Shaking table tests of structures with hysteretic dampers: experimental results vs. prediction using non-linear static methods

The use of seismic hysteretic dampers for passive control is increasing exponentially in recent years for both new and existing buildings. In order to utilize hysteretic dampers within a structural system, it is of paramount importance to have simplified design procedures based upon knowledge gained from theoretical studies and validated with experimental results. Non-linear Static Procedures (NSPs) are presented as an alternative to the force-based methods more common nowadays. The application of NSPs to conventional structures has been well established; yet there is a lack of experimental information on how NSPs apply to systems with hysteretic dampers. In this research, several shaking table tests were conducted on two single bay and single story 1:2 scale structures with and without hysteretic dampers. The maximum response of the structure with dampers in terms of lateral displacement and base shear obtained from the tests was compared with the prediction provided by three well-known NSPs: (1) the improved version of the Capacity Spectrum Method (CSM) from FEMA 440; (2) the improved version of the Displacement Coefficient Method (DCM) from FEMA 440; and (3) the N2 Method implemented in Eurocode 8. In general, the improved version of the DCM and N2 methods are found to provide acceptable accuracy in prediction, but the CSM tends to underestimate the response

Featured Application: Assessment and design of hysteric dampers considering the impulsive effects of earthquakes.

The efficacy of hysteretic dampers can be formulated as the number or equivalent inelastic cycles, or the ratio of normalised dissipated energy to displacement ductility. This parameter is used in the design of framed structures with supplemental dampers and it is strongly influenced by the impulsive effects of earthquakes and other structural parameters. This paper presents an estimate of the cyclic demand of dampers installed in reinforced concrete frames, based on nonlinear time history analyses. Statistical analyses of the results are used to highlight relevant parameters and calibrate a predictive formula and upper-bound design values. The collapse pattern of the frames seems to have no effect on the efficacy of the dampers; thus, the seismological parameters that describe impulsivity should drive the design of hysteric dampers.FEDER/Junta de Andalucia-Consejeria de Economia y Conocimiento B-TEP-306-UGR18Spanish Ministry of Economy and Competitivity BIA2017 88814-

Inelastic torsional seismic response of nominally symmetric reinforced concrete frame structures: shaking table tests

This paper discusses the torsional response of a scaled reinforced concrete frame structure subjected to several uniaxial shaking table tests. The tested structure is nominally symmetric in the direction of shaking and exhibits torsion attributable to non-uniform yielding of structural components and uncertainties in the building process. Asymmetric behavior is analyzed in terms of displacement, strain in reinforcing bars, energy dissipated at plastic hinges, and damage at section and frame levels. The results show that for low levels of seismic hazard, for which the structure is expected to perform basically within the elastic range, the accidental eccentricity is not a concern for the health of the structure, but it significantly increases the lateral displacement demand in the frames (about 30%) and this might cause significant damage to non-structural components. For high levels of seismic hazard the effects of accidental torsion become less important. These results underline the need to consider accidental eccentricity in evaluating the performance of a structure for very frequent or frequent earthquakes, and suggest that consideration of torsion may be neglected for performance levels associated with rare or very rare earthquakes

Shaking table tests of a RC frame structure equipped with hysteretic dampers

This paper provides partial results of an on-going research aimed at investigating the seismic response of reinforced concrete (RC) frames equipped with hysteretic-type energy dissipating devices (EDD). From a prototype RC frame structure designed only for gravity loads, a test model scaled in geometry to 2/5 was defined and built in the Laboratory of Structures of the University of Granada. Four EDDs were installed in the test model to provide the same seismic resistance than a conventional RC bare frame designed for sustain gravity and seismic loads following current codes. The test model with EDDs was subjected to several seismic simulations with the shaking table of Laboratory of structures of the University of Granada. The test results provide empirical evidences on the efficiency of the EDDs to prevent damage on the main frame and concentrating the inelastic deformations on the EDDs

A shake table test of typical mediterranean reinforced concrete structures

This research investigates the ultimate earthquake resistance of typical RC moment resisting frames designed accordingly to current standards, in terms of ultimate energy absorption/dissipation capacity. Shake table test of a 2/5 scale model, under several intensities of ground motion, are carried out. The loading effect of the earthquake is expressed as the total energy that the quake inputs to the structure, and the seismic resistance is interpreted as the amount of energy that the structure dissipates in terms of cumulative inelastic strain energy

Failure mechanism of reinforced concrete structural walls with and without confinement

This paper presents the results of cyclic loading tests on two large-scale reinforced concrete structural walls that were conducted at Purdue University. One of the walls had confinement reinforcement meeting ACI-318-11 requirements while the other wall did not have any confinement reinforcement. The walls were tested as part of a larger study aimed at indentifying parameters affecting failure modes observed to limit the drift capacity of structural walls in Chile during the Maule Earthquake of 2010. These failure modes include out-of-plane buckling (of the wall rather tan individual reinforcing bars), compression failure, and bond failure. This paper discusses the effects of confinement on failure mode. Distributions of unit strain and curvature obtained with a dense array of non-contact coordinate-tracking targets are also presented

Fabricación y ensayo de probetas de fábrica de ladrillo

Material docente elaborado a partir laboratorio realizado en la asignatura “Estructuras de Ladrillo” durante el curso académico 2018-19, se divide en dos sesiones prácticas: en una primera sesión los estudiantes, organizados en pequeños grupos, construyen con sus propias manos unas probetas de ladrillo. Para ello se les facilitan los materiales; ladrillos, mortero, agua, y herramientas. Transcurridos 28 días, en una segunda sesión, se ensayan a compresión las probetas de fábrica, estimando previamente cada grupo la resistencia “esperada” de sus probetas. Para realizar este ensayo, cada grupo es responsable de la instrumentación de su probeta, enseñándoles la base de la medición con bandas extensométricas, sus fundamentos teóricos y las técnicas de colocación.Departamento de Construcciones Arquitectónicas, Ingeniería del Terreno y Mecánica de los Medios Continuos y Teoría de Estructura

Constitutive model for rubberized concrete passively confined with FRP laminates

This article develops an analysis-oriented stress-strain model for rubberized concrete (RuC) passively confined with fiber reinforced polymer (FRP) composites. The model was calibrated using highly instrumented experiments on 38 cylinders with high rubber contents (60% replacement of the total aggregate volume) tested under uniaxial compression. Parameters investigated include cylinder size (100×200mm or 150×300mm; diameter×height), as well as amount (two, three, four or six layers) and type of external confinement (Carbon or Aramid FRP sheets). FRP-confined rubberized concrete (FRP CRuC) develops high confinement effectiveness (fcc/fco up to 11) and extremely high deformability (axial strains up to 6%). It is shown that existing stress-strain models for FRP-confined conventional concrete do not predict the behavior of such highly deformable FRP CRuC. Based on the results, this study develops a new analysis-oriented model that predicts accurately the behavior of such concrete. This article contributes towards developing advanced constitutive models for analysis/design of sustainable high-value FRP CRuC components that can develop high deformability

A GIS based seismic risk scenario of the cities of Santa Fé and Atarfe in Andalucía, Spain

This paper applies a GIS -based methodology to a case study in the cities of Atarfe and Santa Fé in Anadalucía (Spain) which recently suffered a seismic series with six magnitude 4 earthquakes. The framework for estimating the risk scenario essentially relates each housing building in the cadastral, to the probability of reaching different levels of seismic damage, namely negligible, slight, moderate, extensive given the seismic hazard in the area under study. It is built on the python toolbox pandas and QuantumGIS. Although only minor to light damages were observed and reported during the seismic series, this study reveals that there is a high-risk scenario in the area if the 475-year design earthquake occurred nowadays.Este artículo aplica una metodología basada en SIG a un caso de estudio en las ciudades de Atarfe y Santa Fé en Anadalucía (España) que recientemente sufrieron una serie sísmica con seis terremotos de magnitud 4. Esencialmente, se relaciona cada edificación de vivienda en el catastro con su probabilidad de alcanzar diferentes niveles de daño sísmico: insignificante, leve, moderado, extenso dada la amenaza sísmica en el área de estudio. Está desarrollado en python pandas y QuantumGIS. Aunque solo se observaron y reportaron daños menores a leves durante la serie sísmica, este estudio revela que existe un escenario de alto riesgo en el área si el terremoto de proyecto de 475 años ocurriera en la actualidad.Grant PID2020-120135RB-I00 funded by MCIN/AEI/ 10.13039/501100011033 and by the Programa Operativo FEDER 2014-2020/Junta de Andalucía/Consejería de Transformación Económica, Industria, Conocimiento y Universidades/Proyecto B-TEP- 306-UGR18

GIS Framework for Rapid Seismic Loss Assessment: Case Study of Granada Metropolitan Area

Traditional vulnerability methodologies rely on collecting building data through time consuming surveys and visual screening. Geospatial infrastructure systems have rapidly evolved and today we can access massive geospatial data. Digital cadastral databases combine location, attributes, and temporal information for building stock. This paper proposes a GIS-based framework to estimate seismic vulnerability and losses from cadastral data only. The framework is rooted on wellknown displacement-based procedures and uses probabilistic models of the building structural capacity. A featured application to 287,503 housing units in metropolitan area of Granada is presented to showcase outputs for decisionmaking: performance displacement, damage level and repair cost.FEDER/Junta de Andalucía-Conserjería de Economía y Conocimiento, grant number B-TEP-306-UGR18Grant PID2020-120135RB-I00 funded by MCIN/AEI/ 10.13039/501100011033Ministry of Education for ‘Colaboración’ gran