Time filter
Source Type

Phillips C.,Ingetec | Hashash Y.M.A.,University of Illinois at Urbana - Champaign | Olson S.M.,University of Illinois at Urbana - Champaign | Muszynski M.R.,University of Illinois at Urbana - Champaign
Soil Dynamics and Earthquake Engineering | Year: 2012

Lateral spreads are complex dynamic phenomena that are challenging to represent numerically. In this paper numerical models are developed and calibrated using the displacement, acceleration, and pore water pressure time histories recorded in a free-field lateral spreading centrifuge test. The calibrated numerical model then is used to predict another free-field lateral spreading centrifuge test using the same soil profile but different input acceleration time history. The computed response shows good agreement with the centrifuge test measurements. This paper demonstrates that even in a large strain problem, such as lateral spreading, small strain damping plays an important role in numerical simulation results; it also shows the need to have pressure dependent dilation parameters in the employed soil constitutive model implemented in order to simultaneously reproduce measurements of pore water pressure, acceleration and lateral displacement. © 2012 Elsevier Ltd.

Phillips C.,INGETEC | Kottke A.R.,University of California at Berkeley | Hashash Y.M.A.,University of Illinois at Urbana - Champaign | Rathje E.M.,University of Texas at Austin
Soil Dynamics and Earthquake Engineering | Year: 2012

The discrete nature of the numerical methods utilized in 1D site response analysis and calculation of the response spectra (e.g., frequency domain, Duhamel integral, and Newmark Β methods) introduces time-step dependence in the resulting solution. Using an input ground motion with too large of a time-step leads to under-prediction of high-frequency characteristics of the system response due to limitations in the numerical solution of single and multiple degree of freedom systems. In order to reduce potential errors, using a sampling rate at least ten times greater than the maximum considered frequency is recommended. The preferred alternative is selection of input ground motions with a sufficiently small time step to avoid introducing numerical errors. However, where such motions are not available, then the time step of the ground motion can be reduced through interpolation. This paper demonstrates that the use of Fourier transform zero-padded interpolation is the preferred approach to obtain a ground motion with an adequate time step for the calculation of the elastic acceleration response spectra, and to analyze site response using either frequency or time domain methods. © 2012 Elsevier Ltd.

Pulido Herrera E.,Vienna University of Technology | Kaufmann H.,Vienna University of Technology | Secue J.,INGETEC | Quiros R.,Jaume I University | Fabregat G.,Jaume I University
Information Fusion | Year: 2013

A fault detection and correction methodology for personal positioning systems for outdoor environments is presented. We demonstrate its successful use in a system consisting of a global positioning system receiver and an inertial measurement unit. Localization is based on the dead reckoning algorithm. In order to obtain more reliable information from data fusion, which is carried out with Kalman filtering, the proposed methodology involves: (1) evaluation of the information provided by the sensors and (2) adaptability of the filtering. By carefully analyzing these factors we accomplish fault detection in different sources of information and in filtering. This allows us to apply corrections whenever the system requires it. Hence, our methodology consists of two stages. In the first stage, the evaluation is conducted. We apply the principles of causal diagnosis using possibility theory by defining states for normal behavior and for fault states. When a fault occurs, corrective measures are applied according to empirical knowledge. In the second stage, the consistency test of the filtering is performed. If this is inconsistent, principles of adaptive Kalman filtering are applied, which means the process and measurement noise matrices are tuned. Our results indicate a reasonable improvement of the trajectory obtained. At the same time, we can achieve consistent filtering, to obtain a more robust system and reliable information. © 2011 Elsevier B.V. All rights reserved.

Smith-Pardo J.P.,Seattle University | Reyes J.C.,University of Los Andes, Colombia | Ardila-Bothia L.,University of Los Andes, Colombia | Villamizar-Gonzalez J.N.,University of Los Andes, Colombia | Ardila-Giraldo O.A.,Ingetec
Engineering Structures | Year: 2015

Studying the interaction between a structure under base excitation and the objects that it supports is relevant to the seismic design of storage facilities like waterfront yards that carry heavy and nearly permanent container stacks. In the event of a major earthquake, objects may slide/rock and this dynamic action affects the way in which the supporting structure responds to the ground motion. Because such movement is accompanied by energy dissipation associated to friction and/or impact, only a portion of the live load effectively contributes to the inertial forces acting on the structure. This paper presents a lumped-parameter model that describes the seismic behavior of a single-degree-of-freedom (SDF) structure supporting a rigid block with the possibility to slide. After evaluating its capability using finite element software and shake table test results, the numerical model was implemented in a statistical methodology to quantify the portion of the block's mass that should be considered as inertia in the seismic design of one-story storage structures. Various structural periods T, friction coefficients μ, block-to-structure mass ratios α, response modification factors R were included in a parametric study, which involved thousands of analysis cases. In addition, two seismic hazard levels were considered consistent with service and extreme conditions. It was found that the portion of live load that should be included as inertia in seismic design increases significantly with T, μ, and R. However, the variable that best correlates with seismic mass is the total acceleration Amax experienced by the SDF platform alone. If Amax is small, the blocks may behave as rigidly attached to the structure, so their total mass should be included as inertia in the seismic analysis of storage facilities; this may be the case of structures subjected to service ground motions or designed for R values larger than 3. Finally, a design expression is proposed to estimate the portion of the live load to be included as inertia in function of the maximum total floor acceleration, the live load to structure self-weight ratio and the friction coefficient at the block-structure interface. © 2015 Elsevier Ltd.

Alvarez F.R.,INGETEC | Torres A.T.,INGETEC | Escobar C.M.,INGETEC | Aristizabal J.H.,Ecopetrol SA
ASME 2015 International Pipeline Geotechnical Conference, IPG 2015 | Year: 2015

The Colombian petroleum pipelines go through different types of geomorphologies and geological settings; so that the pipeline system is exposed to a variety of processes such as landslides, erosion, scour, sedimentation, and karstification. In order to prevent some of the effects caused by these processes, geotechnical remedial works have been designed and implemented over time. However, in some cases the remedial actions have not exhibited a proper behavior. For this reason, a better understanding of local conditions is required in order to conceive more effective solutions. This paper provides an overview of a methodological framework for geotechnical assessment and design of mitigation measures based on the evaluation of geological and geomorphological aspects, computational tools, and data processing. Finally, the characteristics of an existing and unsuccessful mitigation civil work are described, and a brief summary of the relevant geotechnical aspects of the proposed design are presented. © Copyright 2015 by ASME.

Marulanda A.,INGETEC
Underground - The Way to the Future: Proceedings of the World Tunnel Congress, WTC 2013 | Year: 2013

In the past ITA has advocated for the inclusion of certain provisions and contractual principles in underground construction contracts. However, ITA has refrained from advocating for the implementation of an international tunneling code, partly due to legal and cultural differences around the world. Based on the successful experience of several hundred kilometers of tunnels that have been designed and built in Latin America following Alpine tunneling principles and contractual practices, this article argues that ITA should promote the introduction of an international tunneling code and that the basis for this code could be the Swiss Tunnel Code (SIA 198- G), which incorporates many of the best contractual practices promoted by ITA for decades. © 2013 Taylor & Francis Group.

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