Seismic Analysis and Capacity Based Design of the Bridge Sub-Structure as per IRC: SP: 114-2018

Abstract

Earthquake is one of that unexpected certainty and inevitable. What appears to be an earthquake, still a modern-day threat. Bridges are no exceptions. Bridges have boundaries too, as the bridge can be damaged by earthquake. Several types of bridge failures have been noticed during earthquake. Piers in bridge sub-structure have been found to suffer extensive damage during earthquakes. The damage is mainly attributable to inadequate detailing, which limits the ability of the pier to deforms inelastically.

Meanwhile there had been development in the area of seismic resistant design of bridges, like capacity design approach, which have been incorporated in many international standards of country like New Zealand, Eurocode, Japan and USA.

Recently IRC has come up with IRC: SP: 114-2018 `Guidelines for Seismic Design of Road Bridges'. Several remedial measures have been suggested in IRC: SP: 114-2018, which recommended to adopt capacity-based method. Capacity-based design has been considered for ductile detailing at pre-determined hinge location which dissipate significant amount of energy. Capacity design approach ensures hierarchy in failure modes under strong seismic actions which leads to endorsement of ductile failure mode and also it deals with the proportioning of strengths between ductile and non-ductile regions of the structure by design.

Present study is limited to seismic analysis of bridge sub-structure by modelling for different configuration of pier and pile foundation and identify the possible location of plastic hinge for those specific cases. Then capacity-based design will be considered for ductile detailing at pre-determined hinge location, which dissipate significant amount of energy.

Parametric study for different configuration of pier i.e. Circular, Square, Rectangular and Wall type will be done with two different configuration of pile foundation i.e. 4 number of circular piles and 6 number of circular piles respectively to identify the possible location of plastic hinge in specific design case.