Erection of Precast Members

Abstract

The availability of adequate erection equipment and the feasibility of using the equipment on a specific job site are important considerations in determining whether the use of precast prestressed concrete is appropriate for a specific project. Both factors can have a significant effect on the cost of erecting precast concrete structures. The availability of erection equipment of adequate capacity is of particular importance in the planning and construction of medium-and high-rise buildings where the use of precast concrete is being considered. High reaches require cranes with long booms, and equipping a crane with a long boom can have a significant adverse effect on its lifting capacity. Large mobile cranes of the types required to erect the larger precast members are costly and, most important, are not readily available in all localities. In bridge construction, the use of mobile cranes to erect precast members may not be feasible because of the weights and reaches involved, limited access to the site, the risk of floods, vehicular traffic, or other considerations. The designer must give careful consideration to all the factors affecting the methods that can be used in the construction of a proposed structure, including erection, for each individual structure, and must prepare a design suitable for the job and the conditions of the job site.