NYU Seismic Design Team
The NYU Seismic Design team responded to a request for proposal of a multi-story mixed-use high-rise development in downtown San Diego, California. The initial five stories of the structure have a reduced floor plan to accommodate existing developments, and the following stories expand to the extents of the site. The building consists of residential, office and retail space. The development will be a welcome addition to the downtown San Diego skyline; embodying simple prismatic shapes, a soft blue pallet to reflect the skies and the harbor and a gentle incline to solidify the structure. The structure reinforced by this inclination of the walls and cross bracing in order to ensure that the occupants will be safe in the event of seismic activity
Geotechnical/Site Description
Vancouver lies in the Cascadia Subduction Zone, a place in which the Juan de Foca and North America plate meet. The Cascadia Subduction Zone is known for producing large earthquakes of approximately magnitude 9. Geological evidence indicates that a megathrust earthquake occurs in this region every 400 to 600 years. The Cascadia Subduction Zone has had no major activity recently, so it is believed that there is a 12% chance that within the next 50 years, a megathrust earthquake will occur. The last time a megathrust earthquake occurred in this region was on January 27, 1700. Besides earthquakes produced by the Cascadia Subduction Zone, Vancouver also experiences earthquakes because of active faults underneath the Strait of Georgia and a deep intraslab. The 7.3 earthquake of 1973 and the 9.0 earthquake of 1946 were caused by these. Because of the vast seismic activity in the region, it is important to create an earthquake resilient structure.
The soil conditions expected in the Vancouver area largely consist of fines such as clays and silts, as well as granular soils and glacial till underlain by bedrock. A high-water table is expected in most areas, which, combined with the expected subsurface soils, may pose a significant risk to liquefaction in granular soils and heave in oversaturated clays.
Architectural Description
Vancouver is known to be one of the most beautiful and livable cities in the world, so a building made there must complement that culture. The building will be multi-purpose (commercial, office, and residential) have multiple green and open spaces, mainly throughout the commercial levels of the building, because most people will be interacting with those levels. Vancouver is a very rainy city, with 160 days of rain per year. The first floor will have the greenest space with transparent roofing, so it can include a space for Vancouver residents to still enjoy part of the outside while still being indoors. Glass Curtain walls will be implemented to complement Vancouver’s Aesthetic and to reduce the amount of light pollution, so the use of natural daylight can be maximized. Indoor and outdoor lighting is dependent upon the locations of the neighboring buildings which could block the sun and other light sources (street lights). To encourage people to use the city’s “Sustainable Commuting” Program, there will be a reduced parking footprint for employee parking, and employees are encouraged to bike or carpool instead. Green vehicles will be encouraged, and bicycle facilities will also be implemented.
Structural Description
The stiffness of the structure will be increased by using a centrally located building core consisting of shear walls. As seen in Figure 1, the shear core is composed of walls running parallel to each other, in both directions, and a core wall connected with link beams. The shear core is located in the center of gravity of the T-shaped building, increasing the structure’s ability to resist twisting from lateral loads such as seismic loads. In order to maximize space, the elevator shaft and stairs will be integrated into the core. Shear cores not only allow for an increase in structure stiffness but also the flexibility to design a uniquely shaped structure that reflects Vancouver’s culture. Along with a shear core, trusses will be implemented along the building to help distribute the lateral forces and provide additional support. The wall highlighted in red in Figure 2 is composed of trusses. Additionally, columns will be placed every 2” to provide more support.
Figure 1: Floor Plan
Figure 2: Trusses
Figure 3: Architectural Structure
Economic Consideration
Table 1: Economic Analysis
As seen by the information provided in table 1, the structure consists of 16 floors, both of commercial and residential use. The income generated by each floor use would be $308,000 annually. After taking into consideration construction cost, net annual revenue of $134,600 will be made.