15-01-2014, 03:11 PM
Contemporary Design-Bid-Build Model
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Abstract:
Empirical research was performed into the hypothesis that a substantial number of building performance engineering tasks on
design-bid-build projects are typically provided by entities associated with the construction phase, not with the architect-engineer ͑AE͒ of
record. This hypothesis is contrary to the traditional understanding of design-bid-build and is theorized to result from increased time
pressures on AEs, decreased AE profit margins, AEs’ attempts to minimize liability, increased design and construction specialization, and
increased prefabrication. Project technical specifications were analyzed for 20 $5–45M building construction projects and 16 individuals
directly associated with these projects were interviewed. It was found that 35 building performance engineering tasks were required by the
project specifications to be performed by entities associated with the construction of the buildings. This large number of delegated design
tasks suggests the conventional understanding of the design-bid-build process is not accurate. The increasing fragmentation of the design
and construction process may have implications for the efficiency of communication on design-bid-build projects, lean construction
processes, and constructability.
Introduction
For the past half-century, the dominant design and construction
process for buildings has been understood as a three-step process:
architects and engineers ͑AEs͒ design the entire buildings, bids
are solicited from contractors, and contractors construct the build-
ings. The process has traditionally been viewed as being linear
and compartmentalized, that is, the engineering design is com-
pleted by AEs before the construction begins, and the contractors
͑in conjunction with specialty subcontractors and material ven-
dors͒ merely implement the AEs’ designs. Current design-bid-
build models assume that engineering and design are only
performed by AEs and their specialty engineering and design con-
sultants. Conversely, general contractors and subcontractors only
provide construction services, and material vendors only manu-
facture and deliver ͑Tatum 2000͒.
Research Methods
The exploratory research methodology leading to this paper in-
cluded a combination of technical specification review and case
studies. A total of 20 design-bid-build projects constituted the
convenience sample. Four projects ͑each associated with a differ-
ent AE firm͒ were built for Bucknell Univ. ͑an engineering build-
ing, a building housing the offices and laboratories associated
with geology and psychology, a dormitory, and a recreation and
athletics center͒. The remaining 16 specification sets were ob-
tained from a local construction manager or Bucknell alumni
working for large general contractors or construction managers.
The total construction cost of the projects ranged from $5 to $45
million. All projects were located on the east coast with the ex-
ception of one hospital project in Chicago, Ill. While all of the
delivery methods were design-bid-build and were ostensibly de-
signed by a traditional architectural and engineering firm, some
diversity existed between the project delivery methods. Two of
the projects involved an at-risk construction manager, one in-
volved an agency construction manager, and the final two in-
volved traditional general contractors. In addition to the project-
specific specification sets,
Project Components
To further illustrate the design during construction phenomenon,
four project components will be highlighted. The first, structural
steel, is a project component that is known to require PE involve-
ment during the construction phase. Structural steel is highlighted
because it has traditionally required building performance engi-
neering during construction despite the fact that literature contin-
ues to model the delivery of a project as a three-step linear
process. The second, aluminum storefront, has been selected be-
cause it represents a project component that is designed in the
construction phase by someone other than a professional engineer
on seven of the nine projects that had storefront. The third, pre-
cast concrete, represents a precast component designed by a PE
employed by ͑or consulting to͒ the component manufacturer.
Last, sprinkler systems are unique in that they consistently require
engineering design in the construction phase by a fire protection
engineer ͑FPE͒.
Conclusions
Exploratory research provides preliminary support for the hypoth-
esis that a considerable number of building performance engineer-
ing tasks are provided by entities associated with the construction
phase of a building, not by entities associated with the design
phase. Empirical data to support this hypothesis included review
of the technical specifications from 20 building projects and in-
terviews of key individuals and further document review of five
of these projects. In most cases it was found that engineering
calculations or analysis was required to be provided in the form of
submittals. Therefore, each of the 36 tasks included in Table 1
provides specific evidence of engineering performed by entities
other than the AE of record. Interview data confirmed that each of
these phases indeed were typically designed by individuals re-
tained by entities other than the AE of record or their structural,
MEP, and geotechnical engineering consultants.