Fundamental periods of vibration of RC buildings in Portugal from in-situ experimental and numerical techniques

Oliveira, Carlos Sousa; Navarro, Manuel

doi:10.1007/s10518-009-9162-1

Cited by 93 publications

(67 citation statements)

References 26 publications

(21 reference statements)

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“…As far as damping ratio is concerned, the average value obtained through the transfer function fitting was on the order of 1%. The consistent disagreement (30% or more) between the in-situ and the numerical modeling frequency results found when performing a similar analysis for buildings (see [30]) is due to the great uncertainties in the elastic properties of several elements of those structures as well as the boundary conditions created by adjacent buildings. The interaction of buildings in urban blocks, the existence of non-structural elements, such as infill walls, and the uncertainties in modeling are among the most critical issues when dealing with building frequencies.…”

Section: Modeling the Structure -Linear Analysismentioning

confidence: 82%

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Use ofIn-SituDynamic Measurements to Calibrate Analytical Models of RC-Elevated Water Tanks

Lopes¹,

Oliveira²

2012

Shock and Vibration

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Abstract. Before establishing the priority settings for the reduction of seismic risk of water supply infrastructures, it is necessary to understand the dynamic behavior of elevated water tanks, which are components of those infrastructures. Among other information, the main frequencies of vibration of these structures must be estimated and the analytical models used in their analysis and design should reproduce the frequency values obtained by in-situ dynamic tests. This work focuses exclusively on reinforced concrete (RC) elevated water tanks (200−750 m 3 of water at heights of 30−40 m), which are very common structures in the water supply systems in Portugal since the mid XX th century. This type of structures can also be seen in many regions around the world. First, a nationwide survey was conducted to determine the most common typologies in the country in terms of structural layout. Second, an in-situ campaign using ambient vibration as input was performed for a group of selected structures to determine the main frequencies of vibration and to identify modal shapes and damping values. Third, a finite element model of several different typologies was developed using the water simply as a concentrated mass at the top; the elastic properties of the model of the structure including the foundation were calibrated, so that the frequencies of various mode shapes obtained by the analytical model would match the frequencies of the real structure. Finally, an expression was derived to estimate the fundamental frequency of a group of elevated water tank typologies based on the total mass at the top of the supporting structure, which include the water, the global lateral stiffness, and the height of the tank. This study, providing important information on the frequencies of vibration of RC-elevated water tanks, contributes in a definite way to the analysis and design of such water tanks.

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Section: Modeling the Structure -Linear Analysismentioning

confidence: 82%

“…In buildings the height is the parameter used in all codes and studies [30]. Figure 4 was made based on this idea.…”

Section: Estimating the Natural Frequency Of Elevated Water Tanksmentioning

confidence: 99%

Use ofIn-SituDynamic Measurements to Calibrate Analytical Models of RC-Elevated Water Tanks

Lopes¹,

Oliveira²

2012

Shock and Vibration

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“…On the contrary, the theoretical equation provided by the codes returns periods that are an over-estimation even when this level of damage is observed. This disagreement has to be considered taking into account the construction practices used in each country, with the need to perform a similar investigation and to define a relationship based on typical Italian and European buildings, as showed in previous works by Gallipoli et al (2009Gallipoli et al ( , 2010, Guler et al (2008), and Oliveira et al (2010) for undamaged RC buildings. …”

Section: Data Analysis and Structural Dynamic Characterizationmentioning

confidence: 99%

“…ATC, 1978;BSSC, 2003;CEN, 2005;NZSEE, 2006) provide period-height empirical expressions, usually set up with an elastic force-based design in mind. The recent research into earthquake engineering shows that the fundamental periods estimated by numerical models are often significantly different than those obtained when using an experimental approach (Gallipoli et al, , 2010Oliveira and Navarro, 2010;Michel et al, 2010). These differences are probably due to the fact that the dynamic properties of buildings are evaluated using numerical analyses based on inaccurate FE (finite element) models, based on too simplified models which inadequately reproduce the dynamic behaviour of real structures.…”

Section: Introductionmentioning

confidence: 99%

Evaluation and considerations about fundamental periods of damaged reinforced concrete buildings

Ditommaso

Vona

Gallipoli

et al. 2013

Nat. Hazards Earth Syst. Sci.

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The aim of this paper is an empirical estimation of the fundamental period of reinforced concrete buildings and its variation due to structural and non-structural damage. The 2009, L’Aquila earthquake has highlighted the mismatch between experimental data and code provisions value not only for undamaged buildings but also for the damaged ones. The April 6th, 2009 L’Aquila earthquake provided the first opportunity in Italy to estimate the fundamental period of reinforced concrete (RC) buildings after a strong seismic sequence. 68 buildings with different characteristics, such as age, height and damage level, have been investigated by performing ambient vibration measurements which provided their fundamental translational period. Four different damage levels were considered according with the definitions by EMS 98 (European Macroseismic Scale), trying to regroup the estimated fundamental periods versus building heights according to damage. The fundamental period of RC buildings estimated for low damage level, is equal to previous relationship obtained in Italy and Europe for undamaged buildings, well below code provisions. When damage levels get higher, the fundamental periods increase, but again with values much lower than those provided by codes. Finally, the authors suggest a possible update of the code formula for the simplified estimation of the fundamental period of vibration for RC existing buildings, taking into account also the inelastic behaviour

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“…They have taken into account internal and external in ll walls and the soilstructure interaction e ect. Oliveira and Navarro [23] measured the in-situ dynamic characteristics of 197 RC buildings in Portugal, based on ambient vibration. They obtained fundamental period as a linear function of height or number of storeys for di erent typologies and situations.…”

Section: Introductionmentioning

confidence: 99%

Period formula for RC frame buildings considering infill wall thickness and elasticity modulus

2017

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KEYWORDSPeriod; In ll wall thickness; In ll wall elasticity modulus; RC structures; Modal analysis.Abstract. Estimation of a proper fundamental vibration period is an important issue in the process of the design and/or evaluation of a building. Mostly, in ll walls are assumed nonstructural elements which are ignored in the estimation of the vibration period of a building in terms of sti ness. However, studies showed that in ll wall has signi cant e ect on vibration period and should be considered in the estimation of period. Even in ll walls are considered by some proposed equations in the estimation of period, they do not consider the e ect of in ll wall sti ness. In this study, an empirical equation is proposed as a function of building height, elasticity modulus of in ll wall, and thickness of in ll wall. For this purpose, building periods were determined with considering di erent in ll wall elasticity moduli, in ll wall thicknesses (thus, di erent in ll wall sti ness), and building heights. Nonlinear regression analyses were conducted with a comprehensive statistical study. E ect of elasticity modulus and thickness of in ll wall on vibration period was investigated. Finally, comparisons between the proposed equation of this study and those of previous studies were conducted.

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Fundamental periods of vibration of RC buildings in Portugal from in-situ experimental and numerical techniques

Cited by 93 publications

References 26 publications

Use ofIn-SituDynamic Measurements to Calibrate Analytical Models of RC-Elevated Water Tanks

Use ofIn-SituDynamic Measurements to Calibrate Analytical Models of RC-Elevated Water Tanks

Evaluation and considerations about fundamental periods of damaged reinforced concrete buildings

Period formula for RC frame buildings considering infill wall thickness and elasticity modulus

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