Nick's CPEP

8621 Georgia Avenue

Silver Spring, Maryland

Nick Dastalfo

Structural Option

Advisor: Dr. Thomas Boothby

Building Statistics:

Part 1:

General Building Data:

Building Name	8621 Georgia Avenue
Location	Silver Springs, Maryland
Building Occupant	FP Willco, LLC
Occupancy	Multi-Family Residential/Commercial
Size	347,009 ft.2
Height	161 feet
Stories*	17
Cost	$51 million
Dates of Construction	Requested from Owner
Project Delivery Method	Requested from Owner

Project Team:

Owner - FP Willco, LLC
Developer- Foulger-Pratt Development, LLC
General Contractor – Foulger-Pratt Contracting, LLC
Architect – BBG-BBGM
Landscape Architect – Parker Rodriguez
Consulting Engineers
Civil – Macris Hendricks & Glascock, P.A.
Structural – Holbert Apple Associates
MEP – Century Engineering, Inc.
Geotechnical – Schnabel Engineering
Traffic – The Traffic Group
Utility Consultant – Richter & Associates
Art Consultant – Artists Circle Fine Art
LEED Consultants-
LEED Consultant – Paladino and Company
LEED Fundamental Commissioning Agent – Allen & Sharrif
Envelope/Waterproofing Consultant – Tadjer-Cohen Edelson Associates, Inc.
Elevator Consultant – Williams-Huntt & Associates, Inc.
Code Consultant – Hughes Associates, Inc. Fire Protection and Code Consulting
Interior Designer – TBD

Architectural Design and Function

The building is situated in the Central Business District of Silver Springs which is in the midst of a dynamic and developing area. The global design of the building had to take into account the existing architectural palette of the vicinity while also designing for the future. Consequently, respecting particular street views as well as providing important amenities for residents were both driving forces in design decisions. The North and South corners were areas of particular interest due to their visibility from heavily trafficked areas and became opportunities for distinctive design features.

The structure utilizes mild-reinforced and post-tensioned concrete flat plate slab floors. This allows for an open floor set-up with regular column grids which is indicative and compatible with parking garages and apartments. This system helps to maximize the floor to floor height of the building which was vital due to the zoning height restriction.

At the 5th floor and above, where the parking terminates, the building takes on a U-shape as opposed to the rectangular footprint at its’ base. This allows for each apartment in the upper levels to have window access and a view outside onto the streets below.

The building is 17 stories consisting of 12 stories of residential apartments stacked atop 5 levels of above grade parking and retail areas. The parking levels will serve both the occupants of the apartments as well as members of the immediate community. The existing site was previously a parking lot, and with the small, 3 block distance to the nearest Metro stop, providing ample parking was a priority. The first floor, at street level, is geared towards being a public space opened to the community that is highlighted by a Cyber Café, fitness center, and various retail space. The apartment levels above floor 5 will include single and multi-family apartments as well as moderately priced dwelling units (MPDU) and Work Force Housing Units. In addition to personal terraces and trash and recycle rooms, the apartments have access to a rooftop club room, outdoor pool, and locker facility.

Codes:

International Building code 2012
WSSC Plumbing and Fuel Gas Codes
International Fuel Gas Code 2012
National Electric Code 2008
National Fire Protection Association 2012
Life Safety Code 101 2009
Americans with Disabilities Act for Accessible Design 2010
Maryland Accesibility code Guidelines
International Energy Conservation code 2012

Zoning:

8621 Georgia Avenue is classified as a CBD-2 zoning use according to the Montgomery County Zoning Ordinance. The proposed building height of 161 feet is the maximum allowable building height for the given zoning classification.

As per the zoning requirements for the required parking provisions. The building must provide at least 302 parking spaces, 8 commercial parking spaces, 6 handicap accessible spaces (5 standard, 1 van), and 11 bicycles spaces.

Historical Requirements:

There are no specific historical requirements for the project.

Building Enclosure:
The primary exterior wall assembly will consist of precast concrete panels as well as a proprietary lightweight metal framed precast panel, known as Slenderwall. The façade will consist of both operable windows as well as curtain walls throughout. The curtain wall system includes a 1” insulated glazing and low E coating to improve the heat loss/gain of the building which contributed to the efforts towards LEED Silver status.

Structural glass is utilized in the main vestibule and entry doors to the main lobby on the ground floor of the building. All other entry doors use an aluminum siding system that maintains the same insulating values as the curtain wall system to maintain the thermal savings.

Roofing:

The roofing systems differ depending on location and function. The building sets back after the termination of the parking at floor 5. The roofing system above the parking structure is comprised of a green roof assembly with drainage board, filter fabric, lightweight soil, and various foliage.

The roofing system atop the 17th floor as well as the 5th floor terraces uses precast concrete pavers due to the pedestrian traffic these areas will see. The remaining roofing systems on top of the building will be rigid tapered insulation over concrete deck as well as walking paths in various places to service mechanical equipment. The insulation value of the concrete deck assembly is of R-30 value.

Sustainability Features:
8621 Georgia Avenue is aimed at being a LEED Silver building because of the efforts towards energy efficient design. The bulk of the LEED point earned on the project are due to transportation, optimizing energy performance, and on-site renewable energy.

The close vicinity to a metro stop encourages residents to take public transportation which produces less carbon emissions, comparatively. The accessibility of bicycle parking as well as low-emitting/fuel efficient vehicle restrictions also makes the associated transportation for residents’ greener.

he green roofs in multiple locations provide large benefits for the storm water drainage of the site. These roof systems can become saturated as opposed to an impervious surface. The green roof assembly is 8 inches thick and provides thermal insulation for the top of the building because of the inherent thermal mass of the soil and plants.

Part 2:

Structural:

The foundations provided for 8621 utilizes spread footings beneath the wall loads of the cellar and first floor and deep column footings elsewhere. The column footings are square in plan shape and vary from 9'-0" x 9'-0" to 11'-0" x 11'-0" with a depth of 32-38". At certain conditions on the perimeter of the building, the size of the footings is limited by adjacent properties and structures. These special footings are 10'-0" x 22'-0" with a depth of 48". The footings need to be deeper than the others to account for the eccentricity of the column loads on the footing.

The first four floors are constructed with 2 way cast in place flat plate slabs. These levels are utilized as a parking garage for the tenants of the apartments above. The slab is 8" thick with 8' x 8' x 4" drop panels and is supported by 18" x 24" columns. The bays of the building are inconsistent and sometimes irregular in shape but vary from 16' x 24' is size in each direction.

The fifth floor and above is occupied by apartments. The apartment levels are framed in a 7.25" post-tensioned two way slab with no drop panels. The bays are the same size as is the parking garage but the column size decreases to 16" x 24". The post-tensioning cables are laid out in both directions; distributed in one way, and banded in the other.

The columns of the building will vary in concrete strength throughout the height of the building to be able to maintain the same column dimensions. The concrete strengths vary from 5,000psi to 7,000 psi. The columns and slabs at the parking levels will also be mixed with a corrosion inhibiting admixture to prevent deterioration due to salts and minerals brought in by the cars.

Construction:
The construction of 8621 Georgia Avenue is to be a 17 story, 347,009 ft2 project led by Foulger-Pratt Contracting, LLC. The building is scheduled to begin construction in early 2015 and last for 24-28 months. Important construction constraints would be the surrounding existing buildings as well and the bustling Georgia Avenue, to which the building fronts. Drop off, lay down, crane placement, etc. will all need to be well thought out to cause minimal impact on the occupants of the surrounding buildings

This aerial photo to the right shows a footprint of the building in context of the surrounding buildings and streets. The site is currently a parking lot covering approximately 6 ft. of fill containing debris from previous construction and demolition activity.

Electrical:

The electrical service to the building will be provided by 6 transformers located in the small cellar level as well as underground utility vaults beneath the sidewalk on Georgia Avenue. The power supplied to the building is both 277/480V and 120/208V transformers. Four 120/208V, three phase power transformers serve the residential floors to the building. The house loads, parking garage, fire pump, and emergency generator loads will be supplied by two 277/480V transformers.
Branch panels will be on every 4th residential floor and will serve the lighting, HVAC, utility rooms, and local receptacles.

Lighting:

The lighting system in the building has been designed to meet the standard recommendations developed by the Illuminating Engineering Society (IES) and will also take measures to meet LEED requirements. The building’s exterior perimeter lighting, as well as, the lighting in the parking garage will be typical surface mounted metal halides. The lighting in the apartment level hallways consists of recessed compact fluorescents. Special decorative lighting, such as wall sconces, are provided outside each residence, elevator, and other areas of architectural interest.

Mechanical:

Floors 1-4 (parking garage) will be open which eliminates the need for active mechanical ventilation. Each apartment will be conditioned by a conventional split system heat pump with back-up electric heat. Outdoor air is provided by an exterior louver. Each apartment will have the ability to regulate it's own temperature independently through programmable thermostats.

The office/ammenity space on the first floor, as well as other common rooms or hallways in the building will be conditioned by a gas fired split system. For the spaces on the first floor, the condensers and fan coil units will be suspended in the ceiling plenum above, directly below the third floor. For the hallways and common spaces in the upper floors of the building, the units will be mounted on the roof and vertically feed the supply and return ductwork through open shafts of the building.

The cellar will be provided with ventilation and exhaust by similar gas fired systems located in the cellar itself.

Circulation:

In terms of vertical circulation, the building is serviced by two stair/elevator towers throughout the building. Each tower is located at different wings of the U-shaped footprint of the building and lies with the minimum egress legnth to a living quaters governed by code. There are three elevators, two of which are open to the public, while the third one is strictly for service uses.

The highlighted blue areas to the right designate the two stair cores of the buildings. The lower of the two is the one that includes the public and service elevators.