Page 26 - Forensic Structural Engineering Handbook

DESIGN-CONSTRUCTION PROCESS 1.7

Mechanical Drawings. Mechanical drawings designate the heating, ventilating, and air-
conditioning systems, electrical distribution requirements, fire and security systems, sprin-
klers and necessary plumbing requirements. These drawings will generally contain the
ductwork sizes and locations and will designate required openings in the structure for their
paths. Flowcharts and riser diagrams are produced for electrical conduit runs and plumbing
lines including sprinkler-piping systems. Drawings are prepared for the mechanical equip-
ment rooms indicating the selected, the operating weights of the machinery, and weights of
heavy piping which are detailed to be hung from the structure or floor-mounted.
Tables 1.1 through 1.3 are helpful checklists prepared by CASE, which can be used by
the forensic engineer to assist in establishing the available basic design information for the
investigation.

Design Drawing Phases. The most common design drawing process is in five distinctive
phases.
1. Concept design Sketches (CS): The architect, generally in concert with the structural
engineer, initiates a design which in some cases may require alternate structural fram-
ing systems, stability, and constructability schemes. This phase normally constitutes
10 percent of the total effort for the proposed project and consists of plan dimensions,
general column locations, and architectural features including probable façade materi-
als. This information is presented to the owner in the form of professional sketches or
drawings, and occasionally includes a rendering of the project.
2. Preliminary Design (PD): Upon approval of the CS by the owner, the design enters the
preliminary phase, wherein a selected scheme is developed into a more defined scope
with the structural and mechanical consultants. In this phase, outline specifications for
materials and their use in the construction are noted from which preliminary budgets for
financing requirements, scheduling and construction are derived. The end of this phase
normally is considered as 25 percent of project design completion and is presented in
the form of hard-lined drawings (CAD) representing the basis of the project.
3. Design Development (DD): Upon approval of the PD submittal, the project now begins
to take shape. The structural systems are finalized; the mechanical requirements are
defined; the façade and interior finishes are selected and incorporated; and the project
cost estimates are more firmly designated. The end of this phase is now 50 percent of
project design completion. At this stage, drawings from the design team (architect, struc-
tural engineers, and mechanical engineers) provide sufficient information to professional
estimators for them to evaluate costs within the owner’s project budgetary guidelines.
4. Construction Document (CD): After the necessary approvals from the owner, the pro-
ject enters the final design phase wherein all the disciplines of the design team are in the
stage of finalizing and detailing their work toward 100 percent completion of the
designs, to be ready for bids. However, with respect to the total project, the end of this
phase represents 75 percent of the total design. The remaining 25 percent is assigned to
the “construction phase” also known as the construction administration phase. There are
projects that terminate at the “construction document phase.” Therefore, coordination
of the project drawings among the design disciplines is absolutely paramount wherein
the architect or engineer, as the prime design professional, assumes the responsible role
of heading the team. Refer to Quality Assurance for Consulting Engineers—ACEC. 12
Technical specifications are finalized in this phase by each discipline and are added
to the general conditions including bid forms for distribution to prospective qualified
bidders.
After the design bid documents are released for bidding and subsequent addenda, if
any, are issued, the design portion of the project is complete, and the project enters the
construction administration phase.