Proposing 3-DoF Model to Study of Mass Parameter Effects on Longitudinal Period in Base Isolated Bridges

The effect of mass parameters on the natural vibration period of isolated bridges is discussable, especially in case of substructure mass components, because of the disagreement of different researchers about it. This is while some bridge design codes such as AASHTO guide specification, ignores subs...

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Autores principales:	Mahmoud Reza ُُShiravand, Mahsa Rasouli
Formato:	article
Lenguaje:	FA
Publicado:	Iranian Society of Structrual Engineering (ISSE) 2018
Materias:	base isolated bridges analytical model longitudinal period effective mass parameters simplified method Bridge engineering TG1-470 Building construction TH1-9745
Acceso en línea:	https://doaj.org/article/99a76ad2bfb14ee0b3b52da7c9d583b9
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spelling	oai:doaj.org-article:99a76ad2bfb14ee0b3b52da7c9d583b92021-11-08T15:50:51ZProposing 3-DoF Model to Study of Mass Parameter Effects on Longitudinal Period in Base Isolated Bridges2476-39772538-261610.22065/jsce.2018.126518.1514https://doaj.org/article/99a76ad2bfb14ee0b3b52da7c9d583b92018-09-01T00:00:00Zhttps://www.jsce.ir/article_66857_a3525130a241f1d0ff90b739bf9a0b3e.pdfhttps://doaj.org/toc/2476-3977https://doaj.org/toc/2538-2616The effect of mass parameters on the natural vibration period of isolated bridges is discussable, especially in case of substructure mass components, because of the disagreement of different researchers about it. This is while some bridge design codes such as AASHTO guide specification, ignores substructure mass in simplified method of analysis. Current paper investigates the effects of substructure mass components on the longitudinal period of base isolated bridges. These components include: pier mass, cap beam mass, pier rotational moments of inertia, and cap beam rotational moments of inertia. In this paper, a three degree of freedom analytical model of isolated bridge in longitudinal direction is presented and the natural vibration period of this model is calculated in four cases. These cases are: (1) exact solution, (2) by ignoring the rotational moments of inertia, (3) by ignoring the cap beam mass, and (4) by ignoring the pier and cap beam mass (AASHTO model). The periods obtained from exact analytical model were compared with those obtained from finite element model and the results showed the good conformity. The results also showed that the substructure rotational moments of inertia isn’t a determinative parameter in the calculation of the first longitudinal period; while the cap beam mass have a significant impact on the longitudinal period of base isolated bridges with tall piers or stiff isolators. The ignorance of cap beam mass caused 8% error in the period of such bridges. The results showed that the simplified method of AASHTO guide specification isn't applicable in some bridges and may cause more than 10% error. By increasing the ratio of isolator stiffness to substructure stiffness, the error of period which is calculated by AASHTO model, increases.Mahmoud Reza ُُShiravandMahsa RasouliIranian Society of Structrual Engineering (ISSE)articlebase isolated bridgesanalytical modellongitudinal periodeffective mass parameterssimplified methodBridge engineeringTG1-470Building constructionTH1-9745FAJournal of Structural and Construction Engineering, Vol 5, Iss شماره ویژه 2, Pp 53-64 (2018)
institution	DOAJ
collection	DOAJ
language	FA
topic	base isolated bridges analytical model longitudinal period effective mass parameters simplified method Bridge engineering TG1-470 Building construction TH1-9745
spellingShingle	base isolated bridges analytical model longitudinal period effective mass parameters simplified method Bridge engineering TG1-470 Building construction TH1-9745 Mahmoud Reza ُُShiravand Mahsa Rasouli Proposing 3-DoF Model to Study of Mass Parameter Effects on Longitudinal Period in Base Isolated Bridges
description	The effect of mass parameters on the natural vibration period of isolated bridges is discussable, especially in case of substructure mass components, because of the disagreement of different researchers about it. This is while some bridge design codes such as AASHTO guide specification, ignores substructure mass in simplified method of analysis. Current paper investigates the effects of substructure mass components on the longitudinal period of base isolated bridges. These components include: pier mass, cap beam mass, pier rotational moments of inertia, and cap beam rotational moments of inertia. In this paper, a three degree of freedom analytical model of isolated bridge in longitudinal direction is presented and the natural vibration period of this model is calculated in four cases. These cases are: (1) exact solution, (2) by ignoring the rotational moments of inertia, (3) by ignoring the cap beam mass, and (4) by ignoring the pier and cap beam mass (AASHTO model). The periods obtained from exact analytical model were compared with those obtained from finite element model and the results showed the good conformity. The results also showed that the substructure rotational moments of inertia isn’t a determinative parameter in the calculation of the first longitudinal period; while the cap beam mass have a significant impact on the longitudinal period of base isolated bridges with tall piers or stiff isolators. The ignorance of cap beam mass caused 8% error in the period of such bridges. The results showed that the simplified method of AASHTO guide specification isn't applicable in some bridges and may cause more than 10% error. By increasing the ratio of isolator stiffness to substructure stiffness, the error of period which is calculated by AASHTO model, increases.
format	article
author	Mahmoud Reza ُُShiravand Mahsa Rasouli
author_facet	Mahmoud Reza ُُShiravand Mahsa Rasouli
author_sort	Mahmoud Reza ُُShiravand
title	Proposing 3-DoF Model to Study of Mass Parameter Effects on Longitudinal Period in Base Isolated Bridges
title_short	Proposing 3-DoF Model to Study of Mass Parameter Effects on Longitudinal Period in Base Isolated Bridges
title_full	Proposing 3-DoF Model to Study of Mass Parameter Effects on Longitudinal Period in Base Isolated Bridges
title_fullStr	Proposing 3-DoF Model to Study of Mass Parameter Effects on Longitudinal Period in Base Isolated Bridges
title_full_unstemmed	Proposing 3-DoF Model to Study of Mass Parameter Effects on Longitudinal Period in Base Isolated Bridges
title_sort	proposing 3-dof model to study of mass parameter effects on longitudinal period in base isolated bridges
publisher	Iranian Society of Structrual Engineering (ISSE)
publishDate	2018
url	https://doaj.org/article/99a76ad2bfb14ee0b3b52da7c9d583b9
work_keys_str_mv	AT mahmoudrezashiravand proposing3dofmodeltostudyofmassparametereffectsonlongitudinalperiodinbaseisolatedbridges AT mahsarasouli proposing3dofmodeltostudyofmassparametereffectsonlongitudinalperiodinbaseisolatedbridges
_version_	1718441688196710400

Proposing 3-DoF Model to Study of Mass Parameter Effects on Longitudinal Period in Base Isolated Bridges

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