Note: While great efforts have been taken to provide accurate and complete information on the pages of CPEP, please be aware that the information contained herewith is considered a work-in-progress for this thesis project. Modifications and changes related to the original building designs and construction methodologies for this senior thesis project are solely the interpretation of Timothy Conroy. Changes and discrepancies in no way imply that the original design contained errors or was flawed. Differing assumptions, code references, requirements, and methodologies have been incorporated into this thesis project; therefore, investigation results may vary from the original design.

Building Statistics

primary engineering systems


construction	The project delivery system selected by the owner to use for this project is a construction manager with general contractor (CM with GC). The owner selected this delivery method as to not carry any of the risk themselves and have the general contractor carry this burden. To assist in the checks and balances, the owner decided to incorporate a construction manager into the organizational structure of the project. Davis construction does not generally prefer this delivery method. Davis construction typically prefers general contractor at risk (also known as CM @ Risk) in which they act as the construction manager and general contractor. One reason for this preference is Davis tends to do a great deal of negotiated work which is easier if they hold the only contract with respect to the construction activities. Minshall Stewart Properties holds contracts with the architect, the civil engineer, the structural engineer, the MEP engineer, and the general contractor. They also hold a contract with the construction manager who will provide construction guidance and advice. The owner holds a lump sum contract with all parties except they hold a GMP contract with Davis Construction.

electrical	The main service feeders for the building enter from the Pepco transformer vaults on K Street at the cellar level. Due to the nature of the project, the Pepco vaults were not touched and therefore the size and type of transformers held within is unknown. The existing building has two 6,000A feeders. The electrical service for the new construction enters at 2,000A and is distributed on a 208Y/120V system. To handle the new electrical load, a new switchgear installed and two 2,000A distribution panels were added to service levels B3 through 11. The emergency power is supplied by a 250 KW 208Y/120V diesel generator.

lighting	The lighting is operated on a 120V system and used energy efficient fluorescent lamps with electronic ballasts. A typical lamp used is an F32T8 operating at a color temperature of 4100K. The base building did not include common areas in the new floors. Lighting design and installation will be part of the tenant fit out.

mechanical	The primary mechanical room for this project is located on the penthouse level. Located there is one 1,200 GPM 350 ton induced draft cooling tower which serves eleven self-contained package water cooled units throughout the building. Each of the self-contained units on levels nine, ten, and eleven contain a 14,000 CFM fan with an incoming air temperature ranging between 65 and 80 degrees fahrenheit and a returning air temperature of 53 degrees fahrenheit with respect to cooling. Each SCU is rated for 35 tons of cooling. On the other hand, with respect to heating, electrical resistant heating coils operated on 3-phase 208V power were used. The previously mentioned SCU's service the tenant spaces whereas a closed loop system with VAV's was used in the building core. The new floors, floors nine through eleven, will be controlled by a new building automation system; whereas the existing floors, floors B1 through seven, will be controlled by the existing pneumatic system.

structural	This project involves the addition of three levels of structural steel with lightweight slab on deck construction onto an existing structural concrete eight story building. Levels ten and eleven structural slab is to be 3 1/4" lightweight concrete over 2" deep by 18 gage galvanized composite metal deck measuring a total of 5 1/4" reinforced with 6x6 - W2.0 x W2.0 welded wire fabric. The typical bay size is 23'-3" by 36'-8". To achieve such spans, composite beams were utilized. The crane used to erect the steel and pour the concrete slabs was placed where a future elevator and grand staircase was to be installed. This elevator was to only service levels eight thru eleven. Due to the constraints imposed by the limited space on site, the crane was placed atop four columns in the existing roof. Concrete piers were poured to create the foundation on which the crane was placed. Carbon fiber and/or steel jackets were used to allow the columns to carry the new load imposed by the crane and the material lifted by it. The crane used was a two ton tower crane. For the existing building to be able to carry the newly imposed loads from the new floors, the existing foundation under went some expansion. Several of the existing footings needed to be expanded to be able to carry the new load. These footings were expanded in the x-y plane but not in depth. The existing foundation consists of 48" x 48" x 24" spread footings. The concrete used for the lightweight slab on composite metal deck was 3,000psi (110 PCF) and the concrete used in the above mentioned concrete piers was 4,000psi (145 PCF). Where the footings needed expanding, 3,000psi (145 PCF) concrete was used.

support systems

fire protection	The fire-suppression system combined sprinkler/standpipe system. In areas affected by freezing conditions, a dry system was used. Such a location included a portion of the loading dock. In all other areas, a wet system with heat sensitive sprinkler heads was used.

vertical transportation	Seeing as how this project is an occupied renovation, the existing bank of three elevators posed a unique challenge. Throughout the duration of the project, two elevators had to remain in service while the one was being modernized. Along with the elevator car's receiving a facelift, the elevator shaft had to be extended up to service the three new floors. This process had its challenges with respect to sequencing and safety. Additionally, the work on the elevators could not begin until the new elevator machine room was dried in. With respect to safety, a temporary partition had to be constructed to separate the elevator shaft under construction from the other two operational shafts. Once the first elevator was completed, the team moved immediately to the second and subsequently the third.

telecommunications	The telecommunication system in the existing building uses copper for the transmission lines. Similarly, the new floors also utilize copper lines. Fiber optic lines were considered due to the length of copper line that would need to be run from the penthouse down to the cellar level. The final decision was to go ahead with copper because the connections and terminations associated with a fiber optic systems was much more costly and the engineer on the project ensured that copper would work at the specified length.