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This master’s thesis presents an investigation on the effects of fatigue on fiber- reinforced polymers (FRP) when applied to masonry walls subjected to out-of-plane loading. The project aims to provide further research and add to the general testing database of FRP enhanced masonry. An introduction to the problems and solutions associated with unreinforced masonry is discussed along with a literature review on previous testing done in the field of FRP enhanced masonry. The investigation on the effects of fatigue on FRP when applied to masonry walls subjected to out-of-plane loading is performed through experimental testing. A total of four wall specimens (6 ft x 4 ft x 8 in) were constructed. One of the specimens was left unreinforced and used as a baseline for testing while the remaining three specimens were reinforced with carbon fiber reinforced polymer (CFRP) strips designed to take the out-of-plane loads capable of creating the cracking moment in the unreinforced wall. The material testing, construction of the test specimens, and CFRP application are all presented in this thesis. With the use of an oscillating shake table to generate the out-of-plane loading, the walls were fixed at the base and cantilevered from the shake table. By determining the frequency and amplitude that generated the cracking moment in the baseline unreinforced wall, the remaining three CFRP reinforced walls were tested at the same frequency and amplitude. The results from the testing of the three CFRP reinforced walls are presented along with time histories showing the shake table displacement and wall’s tip displacement versus time. In general, fatigue of masonry walls reinforced with CFRP strips can be managed as long as the out-of-plane reinforcement has sufficient strength and development length. Additional findings were made as a result from the testing. The development length of a vertical CFRP strip can be increased by adding a horizontal CFRP strips near the critical section and surface damage to CFRP may have severe consequences.

Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

The primary objective of this thesis was to study how the behavior of flexure-dominated masonry shear-wall segments is affected by changes in the normalized axial load and the percentage of vertical reinforcement. Six reinforced masonry shear-wall segment were constructed and tested at the Ferguson Structural Engineering Laboratory of the University of Texas at Austin. Specimens were 96-in. wide and 96-in. high (aspect ratio equal to 1.0) and were tested with different combinations of axial load ratio (zero and 0.10) and vertical reinforcement ratios (0.33% and 0.16%). Specimens met the 2011 MSJC Code requirements for special reinforced masonry shear walls, and were tested under quasi-static in-plane reversed cyclic loads. The specimens exhibited predominantly flexural behavior, as expected. Specimens exhibited high displacement ductility (5.6 to 16.7), as expected for flexure-dominated specimens. Specimens constructed with "green" units behaved essentially like otherwise identical specimens constructed with conventional ("gray") units. / text

The primary objective of this thesis was to study how the behavior of flexure-dominated masonry shear-wall segments is affected by changes in the normalized axial load and the percentage of vertical reinforcement. Six reinforced masonry shear-wall segment were constructed and tested at the Ferguson Structural Engineering Laboratory of the University of Texas at Austin. Specimens were 96-in. wide and 96-in. high (aspect ratio equal to 1.0) and were tested with different combinations of axial load ratio (zero and 0.10) and vertical reinforcement ratios (0.33% and 0.16%). Specimens met the 2011 MSJC Code requirements for special reinforced masonry shear walls, and were tested under quasi-static in-plane reversed cyclic loads. The specimens exhibited predominantly flexural behavior, as expected. Specimens exhibited high displacement ductility (5.6 to 16.7), as expected for flexure-dominated specimens. Specimens constructed with “green” units behaved essentially like otherwise identical specimens constructed with conventional (“gray”) units. / text

Due to increasingly stringent requirements on concrete performance and complexity of our infrastructures, concrete with not only high strength but also all-round high performance is called for. This puts forth the notion of the so-called high-performance concrete (HPC). However, one major hurdle in the development of HPC is that the technology is still based largely on empirical approaches. For further advancement of concrete technology into concrete science, it is advocated to adopt a more scientific approach, which can improve our understanding of concrete from a level of “know -how” to a level of “know-why”. The packing characteristics of solid particles have great influence on the performance of a concrete mix, but so far there is no generally accepted method of measurement. Herein, a new wet packing method was developed and applied to blended aggregates and concrete mixes. The results for blended aggregates revealed that whilst the packing density of coarse aggregate is only slightly higher under wet condition than dry condition, the packing density of a blended fine plus coarse aggregate is significantly higher under wet condition. Furthermore, the results for concrete mixes showed that the packing density is substantially higher and the filling effects of ultrafine supplementary cementitious materials are much better revealed under wet condition. Hence, the conventional dry packing method should be abandoned and replaced by the wet packing method. It is well known that the fresh properties of paste/mortar/concrete are governed mainly by the mix parameters: water content, packing density and solid surface area. However, these mix parameters vary simultaneously and therefore their individual and combined effects are difficult to evaluate. It has been found recently by others that the combined effects of these parameters may be evaluated in terms of the water film thickness (WFT), which has the physical meaning of the average thickness of water films coating the solid particles. Herein, it was proposed that besides the WFT, the paste film thickness (PFT) and mortar film thickness (MFT) should also have effects on the performance of mortar and concrete. Extensive tests and correlations of the measured properties of mortar to the WFT and PFT revealed that whilst the WFT is the single most important factor governing the properties of mortar, the PFT also has significant effects, especially on the cohesiveness and adhesiveness. Likewise, the results for concrete revealed that whilst the WFT and PFT have significant effects on the properties of concrete, the MFT also has significant effects, especially on the cohesiveness and passing ability. Based on the above findings, it may be concluded that the major factors governing the performance of concrete are the WFT, PFT and MFT. With the correlations of the various performance attributes of concrete to these factors so established, the door is open for the eventual development of a more scientific “three-tier mix design method” for HPC, by which the concrete mix is designed in three tiers: first the WFT of the paste portion, then the PFT of the mortar portion and finally the MFT of the concrete mix. / published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

This thesis investigates the design of masonry shell structures. Design is understood to involve two main processes; the first one is the specification of shape, form, and thickness, and the second is the justification of such choices through the analysis of its behaviour. The thesis is therefore introduced by an extensive literature review of, first of all, the relevant material properties, such as strength, stiffness, anisotropy, and bi-axial stress states, as well as of some interesting construction techniques, based on minimal or no formworkthe premise being that the contemporary adoption, or otherwise, of masonry shells as a feasible structural solution depends on the "economics" of the construction process. The analysis of the strength of masonry arches and shells is reviewed extensively, with considerable emphasis given to the validity of the application of limit analysis to masonry shells, in view of the presence of finite friction. Techniques for the form-finding of shells and for the optimisation of such forms, are then studied, and a finite-element technique developed for the finding of membrane thrust surfaces for shells incapable of carrying tension (as well as having possibly orthotropic properties). The technique is based on the solution of the partial differential equation relating shape, stress and loading, given a specific loading regime, and specific boundary conditions. The stress distribution, satisfying the given boundary and material conditions, is obtained, not on the basis of a trial-and-error approach, as is often the case, but on a plane stress analysis of the horizontal projection of the shell. The resultant shape hence automatically satisfies the boundary conditions. Various examples of the results of such method are given.

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Masonry infilled walls have been commonly used as interior partitions as well as exterior walls infilled in either steel or reinforced concrete frames in the modern building constructions. In recent years, much research involving both experimentation and numerical modeling has been conducted in an effort to better understand the infill-frame interaction and to provide some rational design approaches. Studies have shown that infill walls can develop a number of possible failure mechanisms, depending on the strength and stiffness of the bounding frames with respect to those of the infills and the geometric configuration of the framing system. Most of models proposed for analysis of infill walls focused on one type of mechanism or the other, and they were not universally applicable to all infilled structures.

No description available.