Recommendations of this report apply to design of precast concrete structures where all members or selected members are cast somewhere other than their final position in the structure.
This report should be used together with ACI 318, “Building Code Requirements for Reinforced Concrete,” the minimum requirements of which may be legally binding.
Because of the nature of precast concrete, certain recommendations contained in this report differ from the requirements of ACI 318. Some of these recommendations may not be applicable to special conditions. Engineering judgment should be used in implementing this report.
Tilt-up concrete construction is a specialized type ofprecast concrete construction. Because panel dimensions in tilt-up are generally much larger than those in plant-cast precast, and roof and floor diaphragms are generally not constructed with precast sections, certain recommendations in this report differ from common practice found in tilt-up concrete construction.
In design of precast members and connections, all loading and restraint conditions from casting to end use of the structure should be considered. The stresses developed in precast elements during the period from casting to final connection may be more critical than the service load stresses. Special attention should be given to the methods of stripping, storing, transporting, and erecting precast elements.
When precast members are incorporated into a structural system, the forces and deformations occurring in and adjacent to connections (in adjoining members and in the entire
structure) should be considered.
The structural behavior of precast elements may differ substantially from that of similar members that are monolithically cast in place. Design of connections to transmit forces due to shrinkage, creep, temperature change, elastic deformation, wind forces, and earthquake forces require special attention. Details of such connections are especially important to insure adequate performance of precast structures.
Precast members and connections should be designed to meet tolerance requirements. The behavior of precast members and connections is sensitive to tolerances. Design should provide for the effects of adverse combinations of fabrication and erection tolerances.
Tolerance requirements should be listed on contract documents, and may be specified by reference to accepted standards.
Tolerances that deviate from accepted standards should be so indicated. All details of reinforcement, connections, bearing elements, inserts, anchors, concrete cover, openings and lifting devices, and specified strength of concrete at critical stages of fabrication and construction, should be shown on either the contract documents prepared by the architect/engineer of record or on the shop drawings furnished by the contractor.
Whether this information is to be shown on the contract documents or shop drawings depends on the provisions of the contract documents. The shop drawings should show, as a minimum, all details of the precast concrete members and embedded items. The contract documents may specify that portions of connections exterior to the member are also to be shown on the shop drawings. The contract documents may also require the contractor to provide designs for the members and/or connections.
The contract documents should show the loads to be considered in design of the precast concrete elements of the structure, and they should indicate any special requirements or functions (for example: seismic loads, allowance for movements, etc.) that should be considered in design assigned to the contractor. In this case, the shop drawings should include complete details of the connections involved.
Learn more about Design Recommendations for Precast Concrete Structures, you can download here
This report should be used together with ACI 318, “Building Code Requirements for Reinforced Concrete,” the minimum requirements of which may be legally binding.
Because of the nature of precast concrete, certain recommendations contained in this report differ from the requirements of ACI 318. Some of these recommendations may not be applicable to special conditions. Engineering judgment should be used in implementing this report.
Tilt-up concrete construction is a specialized type ofprecast concrete construction. Because panel dimensions in tilt-up are generally much larger than those in plant-cast precast, and roof and floor diaphragms are generally not constructed with precast sections, certain recommendations in this report differ from common practice found in tilt-up concrete construction.
In design of precast members and connections, all loading and restraint conditions from casting to end use of the structure should be considered. The stresses developed in precast elements during the period from casting to final connection may be more critical than the service load stresses. Special attention should be given to the methods of stripping, storing, transporting, and erecting precast elements.
When precast members are incorporated into a structural system, the forces and deformations occurring in and adjacent to connections (in adjoining members and in the entire
structure) should be considered.
The structural behavior of precast elements may differ substantially from that of similar members that are monolithically cast in place. Design of connections to transmit forces due to shrinkage, creep, temperature change, elastic deformation, wind forces, and earthquake forces require special attention. Details of such connections are especially important to insure adequate performance of precast structures.
Precast members and connections should be designed to meet tolerance requirements. The behavior of precast members and connections is sensitive to tolerances. Design should provide for the effects of adverse combinations of fabrication and erection tolerances.
Tolerance requirements should be listed on contract documents, and may be specified by reference to accepted standards.
Tolerances that deviate from accepted standards should be so indicated. All details of reinforcement, connections, bearing elements, inserts, anchors, concrete cover, openings and lifting devices, and specified strength of concrete at critical stages of fabrication and construction, should be shown on either the contract documents prepared by the architect/engineer of record or on the shop drawings furnished by the contractor.
Whether this information is to be shown on the contract documents or shop drawings depends on the provisions of the contract documents. The shop drawings should show, as a minimum, all details of the precast concrete members and embedded items. The contract documents may specify that portions of connections exterior to the member are also to be shown on the shop drawings. The contract documents may also require the contractor to provide designs for the members and/or connections.
The contract documents should show the loads to be considered in design of the precast concrete elements of the structure, and they should indicate any special requirements or functions (for example: seismic loads, allowance for movements, etc.) that should be considered in design assigned to the contractor. In this case, the shop drawings should include complete details of the connections involved.
Learn more about Design Recommendations for Precast Concrete Structures, you can download here
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