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Title: Triaxial effects in concrete-filled tubular steel columns
Author: Sen, Hirak Kumar
Awarding Body: University of London
Current Institution: Imperial College London
Date of Award: 1969
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Abstract:
The work described in this thesis consists of three phases: Phase I - Uniaxial analysis: A computer program has been written in a form suitable for calculating the failure loads for a large number of eccentrically-loaded, circular or rectangular concrete-filled columns, using the uniaxial material properties and the part cosine-wave assumption. The experimental failure loads of 22 eccentrically-loaded square and rectangular columns are compared with the computed loads, and a satisfactory agreement is found, i.e. triaxial effects are negligible for the columns tested. Phase II - Stub columns: The elasto-plastic biaxial stresses in the steel are calculated from observed strains for 14 of the available tests on concentrically-loaded stub columns, using the generalised flow-law for plastic solids. The triaxial stresses in the concrete are then calculated from simple statics. It is found that near failure the longitudinal compression in the steel is approximately equal to threequarters of the uniaxial yield stress, and the hoop tension is half the longitudinal compression in magnitude, while the longitudinal compression in the concrete core is twice the strength of uncontained concrete. The equivalent longitudinal 'stress-strain relationships' for the steel and concrete are represented by equations, and a formula is given for predicting the failure load of concentrically-loaded stub columns. Phase III - Triaxial analysis: Moment-load-curvature characteristics are experimentally determined for 35 circular columns comprising 7 tube thicknesses with 5 levels of axial load for each thickness0 Triaxial effects are found to be insignificant when the axial load is less than 40 per cent of the sum of the uniaxial compressive strengths of the steel and concrete. For higher axial loads, triaxial effects are taken into account by using the equivalent stress-strain relationships of Phase II in a semi-rational analysis. All the experimental moment-load-curvature characteristics are numerically simulated on a digital computer.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.283364  DOI: Not available
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