Threaded connectors have been used in a variety of engineering structures for hundreds of years. Although stress analysis of threaded connectors has been performed since the early 1900's, there are still areas that are not fully understood. The way in which eccentricity affects the fatigue performance and stress distribution is one such area, and is the main area of research described in this thesis. The techniques of photoelasticity and fatigue testing were used to determine the effect of eccentricity on the stresses and fatigue performance of bolts. The results show that eccentric loading has a significant effect on the fatigue performance, but that this effect can be quantified if the local stress amplitude is considered. The photoelastic analysis results show the eccentricity slightly increases the stress intensity factors at the crack tip. A number of two-dimensional and three-dimensional finite element models were created to detennine the salient characteristics of the models. The models were validated against the resuh from the photoelastic analysis and the results agreed well. Accurate results can be obtained from a two-dimensional model, but the information obtained is limited unless many models are created. However, if a three-dimensional model is created more information can be obtained, but the nut thread run-out must be accurately modelled to obtain the correct stress distribution. The shape of cracks occurring in cyclically loaded steel bolts and the effect of crack shape on the stress distribution was also investigated. The photoelastic analysis of cracked bolts failed to predict the shapes of cracks occurring in cyclically loaded bolts. It is suggested that the inability of photoelasticity to model plasticity is the cause of this failure and this is supported by results from an elastic-plastic finite element model.

The use of dough moulding compound (DMC) as a structura~ material will be feasible as more information on mechanlcal properties becomes available. In this investigation, room temperature tensile and fatigue properties were determined prior to the testing and evaluation of simple joints in DMC. The DMC was supplied in the form of compression moulded sheets. Tensile tests were conducted to British Standards specification to obtain the mechanical properties and to identify possible sources of variability in properties. Differences in tensile strength due to sheet-to-sheet variability and specimen orientation within a sheet were significant but there was no significant variation due to the cross-head speed over the range O.05mm/min to 300mm/min. Tensile fatigue tests were conducted to British Standards specification. The scatter of fatigue lives was found to be greater than that for other reinforced plastics, but was adequately described by both the Log-Normal and Weibull distributions. In tensile and fatigue tests on larger specimens there was no size effect on tensile strength, but the fatigue strength at a given life and probability of failure was reduced ,slightly. When specimens contained bolt holes, the tensile strength decreased marginally, but the fatigue strength was not affected. Transverse compressive stresses due to a bolt load had little effect on the fatigue behaviour and changes in the cyclic-or static stress did not significantly alter the bolt load relaxation. Cyclic stress was found to cause greater bolt load relaxation than the corresponding mean stress. In tensile and fatigue tests on single shear lap joints, benditig wa~ the main cause of failure and the joint efficiency was low, 43% in tension and 51% in fatigue. By loading the specimens through the bolts at one end, bending was eliminated and the joint efficiency increased to 62% in tension and to 78% in fatigue

Thesis. 1978. M.S.--Massachusetts Institute of Technology. Dept. of Civil Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography: leaves 185-186. / M.S.

This study examines the effects of various rib properties and reinforced section geometries on the splitting force distribution around tensile lapped splices. The study makes use of a test specimen which idealizes the situation that exists in a tensile lapped splice between adjacent lateral cracks. The test specimen always failed by a longitudinal splitting of the concrete cover along a predefined failure plane. During the study the Influence of relative rib area, rib profile, amount of secondary link reinforcement, lateral pressure and bar spacing within the lap on the ultimate bond strength of the lap were examined. It was found that, for hot rolled (untwisted) deformed bars with crescent shaped ribs the orientation of the ribs to the splitting plane significantly affected the ultimate bond strength of the test specimen and, whilst the relative rib area was a good measure of a deformed bars performance In bond, it could not distinguish between the different orientations used. Further, since the maximum percentage Increase In ultimate bond stress for the same bar between orientations was of a similar magnitude to that observed for a doubling of a bars relative rib area the author recommends that bar orientation be taken into account when detailing tensile lapped splices. The presence of link steel perpendicular to the splitting plane did not significantly influence the ultimate bond strength of the model test specimen although the presence of lateral pressure did. The stress in the links at the occurrence of a full length splitting crack was less than 100 N/mm2. The finite element method was used to examine the two fundamental hypotheses describing the bond action of deformed reinforcing bars and to examine the implications of the assumption that the splitting forces around the circumference of a reinforcing bar are distributed proportionally to the rib height. The finite element analysis was also used to study the effect of varying the distance between the lapped bars on the spitting force distribution around the lapped bars. The results of a linear elastic analysis showed that both rib profile and bar spacing had a significant effect on the distribution of splitting forces around a tension lapped splice

The design of service connections to deeply buried sewers involves a number of challenges. In practice, the loads that develop from vertical risers can damage the Tee or Wye fitting to which it is connected. This thesis studies the expected loads and resistance of these connections, and provides some recommendations for the solution of this engineering problem. Laboratory tests have been performed to explore the capacities of the existing fittings both in air and when buried in uniform sand. A test procedure different from the standard quality control test methods described in ASTM F1336-02 is used to study the performance of the fittings in air. A special test configuration was also developed for an existing pipe test cell to explore the capacities of the existing PVC Tee and Wye fittings when buried in uniform sand. An analytical formula analogous to pile downdrag and numerical analyses have been used to evaluate the test results, to calculate the capacities of the buried heavy-wall fittings, and to explore the downdrag forces that develop along vertical risers. Through comparisons with experimental measurements, it was demonstrated that these methods of analysis can be used to estimate the downdrag forces and determine the adequacy of specific fittings to resist those forces. The major conclusions drawn for the specific fittings tested in this project are summarized as follows. When axially loaded in air, both Tee and Wye fittings experience plastic yield failure. When buried, the Tee fitting fractures or yields only along the base of the riser part; while the Wye fitting itself does not fail, the riser cracks near its base where it connects to the curved pipe (450 elbow) above the Wye. Both the capacities and stiffness of the buried fitting system (either Tee or Wye) are approximately linear functions of the confining stress supplied by the surrounding soil. The accumulated downdrag along the riser in the coarse-grained soil is much smaller than that in fine-grained soil. Various practical solutions for the vertical riser problem are then discussed and recommended. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2008-12-28 21:18:30.363

No description available.

No description available.

No description available.

No description available.

No description available.