Problem Statement (Structural Depth)

The existing High End Apartments is currently a dual structure consisting of a composite steel framed system with ordinary moment frames, and typical wood framed construction with wood bearing and shear walls. Benefits of the existing design is the relative light weight of both systems and the constructability of the wood structure. Material cost for the wood structure is also very economical for the building height. It is critical to respect the original design concerning the building use, and the low gravity load, but it is also important to consider possible alternatives and changes.

The current wood stud wall construction is not a very rigid system. Because of the flexibility and movement that can be associated with the current system, cracking in the drywall or interior finish can occur. The proposed structure is the implementation of precast concrete wall systems. The determination and feasibility to use this system for interior and exterior walls will be a large investigation. Wall locations will remain the same, to not interfere with the existing architectural layout and design. An investigation in insulated concrete panels will also be of interest for the exterior use. Observing many repetitive openings for balconies and windows allows the precast wall system to be used efficiently, however openings will make designs harder to prevent cracking and damage. Further research will be conducted if precast panels will not be used for the interior walls, light gauge steel studs as bearing and shear walls is a consideration. Multiple floor systems for the residential levels will be considered, as to not rule out any feasible designs. The systems being considered for the gravity floor system are wood, light gauge steel joists, and heavy steel with light concrete decking. For the parking levels, little investigation will occur, as attention will be mostly on the wall system changes. However, a one-way concrete slab will be implemented to easily incorporate transfer beams and easily pick up large line loads from load bearing walls. Little to no changes in the layout of columns and beam locations will occur, due to the efficiency of the column layout with respect to the existing parking garage layout.

Methods

            Design for the concrete precast wall panels will be in accordance with ACI specifications and design examples will be referenced in the CSRI manual. Guidance will be provided through design professionals at Providence Engineering that have experience designing precast concrete wall panels. Lateral systems will be designed and analyzed using ETABS. Through hand calculations, research and investigation, combinations of the appropriate floor system and wall system and where the precast concrete wall systems will be implemented.

Breadth Topics

            Changes will mainly occur with the wall systems primarily for the exterior wall construction. Interior walls may or may not implement the precast concrete wall systems. Because of these changes to the wall system, construction cost, timeline, and mechanical properties that insulated exterior concrete wall panels provide, breadth topics will be chosen on these affects.

Construction Breadth

            Prefabrication of concrete wall panels greatly economize project timeline. By switching to this system, the building could be enclosed much sooner and building finishes could be applied sooner. Prefabricated concrete panels also provide very consistent materials and products, whereas a wood constructed building, has a much more lenient building tolerance. Much more time and consideration will be needed by the engineer to design wall panels to coordinate with other building systems that concrete wall panels may effect.

Mechanical Breadth

            The insulated concrete wall system will be compared to the current wall construction being typical residential wood stud. Thermal conductivity and moisture transmission will be the main focus used to compare the original wood stud system to the revised concrete wall panel.