As part of the ongoing research on shear at the Phil M. Ferguson Structural Engineering Laboratory (FSEL) located at The University of Texas at Austin, the anchorage controlled shear capacity of prestressed concrete bridge girders was in this research studied in two distinct ways, experimentally and analytically. The results of this research are an important step towards improving understanding of strand anchorage related issues. For the experimental program, two full-scale Tx46 prestressed concrete bridge girders were fabricated at FSEL. The Tx46 girders were topped with a concrete, composite deck. Both ends of the two girders were instrumented and tested. For the analytical program, a new Anchorage Evaluation Database (AEDB) was developed, by filtering and expanding the University of Texas Prestressed Concrete Shear Database (UTPCSDB), and then evaluated. The AEDB contained 72 shear tests, of which 25 were anchorage failures and 47 were shear failures. The results and analysis from the experimental and analytical programs generated the following three main conclusions: (1) A reasonable percentage of debonding in Tx Girders does not have a marked impact on girder shear capacity calculated using the 2010 AASHTO LRFD General Procedure. (2) The AASHTO anchorage equation is conservative but not accurate. In other words, this equation cannot be used to accurately differentiate between a shear failure and an anchorage failure. In regards to conservativeness, anchorage failures in AASHTO-type girders may lead to unconservative results with respect to the 2010 AASHTO LRFD General Procedure. (3) The 2010 AASHTO anchorage resistance model and its corresponding equation do not apply to Tx Girders. Because of the Tx Girders' wider bottom flange, cracks do not propagate across the strands as they do in AASHTO-type girders. This fact yields overly conservative results for Tx Girders with respect to AASHTO Equation 5.8.3.5-1. In summary, this research uncovered the short-sided nature of the AASHTO anchorage design method. Given its short-comings, there is an obvious need for a validated, comprehensive, and rational approach to anchorage design that considers strength and serviceability. To appropriately develop this method, additional full-scale experimental testing is needed to expand the AEDB, as currently there are not enough tests to distinguish major, general trends and variables. Any future additional research would be expected to further validate and expand the significant findings that this research has produced and so take the next step toward safer, more-efficient bridge designs. / text

Torpedo-shaped anchors serve as foundations for risers and floating structures in the deep-water marine environment. Such cone-tipped, cylindrical steel pipes, ballasted with concrete and scrap metal, penetrate the seabed by the kinetic energy they acquire during free fall. Estimation of the embedment depth is a crucial part of the design process in that the pull-out capacity is strongly dependent on the strength of the surrounding soil. This dissertation presents the development of a procedure based on a computational fluid dynamics (CFD) model for the prediction of the embedment depth of torpedo anchors. By means of a representation of the soil as a viscous fluid, the CFD model leads not only to the resisting forces on the anchor but the distributions of pressure and shear in the soil as well. These distributions are then imported in another computational tool for finite-element (FE) analysis of coupled deformation and fluid flow in porous media for further simulations of reconsolidation of the soil next to the anchor and, ultimately, short-term and long-term capacity estimation. This dissertation presents CFD results for torpedo-anchor installation in soil, comparisons with experimental data and, finally, results from FE analysis of soil reconsolidation and anchor pull-out. / text

Existing reinforced concrete (RC) structural members such as beams, columns and joints can be strengthened and repaired with externally bonded high-strength and light-weight fibre-reinforced polymer (FRP) composites. The effectiveness of such strengthening can, however, be limited by premature debonding of the FRP at strains well below the strain capacity of the FRP. Such failures are also generally sudden and give rise to brittle member behavour. It is therefore important to prevent or even delay debonding failure in order for the FRP strengthening to be more effectively and efficiently used. Anchorage of the FRP strengthening is a logical solution and to date several different types of anchorage systems have been developed and tested. Anchors made from FRP, which are herein referred to as FRP anchors, are singled out for deeper inspection in this doctoral program of research. FRP anchors are an attractive form of anchorage as they are non-corrosive, relatively easily made by hand, and can be used in a variety of shaped RC elements ranging from beams to walls. There have been limited systematic studies though conducted on anchorage devices including FRP anchors. This knowledge gap forms the scope of the program of doctoral research reported herein. This dissertation is concerned with investigating the ability of FRP anchors to anchor externally bonded FRP in flexural strengthening applications. This is done by investigating the influence of FRP anchors on FRP-to-concrete bonded interfaces. Following a review of relevant literature, tests on FRP-to-concrete joints anchored with FRP anchors are reported as well as tests on FRP-strengthened RC slabs anchored with FRP anchors. The joint tests are used to investigate and understand the influence of key geometric and material properties such as, but not limited to, anchor type and position as well as plate length. The optimal arrangement of FRP anchors enabled significant increases in FRP plate strain utilisation to be achieved in the joints. Two modelling approaches based on regression analysis as well as partial interaction modelling are developed for the modelling of the joint tests. In the latter method of analysis, the complete debonding process is able to be simulated. The test and modelling results of the joint specimens are then used to design anchorage schemes for application to RC slabs strengthened in flexure with externally bonded FRP plates. The slab test results show the importance of strategic FRP anchor installation for enhancing the strength, ductility and deformability of FRP-strengthened RC slabs. Future research needs are finally presented in light of the outcomes of the experimental and analytical components of the research reported herein. / published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

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Autoclaved aerated concrete (AAC) is a lightweight cellular building material. In Spring 2008, an experimental study was conducted at The University of Texas at Austin to evaluate the load-deflection behavior and capacity of six different factory-reinforced AAC lintel groups. The results the test program are used to evaluate the shear design provisions of ACI 523.4R “Guide for Design and Construction with AAC Panels”. / text

The University of Aberdeen has conducted research into ground anchorage systems since the early 1980's. During this time, the non-destructive GRANIT system (GRound ANchorage Integrity Testing) has been developed for anchorages in rock. The system is based on observing the dynamic response from anchorages to which an impulse of a known intensity has been applied. This technique has been proven to be a reliable system to assess the integrity of rock anchorages, which is then used as a base to study the integrity of soil anchorages. This research aims to implement a non-destructive testing system at small scale size and full scale stress levels by means of centrifuge modelling at the University of Dundee. Accordingly, centrifuge modelling was undertaken to monitor and assess the dynamic response of soil anchorages installed in dry sand reinforcing a retaining wall in 3x3 anchorage array sets, subject to different post tension levels within different bonding ratios and different inclinations. In order to perform non-destructive testing, an In-flight Robotic Manipulator, previously developed, was used to apply a post tension load followed by an impact load to the anchorage head to obtain the dynamic response of the system. Anchor frequency response signatures were then evaluated in order to validate the consistency of results obtained. The practical importance of this research is that non-destructive testing may be usable to assess the soil anchors integrity to define the relationship between both anchor load and geometrical characteristics with frequency response accomplished using centrifuge modelling. This research presents a further development of the physical model in which additional instrumentation is included in order to obtain load/deflection information of the anchor head, which has been proven crucial for monitoring load on rock anchorage. Additionally, load distributions along scaled model soil anchors are measured and found to reduce gradually within the fixed length, similarly as it was reported for the fixed length of rock anchorages. Furthermore, a lumped parameter model for a single soil anchorage was adapted to investigate the dynamic response under the same physical and geometrical characteristics studied during centrifuge modelling. Mode shapes helped to understand the origin of some of the frequency modes present in the frequency response of the centrifuge results. The results from the numerical and centrifuge models were compared and good agreement was observed. Soil anchorage does not show as much frequency shift as was observed for rock anchorages under different post tension load, suggesting that the bonding strength of the fixed length with the surrounding ground plays an important role on the dynamic response of the system. The accomplishment of the assessment of soil anchorage can not be exclusively judged on its ability to diagnose controlled changes under centrifuge and numerical modelling. Therefore a preliminary phase to assess a soil anchorage under field conditions was carried out deploying the GRANIT system. This research showed that the GRANIT non-destructive testing technique has potential for use in soils, but that the results are not as well defined as in rock, necessitating more careful characterization of each anchorage signature response.

No description available.

The development of a more rational design procedure to predict not only ultimate tieback capacities in cohesive soils, but associated tieback displacements as well, requires a basic understanding of short-term and long-term tieback behavior. In view of the above, a series of full-scale and model tieback tests were conducted on instrumented and non-instrumented straight-shafted, postgrouted, and single-underreamed tiebacks anchored in different cohesive soils. In addition, laboratory shear strength tests were conducted on soil-soil samples and grout-soil samples to allow a better interpretation of field and model results. A better understanding of (1) the load-transfer mechanism of each type of tieback and (2) both time-independent and time-dependent component movements has led to the development of a physical model to describe short-term and long-term tieback behavior in a cohesive soil.

Thesis (M.S.)--University of Michigan, 2005. / Includes bibliographical references.