Foundation design and construction for Pre-Engineered Buildings are important to the assembly
process. To ensure optimum integrity of new building, the foundation must meet
certain design criteria and load conditions. It is required that all building
foundations be designed by an experienced foundation engineer, and coordinated
with all local city, county and state codes. Improper foundation construction
will limit the building’s performance. The foundation should be sharply formed
with true corners, straight sides, and a level top. This will allow for proper
seating and alignment of all building components. Strict adherence to OSHA and
other local codes or laws governing “shoring of excavation to prevent
accidental cave-ins” is critical.
Manufacture
of Building Systems will furnish anchor bolt drawings to outline basic
guidelines and considerations for foundation design. The accuracy of foundation
construction and anchor bolt settings is the most important factor in achieving
trouble-free component alignment and fit-up. Foundation errors and mis-location
of anchor bolts are among the most frequent and troublesome errors made in
metal building construction.
Foundation must possess the following
important characteristics.
v It is recommended that the
foundation be designed by an experienced foundation engineer, and coordinated
with all local city, county and state codes.
v The foundation must be square, level and
smooth.
v Anchor bolts must be set within
+/- 1/16” of the specified anchor bolt drawing dimensions.
Foundation Layout Setting Anchor Bolts
Regardless
of the type of foundation that is used and its specific configuration, the
foundation outline should be carefully and accurately laid out before any
excavation is made. Whenever possible, a transit or similar means should be
used to layout the foundation perimeter. This will ensure accurate placement of
corner measures and in turn, ensure a square foundation.
Check
the foundation is square and level. Measure diagonally to the farthest points
of the foundation frame / string-line. Adjust the frame / string-line as
necessary until the two diagonal dimensions are equal. If the diagonal lengths
are equal, the framing is square. Ensure the foundation is level.
Setting Anchor Bolts:-
To
reduce the risk of anchor bolts pulling loose, do not erect any building
components on “green” concrete. Concrete that has not cured properly may be
damaged by erection equipment or building component affects. Normal Portland
cement concrete should cure at least seven days, and high-early-strength
concrete at least three days before the structural columns are erected. Due to
tight tolerances in which your building was manufactured, it is extremely
important that all anchor bolts are accurately placed (+/- 1/16”) in accordance
with the provided anchor bolt plan.
All
anchor bolts should be held in place with a template or similar means in order
to maintain a plumb setting during the pouring of the concrete. Refer to the
anchor bolt plan dimensions then make the necessary quantity of templates out
of plywood or equivalent. All templates should be prepared in advance so they
can be quickly nailed in place. Drill air relief holes in the template to allow
trapped air to escape. When floating concrete, vibrate until wet concrete seeps
though the top of air relief holes. A final inspection of all foundation
requirements should be conducted prior to pouring concrete.