Effect of Earthquake on Embankment based on Reliability Index Using Spreadsheet Optimization Method

Abstract

To obtain varying parametric sensitivities from case to case, a reliability analysis is most efficient method for designing any structure. Reliability based design illustrates the standard deviations and the correlation structure of the input parameters. The aim of this paper is to delineate the ultimate limit states or reliability based assessment and to describe the reliability index or Hasofer-Lind (H-L) index using object-oriented constrained optimization in the ubiquitous spread sheet platform of the concrete embankment leading to earthquake force and non-earthquake force. To evaluate the H-L second moment reliability index that depends not only on the mean values of the parameters but also on their scatters which is a more rational approach. For calculation of traditional safety factor or reliability indices the tallest monolith of the pine flat concrete dam is used as an example case. The H-L index i.e. reliability index value (β) is found to be about 2–16 times greater while considering earthquake force than the condition when the earthquake force is not considered for the same design variables (up-stream water head H1 and down-stream water head H2). This paper represents the potential reflection of the reliability based analysis and design of stabilized concrete dam provides a consistent level of structural reliability in the stability analysis of such structure when some measures of safety is ascertained by conventional factor of safety approach in the stability analysis and subsequent remedial design.

Keywords: Hasofer-Lind Index, earthquake force, constraint optimization, objective function, decision variable or design variable