This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
The aim of this paper is to present a performance-based method to estimate uniform risk spectra (... more The aim of this paper is to present a performance-based method to estimate uniform risk spectra (URS) for the seismic design and assessment of structures. These spectra, computed with the proposed methodology, provide the lateral capacity (in terms of spectral acceleration) that should be given to a structure, characterized by a reference single degree of freedom system, to achieve a predetermined exceedance rate of economic loss. This procedure involves the seismic hazard assessment necessary to define a seismic design level consistent with the accepted loss value, using a large enough number of synthetic seismic records of several magnitudes, which were obtained by means of an improved empirical Green function method. The statistics of the expected losses of a reference single degree of freedom system are obtained using Monte Carlo simulation, considering the seismic demand and the lateral strength of the structure as random variables. The method is divided into two main stages: (...
Earthquake Engineering & Structural Dynamics, 2008
An overview of the applicability of a typical single-mode pushover method (the N2 method) and two... more An overview of the applicability of a typical single-mode pushover method (the N2 method) and two typical multi-mode pushover methods (the modal pushover analysis (MPA) and incremental response spectrum analysis (IRSA) methods) for the analysis of single column bent viaducts in the transverse direction is presented. Previous research, which was limited to relatively short viaducts supported by few columns, has been extended to longer viaducts with more bents. The single-mode N2 method is accurate enough for bridges where the effective modal mass of the fundamental mode is at least 80% of the total mass. The applicability of this method depends on (a) the ratio of the stiffness of the superstructure to that of the bents and (b) the strength of the bents. In short bridges with few columns, the accuracy of the N2 method increases as the seismic intensity increases, whereas in long viaducts (e.g. viaducts with lengths greater than 500 m) the method is in general less effective. In the case of the analyzed moderately irregular long viaducts, which are common in construction design practice, the MPA method performed well. For the analysis of bridges where the modes change significantly, depending on the seismic intensity, the IRSA method is in principle more appropriate, unless a viaduct is torsionally sensitive. In such cases, all simplified methods should be used with care. Copyright
Determinación Experimental De Esfuerzos Residuales en Tubos De Acero Con Soldadura Helicoidal
This paper presents the results of an experimental study to evaluate the residual stresses in ste... more This paper presents the results of an experimental study to evaluate the residual stresses in steel pipes with helical welding made by TUBESA S.A. de C.V. The motivation of this was to validate the mechanical expansion procedure used for reducing the residual stresses generated during its fabrication. For the determination of the residual stresses the Hole-drilling Strain-Gage Method was used. Three specimens corresponding to three different levels of mechanical expansion were evaluated, and a fourth specimen, tested under hydrostatic pressure, was studied by a photo-elastic analysis to obtain its configuration of stresses when subjected to this type of loading.
This study evaluates the seismic risk of weak first-story reinforced concrete (RC) structures ret... more This study evaluates the seismic risk of weak first-story reinforced concrete (RC) structures retrofitted with inerter dampers at their ground level when subjected to narrow-band seismic excitations. The main advantages brought about by the ground-level inerters are the reductions in seismic demands (e.g., drifts, floor accelerations). This study shows that structures with inerters are reliable systems in terms of peak story drifts for large ground motions. For moderate ground-motion intensities, the opposite could occur, mainly for soft soil sites. The reliabilities of structures with inerter dampers at their ground level are in general higher for buildings under seismic intensities associated to limit state of incipient collapse, especially for low-height buildings. This could be reversed for intensities associated to the limit state of damage limitation. The findings of this study could guide practicing engineers to use inerter-based dampers in retrofitting ductile structures con...
This paper proposes a methodology and an equation to determine the vulnerability of masonry struc... more This paper proposes a methodology and an equation to determine the vulnerability of masonry structures taking into account the variability of mechanical properties due to lack of supervision during its construction in terms of three important parameters: the type of mortar defined by its resistance, the thickness of joints between bricks and the concrete strength on confinement beams and columns. The proposed expression is based on the statistical treatment of results obtained from carrying out Incremental Dynamic Analysis (IDA) using a set of seismic records for common structures built in the country. With the proposed expression the estimation of expected damage on masonry buildings under seismic actions will be more accurate.
This paper presents a Performance Based Seismic Design (PBSD) procedure to determine consistent u... more This paper presents a Performance Based Seismic Design (PBSD) procedure to determine consistent uniform hazard design spectra for structures with the same probability to reach a performance level for a given design level. The spectra correspond to given rates of exceedence of performance indices, chosen to represent the performance level for which a structure will be designed. Its formulation considers the nonlinear behaviour of the structures and an accepted distribution of damage under design conditions. This procedure involves the determination of the seismic hazard, necessary for the definition of design levels consistent with the PBSD philosophy; a sufficient large number of earthquakes of different magnitudes, simulated using the empirical Green function method; and the statistics of the response of equivalent single degree of freedom systems with behaviour curves function of the capacity curves of real structures, obtained using the Monte Carlo method. With these results the ...
Durante algunos eventos sísmicos recientes en México, se ha observado que, a pesar de haber un ad... more Durante algunos eventos sísmicos recientes en México, se ha observado que, a pesar de haber un adecuado comportamiento del sistema estructural, no siempre existe un adecuado comportamiento de los sistemas no estructurales. En esta investigación se llevan a cabo análisis no lineales paso a paso para estudiar el comportamiento de fachadas prefabricadas de concreto del tipo “piso a piso”, las cuales han presentado fallas y desprendimientos aun cuando la estructura no ha sufrido daño. Para alcanzar este objetivo, se evalúan los desplazamientos y aceleraciones de cada uno de los pisos de un edificio de 15 niveles y 4 crujías, donde se calcula el nivel de daño de diferentes paneles. Para obtener estas respuestas, se diseña el sistema estructural mencionado utilizando el Apéndice A de las Normas Técnicas Complementarias para Diseño por Sismo del Reglamento de Construcciones del Distrito Federal del 2004 y se realiza un análisis dinámico incremental utilizando el registro sísmico del sismo ...
Wind Risk Assessment of Electric Power Lines due to Hurricane Hazard
Natural Hazards Review, 2020
AbstractThis paper proposes a methodology to assess the wind risk of electrical transmission towe... more AbstractThis paper proposes a methodology to assess the wind risk of electrical transmission towers considering the coupling of the tower with the cables and a failure mechanism based on capacity. ...
Earthquake Engineering & Structural Dynamics, 2018
This paper presents a new methodology based on structural performance to determine uniform fragil... more This paper presents a new methodology based on structural performance to determine uniform fragility design spectra, i.e., spectra with the same probability of exceedance of a performance level for a given seismic intensity. The design spectra calculated with this methodology provide directly the lateral strength, in terms of yield-pseudo-accelerations, associated with the rate of exceedance of a specific ductility characterizing the performance level for which the structures will be designed. This procedure involves the assessment of the seismic hazard using a large enough number of seismic records of several magnitudes; these records are simulated with an improved empirical Green function method. The statistics of the performance of a single degree of freedom system are obtained using Monte Carlo simulation considering the seismic demand, the fundamental period, and the strength of the structure as uncertain variables. With these results, the conditional probability that a structure exceeds a specific performance level is obtained. The authors consider that the proposed procedure is a significant improvement to others considered in the literature and a useful research tool for the further development of uniform fragility spectra that can be used for the performance-based seismic design and retrofit of structures.
Probabilistic Wind Risk Assessment Induced by Hurricanes on Economically Vulnerable Households in Mexico
Natural Hazards Review, 2018
AbstractThe economically vulnerable households in Mexico are used as an illustrative case study t... more AbstractThe economically vulnerable households in Mexico are used as an illustrative case study to present wind risk assessment induced by hurricanes, in which the risk parameters are assessed in a...
In the distribution-free property testing model, the distance between functions is measured with ... more In the distribution-free property testing model, the distance between functions is measured with respect to an arbitrary and unknown probability distribution D over the input domain. We consider distribution-free testing of several basic Boolean function classes over {0, 1} n , namely monotone conjunctions, general conjunctions, decision lists, and linear threshold functions. We prove that for each of these function classes, Ω((n/ log n) 1/5) oracle calls are required for any distribution-free testing algorithm. Since each of these function classes is known to be distribution-free properly learnable (and hence testable) using Θ(n) oracle calls, our lower bounds are polynomially related to the best possible.
In this study, with the objective to develop a reliability-based seismic design tool, ductility a... more In this study, with the objective to develop a reliability-based seismic design tool, ductility and dissipated hysteretic energy uniform annual failure rate (UAFR) spectra are obtained and compared using the spectral acceleration at first mode of vibration of the structure Sa(T1) and the well-known spectral shape-based intensity measure INp. Notice that this is the first time in the literature that UAFR spectra are obtained for the advanced spectral shape intensity measure INp. For this aim, 110 simulated ground motions recorded from the soft soil of Mexico City were selected due to their large energy amount demanded to the structures; moreover, four elastoplastic hysteretic behavior models are considered for the dynamic analyses with post-yielding stiffness of 0, 3, 5, and 10%. It is observed that the use of elasto-perfectly plastic models provided similar UAFR spectra in comparison with hysteretic models with different post-yielding stiffness. This conclusion is valid for the two ...
We propose to obtain translational landslides due to earthquake in Mexico estimating Newmark disp... more We propose to obtain translational landslides due to earthquake in Mexico estimating Newmark displacements in terms of the relationship between the critical acceleration, ac (the peak ground acceleration threshold to start the landslide) and the peak ground acceleration, amax. With the obtained results from a proposed displacement equation it is possible to define a translational landslide map at regional level induced by earthquakes. Soil parameters such as cohesion, volumetric weight and angle of friction are inferred from geological maps, scale 1:1’000,000, and a digital elevation map is employed to obtain the slope of the potential landslide. We present a landslide hazard map for Mexico associated to a peak strong ground motion acceleration with a return period of 150 years at regional level, and an example map of displacements triggered by the
A risk index due to natural hazards based on the expected annual loss
Natural Hazards
This study proposes a risk index (RI) to identify the potential areas at national, sub-national a... more This study proposes a risk index (RI) to identify the potential areas at national, sub-national and local levels that may suffer losses to natural hazards, taking into account the expected physical damage to the structures. The quantitative measure of the risk is the expected annual loss obtained as a result of the formal probabilistic estimation of structural damage. To estimate RI, a computational system that takes into account the occurrence of all possible events and its exceedance rates for a given hazard and the characteristics of the local construction is employed. Although losses can be obtained for individual structures in percent, the proposed RI establishes a scale of qualitative levels: Very Low, Low, Medium, High and Very High. RI is transparent, robust and representative of the risk, and can be used as a first sound approach in order to better use resources to carry out site- and building-specific studies for the regions at the highest risk. As a case study of RI, thre...
Hurricane event-based method to create regional hazard maps for heavy rainfall-induced translational landslides
Natural Hazards
This paper proposes a hurricane event-based method to construct a map for heavy rainfall-induced ... more This paper proposes a hurricane event-based method to construct a map for heavy rainfall-induced translational landslides. This method involves five steps: (1) construct a GIS-based geotechnical database; (2) identify the areas in the vicinity which are susceptible to translational landslides based on the slope of the terrain and the geological information available; (3) characterize the heavy rainfall hazard due to hurricanes (typhoon) as a set of collectively exhaustive and mutually exclusive stochastic events, that fully describe spatial distribution and annual frequency of occurrence (in accordance with storm category, storm position, distance between the eye of the storm and the site of interest, among others factors); (4) compute the ratio between the steady-state rainfall produced by a hurricane event affecting the tributary area of the slope under analysis, Q s, and the critical steady-state rainfall necessary to trigger slope instability, Q c, and finally; (5) carry out a p...
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