Precast design process and team members

Precast buildings are made of precast concrete elements which are fabricated using special equipment and machinery. After production and curing, the precast concrete components are transported to the construction site where they are erected by cranes which lift the precast elements to their final position. Precast design engineers will have to prepare various design calculations for the purpose of precast production, transportation and final installation at site. The structural draftsman will have to prepare the detailed shop drawings of each precast component. This blog article will briefly describe some of the aspects of the precast design process and the team members involved in the design and detailing activities.

 

The building owner appoints the architect and structural engineer who have to design the building and recommend a suitable building system. During the schematic and concept design phases they will have to investigate how precast building technology can shorten the construction time, reduce the cost and increase energy efficiency. Many other reasons can be considered to utilize precast building components in the design. Eventually the design team shall have to prepare contract documents which will include the contract drawings with specifications about the precast members and how they are placed in the building. The contract drawings will enable the building contractor to assess the total size of the project and prepare a cost estimate based on the difficulties of execution. However the contract documents will not be suitable to start the execution of the building project. The contractor shall require additional design calculation documents and detail drawings with all the exact dimensions and specifications so that they can be used for the precast fabrication and construction. Preparation of this detailed precast design is generally done by specialized precast engineering firms with a team of precast detailers and precast design engineers. These precast design firms have an in-depth understanding on how to analyze and design the precast building structures combined with practical knowledge about the precast production and erection process.

 

As soon as the project has been awarded to the contractor and precast manufacturer the role of the precast design team begins to take shape. This team basically consists of the following members:

1. Precast coordinator

2. Precast structural engineer

3. Precast detailer

4. Precast drawing checker

5. Senior drafter

Project coordinator

The project coordinator monitors and develops the project planning in assistance with the other team members. The coordinator has to attend the project meetings and coordinate the design activities of the precast design team. Furthermore he will have to communicate with the contractor, client and other design consultants involved in the project.

Precast structural engineer

The precast structural engineer prepares the load calculations and structural analysis of the building followed by detailed design calculations of each precast concrete component. The precast engineer also has to review the precast shop drawings prepared by the detailing team and check if they comply with his design calculations. Furthermore the precast engineer has to provide support to the execution team with respect to the stability of the precast structure during erection at site.

 

Precast detailer

The precast detailer prepares the precast erection drawings and precast shop drawings in 2D or 3D drafting software. He will generally work under supervision of the senior drafter and checker and he will have to complete the precast detail drawings based on the markups and instructions given by them.

Precast drawing checker

The precast drawing checker has to check and review the precast detail drawings prepared by the detailing team. The checker has to ensure that the team has correctly interpreted the contract documents and all the correct information has been included on the precast drawings. He also has to check the drawing presentation and their consistency with the precast production methods and company detailing standards. Finally he will check the accuracy of the precast panel geometry, the tolerances, bill of materials and other details on the precast shop drawings.

Senior drafter

The senior drafter will head the team of precast detailers and will perform all the drafting functions like preparing the precast erection drawings, piece tickets and material lists. He will coordinate with the precast engineer and the project coordinator regarding the project schedules and the estimated time required for new and ongoing projects. He will also take care of the quality improvement program of the precast drafting team and he will train all the new staff.