Counterfort Retaining Walls under Earthquake Force   Indrajit Chowdhury Chief Discipline Supervisor; Civil & Structural Engg. Petrofac International Limited; Sharjah, UAE and Shambhu P. Dasgupta Professor, Department of Civil Engineering Indian Institute of Technology; Kharagpur, India.
			ABSTRACT

This paper outlines a method for analyzing the dynamic response of counterfort type retaining walls under earthquake force. For this type of walls no standard procedure or formulation exists. Normally a psuedo-static method of Mononobe and Okabe is used which uses the concept of the soil wedge behind the wall to be at the point of incipient failure. Thus the soil mass is assumed to behave as a rigid body while the force on the wall is found out without calculating any time period.

In the proposed analysis, time period and spatial distribution of the developed loads have been accounted for based on modal response analysis. The counterfort retaining wall has been assumed to respond like a plate having three sides fixed and one side free. Dynamic responses are sought for the wall for first mode analysis, based on Rayleigh Ritz technique and dynamic amplitude, moments and shears are finally obtained based on classical plate equations.

Keywords: Counterfort, dynamics, eigen values, energy, earthquake, stiffness, mass-participation factor, mode shape, retaining wall.

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