Construction Management
Faculty Consultant: Messner
Elliott School of International Affairs
1957 E Street NW, Washington, DC 20006 /
Contents
Site Layout Planning / 2Temporary Utilities / 8
Structural Systems Estimate / 10
General Conditions Estimate / 13
Project Schedule and Cash Flow / 14
Appendix I – Cash Flow Table / 16
Appendix II – Structural Estimate Worksheets / 18
Site Layout Planning
Excavation
· Site enclosed in 8-foot high construction fence—gates located at vehicular entrance along 19th or E Streets and along 20th for workers and site visitors
· Sidewalks closed along site boundary at 19th and E Streets
· Parking lane of 19th Street utilized for vehicular access and deliveries—permits for 20th Street could not be obtained, since they were already held by adjacent construction project
· Ramp moved as excavation progressed—initially at location marked as “Ramp 1,” then to location marked “Ramp 2,” and ultimately back to “Ramp 1”—to allow for sheeting and shoring as well as complete excavation
· Diesel fuel tank located within excavated area to provide fuel to excavator, as well as pile-driver and tie-back equipment
· Temporary staircase and ladder provided access to excavation work to minimize congestion on ramp
· Gilbane office trailer and excavation contractor trailers located along southern site boundary
· No construction worker parking on site, however ample parking available in nearby public garages
Cast-In-Place Concrete
· Permit obtained for E Street parking lane, so site fence was extended to provided access to delivery and concrete trucks as well as additional material storage
· Two tower cranes located in staircase cores
· Temporary concrete batch plant erected on site to supply large amount of concrete required
· Concrete floor pours separated into four distinct activities, with westernmost—entire residential component footprint—pour proceeding others
· Material-only hoist erected at east-end of structure
· Additional subcontractor trailers located along southern site boundary
Finish Work
· Construction office and storage moved from trailers to temporary structures on the parking levels located 2 to 4 stories below grade
· Permit obtained for the utilization of 20th Street during non-rush-hour traffic
· Sidewalk closed along 20th Street—as in two other site boundaries, pedestrians directed across the street
· Additional hoist erected at southwest corner of building
· Site access and hoist at southwest generally serviced residential component, while site entrance and hoist at east served the academic component
· Trash chute located at east end of structure
Analysis of Site Plans
The relocation of construction offices and storage to within the building, while minimizing congestion on the exterior of the building, greatly minimized the opportunity for communication amongst trades and with the construction manager. The underground location did not provide adequate reception for the utilization of cellular phones— especially the two-way capabilities provided by NEXTEL so widely used in the construction industry. Also, the location of the CM offices and meeting rooms on the parking levels below the residential component required Gilbane to obtain additional permits to allow for the dorm rooms to be turned over to the owner while construction on the academic component continued.
The extremely compact site and building requirements that necessitated such little available space on site was dealt with adequately by Gilbane. Deliveries and construction vehicles were directed in and out of the construction fencing, so as to have the smallest impact on the heavy traffic provided by the sites proximity to the E Street Expressway ramp.
Two separate hoists and site entrances were used to keep the construction of the residential and academic components practically independent. This was especially effective since the two components were phased separately. Work on the residential component progressed more rapidly, so having separate site and building entrances kept materials and equipment for residential finish work from being moved through or stored in the academic component where they could have been damaged.
Temporary Utilities
Cast-In-Place Concrete
The environmental conditions required for the placing and curing of cast-in-place for the Elliott School of International Affairs are outlined in Section 03310 of the project’s specifications. The processes for concreting in conditions of hot and cold weather are briefly discussed; however the specifications call for placing concrete in accordance with American Concrete Institute (ACI) articles.
The project specifications state that concrete is not to be placed in temperatures below 40°F without prior approval of the Architect and, when it is placed in cold temperatures, it is to be done as outlined by ACI 306, “Cold Weather Concreting.”
ACI 306 defines cold weather as a period when, for three consecutive days, the average daily temperature is not greater than 40°F and the air temperature does not exceed 50°F for more than half of any 24 hour period. To provide for proper curing and to ensure that the concrete reaches sufficient compressive strength, the article calls for keeping the curing environment temperature above 50°F, and recommends that this be done for a minimum of three days. Placing insulated blankets or straw covered in polyethylene over maturing concrete to trap a sufficient amount of heat to provide both protection from freezing and to facilitate strength gain. Heat can also be supplied externally using mechanical heaters. ACI 306 also directs that the surface upon which concrete is to be placed be at least 35°F and should never be done on frozen material.
The project specifications forbid placing concrete in extreme hot temperatures when “atmospheric conditions endanger the quality of concrete.” To provide appropriate conditions in hot weather, the specifications call for the placement of concrete in accordance with ACI 305, “Hot Weather Concreting.”
Hot weather is defined as any combination of high ambient temperature, high concrete temperature, low relative humidity, wind velocity, or solar radiation that impairs the quality of concrete or cause detrimental results. Prematurely drying concrete in high temperatures reduces its strength. ACI 305 suggests cooling the concrete itself and transporting, placing, consolidating, and finishing in a method with little delay.
Painting and Finishing
Under the heading of Project Conditions, the environmental requirements for painting and finishing can be found in Section 09900 of the Elliott School of International Affairs project specifications.
Paint is to be applied to surfaces free of moisture and is not to be applied in rain, snow, fog, mist or any condition in which relative humidity exceeds 85%. During periods of inclement weather, painting is permitted as long as the area of work is enclosed and artificially heated or cooled to provide consistent temperature and humidity.
Exterior paint is restricted to periods when the ambient temperature is above 50°F or if the temperature is expected to drop below 32°F within 24 hours of application. For interior painting, a constant temperature of at least 65°F must be maintained in the area of work.
The area of work is also to be ventilated “to guard against the potential hazards of paint fumes as necessary and as required by regulations, codes, and laws.” Also, additional ventilation or protective equipment is to be provided as necessary by the conditions of the job.
Detailed Structural System Estimate
Description and Assumptions
· Due to the complexity and lack of repetitive components, the structural system estimate was performed only for the academic component of the Elliott School of International Affairs
· All costs were taken from 1996 RS Means Building Construction Cost Data
· All costs include labor and equipment
· Prices were adjusted to account for bidding and mobilization in 2000
· Prices were adjusted from the national average for Washington, DC location
· It was assumed that formwork would be used for multiple pours
Formwork
· The formwork for columns, beams, slabs, drop panels, and footings utilized on the Elliott School of International Affairs construction project was typical strip formwork
· Foundation walls—basement and three parking levels—were formed using “flying forms” which were placed on a floor and then dismantled and reassembled for the following floor pour
General Conditions Estimate
Description and Assumptions
· Tax was excluded
· Performance and Payment Bonding was not required for the project
· Field office conditions changed from a trailer established on site, to a temporary facility with offices, meeting rooms, and a drawing room constructed a level of parking within the structure as construction progressed
Project Schedule and Cash Flow
Description and Assumptions
· The schedule for which costs were loaded is based on the original estimated project schedule created by the Gilbane Building Company, however the provided schedule was reproduced and simplified
· Costs were distributed by CSI division
· Costs were taken from a Direct Cost Breakdown, as provided by the Gilbane Building Company
· The calculated cash flow curve does not adhere to the standard “S” representation because of the separate phasing of the residential and academic components of the Elliott School of International Affairs—the phasing provided a more even distribution of cost over time, resulting in the almost linear curve
Appendix I – Cash Flow Table
Appendix II – Structural Estimate Worksheets
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