Building Name: Office Building (With held by Owner’s request)
Location and Site: Washington, DC (Owner’s request to with hold direct address to the building)
Building Occupation Name: The tenant’s of the building will be determined by the Owner at a later date
Occupancy or function types: B1 - Business; Commercial Office Building
Size: 741,200 square foot
Number of Stories: 10 stories above grade, one level of office space below grade, three levels of parking below grade, and an intermediate penthouse and penthouse levels
Primary Project Team:
Construction Manager - Balfour Beatty Construction (www.balfourbeattyus.com)
(All other members of the project team shall not be released per owner’s request)
Dates of Construction: August 2006 - April 2009
Base Building Cost: $99,000,000
Project Delivery Method: GMP
This new office building is the third and final structure of a three phase project that will help with the continued revitalization of the local area. The 10-story building provides efficient and productive work spaces, state-of-the-art technology, one main lobby, two secondary lobbies, three paver terraces located on the second, third, and fourth levels, and includes three levels of parking. With well-located core services, the office building has the flexibility to meet the needs of small, medium, and large space users. This LEED Silver certified building offers tenants direct access to MACR Train Service, Virginia Railway Express trains, and Amtrak, as well as Metrobus systems and Washington’s Metrorail. Existing low-scale surroundings also offer tenants high visibility, access to natural light and air, and spectacular views of Washington, DC.
Major National Model Codes:
1986 ANSI A117.1-86
CABO 95 Model Energy Code
1996 BOCA Nation Building Code
1996 NFPA National Electrical Code
1995 ICC – International Plumbing Code
1996 ICC – International Mechanical Code
1996 BOCA National Fire Prevention Code
1996 BOCA National Property Maintenance Code
999 Supplement – The District of Columbia Construction Codes
1993 ASME A17.1-93 Safety Code for Elevators and Escalators – 1994 Addendum
District C-3-C: Permits matter-of-right high density development, including office, retail, housing, and mixed uses to a maximum lot occupancy of 80% for residential use, a maximum FAR of 6.0 for residential and 2.0 FAR for other permitted uses, and a maximum height of ninety (90) feet (www. dcoz.dc.gov/info/districts.shtm)
The office building’s envelope features a glass curtain wall system with granite stone panels on three elevations. The East elevation displays a different curtain wall pattern than the West elevation, however the two designs converge on the North elevation of the building. Furthermore the South wall is shared with the adjacent second building of the three phase project, thus no exterior envelope is present. The one-story high glass and granite panels are put into place by a crane, starting at one end of the building and making its way across to the other side. The remainder of the building envelope consists of handset stone between the curtain wall units and exterior columns of the building.
The roofing system for this project is a material called Thermoplastic single-ply roofing membranes (TPO); it is designed to combine the durability of rubber with the proven performance of hot-air weldable seams. TPO has been tested as having excellent resistance to ozone, ultraviolent, chemical exposure, and is environmentally friendly and safe to install.
Building Stats Part II:
The project delivery method for this building is design-bid-build. First the owner hired design professionals to prepare a complete set of contract documents, which includes plans and specifications, for a set price. Once the project plans and specifications are complete and given to the owner, he/she pays the designers a fixed price. Then the owner will hire a Construction Manager (CM). Balfour Beatty Construction (BBC) was hired by the owner to manage the project. The owner negotiated with BBC the contract, and they agreed on a Guaranteed Max Price (GMP) type of contract. However, the owner only has a contract with BBC, thus they must manage all of the subcontractor’s contracts.
Once BBC was awarded the project, they had to hire every subcontractor for every trade. BBC bided the project, and a different contractor was selected for every trade each being the lowest bidder. BBC then negotiated a lump sum contract with every subcontractor. The cost of the work for every trade was set before any work begun. Moreover, every subcontractor needed insurance and bonds before starting any activity.
During the bidding phase the building was non-LEED rated. However, with LEED certified buildings becoming the future in construction, the owner wished to achieve a LEED Silver rating for the project. Thus a LEED design was noted as a bulletin to the drawings and was priced as a correction to the contract.
Structural Steel Frame:
The structural steel for this building is located on the West side and is positioned directly above the M Street Ramp. This portion of the building was designed to fit the ramp’s form, thus clear spanning was used to allowing for two way traffic underneath of the steel structure. The structure steel will utilize the ramp’s current foundation and structural system to support its loads on one side. The ramp was pre-engineered to compensate for the steel’s load during the construction of the first building. In order for the steel structure to connect to the ramp, seven (7) wide flange beams encased in concrete (W14X257) must brace diagonally four (4) wide flange columns encased in concrete (W 14X120) thus transferring the loads down to the ramp’s foundation.
The composite decking for the 5th and 6th Floor in the steel structure utilizes two different methods of floor systems. Flooring north of line 144 use 5” lightweight concrete fill reinforced with #6 @ 6” E.W. at mid-depth over 1-1/2” composite metal deck (gal., 19 GA. Min) and flooring south of the 144 uses 3-1/4” lightweight concrete fill over 1-1/2” composite metal deck (gal. 20 GA. min.) reinforced with W.W.F. 6x6 – W2.1xW2.1. These two methods are used to provide adequate blast resistance in case of terrorist threats from the road, such as car booms. All other floors in the steel structure utilize the 3-1/4” lightweight concrete method.
Cast in Place Concrete:
The mat slab foundation, the four underground levels, and the post tensioned floor decks are made of cast in place concrete. The mat slab is 4’-6” thick at 5000psi normal weight reinforced concrete and has a minimum 4” thick mud slab at 4000psi normal weight concrete underneath it to aid in stopping water penetration. Directly on top of the mat slab is an 8” layer of granular fill with a 6” minimum topping slab as the floor’s finish. The underground level and ground level floors are of 9” thick two-way reinforced concrete slab with 3-1/2” thick drop panels at 500psi normal weighted concrete. The post tension floor above grade is 12” thick at 5000 psi normal weight concrete and once the strength reaches 3000psi tensioning of the cables can occur. Most of the concrete was placed with crane and bucket or by direct chute. The Plywood was used to form the post tension slabs, columns, and walls.
The majority of the mechanical equipment is located on the P3 Level in the Chiller Plant and on the Roof. The Chiller Plant contains four (4) chillers with a nominal capacity of 500 tons, five (5) condenser water pumps, five (5) primary chilled water pumps, two (2) secondary chilled water pumps, and one (1) heat exchanger. The Roof has four (4) cooling towers with a nominal capacity of 650 tons, one (1) condenser water pump, two (2) primary chilled water pumps, one (1) secondary chilled water pump, and one (1) heat exchanger. On both sides of the building core from the Lower Level to 10th Floor are three (3) water cooled air conditioning units (AHU) per a floor ranging from 4000 CFM to 23400 CFM supply, thus totaling thirty (30) AHU in the building.
The mechanical system for this building is split into two systems, the primary and the secondary. The primary system’s cooled condenser water is pumped through the chillers and used to cool the water in the chilled water system. The used hot condenser water is sent back to the cooling towers to remove heat, and then the process is repeated. The secondary condenser water system provides water to the AHU throughout the building and then returns the hot water to the cooling towers to remove the heat, and then the process is once again repeated. From then on the AHUs cool the outside air, brought in through outdoor air riser supply vents, and distribute it to the VAVs found throughout each floor in the building.
The building’s electricity runs through three switchboards, each of 4000 A, 265/460 volts, 3 phase, and 4 wire systems. Power is fed from the PEPCO transformer vaults, located underground outside the building’s foundation wall, into the switchgear room on the Lower Level. Transformers, located on every level of each riser, provide step down voltages from 480/277 volts to 120/208 volts power, thus making it suitable for normal use of computers, vacuum cleaners, and corridor lighting. Most lighting fixtures in the building are fluorescent because it adds efficiency to the design and helps to attain the appropriate LEED points.
The backup generator is sized at 750 kw and 208/120 volts, this would provide power to all emergency lighting, fire alarms, stair pressure fans, smoke removal fans, fire pump, emergency for elevators, and selected circuits for security if the power should ever fail.
The building’s sprinkler system was designed and installed in accordance with NFPA 13. The office building, Ground Floor to the 10th Floor, is fully sprinkled with an automatic wet pipe system pressurized at 175 psig. Class 1 standpipes are also present in the stairwells of the office building. The below grade parking garage, P3 Level to the Lower Level, is fully sprinkled as well with a pre-action system that is pressurized at the same psig as the wet pipe system. A pre-action sprinkler system employs the basic concept of a dry pipe system, in that the water is not normally contained within the pipes, thus the water is held from the piping by an electronic operated valve. Furthermore, all of the main structural, as well as all interior framing members have various layers of spray-on fireproofing.
There are sixteen elevators total in the building, four hydraulic and twelve traction elevators. Three hydraulic elevators and ten traction elevator have a bearing capacity of 4,000 lbs., while one hydraulic elevator has a bearing capacity of 2,100 lbs. and two traction elevators have a bearing capacity of 5,00lbs. The traction elevators operate at 350 fpm, the three 4,000 lbs hydraulic elevators operate at 125fpm, and the one 2,100 lbs. hydraulic elevator operates at 100fpm. In the center of the office building, past the Lobby on the Ground Floor there is an elevator core that has access to the Lower Level and every floor up to the 10th Floor. This elevator core contains ten passenger elevators and two service elevators. There is also a single passenger elevator on the far North end of the building that accesses the 4th Floor down to the Lower Level. Also two passenger elevators located in the Southeast quadrant of the building provide transportation from the P3 Level to the Ground Floor. Lastly, a single passenger elevator located in the Northwest quadrant of the building runs from the 10th floor to the Roof.
The telecommunication systems design will be up to par with Office Building’s standards. Raceways for communication systems wiring will be provided throughout the building, as well as communication closets on each floor in a stacked pattern to allow for vertical distribution. Cable trays will be aluminum ladder style and will be provided in corridor spaces.