315 East 46th Street
Manhattan, NY
Proposal
Structural Depth
The proposed design alternative will include a complete redesign of 315 East 46th Street’s gravity and lateral systems using steel framing. The decision to use steel framing was made from an educational standpoint. After analyzing the existing concrete structure for a semester it would be very valuable to spend a semester studying steel design of a high-rise building.
Notebook B, will be used as the starting point for the gravity system redesign. A preliminary column layout was developed but will need to be refined. Initially girders were designed to span N-S, as shown in Figure 16, due to the fact that the columns were aligned in this direction. This resulted in a member size governed by deflections. When refining the column layout this will be important to keep in mind as it is more economical to have the girders spanning the shorter direction and beams spanning the longer direction. Aligning the columns in the E-W direction could be a viable option so long as the architecture is not affected a great deal. Preliminary sizes for beams and girders using non-composite steel design were also determined in Notebook B and can be seen in Figure 17. As part of the redesign, composite steel design will be investigated in order to have the longest spans possible, therefore interrupting the architecture the least.
The proposed lateral system will be braced frames in both directions. Once the column layout is selected the location of these frames will need to be investigated with the goal of minimizing torsional effects from lateral loading. The type of bracing to be used is also something that will need to be considered and investigated.
Acoustical Breadth
The proposed redesign from concrete to steel will result in a floor system with less mass, this will have an effect on the acoustical performance of the floor system. Specifically this can be a problem at the roof level where there is a mechanical room above bedrooms. Another potential acoustical problem could result from the removal of the concrete shear walls around the elevator core which will have to be replaced by partitions. The proposed acoustical breadth will include an investigation into both the original reinforced concrete system and the new steel framing system addressing any deficiencies found. Solutions to these deficiencies will be provided to insure no acoustical performance is lost due to the change in structural system.
Construction Breadth
When completely changing structural systems from concrete to steel, construction costs and schedule are greatly affected. The proposed construction breadth will include an investigation into both of these components and how they positively or negatively affect the project. It is expected that steel construction will result in a faster schedule due to the rate at which steel can be erected. As for cost it is expected that the cost associated with materials will increase but if in fact the schedule is reduced the overall cost of the building could possible decrease. The investigation into cost will also take into account the results of the acoustical breadth if these results show that upgrades in acoustical performance are needed.
MAE Requirements
The proposed design alternative will incorporate the graduate level coursework of AE 530 - Computer Modeling of Building Structures through the construction and verification of an ETABS model that will be used to analyze and design the steel framed structure. Also the coursework from AE 534 Analysis and Design of Steel Connections will be used to design the connections of the braces in the lateral force resisting system.
CPEP finalized and ready for review
4/21/18
4/21/18
Final CPEP Review
12/8/17
12/8/17
11/14/17
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