Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 556-561). Available also in a digital version from Dissertation Abstracts.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 110-111). Also available via the Internet.

Thesis (Ph.D.)--Aberdeen University, 1994. / Title from web page (viewed on Mar. 22, 2010). Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2005. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

The object of this thesis is twinfold. Firstly, to study and check the effective width requirements recommended by different committees¹ for the design of ribbed precast concrete load bearing walls. Secondly, to rationalize the practice of the designing of the precast prefabricated components of any general polygonal shape. The recommendations regarding the minimum thickness of a thin wall, the effective width, etc., have been specified for some cases in code books and other tentative specification books², in the form of rules of thumb. In these rules of thumb, several parameters which may be of significance, such as dimensions of the rib itself, are not taken into account. A finite element approach has been adopted to investigate various combinations of these parameters, as well as the effects of different boundary conditions. Similar problems arise also in the cases of T-beams, L-beams and design of aircraft structures, in which a stressed skin is mounted on ribs, which are assembled in the form of a space frame. So far interaction curves have been made available in some design books only for the prestressed concrete member having rectangular cross-sections and for any other shape, approximations are made, such as making a rectangular section having an equivalent area or having the same moment of inertia or section modulii, etc. But this practice seems very irrational especially in the case of precast components which are always produced in a factory on a mass scale. A computer program has been written which can give the interaction curve for the member of any polygonal shape. 1. DRAFT 3: Of PCI Committee, 'Recommendations for Prestressed Bearing Wall Design.' 2. 'Symposium on Precast Concrete Wall Panels.' Publications ACI, SP-11, Second Printing 1966, pp. 39-44. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

M.Ing. (Civil Engineering) / The shear strength of a concrete structure is usually determined in practice in accordance with the applicable national concrete design code. Calculation methods prescribed in national design codes differ from code to code and yield widely divergent results. The methods given for different cases in specific codes are often based on different approaches. Further, some of the methods do not agree with the observed behaviour during failure. This shows that there is a need for more accurate methods of determining shear strength, as well as approaches leading to universally applicable methods. A literature study was undertaken to establish whether such methods or approaches have already been developed. Special attention was given to the underlying mechanisms involved in shear resistance, to the shear resistance of concrete elements without shear reinforcement, of elements with varying depth, and of areas near points of contraflexure, and to punching resistance of flat slabs. A review of the latest research on the subject is given, and areas where further research is required, are identified.

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A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science in Engineering, Johannesburg, 2019 / Premature deterioration of reinforced concrete railway bridges before and after repair is a serious concern as it is costly and poses a major risk on safety and performance. Reinforced concrete railway bridges in aggressive environments (near the sea) face the risk of ingress of corrosion agents (oxygen, moisture and chlorides) into the concrete to the reinforcing steel. Although, corrosion of the reinforcing steel is not the only cause of structural deficiencies in railway bridges, it is a significant contributor to deterioration and therefore of major concern. In order to guide the selection of a suitable repair option, one repair material from each category (patch repair mortars, barrier systems, electrochemical methods and corrosion inhibitors) was investigated. The effectiveness of selection was assessed by employing electrochemical techniques to quantify the performance of each selected repair material in stifling chlorideinduced corrosion in reinforced concrete. This study focuses on the evaluation of selected repair materials for chloride-induced corrosion in reinforced concrete using 100 x 100 x 500 mm long beam specimens. The four selected repairs were applied to the reinforced concrete beams after a period of 200 days after casting. The beams had a constant concrete cover to reinforcing steel of 20mm. The beam specimens were casted using admixed chlorides into the mix and were subjected to a cycle of 3 days wetting (with 5% NaCl solution) and 4 days drying. The beam specimens were monitored for half-cell potential (Cu/CuSO4), corrosion rate (coulostatic technique) and concrete resistivity (Wenner probe technique). Results indicate that the selected repair materials in this study had varied influences on the halfcell potential and corrosion rate values. The patch repair material replaced the concrete cover with a more durable material, confirmed from the Durability Index (DI) tests conducted. The resistivity of the repair mortar was measured to be higher than the concrete. Due to the replacement of the concrete cover, the corrosion rate values reduced when compared to the control reinforced beam specimens. However, the half-cell potential values indicated the probability of corrosion is still high after application. The barrier method, applied a silane-based sealer on the reinforced concrete beams. The resistivity of the concrete increased after application of the barrier method. The corrosion rates after application of the barrier method was lower than the corrosion rates of the control reinforced concrete beams. The half-cell potential results indicated the corrosion risk is still high after application of the barrier method. The electrochemical repair was the only repair material that showed more negative potentials than the control beams and corrosion rates were significantly higher than all the other repair methods after application. The reason for this can be attributed to the zinc anode dominating the potential and corrosion rate values. Therefore, no conclusion can be made on the corrosion condition of the reinforcing steel. Alternative methods should be employed in determining the effectiveness of sacrificial anode repairs. / PH2020

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