1,721,082 research outputs found
Failure load and collapse mode of an RC beam in a large collapsed roof
No full textThe present work focused on the determination of the collapse load and of the failure mode of a collapsed framed structure constructed in the South of Italy and failed in 2004 under its self-weight. Information available was the results on extensive experimental test campaign, for the determination of mechanical properties of concrete and steel bars of beams, floors and columns involved in the failure. Moreover, draws of original design with construction details and design rules valid in Italy at the time of construction were found.
A simple monodimensional beam model for prediction of load-deflection curve, able to include degradation of constituent materials (concrete, steel and bond) was developed.
Ultimate load predicted analytically at the time of the failure was very closed to that estimated on the structures at the time of collapse and due to the self-weight justifying the failure of building. Results obtained highlighted that concrete degradation phenomena were the main causes of collapse.
In addition, numerical analyses with Response (2000) and ATENA 3D (2004) were carried out to predict ultimate load, failure mode and crack patterns at failure. Results obtained numerically showed good agreement with available experimental data and with proposed one-dimensional model.
Comparison between simplified analytical and numerical responses showed that although the use of refined nonlinear finite element models give much more detailed information with respect to the one-dimensional model, but the latter can be very useful for preliminary check of the structures
Cyclic axial testing of columns confined with Fiber Reinforced Cementitious Matrix
No full textResults of monotonic and cyclic compression tests on medium size specimens of circular and prismatic low strength (15 MPa) concrete columns wrapped with Carbon Fiber Reinforced Cementitious Matrix (CFRCM) are reported. Unconfined and confined specimens with two different confinement volumetric ratios have been considered. Moreover, in order to investigate sharp edge effects on elements confined with CFRCM, two series of square and rectangular specimens have been tested, having rounded corner radius of 15mm and 30 mm. The comparison of stress-strain curves of the unconfined and confined specimens shows the ability of the composite to confer strength and ductility to the concrete, stressing the role played by cross section shape and corner radius
Compressive response of substandard steel-jacketed RC columns strengthened under sustained service loads: From the local to the global behavior
No full textThis paper presents an experimental investigation on substandard partially steel jacketed RC columns strengthened under sustained loads and loaded until failure. The aim of the study is to compare the compressive response of preloaded columns with respect to the tests without preload to obtain a more realistic prediction of load-carrying capacity of structural columns after retrofitting under serviceability loads. The influence of the preload level, the delayed contribution of the confining device during the loading process and the time dependent effects are highlighted for the tested specimens. Based on the experimental observations, an analysis-oriented model is proposed for the reproduction of the compressive response of steel jacketed columns taking into account the effects of the preload
Structural ductility in reinforced concrete buildings stiffened by cross braces- Criteria for dimensional optimization
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Risultati teorici e sperimentali sulla stabilità e la rigidezza di pannelli di controvento
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