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Effect of confinement on shear dominated reinforced concrete elementsPowanusorn, Suraphong 17 February 2005 (has links)
It has been demonstrated that transverse reinforcement not only provides the strength and stiffness for reinforced concrete (RC) members through direct resistance to external force demands, but also helps confine the inner core concrete. The confinement effect can lead to improved overall structural performance by delaying the onset of concrete fracture and allowing more inelastic energy dissipation through an increase in both strength and deformability of RC members.
The objective of this research was to evaluate the effect of confinement due to the transverse reinforcement on enhancing the shear performance of RC members. A new constitutive model of RC members was proposed by extending the Modified Compression Field Theory (MCFT) to incorporate the effect of confinement due to transverse reinforcement by adjusting the peak stress and peak strain of confined concrete in compression. The peak stress of confined concrete was determined from the five-parameter failure surface for concrete developed by Willam and Warnke (1974). The peak strain adjustment was carried out using a relationship proposed by Mander et al. (1988).
The proposed analytical model was compared with results from an experimental program on sixteen RC bent caps with varied longitudinal and transverse reinforcement details. Two-dimensional Finite Element Modeling (FEM) using the proposed constitutive model was conducted to numerically simulate the RC bent cap response. Results showed that the proposed analytical model yielded good results on the prediction of the strength but significantly overestimated the post-cracking stiffness of the RC bent cap specimens. The results also indicated that the confinement effect led to enhanced overall performance by increasing both the strength and deformability of the RC bent caps.
Two potential causes of the discrepancy in the underestimation of the RC bent cap deformations, namely the effects of concrete shrinkage and interfacial bond-slip between the concrete and main flexural reinforcement in the bent caps, were discussed. Parametric studies showed that the tension-stiffening in the proposed constitutive models to implicitly take into account the bond-slip between the concrete and main flexural reinforcement was the major cause of the overestimation of the post-cracking stiffness of RC bent caps. The explicit use of bond-link elements with modified local bond stress-slip laws to simulate the slip between the concrete and main flexural reinforcement led to good predictions of both strength and deformation.
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Seismic fragility estimates for reinforced concrete framed buildingsRamamoorthy, Sathish Kumar 25 April 2007 (has links)
Gravity load designed (GLD) reinforced concrete (RC) buildings represent a common
type of construction in the Mid-America Region. These buildings have limited lateral
resistance and are susceptible to story mechanisms during earthquake loading. Fragility
estimates are developed to assess the seismic vulnerability of GLD RC buildings in the
Mid-America Region. Fragility is defined as the conditional probability of reaching or
exceeding a performance level for a given earthquake intensity measure.
Five sample buildings of various story heights (1, 2, 3, 6, and 10 stories) are used to
represent generic RC frame buildings of 1 to 10 stories tall. A Bayesian methodology is
used to develop probabilistic demand models to predict the maximum inter story drift
given the spectral acceleration at the fundamental period of the building. The unknown
parameters of the demand models are estimated using the simulated response data
obtained from nonlinear time history analyses of the structural models for a suite of
synthetic ground motions, developed for Memphis, Tennessee. Seismic structural
capacity values are selected corresponding to the performance levels or damage states as
specified in FEMA-356 and as computed by nonlinear pushover analyses.
For the sample buildings, fragility estimates are developed using the predicted drift
demands and structural capacity values. Confidence bounds are developed to represent
the epistemic uncertainty inherent in the fragility estimates. In addition, bivariate fragility estimates, formulated as a function of spectral acceleration and the fundamental
building period, are developed from the fragility estimates of the individual buildings.
The bivariate fragilities can be used to quantify the seismic vulnerability of GLD RC
frame buildings of 1 to 10 stories. Using the Bayesian approach, a framework is
developed to update the analytical fragility estimates using observed damage data or
experimental test data. As an illustration of the updating framework, the analytical
bivariate fragility estimates for the sample buildings in the Mid-America Region are
updated using the damage data obtained from 1994 Northridge, California earthquake.
Furthermore, to investigate and demonstrate the increase in seismic performance
of the GLD RC frame buildings, the columns of the 2 and 3 story buildings are
retrofitted by column strengthening. Fragility estimates developed for the retrofitted
buildings show the effectiveness of the retrofit technique by the improved seismic
performance of GLD RC frame buildings.
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Detection of delaminations of FRP retrofitted reinforced concrete columnsKuper, Alan Benjamin. January 2009 (has links) (PDF)
Thesis (M.S. in civil engineering)--Washington State University, December 2009. / Title from PDF title page (viewed on Dec. 28, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 51).
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Condition auditing and repair of marine concrete structures in Hong KongLai, Tsan-kei. January 2001 (has links)
Thesis (M. Phil.)--University of Hong Kong, 2001. / Includes bibliographical references.
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Effect of compaction effort on SuperPave base course materialsAdamah, Cornelius. January 2009 (has links)
Thesis (M.S.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains viii, 79 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 52-54).
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Accelerated corrosion testing, evaluation and durability design of bonded post-tensioned concrete tendonsSalas Pereira, Rubén Mario, January 2003 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.
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Evaluation of tsunami loads and their effect on reinforced concrete buildings /Pacheco, Kason Hoku. January 2005 (has links)
Thesis (M.S.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references (leaf 184). Also available via World Wide Web.
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Exploratory study on high performance concrete for bridge decks in West VirginiaZhang, Wenbo, January 2001 (has links)
Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains x, 92 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 79-83).
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Concrete hydration, temperature development, and setting at early-agesSchindler, Anton Karel. January 2002 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.
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Pervious concrete paste composition a thesis presented to the faculty of the Graduate School, Tennessee Technological University /Phillips, Jason B., January 2009 (has links)
Thesis (M.S.)--Tennessee Technological University, 2009. / Title from title page screen (viewed on Mar. 3, 2010). Bibliography: leaves 87-91.
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