Seismic evaluation of the north bound N1-R300 bridge interchange

Solms, Michael Nicolas (2015-12)

Thesis (MEng)--Stellenbosch University, 2015.

Thesis

ENGLISH ABSTRACT: The N1 / R300 or Stellenberg interchange was designed in 1982 and construction was completed in early 1986. The bridge was designed according to the Code of procedure for the Design of Provincial Bridges and Culverts published by the Cape Province Department of Roads in June 1977. The design of the bridge over the N1 did not account for any significant form of seismic excitation but a review of current design code states that it falls within the highest seismic risk bracket in South Africa. Although this highest risk bracket still only equates to a moderate intensity earthquake, structures not designed accordingly could undergo serious damage. Current research suggests that the maximum possible peak ground acceleration expected in the region is almost double the modern design requirements. Additionally, numerous features of the bridge do not agree with many of the recommended best practices for bridges in seismic prone areas. This study evaluates the structural response of the Stellenberg interchange bridge when subjected to moderate intensity earthquakes. This was achieved through experimental tests to determine the mode shapes and accompanying frequencies to calibrate the finite element model of the horizontal circular arch bridge. A detailed finite element model was developed using Abaqus software. Once the finite element model was calibrated, the model was subjected to various scaled earthquakes to determine whether the bridge would be able to sustain a moderate intensity earthquake.

AFRIKAANSE OPSOMMING: Die N1 / R300 of Stellenberg wisselaar was ontwerp in 1982 en was voltooi in Februarie 1986. Die ontwerp was gedoen volgens die "Code of procedure for the Design of Provincial Bridges and Culverts" wat deur die Kaap Provinsie se Departement van Paaie gepubliseer is in Junie 1977. Die ontwerp van die brug wat strek bo-oor die N1 het nie voorsiening gemaak vir enige vorm van seismiese aktiwiteit nie. Die huidige ontwerp kode dui wel aan dat die brug in die hoogste seismiese risiko groep val wat in Suid-Afrika voorgeskryf word. Alhoewel hierdie hoogste risiko groep steeds net gelykstaande is aan ’n matige intensiteit aardbewing kan dit tot groot skade lei as dit nie daarvoor ontwerp word nie. Navorsing dui aan dat die maksimum moontlike grond versnellings wel in ’n orde van meer as dubbel die is wat voorgeskryf is deur die ontwerp kodes. Daarbenewens is daar van die strukturele aspekte van die brug wat nie ooreenstem met die voorgestelde beste praktyk om te volg vir brûe in seismiese gebiede nie. Hierdie studie evalueer dus die strukturele eienskappe van die Stellenberg wisselaar brug wanneer dit onderworpe is aan ’n matige intensiteit aardbewing. Hierdie was gedoen deur fisiese toetse om die modus vorme en hul frekwensies te bepaal sodat die numeriese model van die horisontale boog brug bevestig kan word. Verder was ’n gedetailleerde numeriese model ontwikkel met die gebruik van Abaqus sagteware. Die fisiese toets resultate was gebruik om die numeriese model te verifieer. Verskeie afgeskaalde aardbewings tot en met ’n grond versnelling van 0.2g is dan toegepas op die numeriese model wat dan die struktuur se reaksies sal toets.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/97969
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