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PROCEEDINGS OF THE SECOND INTERNATIONAL CONFERENCE ON SOFT COMPUTING TECHNOLOGY IN CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING
Edited by: Y. Tsompanakis, B.H.V. Topping
Optimum Seismic Design of Gravity Retaining Walls using the Heuristic Big Bang-Big Crunch Algorithm
A. Kaveh1, S. Talatahari2 and R. Sheikholeslami2
1Department if Civil Engineering, Iran University of Science and Technology,
A. Kaveh, S. Talatahari, R. Sheikholeslami, "Optimum Seismic Design of Gravity Retaining Walls using the Heuristic Big Bang-Big Crunch Algorithm", in Y. Tsompanakis, B.H.V. Topping, (Editors), "Proceedings of the Second International Conference on Soft Computing Technology in Civil, Structural and Environmental Engineering", Civil-Comp Press, Stirlingshire, UK, Paper 4, 2011. doi:10.4203/ccp.97.4
Keywords: gravity retaining wall, seismic design, optimization, heuristic big bang-big crunch algorithm.
Retaining walls are designed to withstand lateral earth and water pressures, the effects of surcharge loads, the self-weight of the wall and in special cases, earthquake loads in accordance with the general principles as specified in this paper. The seismic vibrational energy in the bedrock propagates towards the wall through the soil layers. In order to assess the wall stability during earthquakes, it is necessary to know the earth pressure acting on the wall. The dynamic earth pressure is influenced by a range of factors including: thicknesses of the soil layers, the wall dimensions, properties of the wall material, properties of the soil (e.g. shear wave velocity, stress-strain characteristics and density), etc. There are different methods to calculate dynamic earth pressure that can be grouped into two broad categories, namely pseudo-static approach and dynamic response analysis. In the conventional pseudo-static approach, the dynamic response of the wall/soil system in terms of amplification is assumed to be insignificant. The wall and the associated soil wedge are taken to behave as a rigid block. The seismic loading is considered as equivalent inertial forces, and the dynamic earth pressure is determined on the basis of static equilibrium consideration. In this paper, we used the Mononobe-Okabe method which is one of the pseudo-static approaches to determine the dynamic earth pressure.
On the other hand selection of an appropriate wall type is based on an assessment of the design loading, depth to adequate foundation support, presence of deleterious environmental factors, physical constraints of the site, cross-sectional geometry of the site both existing and planned, settlement potential, desired aesthetics, constructability, maintenance, and cost. Gravity retaining walls are one of the familiar types of the retaining walls which may be constructed of stone masonry, unreinforced concrete, or reinforced concrete. These walls can be used in both cut and fill applications and they have relatively narrow base widths. But the material cost is one of the major factors in the construction of gravity retaining walls. Despite these facts, designers and owners have always desired to have optimal structures. In order to fulfil this aim, we have proposed the heuristic big bang-big crunch (HBB-BC), for the optimum design of gravity retaining walls subject to seismic loading. In order to evaluate the efficiency of the HBB-BC, an example is presented. Comparing the results of the retaining wall designs obtained by the HBB-BC, PSO and standard BB-BC illustrates the good performance of the HBB-BC.
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