Browsing by Author "Alarcón Olivari, Cristóbal Nicolás"
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- ItemCharacteristics and displacement capacity of reinforced concrete walls in damaged buildings during 2010 Chile earthquake(2015) Alarcón Olivari, Cristóbal Nicolás; Hube Ginestar, Matías Andrés; Junemann, Rosita; Llera Martin, Juan Carlos de laAbout 2 % of reinforced concrete (RC) buildings taller than nine stories suffered important structural damage during 2010 Chile earthquake. The typical structural configuration of residential buildings is characterized by a large number of RC structural walls which provides high lateral stiffness and strength. The first objective of this paper is to obtain global geometric and design parameters of RC structural walls in damaged buildings and correlate their values with the observed damage. The second objective is to compare the roof displacement capacity with the roof displacement demand in critical walls, and hence, try to explain the observed damage. The wall parameters were obtained from five representative damaged structural wall buildings; these are: wall thickness, aspect ratio, axial load, reinforcement ratios, and the ratio between horizontal reinforcement spacing and the vertical bar diameter. The roof displacement capacity is obtained using a plastic hinge approach, and the ACI 318-08 approach, since both methods are proposed in the current Chilean seismic code. The displacement demand is estimated from ground motions recorded in the vicinity of the buildings. It is found that values of wall parameters correlate well with the observed damage. The structural walls were subjected to relatively high axial loads, and some walls included a large amount of vertical reinforcement to provide the required strength, but had inadequate transverse reinforcement thus compromising ductility. Findings from this research suggest that the plastic hinge approach is inadequate to estimate the roof displacement capacity and lacks correlation with the observed damage. Moreover, the use of the ACI 318-08 approach to estimate the roof displacement capacity is also inadequate, but leads to better predictions of wall displacement capacity. As shown by the results of response history analysis, the failure of walls was triggered by high axial loads rather than flexural deformation.
- ItemEffect of axial loads in the seismic behavior of reinforced concrete walls with unconfined wall boundaries(Elsevier Sci Ltd, 2014) Alarcón Olivari, Cristóbal Nicolás; Hube Ginestar, Matías Andrés; Llera Martin, Juan Carlos de la; Pontificia Universidad Católica de Chile. Department of Structural and Geotechnical Engineering; Pontificia Universidad Católica de Chile. National Research Center for Integrated Natural Disaster ManagementAbout 2% of Reinforced Concrete (RC) buildings taller than nine stories suffered serious damage in structural walls during the 2010 Chile earthquake. The observed damage involved mostly crushing of concrete, buckling of vertical reinforcement, and opening of the horizontal reinforcement. This damage is attributed to poor concrete confinement in the web and boundaries, inadequate horizontal reinforcement detailing, and high axial loads. This research aims to reproduce the observed damage and evaluate the influence of axial loads in the seismic behavior of RC walls with unconfined boundaries. To achieve these objectives, three identical wall specimens were tested. The wall specimens were designed with characteristic wall detailing obtained from data of five damaged buildings. These wall specimens were tested under equal lateral displacement cycles and subjected to different axial load ratios. The flexural-compressive failure mode exhibited by damaged walls during the earthquake was reproduced in these tests. Experimental results indicate that high axial load has a significant effect on the seismic performance and failure mode of RC walls. Indeed, it triggers a dangerous brittle concrete crushing failure which occurs immediately after spalling of the concrete cover. (C) 2014 Elsevier Ltd. All rights reserved.
- ItemInfluence of axial load in the seismic behavior of reinforced concrete walls with nonseismic detailing(2013) Alarcón Olivari, Cristóbal Nicolás; Hube Ginestar, Matías Andrés; Pontificia Universidad Católica de Chile. Escuela de IngenieríaAproximadamente el 2% de los edificios de hormigón armado de 9 pisos o más sufrió daño serio en el terremoto de Chile de 2010. El daño observado en estos muros consistió principalmente en aplastamiento del hormigón, pandeo del refuerzo vertical y apertura del refuerzo horizontal. Este daño se atribuye al bajo confinamiento del hormigón, el detallamiento inadecuado de la armadura de borde y cargas axiales elevadas. Los objetivos de esta tesis son reproducir el daño observado y estudiar la influencia de la carga axial en el comportamiento sísmico de muros de hormigón armado sin detallamiento sísmico. Para cumplir estos objetivos, se diseñaron tres muros a escala 1:2 con características representativas de los edificios chilenos dañados. Estas características fueron obtenidas de cinco edificios que sufrieron daño en el terremoto del 2010. Los muros se ensayaron bajo ciclos de desplazamientos laterales y sujetos a diferentes razones de carga axial de 0.15, 0.25 y 0.35.