Browsing by Author "Ledezma, Christian"

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    Earthquake-induced pressures on discontinuous piling support on Santiago gravel
    (ELSEVIER SCI LTD, 2012) Saez, Esteban; Ledezma, Christian
    Discontinuous anchored piling support (anchored soldier piles without lagging) is one of the most frequent earth-retaining systems used in temporary deep excavations in Santiago, Chile. The main advantages of using discontinuous piling support are their relatively low cost and ease of installation. This system is particularly efficient on stiff soils with deep groundwater table, conditions usually found in Santiago. This paper presents a numerical investigation of the characteristics of earthquake induced lateral pressures on discontinuous pile-supported excavations in Santiago gravel. An equivalent bi-dimensional plane-strain model was developed on the basis of a more refined 3D model in order to quantify the influence of the "arching effect" on the dynamic lateral earth-pressures. The dynamic response was studied for a suite of Chilean ground motion recorded on rock in order to evaluate the variability of the dynamic pressures and their influence on the piles' internal forces. These results are then compared against some simplified design recommendations. (C) 2012 Elsevier Ltd. All rights reserved.
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    Effects of Ground Failure on Bridges, Roads, and Railroads
    (EARTHQUAKE ENGINEERING RESEARCH INST, 2012) Ledezma, Christian; Hutchinson, Tara; Ashford, Scott A.; Moss, Robb; Arduino, Pedro; Bray, Jonathan D.; Olson, Scott; Hashash, Youssef M. A.; Verdugo, Ramon; Frost, David; Kayen, Robert; Rollins, Kyle
    The long duration and strong velocity content of the motions produced by the 27 February 2010 Maule earthquake resulted in widespread liquefaction and lateral spreading in several urban and other regions of Chile. In particular, critical lifeline structures such as bridges, roadway embankments, and railroads were damaged by ground shaking and ground failure. This paper describes the effects that ground failure had on a number of bridges, roadway embankments, and railroads during this major earthquake. [DOI: 10.1193/1.4000024]
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    Effects of Ground Failure on Buildings, Ports, and Industrial Facilities
    (EARTHQUAKE ENGINEERING RESEARCH INST, 2012) Bray, Jonathan; Rollins, Kyle; Hutchinson, Tara; Verdugo, Ramon; Ledezma, Christian; Mylonakis, George; Assimaki, Dominic; Montalva, Gonzalo; Arduino, Pedro; Olson, Scott M.; Kayen, Robert; Hashash, Youssef M. A.; Candia, Gabriel
    Soil liquefaction occurred at many sites during the 2010 Maule, Chile, earth-quake, often leading to ground failure and lateral spreading. Of particular interest are the effects of liquefaction on built infrastructure. Several buildings were damaged significantly due to foundation movements resulting from liquefaction. Liquefaction-induced ground failure also displaced and distorted waterfront structures, which adversely impacted the operation of some of Chile's key port facilities. Important case histories that document the effects of ground failure on buildings, ports, and industrial facilities are presented in this paper. [DOI: 10.1193/1.4000034]
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    From Multi-Risk Evaluation to Resilience Planning: The Case of Central Chilean Coastal Cities
    (2019) Barria, Pilar; Luisa Cruzat, Maria; Cienfuegos, Rodrigo; Gironas, Jorge; Escauriaza Mesa, Cristian Rodrigo; Bonilla, Carlos; Moris, Roberto; Ledezma, Christian; Guerra, Maricarmen; Rodriguez, Raimundo; Torres, Alma
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    Probabilistic Performance-Based Procedure to Evaluate Pile Foundations at Sites with Liquefaction-Induced Lateral Displacement
    (ASCE-AMER SOC CIVIL ENGINEERS, 2010) Ledezma, Christian; Bray, Jonathan D.
    Liquefaction-induced ground deformation has caused major damage to bridge and wharf structures in past earthquakes. Large lateral ground displacements may induce significant forces in the foundation and superstructure, which may lead to severe damage or even collapse. A performance-based earthquake engineering (PBEE) approach can provide an objective assessment of the likely seismic performance, so that agencies can evaluate bridge or wharf structures, compare retrofit strategies, and rank them within their overall system. In this paper, a probabilistic PBEE design procedure that incorporates findings from recent research on this problem is presented. The proposed approach can provide answers in terms that are meaningful to owners, such as expected repair costs and downtimes. The methodology is validated through its application to a well-documented case history. Results show that the proposed approach provides a good estimate of the seismic performance of pile-supported structures at sites with liquefaction-induced lateral displacement.
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    Site Effects and Damage Patterns
    (EARTHQUAKE ENGINEERING RESEARCH INST, 2012) Assimaki, Dominic; Ledezma, Christian; Montalva, Gonzalo A.; Tassara, Andres; Mylonakis, George; Boroschek, Ruben
    A set of observations on site effects and damage patterns from the M-w 8.8 Maule, Chile, earthquake is presented, focusing on identification of structural damage variability associated with nonuniform soil conditions and subsurface geology. Observations are reported from: (1) the City of Santiago de Chile (Americo Vespucio Norte Ring Highway, Ciudad Empresarial business park), (2) the Municipality of Vina del Mar, and (3) the City of Concepcion, extending over 600 km along the Chilean coast. Reconnaissance information and ground motion recordings from the megathrust event are combined with site investigation data in the regions of interest. Comparisons against macroseismic observations related to uneven damage distribution from the M-w 8.0 1985 Valparaiso earthquake are discussed. Complexities associated with identifying the mechanics and underlying physical processes responsible for the manifestation of these effects are elucidated. [DOI: 10.1193/1.4000029]