Browsing by Subject "Anchors"
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Item Analytical and Experimental Studies of Drag Embedment Anchors and Suction Caissons(2011-08-08) Beemer, RyanThe need for experimental and analytical modeling in the field of deep water offshore anchoring technologies is high. Suction caisson and drag embedment anchors (DEA) are common anchors used for mooring structures in deep water. The installation process of drag embedment anchors has been highly empirical, employing a trial and error methodology. In the past decade analytical methods have been derived for modeling DEA installation trajectories. However, obtaining calibration data for these models has not been economical. The development of a small scale experimental apparatus, known as the Laponite Tank, was developed for this thesis. The Laponite Tank provides a quick and economical means of measuring DEA trajectories, visually. The experimental data can then be used for calibrating models. The installation process of suctions caissons has benefited from from a more rational approach. Nevertheless, these methods require refinement and removal methodology requires development. In this thesis, an algorithm for modeling suction caisson installation in clay has been presented. An analytical method and modeling algorithm for removal processes of suction caissons in clay was also developed. The installation and removal models were calibrated to field data. These analytical and experimental studies can provide a better understanding of installation of drag embedment anchors and the installation and removal of suction caissons.Item Shear behavior of reinforced concrete T-beams strengthened with carbon fiber reinforced polymer (CFRP) sheets and CFRP anchors(2011-12) Kim, Yun Gon, 1977-; Ghannoum, Wassim M.; Jirsa, J. O. (James Otis); Wood, Sharon L.; Bayrak, Oguzhan; Liechti, KennethThe objective of this research is the evaluation of shear behavior of full-scale reinforced concrete T-beams strengthened with carbon fiber reinforced polymer (CFRP) sheets and CFRP anchors. Although the CRFP material has high tensile strength, premature failure due to debonding CFRP sheets prevents utilizing that strength. The use of CFRP anchors prevents this failure, so the CFRP sheets are able to reach ultimate strain. The current shear design is based on plasticity, which assumes that all steel (ductile material) stirrups, across the critical section yield at ultimate. However the strain in the CFRP (brittle material), is essential to estimate the shear contribution of CFRP. To evaluate the validity of CFRP strengthening for shear, 24 tests were conducted with several parameters including shear-span-to-depth ratio, depth of beams, different transverse reinforcement ratios, and the layout of CFRP strips. In addition, a simple shear behavior model was developed to explain the differences between ductile and brittle material. From test observation, the use of CFRP anchors resulted in U-wrap application to perform like continuous wrapping which implies that a CFRP strip reached rupture strain because the anchors prevented debonding failure. However, all FRP strips did not rupture simultaneously because the strain distribution across a critical crack was not uniform. The average strain across the critical crack was about 0.005. Therefore a conservative value of effective strain (0.004) was selected for design purposes. In addition, when a beam is strengthened with CFRP, interactions between the contributions of the CFRP, steel or concrete must be taken into account. Factors ka, ks, and kf were introduced in the proposed shear design equations. Factor ka reflects the change in the material contributions as the shear span to depth ratio (a/d ratio) changes in deep beams. Factors ks and kf account for the change in steel or CFRP shear contribution due to the change in the critical crack angle as well as the interactions between the steel and FRP transverse reinforcement. As the amount of either steel or FRP material increase, the efficiency of the other material decreases.Item Test of glass fiber reinforced polymer (GFRP) anchors(2013-12) Wang, Haomin Helen; Jirsa, J.O. (James Otis); Ghannoum, Wassim M.A study to investigate the behavior of glass fiber reinforced polymer (GFRP) anchors was conducted at the Ferguson Structural Engineering Laboratory as part of a project funded by the Texas Department of Transportation, Project number 0-6873. The purpose of this study was to test the effectiveness of GFRP anchors by comparing their performance to that of anchors made from carbon fiber reinforced polymer (CFRP). The findings of this research give insight into the advantages and disadvantages of using alternative materials in the design of FRP anchorage systems and provides a means for developing quality control procedures of GFRP anchors. Quantitative comparisons were made between results from beam tests that used GFRP anchors and the results from those that used CFRP anchors. It was found that specimens with GFRP anchors exhibited similar trends to specimens with CFRP anchors. Similarities were achieved in concrete cracking loads, strength capacities, and in some cases duration of force transfer, suggesting that GFRP anchors are equally as effective as CFRP anchors for strength development. However, material differences played a major role in the explanation of GFRP and CFRP behavior. Notable advantages in material handling was observed with the GFRP anchors since the fibers were found to be easier to bend as well as easier to install into drilled anchor holes. On the other hand, the lower tensile strength of GFRP presented a potential need for larger sized anchors to achieve the equivalent strength of a CFRP anchor. Finally, a pull-out failure mode was observed in GFRP anchors that had not been previously observed in CFRP anchors. It was suggested that the pull-out failure mode was a function of differences in deformation capacity between the two materials. However, little information regarding the cause of performance differences demonstrates the need for quality control tests for GFRP anchors. As a result, recommendations for further studies were made.