Thesis Final Report
The thesis redesign of Hunter's Point South School consisted of redesigning the structure's lateral system for a higher seismic region after changing the building location from Long Island City, NY to Redding California. To comply with the higher seismic loads from the new seismic zone, the structure was redesigned using Eccentrically Braced Frames (EBF's) in place of the original lateral framing system that consisted of concentrically braced frames. An EBF system was designed for its high ductility and energy dissipation characteristics. Also, this type of lateral system is very compliant with the original building design, allowing for minimal changes or impacts to the rest of the building. Two design methods were used to create two separate lateral system redesigns. The Equivalent Lateral Force Procedure (ELFP) and Modal Response Spectrum Analysis (MRSA) procedure from ASCE7-10.12 were used to create a transition from original design methods to commonly used seismic design methods. The ELFP method proved to be simpler to design with, but created larger loads and required additional bracing to prevent torsional irregularity to be allowed under code. The MRSA method was a more lengthy, in-depth, analysis, but created a much more efficient design with smaller loads (85%), better serviceability characteristics, and no necessary additional frames. Conclusions showed that both redesigns of the lateral system were effective options, but the MRSA design was chosen as the one that should ultimately be used.
An architectural impact study was done to determine whether either redesign had any negative impacts on the architectural layout of the school building, and what could be done to remedy such an issue. After analysis was completed, it was found the the MRSA method created no architectural impacts, as it was the same layout as the original lateral system, only with better bracing angles to allow for fitting the interior doors and windows better. The ELFP design proved to be problematic in regards to architectural layout. Because frames were moved to the exterior, the facade had to be redesigned to help hide the framing on the exterior. This led to lighting issues in several classrooms, and a new floor plan had to be developed.
A construction management impact study was also done on the two redesigns of the lateral system. Both cost and schedule impacts were analyzed. The ELFP design created a system that took 7 additional days to erect, delaying the critical path of construction by 10 days. The overall structural cost of the project was increased by less than 0.5% (5.5% without inclusion of location factors). The MRSA design created a system that took 3 days more to erect than the original, delaying the critical path schedule by 8 days. Final cost of the structure under the MRSA design ended becoming 3.25% cheaper than the original design (2.25% more if location factor is not included once again).
*To view the entire Final Report in PDF Format, click HERE
*To view the executive summary and conclusion in PDF Format, click HERE