Browsing by Author "Hube, Matias"

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    Compression behavior of square and circular SFRC columns confined with external steel straps
    (2024) Carrillo, Julian; Hube, Matias; Blandon, Carlos; Mata, Ramon; Abellan-Garcia, Joaquin
    Steel-Strapping Tensioning-Techniques (SSTT) have been proposed recently as a confinement strategy to enhance the strength and deformation capacity of new and existing Reinforced Concrete (RC) columns. Main advantages of SSTT are the low cost, simple installation and modest installation time. Existing methods to quantify the increase of the compressive strength and deformation capacity of actively confined concrete have been obtained considering conventional deformed steel. Additionally, previous studies have observed that toughness and deformation capacity of concrete increase when adding steel fibers to the concrete matrix. However, the combined effect of SSTT applied to Steel Fiber Reinforced Concrete (SFRC) columns has not been assessed. Hence, the objective of this study is to evaluate the compressive behavior of SFRC columns confined with SSTT. A total of 34 short columns with SFRC and plain concrete were subjected to monotonic compression tests. The studied variables consider the cross-section of the columns (square and circular), the steel fibers dosage (15, 30 and 60 kg/m3), 3 ), and the spacing of the steel straps (37.5, 50 and 75 mm). The obtained results demonstrate that the SSTT increased the compressive strength between 4 % and 18 %, and the deformation capacity up to 800 %. Additionally, the use of steel fibers was effective in further increasing the deformation capacity of columns confined with SSTT. A numerical model based on a database of 150 tests, where 34 are from this study, is also proposed to predict the compressive behavior of SFRC columns confined with SSTT.
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    Contribution of coupling elements to the seismic demand of walls in reinforced concrete buildings
    (2020) Ramos, Lilibeth; Hube, Matias
    Architectural configurations of reinforced concrete (RC) wall buildings force the connection of structural walls with beams, slabs and adjacent walls to distribute habitational spaces, generating interaction between those structural elements that results in a coupled structural system. Studies on resisting planes of RC buildings damaged during 2010 Chile earthquake suggest that the behavior of structural walls was highly influenced by the interaction of the resisting plane with the rest of the structure. Furthermore, researchers have identified 7the high levels of axial load as one of the principal causes of the observed wall damage on these buildings, and that a significant amount of this load comes from the seismic demands. However, there is uncertainty about how different coupling elements contribute to the seismic demands in RC walls. In this work, the seismic demands of axial load, shear and moment of RC walls are estimated from three buildings damaged during the 2010 earthquake using detailed finite element models that consider their three-dimensional layout. the contribution of coupling elements to the seismic demands of the studied RC walls is determined. Additionally, the effects of the assumed stiffness of structural elements over the seismic demands is evaluated. The results show that slabs have the largest contribution to the seismic axial load in walls, contributing with more that 90%, followed by adjacent walls and connecting beams. Furthermore, the obtained moment and shear diagrams of the studied walls are significantly different than those of cantilever walls, and it was found that the assumed stiffness of structural elements exerts an important effect on the prediction of the seismic demands in RC walls.
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    Structural Performance of Bridges in the Offshore Maule Earthquake of 27 February 2010
    (EARTHQUAKE ENGINEERING RESEARCH INST, 2012) Buckle, Ian; Hube, Matias; Chen, Genda; Yen, Wen Huei; Arias, Juan
    Of the nearly 12,000 highway bridges in Chile, approximately 300 were damaged in this earthquake, including 20 with collapsed spans. Typical failure modes include damage to connections between super- and substructures, unseating of spans in skewed bridges due to in-plane rotation, and unseated spans with some column damage due to permanent ground movement. Unusual failure modes include unseating of spans in straight bridges due to in-plane rotation, plate girder rupture due to longitudinal forces, scour and pier damage due to tsunami action, and collapse of a historic masonry bridge. The most common damage mode was the failure of super-to-substructure connections (shear keys, steel stoppers, and seismic bars), which is the most likely reason for the low incidence of column damage. Whereas the fuse-like behavior of these components is believed to have protected the columns, the lack of adequate seat widths led to the collapse, or imminent collapse, of many superstructures. [DOI: 10.1193/1.4000031]