Browsing by Author "Maria, Hernan Santa"

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    CFT Connections: State-of-the-art Report and Numerical Validation by 3D FEM
    (2024) Wilches, Jose; Leon, Roberto; Maria, Hernan Santa; Graterol, Anibal
    Connections between concrete filled members are common in tall buildings, bridges, and offshore structures because of their robust structural performance. While extensive research has been done on isolated concrete-filled structural members, relatively little research has been conducted on composite connection regions. This article first describes a database on experimental/analytical investigations on concrete-filled connections comprising 135 tests. It then develops a generic numerical model capable of capturing the entire range of behavior of these connections, including local buckling of the steel tubes and friction/contact resistance between steel and concrete. The model was calibrated against a single test and its performance was verified against three other very different tests. The results indicate that the four models can track well the strength and stiffness of the specimens up to ultimate and predict well different failure patterns. Comparisons of the experimental and numerical load-deformation curves show very good agreement in predicting the strength and deformations at which different behaviors arise, and that performance is controlled primarily by both the strength of the concrete and the confinement effect of the steel tube in the connection area.
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    Empirical fragility curves for houses in Chile using damage data from two earthquakes
    (2024) Cabrera, Tamara; Hube, Matias A.; Maria, Hernan Santa; Silva, Vitor; Martins, Luis; Yepes-Estrada, Catalina; Chacon, Matias F.
    Strong seismic events frequently strike Chile. The last three significant events that caused considerable damage and losses are the 2010 (Mw\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${M}_{w}$$\end{document} 8.8, Maule), 2014 (Mw\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${M}_{w}$$\end{document} 8.2, Iquique), and 2015 (Mw\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${M}_{w}$$\end{document} 8.3, Illapel) earthquakes. Therefore, reliable fragility curves are necessary to evaluate the threat of earthquakes to the built environment. This study aims to develop empirical fragility curves of Chilean houses using damage from the 2014 and 2015 earthquakes. The data from 9085 and 7431 damaged houses from the 2014 and 2015 earthquakes, respectively, was obtained by the government. The fragility curves were estimated for reinforced concrete, reinforced masonry, timber, and adobe houses. Additionally, the fragility curves were constructed using three different Peak Ground Acceleration (PGA) maps to quantify the variation of the fragility parameters based on the selected PGA map and to identify which PGA map generates the highest correlation with observed damage. Additionally, fragility curves obtained in this study are compared with curves from other studies. The median theta\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\theta$$\end{document} values of the fragility curves obtained in this study are larger than those from other reported studies.
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    Finite element analysis of the influence of dowel angle on CFRP anchors
    (2024) Jimenez, Jose Luis; Maria, Hernan Santa
    In current retrofitting design guidelines, carbon fiber reinforced polymer (CFRP) anchors are recognized as an efficient and minimally invasive approach to delaying delamination. Recent research has demonstrated the capability of Finite Element Method (FEM) models to accurately reproduce the behavior of experimentally tested CFRP anchors. Among the various design parameters of CFRP anchors, the dowel angle is one of the least studied, yet it is a crucial factor. There is limited experimental data available for this parameter and there are no numerical models focused on its influence on anchor behavior. This article reports the results of a comprehensive three-dimensional FEM model for CFRP anchors, with a particular emphasis on varying dowel angles. The model accuracy is verified against direct shear joint tests drawn from the literature, including aspects such as the maximum load, load-slip curves, and the distribution of strains along the CFRP. Subsequently, the model is used to conduct a sensitivity analysis of the dowel angle in conjunction with other important parameters for the design of CFRP anchors. These parameters are the length of the CFRP ply behind the anchor, the number of anchors within the joint, the fiber content, and the depth of the dowel. The results obtained from the modeling show an important influence of the dowel angle on the effective use of carbon fibers and the enhancement of joint strength. By offering insights into the interactions between the dowel angle and other design parameters, this research contributes information that can guide the development of design guidelines for the optimization of CFRP anchor systems.
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    Residual Seismic Capacity of Reinforced Concrete Walls with Unconfined Boundaries
    (2021) Moscoso, Jorge F.; Hube, Matias A.; Maria, Hernan Santa
    An experimental study was conducted to evaluate the residual seismic capacity of reinforced concrete (RC) walls with unconfined boundaries. Six walls were subjected to constant axial load and cyclic lateral loading protocols. Three walls were tested under one cyclic lateral loading protocol, and the other three walls were tested under two cyclic lateral loading protocols to induce initial damage. Primary test variables were the shear span-depth ratio and the target drift ratio of the initial loading protocols. Test results indicate that the six wall specimens showed a flexural dominated behavior. The residual crack widths measured in the three walls tested with initial damage were only 6% of the crack width suggested by FEMA 306 for the identified damage severity levels. The effective stiffness decreased significantly due to previous damage. Finally, the maximum strength was not considerably affected and the lateral drift capacity was not reduced due to previous damage.