NON-LINEAR ANALYSIS OF AN INTEGRAL BRIDGE

Abstract

This study describes the implementation of a 2‐D finite element model of an integral abutment bridge (IAB) system which explicitly incorporates the nonlinear soil response. The superstructure members have been represented by means of three‐node isoparametric beam elements with three degrees of freedom per node. The soil mass is idealized by eight node isoperimetric quadrilateral element at near field and five node isoparametric infinite element to simulate the far field behavior of the soil media. The non‐linearity of the soil mass has been represented by using the Duncan and Chang hyperbolic model. The applicability of this model was demonstrated by analyzing a single span IAB. This study has shown that the soil nonlinearity has significant effect on the response of the structure, where the displacement that have been obtained on basis of nonlinear analysis is 1.5–2.0 times higher than that obtained from linear analysis. The stress magnitudes in the nonlinear analysis are also higher where in some point the difference reached almost 3 times. Santrauka Straipsnyje aprašoma, kaip taikomas 2‐D baigtiniu elementu metodas tilto sistemai su integraliniais ramtais analizuoti, apimant ir netiesine grunto elgsena. Antžemines tilto dalies laikantieji elementai modeliuojami taikant triju mazgu izoparametrinius strypinius elementus su trimis laisves laipsniais kiekviename mazge. Grunto masyvui modeliuoti taikomi aštuoniu mazgu izoparametriniai ketursieniai elementai arti tilto esančioje aplinkoje ir penkiu mazgu izoparametriniai begaliniai elementai, imituojantys grunto terpes elgsena nuo tilto nutolusiose srityse. Grunto masyvo elgsenos netiesiškumas ivertinamas Duncan ir Chang hiperboliniu modeliu. Jo tinkamumas aiškinamas analizuojant vieno tarpatramio integralini tilta. Atlikti tyrimai parode, kad grunto savybiu netiesiškumas turi didele itaka tilto konstrukciju elgsenai. Tilto poslinkiai, nustatyti taikant netiesine analize, yra 1,5–2,0 karto didesni už poslinkius, nustatytus taikant tiesine analize. Atlikus netiesine analize nustatyti itempiai taip pat yra didesni, o kai kuriais atvejais skirtumas siekia beveik tris kartus.