theory does not account for the decreased ability of shear stresses to transfer across open cracks. Experimental results from Chapter II, such as the friction coefficient mu, are used along with a previously developed crack angle model to layout the geometry of the truss within a deck-panel span. Design solutions are presented utilizing the Rock Creek Bridge in Parker County, Texas as an example structure.

Beef retail steaks from establishments in twelve US cities and beef foodservice steaks from establishments in five US cities were evaluated using Warner-Bratzler shear and consumer sensory panels. Postmortem aging times for retail establishments ranged from 1 to 358 d with a mean of 20.5 d, and those from foodservice establishments aging times ranged from 9 to 67 d with an average of 15.9 d. For retail, top blade had the lowest (P < 0.05) WBS values, while cuts from the round top round and bottom round had the highest (P < 0.05) WBS values. Top loin and ribeye steaks had the lowest (P < 0.05) WBS values compared to top sirloin foodservice steaks. Retail top blade steaks received the highest (P < 0.05) ratings by consumers for overall like, tenderness level, like tenderness, juiciness level, and like juiciness; and foodservice top loin steaks received the highest (P < 0.05) for tenderness level, like tenderness, flavor level, juiciness level, and like juiciness. USDA quality grade did have an effect on foodservice ribeye and top sirloin steaks for sensory panels. Prime foodservice ribeye steaks were rated highest (P < 0.05) for overall like, like tenderness, tenderness level, like juiciness, and juiciness level, whereas ungraded ribeye steaks were rated lowest (P < 0.05) for like tenderness and tenderness level. Ungraded foodservice top sirloin steaks were rated highest (P < 0.05) for overall like, like tenderness, like flavor, and like juiciness. Additional improvements to reduce the range of tenderness levels are necessary to increase consumer acceptability.

The main objective of the study is to verify the accuracy of the approximate hand calculation method used extensively by the engineers for the calculation of the rigidity of shear walls with openings. Different types of shear walls are considered varying in the dimensions and positions of the opening, however, maintaining the same basic material properties. The results obtained by the hand calculation are compared to the finite element approach to check for the discrepancy. The finite element analysis software NISA/DISPLAY IV and SAP2000 is considered for the purpose.