Papers by Ricardo Tupayachi Herrera
Metals
This paper presents a numerical study on the seismic performance of end-plate moment connection b... more This paper presents a numerical study on the seismic performance of end-plate moment connection between I-beam to HSS (hollow structural section) column stiffened by outer diaphragms (EP-HSS). In previous experimental research, this moment connection showed a satisfactory performance according to requirements established in Seismic provisions. However, one type of joint was studied and bidirectional and axial loads were not considered. In this since, several configurations representative of 2D interior joints and 3D interior and exterior joints in a steel building were modeled and subjected to unidirectional or bidirectional cyclic displacements according to protocol in seismic provisions. Firstly, a similar joint configuration was calibrated from experimental data, obtaining an acceptable adjustment. The assessment of seismic performance was based on hysteretic curves, failure mechanisms, stiffness, dissipated energy, and equivalent damping. The results obtained showed a ductile fa...
Metals, 2020
The 2008 Wenchuan-China earthquake showed the importance of considering the bidirectional seismic... more The 2008 Wenchuan-China earthquake showed the importance of considering the bidirectional seismic action as a cause of failure in column hinge mechanisms. Subsequently, the large 2011 Tohoku-Japan earthquake revealed that Special Moment Frames buildings, made of tubular columns (Hollow Structural Section or Built-up Box Section) and rigid connections with I-beams, did not suffer serious damage. However, only the ConXtech® ConXL™ moment connection has been prequalified according to the (American Institute of Construction) AISC Seismic Provisions for use with tubular columns and the rest of connections do not consider biaxial resistance. The research reported herein investigated the cyclic response of box-columns joints, connected to I beams using the four-bolt extended endplate connection, subjected to bidirectional bending and axial load on the column. To conduct the study, complex nonlinear finite element models (FEMs) of several I beam to box column joint configurations were const...
study of El Nino-Southern Oscillation (ENSO) phenomenon above the troposphere has traditionally b... more study of El Nino-Southern Oscillation (ENSO) phenomenon above the troposphere has traditionally been difficult because of the lack of global observations at high altitudes and also because of the presence of other sources of variability whose signals are difficult to disentangle from ENSO effects. Recent works with general circulation models that isolate the ENSO signal have demonstrated its upward propagation into the stratosphere. Here we use a recent version of the Whole Atmosphere Community Climate Model to illustrate the propagation and mechanisms whereby the signal manifests itself in the stratosphere. The ENSO signal propagates upwards to about 40 km at middle latitudes in Northern Hemisphere boreal winter months by means of
Mauricio Sarrazin, María Ofelia Moroni, Rubén Boroschek, Ricardo Herrera Dept. of Civil Engineeri... more Mauricio Sarrazin, María Ofelia Moroni, Rubén Boroschek, Ricardo Herrera Dept. of Civil Engineering, University of Chile, Casilla 228/3 Santiago, Chile [email protected], [email protected], [email protected], [email protected] Paul Roschke Dept. of Civil Engineering, University of Texas A&M,Texas, USA [email protected] Miguel Tornello National Technical University, Mendoza, Argentina [email protected] ABSTRACT
Metals, 2020
A seismic performance evaluation of selective storage racks subjected to Chilean Earthquakes was ... more A seismic performance evaluation of selective storage racks subjected to Chilean Earthquakes was conducted using nonlinear pushover and nonlinear dynamic time-history analyses. Nine seismic records with two horizontal components and magnitude Mw > 7.7 were applied to numerical models of prototype rack structures. The prototype racks were designed considering two types of soil and two aspect ratios. The inelastic behavior of beam connections was included in the models. The results showed a predominantly elastic behavior, mainly in the cross-aisle direction, in comparison to the down-aisle direction. The inelastic action was concentrated in pallet beams and up-rigths. Higher values of base shear were reached, due to elevated rigidity in rack configurations, and an acceptable performance was obtained. A response reduction factor was reported in both directions, reaching values larger than the limit imposed by the Chilean standard. However, values below this limit were obtained in th...
Metals, 2020
Brittle failure mechanisms can affect the seismic performance of structures composed of intersect... more Brittle failure mechanisms can affect the seismic performance of structures composed of intersecting moment resisting frames, if the biaxial effects are not considered. In this research, the bidirectional cyclic response of H-columns with weak-axis moment connections was studied using numerical models. Several configurations of joints with bidirectional effects and variable axial loads were studied using the finite element method (FEM) in ANSYS v17.2 software. The results obtained showed a ductile behavior when cyclic loads are applied. No evidence of brittle failure mechanisms in the studied joint configurations was observed, in line with the design philosophy established in current seismic provisions. However, beams connected to the column minor axis reached a partially restrained behavior. Joints with four beams connected to the column exhibited a partially restrained behavior for all axial load levels. An equivalent force displacement method was used to compare the hysteretic re...
Alternativas, 2017
Este artículo forma parte de un plan de investigación que busca proporcionar a la industria ecuat... more Este artículo forma parte de un plan de investigación que busca proporcionar a la industria ecuatoriana de la construcción en acero alternativas de sistemas estructurales para edificios altos y de mediana altura, diferentes a los de acero y hormigón armado convencionales usados actualmente en Guayaquil. Los Pórticos Resistentes a Momento Compuestos (PRMC) con columnas CFT (CFT, Concrete-Filled Steel Tube Column, por su nombre en inglés) y los Pórticos con Arriostramientos de Pandeo Restringido (PAPR) son los sistemas estructurales que se presentan en este estudio. Se realiza primero una revisión de los aspectos más importantes relacionados al análisis y diseño de un edificio prototipo de 24 pisos de altura en el que los sistemas PRMC y PAPR constituyen el Sistema Resistente a Cargas Sísmicas. Este diseño fue realizado en base a las disposiciones de diseño sísmico de códigos Norteamericanos y recomendaciones de investigaciones previas relacionadas a estos sistemas. Luego se, describe...
Journal of Constructional Steel Research, 2017
The brittle failures detected during the 1994 Northridge earthquake on steel moment-frame buildin... more The brittle failures detected during the 1994 Northridge earthquake on steel moment-frame buildings prompted significant investigations on steel moment connections. This work resulted in the proposal of several prequalified connections, including the Double Split Tee (DST) connection, to be used in beam-to-column moment joints of seismic resistant steel buildings. The DST connection is a partially restrained-full strength connection, which consists of two T-stubs bolted to the column flange and the beam top and bottom flanges. The prequalification process was conducted using hot-rolled shapes, whose availability is still limited in Chile and other countries. In addition, the range of usable T web and flange thicknesses is narrow for these shapes. These reasons led to study the use of built-up T-stubs as an alternative on the DST connection, considering that they offer a larger freedom of sizing and improved material utilization. This experimental research aims to validate the use of current design recommendations for the DST connection when built-up T shapes are used instead, by testing three beam-to-column full-scale welded T moment connections under cyclic loading. The parameter varied between the specimens was the T flange thickness, in order to observe the most significant limit states of the connection. The experimental data allowed the identification of the failure modes of the beam and connection, which were the development of plastic hinges and T flange prying effect, respectively. The results indicate that the major contributors to energy dissipation in the connection were the T flange prying and plastic hinging mechanisms, as predicted, and that the three Beam-to-Column connections accomplish the requirements for use in Special Moment Frames, in terms of acceptable strength degradation at a story drift angle of 0.04 rad, with no visible damage on the T-stubs' welds.
Smart Structures and Systems, 2014
ABSTRACT Shape memory alloys (SMA) can dissipate energy through hysteresis cycles without signifi... more ABSTRACT Shape memory alloys (SMA) can dissipate energy through hysteresis cycles without significant residual deformation. This paper describes the fabrication and testing of copper-based SMA hourglass-shaped plates for use in energy dissipation devices and the development of a numerical model to reproduce the experiments. The plates were tested under cyclic flexural deformations, showing stable hysteresis cycles without strength degradation. A detailed nonlinear numerical model was developed and validated with the experimental data, using as input the constitutive relationship for the material determined from cyclic tests of material coupons under tension loading. The model adequately reproduces the experimental results. The study is focused on the exploitation of SMA in the martensite phase.
Tierra Y Tecnologia Revista De Informacion Geologica, 2007
Desde hace mas de 160 anos se perforan en Tenerife tuneles o galerias subterraneas en busca del a... more Desde hace mas de 160 anos se perforan en Tenerife tuneles o galerias subterraneas en busca del agua almacenadas durante siglos, o miles de anos en el acuifero volcanico. Su perforacion requiere tecnicas espcializadas y la circulacion por su interior debe ir acompanada de medidas de seguridad para evitar accidentes.
La importancia economica del uso de las praderas de alfalfa en la constitucion de las cadenas for... more La importancia economica del uso de las praderas de alfalfa en la constitucion de las cadenas forrajeras y teniendo en cuenta que los efectos beneficiosos de esta pastura se ven contrarrestados por los peligros de producir cuadros de empaste, llegando hasta la muerte de los animales, es que se pretende investigar sobre el uso de capsulas antitimpanicas como preventivas de este cuadro clinico y su impacto economico en la produccion animal. El precio de estas capsulas es elevado para el productor, pero se evaluara si los beneficios que pudiera obtener como preventiva del empaste y en la ganancia de peso, evitar la muerte de animales, disminucion de los gastos de tratamiento (farmacologico y/o quirurgico) hacen que el costo inicial sea inferior a los beneficios obtenidos o que la inversion realizada supere las perdidas que sufre el productor. Objetivo general: * Analizar la factibilidad tecnica-economica del uso de las capsulas antiempaste en novillos que pastorean alfalfa. Objetivos especificos: * Determinar la influencia en la ganancia diaria de peso vivo. * Determinar la efectividad de estas capsulas para la prevencion del meteorismo. * Determinar la relacion costo-beneficio de este tratamiento.
Anales Espanoles De Pediatria Publicacion Oficial De La Asociacion Espanola De Pediatria, 1999
Boletin Medico Del Hospital Infantil De Mexico, Feb 1, 2011
Acta Psiquiatr Psicol Am Lat, Sep 1, 1995
Clarin Revista De Nueva Literatura, 2009
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Papers by Ricardo Tupayachi Herrera