Optimization of shoring/reshoring levels in high-rise building construction

Abstract Formwork system is a significant constituent and a basic requirement for high-rise cast-in-place reinforced concrete buildings. Usually, the builders are confronted with the decision to choose the safe, optimum number of levels of shores/reshores for a predetermined safety factor and given grade of concrete, giving due consideration to the cost of formwork system. In this study, MATLAB program is developed to calculate the load distribution between the interconnected slabs and levels of shore/reshore of a slab formwork based on a simplified method. This program is further modified by incorporating genetic algorithm for the optimization of cost of construction for high-rise building. The cost of level of shores and reshores per floor is defined as a function of cycle time which directly reflects the increase in the cost of construction. Various combinations of shore and reshore levels with several grades of concrete for various safety factors are checked to minimize the cost of construction. The optimization equation is solved using genetic algorithm considering appropriate constraints to practically ensure feasible solutions. The case of one level of shores and numerous levels of reshores is better than one level of reshores and numerous levels of shores. The result of certain combination of shore and reshore levels is not the same when the level numbers are reversed. A comparative study is carried out to check the optimum cost for various safety factors. The program is useful for the designers to decide the levels of shores and reshores with minimized cost without compromising the safety of construction.