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Seismic Safety Evaluation of Bridges

Author(s):

Himanshu Mishra , SIET

Keywords:

Reliability Theory, Response Surface Method, Earthquake-Resistant, Soil-Abutment Interaction, Reinforcing Steel Bars, Tensile Strength/Yield Strength Ratio, Elongation

Abstract

This study considers uncertainties in material strengths and the modeling which have important effects on structural resistance force based on reliability theory. After analyzing the destruction mechanism of a RC bridge, structural functions and the reliability were given, then the safety level of the piers of a reinforced concrete continuous against earthquake was analyzed. Using response surface method to calculate the failure probabilities of bridge piers under high-level earthquake, their seismic reliability for different damage states within the design reference period were calculated applying two-stage design, which describes seismic safety level of the built bridges to some extent. Capacity design procedure for the earthquake-resistant reinforced concrete (RC) structures is effective when actual member capacities do not greatly exceed the assumed design capacities. Moreover, RC members are expected to undergo large inelastic deformations for adequate seismic energy dissipation. Since flexural capacity and post-yield behavior of an RC member is largely controlled by steel reinforcing bars, it places certain special requirements on their properties, such as, yield strength (YS), ultimate tensile strength to yield strength ratio (UTS/YS ratio) and elongation, which are sensitive to the method of manufacturing bars. Flexural tests on RC beams which used re-bars of carefully controlled properties was conducted and it was observed that for dependable flexure behavior, YS and UTS values should lie in a narrow band around values used in the member design. If these values are greater than the specified value, it may cause brittle shear failure instead of more ductile and desirable flexure mode of failure. Moreover, a high UTS/YS ratio equal to 1.25 is necessary to have dependable peak strength which is larger than the yield strength. This study investigates the effects of soil abutment interaction on seismic analysis abutment attract a large portion of seismic forces. A design drive methodology to model the abutment stiffness for either linear or non-linear analysis considering the backfill and pier foundation.

Other Details

Paper ID: IJSRDV7I21231
Published in: Volume : 7, Issue : 2
Publication Date: 01/05/2019
Page(s): 1408-1413

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