Structural Depth

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​The proposed alternative system consists of a biaxial voided flat slab for the gravity system and concrete shear walls for the lateral system.  A voided concrete slab removes concrete from the middle of the slab where it is not structurally efficient by placing plastic voids in the shape of flattened spheres. Theses voids reduce the dead load by as much as 35% compared to a solid reinforced concrete slab, which allows for larger spans, lower floor to floor heights due to the reduced slab thickness, and thus a reduced height of the structure. This reduced height of the building can help reduce costs for the façade, pipes, and ductwork. Figure 20 shows a side by side comparison of a conventional concrete slab system next to the voided concrete slab system. For the gravity system, the current column configuration will have to be rearranged in order to achieve a standard typical bay throughout the building. The redesign of the lateral system will consist of shear walls located in the same place as the current moment frames and braced frames. As shear walls have higher stiffness’s than moment frames and braced frames, strength and drift should perform better for the proposed lateral system compared to the existing lateral system.  

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Construction Management Breadth 

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This alternate system will have an effect on both the time and cost of construction. Since concrete is typically cheaper than steel, the overall cost of the building should be cheaper. In addition, the overall building height will be several feet shorter which will help reduce the cost. Although the current cost is being withheld from the owner, this breadth will determine if the new system will reduce the overall cost, and ultimately the feasibility of the alternate system.

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Mechanical Breadth 

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With the depth of the floor system reduced, the sizes of pipes and ductwork will need to analyzed. There will most likely not be enough height for the existing pipes and ductwork with the new alternate design. This breadth will determine how the alternate system will affect the mechanical coordination and mechanical equipment sizes.  

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MAE Requirements

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The graduate coursework that will be included into this report is from AE 530: Computer Modeling of Building Structures. ETABs will be used to create a three dimensional model to design the new gravity and lateral system.