Evaluation of Aa And Av Coefficients in Iran for Limited Displacement Design Method of Retaining Walls

Document Type : Research Note


Tarbiat Modares University


The walls are permitted to displace to a specific amount in the seismic designing of the retaining walls using the limited displacement methods. As a result, the dynamic pressure of the earthquake on the retaining walls decreases compared to the case in which the wall is not allowed to move. The purpose of this paper is calculating the coefficients of the Richards and Elms equations in seismic designing of retaining walls, so that they can be applied in seismic provisions of Iran. Since this method requires determining the Aa and Av coefficients, the records with the magnitude of higher than 5.5 were selected among the three-component records of the accelerograph network of the country. The baseline correction and filtering of all accelerograms have been conducted using SeismoSignal V.3.2.0 software. From a total of 426 records, a set of 142 records were selected with a distance to the epicenter less than 60 km and peak ground acceleration of more than 0.05 g (50 cm/sec2). Since the results could be used in Iranian code, the macrozonation of Aa and Av has been done throughout the country. Depending on the location of the accelerograph, the related records have been normalized according to the acceleration coefficients of the zone plan. Finally, a zoning map of Aa and Av is proposed. Using this map and determining the permitted displacement, the designers can achieve the horizontal seismic coefficients for designing of retaining walls.