No description available.

The research reported in this thesis was carried out in two phases to investigate the behaviour of reactive powder concrete (RPC) columns. In the first phase of this study, six steel fibre reinforced RPC columns of 150 mm square cross section were tested to failure under various loading eccentricities. The RPC mix contained 2 percent (by volume) of straight steel fibres with a concrete strength of about 150 MPa. The columns contained either 4 or 7 percent of longitudinal reinforcement but no tie reinforcement in the test region. All the columns failed in a controlled manner and no buckling of the longitudinal steel or cover spalling was observed, even well beyond the peak load. The tests revealed that stirrups can be significantly reduced for steel fibre reinforced RPC columns, which could lead to an increase in the speed of construction with an associated potential reduction in construction costs. In the second phase, 17 RPC columns were tested with 16 confined using carbon fibre reinforced polymer (CFRP). The concrete mix contained either no fibres or 2 percent (by volume) of straight steel fibres with concrete strength of approximately 160 MPa. The columns contained no conventional steel reinforcement. For the concentrically loaded specimens, failure occurred at or close to the peak loading and the CFRP increased the strength by 19 percent compared with the unconfined specimen. The tests showed that the formulae developed to predict the peak strength of concentrically loaded FRP confined conventional strength concrete columns, in general, overestimate the load carrying capacity of FRP confined RPC specimens. The CFRP was shown to be effective in controlling the failure for the eccentrically loaded specimens. There was no evidence, however, that the use of CFRP in the hoop direction significantly increased the strength of the columns. Three dimensional nonlinear FE analyses of the test specimens were undertaken using the program DIANA. The FE analyses showed a reasonable comparison with the experimental results for the specimens tested under eccentric loading.

Thesis (M.S.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed December 4, 2007) Includes bibliographical references (p. 184-186).

Thesis (Ph. D.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Chloride ion migration was studied under accelerated cathodic protection conditions using 6" x 6" x 6" mortar blocks of varying initial chloride content and water to cement ratios. An iron mesh embedded parallel to one face in the blocks acted as the cathode and zinc was thermally sprayed on the opposite face to form an anode. First, the potential response of two blocks was studied at a current density of 3 mA/ft��. One block was outfitted with a heat sink and moisture barrier while the other block was periodically wetted. Second, eight blocks were polarized at various current densities for a period of one year. In both sets of experiments, the blocks were maintained in controlled humidity and temperature. The potential across the blocks was recorded at periodic intervals and mortar samples were drilled to measure the chloride content as a function of aging. Based on observations of the first study a theoretical model was constructed which indicates that zinc based electrochemical products form at the zinc-concrete interface. The effect of the electrochemical product on raising the resistance across a cathodic protection set-up may be of consequence and should be further studied. Blocks polarized at 6 mA/ft�� exhibited similar behavior as the blocks polarized at 3 mA/ft��, but the response was twice as fast. This result indicates that studying cathodic protection under accelerated conditions is valid. The chloride content of samples obtained from one set of blocks over the course of the experiment was normalized against the initial chloride profile. The normalized profiles were calculated as a function of aging and they supported the hypothesis that chloride ions would move away from the rebar and towards the sprayed zinc anode under cathodic protection. / Graduation date: 2001

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (leaves 119-121). Also available in electronic version.

The close proximity to the New Madrid Seismic Zone and the significant population and infrastructure presents a potentially substantial risk for central U.S. cities such as Memphis, Tennessee. However, seismic provisions in currently adopted Memphis building codes for non-essential structures have a lower seismic design intensity level than the 2003 International Building Code (IBC) with broader acceptance nationally. As such, it is important to evaluate structures designed with these local seismic provisions to determine whether they will perform adequately during two different design-level earthquakes in this region. A four-story reinforced concrete (RC) moment frame with wide-module pan joists was designed according to current building codes relevant to the central U.S.: the 2003 IBC, the City of Memphis and Shelby County locally amended version of the 2003 IBC, and the 1999 Standard Building Code (SBC). Special moment frames (SMFs) were required for the IBC and SBC designs, but lower design forces in the amended IBC case study permitted an intermediate moment frame (IMF). However, the margin by which a SMF was required was very small for the SBC design. For slightly different conditions IMFs could be used. Nonlinear push-over and dynamic analyses using synthetic ground motions developed for Memphis for 2% and 10% probabilities of exceedance in 50 years were conducted for each of the three designs. The FEMA 356 recommended Basic Safety Objective (BSO) is to dually achieve Life Safety (LS) for the 10% in 50 years earthquake and Collapse Prevention (CP) for the 2% in 50 years earthquake. For the member-level evaluation, the SMF designs met the LS performance objective, but none of the designs met the CP performance objective or the BSO. However, the margin by which the SMF buildings exceeded CP performance was relatively small compared to that of the IMF building. Fragility curves were also developed to provide an estimate of the probability of exceeding various performance levels and quantitative performance limits. These relationships further emphasize the benefits of using an SMF as required by the IBC and, in this case, the SBC.

Non-corroding materials, such as Fibre-Reinforced Polymer (FRP) bars, are now being used as reinforcement for reinforced concrete structures in order to extend their lifetime and minimize maintenance costs. Because of the softer and brittle behaviour of GFRP bars, behaviour of structural members reinforced with this material is different than that of steel-reinforced members. In this study, 16 GFRP reinforced beams were constructed and tested under flexure and shear loads to failure. Effects of different variables, such as amount of longitudinal and lateral reinforcements, type of bars and concrete strength, were investigated for their effects. The flexural provisions of design codes, namely CSA S806-12, CSA S6-06, and report ACI 440.1R-06, were evaluated against the test data. The main provisions investigated are failure modes, ultimate strength, moment-curvature response, deflection, crack widths, and deformability.

Non-corroding materials, such as Fibre-Reinforced Polymer (FRP) bars, are now being used as reinforcement for reinforced concrete structures in order to extend their lifetime and minimize maintenance costs. Because of the softer and brittle behaviour of GFRP bars, behaviour of structural members reinforced with this material is different than that of steel-reinforced members. In this study, 16 GFRP reinforced beams were constructed and tested under flexure and shear loads to failure. Effects of different variables, such as amount of longitudinal and lateral reinforcements, type of bars and concrete strength, were investigated for their effects. The flexural provisions of design codes, namely CSA S806-12, CSA S6-06, and report ACI 440.1R-06, were evaluated against the test data. The main provisions investigated are failure modes, ultimate strength, moment-curvature response, deflection, crack widths, and deformability.

The close proximity to the New Madrid Seismic Zone and the significant population and infrastructure presents a potentially substantial risk for central U.S. cities such as Memphis, Tennessee. However, seismic provisions in currently adopted Memphis building codes for non-essential structures have a lower seismic design intensity level than the 2003 International Building Code (IBC) with broader acceptance nationally. As such, it is important to evaluate structures designed with these local seismic provisions to determine whether they will perform adequately during two different design-level earthquakes in this region. A four-story reinforced concrete (RC) moment frame with wide-module pan joists was designed according to current building codes relevant to the central U.S.: the 2003 IBC, the City of Memphis and Shelby County locally amended version of the 2003 IBC, and the 1999 Standard Building Code (SBC). Special moment frames (SMFs) were required for the IBC and SBC designs, but lower design forces in the amended IBC case study permitted an intermediate moment frame (IMF). However, the margin by which a SMF was required was very small for the SBC design. For slightly different conditions IMFs could be used. Nonlinear push-over and dynamic analyses using synthetic ground motions developed for Memphis for 2% and 10% probabilities of exceedance in 50 years were conducted for each of the three designs. The FEMA 356 recommended Basic Safety Objective (BSO) is to dually achieve Life Safety (LS) for the 10% in 50 years earthquake and Collapse Prevention (CP) for the 2% in 50 years earthquake. For the member-level evaluation, the SMF designs met the LS performance objective, but none of the designs met the CP performance objective or the BSO. However, the margin by which the SMF buildings exceeded CP performance was relatively small compared to that of the IMF building. Fragility curves were also developed to provide an estimate of the probability of exceeding various performance levels and quantitative performance limits. These relationships further emphasize the benefits of using an SMF as required by the IBC and, in this case, the SBC.