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Interaction domain in non-prestressed circular concrete bridge piers using simplified modified compression field theoryAbouelleil, Alaaeldin January 1900 (has links)
Master of Science / Department of Civil Engineering / Hayder Rasheed / The importance of the analysis of circular columns to accurately predict their ultimate confined capacity under shear-flexure-axial force interaction domain is recognized in light of the extreme load event imposed by the current AASHTO LRFD specification. In this study, various procedures for computing the shear strength are reviewed. Then, the current procedure adopted by AASHTO LRFD 2014, based on the simplified modified compression field theory, is evaluated for non-presetressed circular concrete bridge piers. This evaluation is benchmarked against experimental data available in the literature and against Response 2000 freeware program that depicts interaction diagrams based on AASHTO 1999 requirements. Differences in results are discussed and future improvements are proposed. A new approach is presented to improve the accuracy of AASHTO LRFD calculations. The main parameters that control the cross section shear strength are discussed based on the experimental results and comparisons.
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[es] DIAGRAMAS DE INTERACCIÓN PARA EL DIMENSIONAMIENTO DE PILARES ESBELTOS Y SECCIONES DE CONCRETO DE ALTA RESISTENCIA / [pt] DIAGRAMAS DE INTERAÇÃO PARA O DIMENSIONAMENTO DE PILARES ESBELTOS E SEÇÕES DE CONCRETO DE ALTA RESISTÊNCIA / [en] INTERACTION DIAGRAMS FOR THE DESIGN OF HIGH STRENGTH CONCRETE SLENDER COLUMNS AND CROSS-SECTIONSEVELYN GABBAY ALVES 01 August 2001 (has links)
[pt] A utilização do concreto de alta resistência já é uma
realidade e muitos países estão adaptando suas normas para
levar em conta as propriedades deste material. No
dimensionamento de pilares esbeltos e seções com concreto
de alta resistência é importante observar a relação tensão-
deformação adotada no cálculo, pois enquanto para o
concreto convencional a deformação máxima, ecu, é 0,0035,
para o de alta resistência esta deformação depende do valor
da resistência do concreto, diminuindo com o aumento do
fck. Para um concreto com fck = 80 MPa, por exemplo,
ecu é em torno de 0,0022 de acordo com as relações tensão -
deformação propostas pelo MC90-CEB. A relação tensão-
deformação com ecu dependente de fck irá alterar os
diagramas de interação adimensionais para o dimensionamento
de pilares esbeltos e concreto de alta resistência. São
construídos neste trabalho diagramas de interação força
normal - momento fletor - curvatura (n,m,f) e força normal -
momento fletor - índice de esbeltez (n,m,l) para o
dimensionamento de pilares esbeltos e diagramas de
interação (nd,md) e (nd,mdx,mdy) para o dimensionamento de
seções submetidas a flexão composta reta e oblíqua. Adotou-
se a relação tensão-deformação proposta pelo MC90-CEB e
valores de fck de 50 a 80 MPa. Os diagramas para pilares
esbeltos foram construídos com auxílio do programa PCFRAME
(KRÜGER, 1989) e os diagramas para o dimensionamento de
seções foram construídos com um programa desenvolvido neste
trabalho. Através dos resultados, observa-se que, como ecu
depende de fck, todos os diagramas de interação sofreram
diferenças, podendo ser dito ainda que o uso dos
diagramas já existentes, construídos com ecu constante e
igual a 0,0035, pode conduzir a erros contra a segurança
estrutural. / [en] The use of high strength concrete is already a reality and
many countries are adapting their design codes to take into
account the properties of this material. For the design of
slender columns and sections subjected to combined axial
force and bending, the most important property is the
stress-strain relationship. While for normal concrete
the strain at ultimate, ecu, can be considered constant and
equal to 0,0035, for high strength concrete ecu depends on
the concrete strength, decreasing as the strength
increases. For a concrete with fck of 80 MPa, for instance,
ecu is around 0,0022 according to the CEB Model Code (1990).
Stress-strain relationship with ecu dependent of fck will
affect the nondimensional interaction diagrams for the
design of slender columns and sections of high strength
concretes. Nondimensional interaction diagrams moment-axial
load-curvature (m,n,f) and diagrams moment-axial load-
slenderness ratio (m,n,l), for the design of slender
columns, and nondimensional interaction diagrams (md,nd)
and (nd,mdx,mdy) , for compression plus axial and biaxial
bending of sections, are constructed in this work. The
diagrams were constructed for concretes with strength
between 50 MPa and 80 MPa, adopting suitable stress-strain
relationships recommended by the CEB Model Code 1990. The
diagrams for slender columns were constructed with the aid
of an existing computational program developed in an
earlier thesis, while the diagrams for the design of
sections were constructed with a new program, specially
developed in this work. The results have shown that all
these diagrams are affected, even when presented in a
nondimensional form, when stress-strain diagrams with ecu
dependent of fck are adopted. The use of traditional
nondimensional interaction diagrams, constructed
with ecu constant and equal to 0,0035, may lead to errors
against structural safety. / [es] La utilización del concreto de alta resistencia es una realidad actual y muchos países estan
adaptando sus normas para tener en cuenta las propiedades de este material. En el
dimensionamiento de pilares esbeltos y secciones con concreto de alta resistencia es importante
observar la relación tensión-deformación que se adopta en el cálculo, porque mientras para el
concreto convencional la deformación máxima, ecu, es 0,0035, para el de alta resistencia esta
deformación depende del valor de la resistencia del concreto, diminuyendo con el aumento del fck.
Para un concreto con fck = 80 MPa, por ejemplo, ecu es en torno de 0,0022 de acordo con las
relaciones tensión - deformación propostas por el MC90-CEB. La relación tensión- deformación con
ecu dependente de fck alterará los diagramas de interacción adimensionales para el
dimensionamiento de pilares esbeltos y concreto de alta resistencia. En este trabajo se construyen
diagramas de interacción fuerza normal - momento flector - curvatura (n,m,f) y fuerza normal -
momento flector - índice de esbeltez (n,m,l) para el dimensionamiento de pilares esbeltos y
diagramas de interacción (nd,md) y (nd,mdx,mdy) para el dimensionamiento de secciones sometidas
a flexión compuesta recta y obliqua. se adoptó la relación tensión-deformación propuesta por el
MC90-CEB y valores de fck de 50 la 80 MPa. Los diagramas para pilares esbeltos fueron construidos
con auxilio del programa PCFRAME (KRÜGER, 1989) e implementamos un programa para obtener
los diagramas para el dimensionamiento de las secciones. A través de los resultados se observa que,
como ecu depende de fck, todos los diagramas de interacción sufren diferencias, y puede decirse que
el uso de los diagramas construidos con ecu constante e igual la 0,0035, pueden conducir a errores
que afectan la seguridad extructural.
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The Influence of the Recommended LRFD Guidelines for the Seismic Design of Highway Bridges on Virginia BridgesWidjaja, Matius Andy 26 August 2003 (has links)
The influence of the recommended LRFD Guidelines for the seismic design of highway bridges in Virginia was investigated by analyzing two existing bridges. The first bridge has prestressed concrete girders and is located in the Richmond area. The second bridge has steel girders and is located in the Bristol area. The analysis procedure for both bridges is similar. First the material and section properties were calculated. Then the bridge was modeled in RISA 3D. Live and dead load were imposed on the bridge to calculate the cracked section properties of the bridge. The period of vibration of the bridge was also calculated. After the soil class of the bridge was determined, the design response spectrum curve of the bridge was drawn. The spectral acceleration obtained from the design spectrum curve was used to calculate the equivalent earthquake loads, which were applied to the superstructure of the bridge to obtain the earthquake load effects. Live and dead loads were also applied to get the live and dead load effects. The combined effects of the dead, live and earthquake loads were compared to the interaction diagram of the columns and moment strength of the columns. The details of the bridge design were also checked with the corresponding seismic design requirement.A parametric study was performed to explore the effects of different column heights and superstructure heights in different parts of Virginia. The column longitudinal reinforcing was increased to satisfy the bridge axial loads and moments that are not within the column interaction diagram. / Master of Science
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