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  • Author: Marian Daraban x
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Comparative Study for Buckling Resistance of Steel Sheets Provided with Stiffeners Used in Bridge Structures

Abstract

The subject discussed in this paper is based on an experimental bridge model which was built to study the pre-critical and post-critical buckling behaviour of steel webs of box girders provided with longitudinal and transversal stiffeners. The article presents a comparison between the experimental results and the numerical ones for buckling resistance of stiffened steel webs. For this purpose two types of analysis will be carried out: an analysis to establish the values and eigenvectors of buckling, after which the critical factor for the first mode of buckling will be obtained, and then a geometrical and physical nonlinear analysis will be performed.

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Comparative Study Between Experimental Results and the Numerical One of the Lateral Buckling Resistence for the Two Curved I Girders of a Curved Bridge Model

Rezumat

Articolul prezintă un studiul al rezistenţei la flambaj lateral pentru grinzile curbe utilizate la poduri.

Rezistenţa la flambaj lateral va fi evaluată printr-o analiză geometric şi fizic neliniară utilizând programul de calcul Lusas®, fară a considera imperfecţiunile de execuţie. Pentru a da veridicitate rezultatelor analitice, studiul numeric se va realiza pe unul din modelele fizice prezentate în lucrarea [1] care pune la dispoziţie valori ale încercărilor experimentale.

Geometria modelului fizic din lucrarea [1] se bazează pe o analiză dimensională a grinzilor curbe „I” utilizate în mod frecvent la poduri. Modelul fizic este alcătuit din două grinzi I curbe, dublu simetrice, prevăzute cu antretoaze şi contravântuiri la nivelul tălpilor. De antretoazele de capăt sunt sudate pe direcţia axei curbe două console scurte de lungime e .

Schema statică a structurii este grinda simplu rezemată cu console, ale cărei aparate de reazem sunt dispuse pe direcţia coardei. Consolele scurte vor fi încărcate cu prese hidraulice la o forţă P care are ca efect în grinda principală un moment încovoietor uniform având valoarea P *e şi forţă tăietoare zero.

Pentru analiza neliniară s-a folosit formularea Total Lagrange, împreună cu utilizarea metodei lungimii arcului modificat formulată de Crisfield. De asemenea s-a considerat comportarea neliniară a materialului.

Evaluarea rezistenţei la flambaj lateral constă în determinarea momentului încovoietor critic pentru care grinda îşi pierde stabilitatea. Comparaţia rezultatelor numerice cu cele experimentale preluate, confirmă posibilitatea evaluării numerice a rezistenţei la flambaj lateral pentru grinzile curbe.

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Some Investigations Performed for the Bridge Over Jiu at Aninoasa

Abstract

The carrying structure of the bridge over the Jiu River at Aninoasa consists in two parallel concrete arches with variable height of the cross section, sustaining a concrete deck through vertical concrete hangers. In the time period passed since the bridge was erected, some structural elements shown damages. In order to establish the technical state of the bridge, a technical appraisement was performed and according to this, the most exposed elements to the risk of failure are the hangers.

The purpose of this paper is to present briefly both, the method used to test the actual bridge carrying capacity in situ and the finite element model developed for the static and dynamic analysis of the structure.

In order to estimate the state of the structural elements, two ways were followed. In the first stage, a test project was carried out and in the second stage, a complete 3D finite element model was developed to analyze the bridge structure.

The test project has foreseen the loading of the bridge by heavy unloaded trucks, disposed in some positions on the deck and the measurements of the deck and arches displacements. The positions of the trucks were established in order to obtain the maximum values both for arches transverse displacements and vertical displacements of the deck. Using electro-resistive transducers the hangers elongations and strains values on their cross section were also measured. These measured values were compared with those obtained from the numerical calculations performed by using the complete finite element model. By means of the finite element model, also the response of the structure following the dynamic action of vehicles was investigated.

Open access