Thesis (MEng) -- University of South Australia, 1994

Thesis (M.S. in Civil Engineering)--Washington State University. / Includes bibliographical references.

Thesis (Ph. D.)--Lehigh University, 2006. / Includes vita. Includes bibliographical references (leaves 675-691).

The effects of the variability in strength and loading on the reliability of slender, reinforced concrete columns are investigated using the Monte Carlo simulation technique. The columns are considered to be axially loaded with equal end eccentricities and no lateral load. Variabilities in strength, axial load and eccentricity of axial loads are considered. A new procedure called the Implicit Uncorrelation Procedure has been developed to find the values of the failure function from the values of the basic variables named above. The allowable axial load at various eccentricity levels corresponding to a probability of failure of one in one hundred thousand has been found for three different cross sections. Seven different slenderness ratios are considered for each cross section. The results are compared with those obtained by following the code procedures outlined in CAN3-A23.3-M77 and CSA-A23.3 (1984). A change in the performance factor for moment magnification, ⌀m , (as given in CSA-A23.3 (1984)) is recommended in order to obtain a more accurate and consistent level of reliability in the design of slender reinforced concrete columns. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

Reinforced concrete (RC) columns are the primary load-bearing structural components in buildings. Over time these columns may need to be repaired or strengthened either due to defective construction, having higher loads than those foreseen in the initial design of the structure, or as a result of material deterioration or accidental damage. Three external strengthening methods, namely steel jacketing, concrete jacketing and composite jacketing, are commonly adopted for upgrading the ultimate load capacity of RC columns. Among these strengthening techniques for RC columns, steel jacketing, which is easy to construct, less prone to debonding and has better fire resistance than bonded plates, has been proven to be an effective retrofitting scheme and is the most commonly used. Different methods for strengthening existing RC columns have been proposed in the literature. However, no matter which jacket is used to strengthen RC columns, the adverse effects of pre-existing loads on stress-lagging between the concrete core and the new jacket have yet to be solved. In order to deal with this problem, a new postcompression approach was proposed for strengthening preloaded RC columns. In this approach, the slightly precambered steel plates were used. The advantages of this ‘post-compressed plates’ (PCP) strengthening technique are that both the strength and deformability of existing columns can be enhanced and the design life of old buildings can be prolonged. Due to the aforementioned advantages, the PCP strengthening technique was investigated in this study. To begin with, axial compression tests of the PCP strengthened columns were conducted. The overall response, in particular the internal force distribution between concrete and steel plates was obtained. It was observed that the plate thickness and preloading level had dominant effects on the behaviour of PCP strengthened columns. Subsequently, eccentric compression tests of PCP strengthened columns were undertaken. The behaviour of PCP strengthened columns was mainly affected by the degree of eccentricity and plate thickness. Placing flat and precambered steel plates on the tension and compression sides respectively of the RC columns and using post-compression method on the compression side can significantly improve the ultimate load capacity of RC columns under large eccentricity; while placing precambered steel plates on the side faces of the RC columns can significantly improve the ultimate load capacity of RC columns under small eccentricity. Finally, axial compression tests of PCP repaired fire-exposed columns were carried out. The ultimate load capacity of fire-exposed columns can be restored up to 72% of original level by using this post-compression approach. The corresponding theoretical models were also developed to predict the ultimate load capacity of PCP strengthened columns. Comparison of theoretical and experimental results showed that the theoretical models accurately predicted the load-carrying capacities of PCP strengthened columns. According to the experimental and theoretical results, a unified design procedure for the PCP strengthened columns was proposed to aid engineers in designing this new type of PCP strengthened columns and to ensure proper column detailing for desirable performance. The design procedure was validated by the available experimental and theoretical results. / published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

Thesis (PhD)--University of South Australia, 1996

Thesis (PhD)--University of South Australia, 1996

Thesis (PhD)--University of South Australia, 1996

Thesis (PhD)--University of South Australia, 1996

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains xxiv, 201 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 170-175).