Safety and Economy of Shoring/Reshoring Schemes in Construction of Multistory Concrete Buildings

The objective of this paper is to describe a computerized model for selecting a cost-effective slab shoring/reshoring scheme for construction of multi-story concrete buildings. The model is based on two main criteria: safety during construction and cost-effectiveness. As construction of high-rise concrete buildings moves up, shoring of lower slabs are stripped and placed on top of the just stripped slabs in order to cast the upper slabs. Some of the stripped lower slabs must be reshored to carry the additional construction load. Both safety and cost must be considered in a reasonable manner in order to determine the optimum shoring/reshoring combination for a particular construction. Factors such as cycle time (duration between casting of two consecutive slabs), concrete strength, building configuration and member dimensions, cost of shoring and reshoring materials, and labor productivity must be taken into account in order to analyze and determine the optimum combination. In this study, thirty customary and practical shoring/reshoring combinations are investigated. SHORING2, a program developed by Chen and Mossalam is used to analyze load distribution and check safety of construction. A database module in Access® is developed to store various possible building configuration data, labor and materials unit prices, and other material properties data. Another module developed in Excel® is used to compile and further analyze results from SHORING2 and Microsoft Access® modules. As a result, information on cost and duration of the construction is obtained. In the final operation of the system, the results are displayed in graphically Access® module. These results provide a helpful guide to users in choosing the best shoring/reshoring combination.