PRECAST CONCRETE STRUCTURES

 

Precast Concrete Fabrication

      Prestressed products

            In molds

            Stressed cables to tension before concrete pour

            Release cable tension after hardening placing concrete into compression

            Further strengthening by nonstressed reinforcing bars, rods, and wire

      Reinforced products

            Also poured in forms with reinforcing bars, rods, and wire but without prestressed strands

      Horizontal structures

            Slabs, Beams or Lintels

      Vertical structures

            Piles, column, or piers

 

Precast Concrete Framing Plans

      Precast Concrete Faming Plans

            Blockouts

                  Opening in a precast member for windows, doors, skylights, conduit, ductwork, piping, etc.

                  Wooden, styrofoam, or cardboard placed in form to deflect and displace concrete

                  Removed after concrete hardens

                  Labeled for ID in legend

            Mark numbers

                  Assign mark numbers to each individual member

Same number only for members that have the same length, width, thickness, shape, reinforcing, and stranding

            Product Schedules

                  Summary of all structural products in Framing Plans

                  Containing, as a table or chart

                        Mark Numbers

                        Quantity required

                        Description of product type

                        Length

                        Width

                        Dimension of flange weld plates for Tees from end of members

                        Dimension of lift hooks

                        Remarks for size of Blockouts and miscellaneous notes

            General notes on the first/cover page, specific notes on individual pages

            Legend

                  Key to explain symbols and abbreviations

                  General symbols/abb. on the first/cover page, specific symbols/abb. on individual pages

      Drawing Framing Plans

            Order

                  Column Framing Plan

                        Using the raw data, determine appropriate scale

                        Layout column centerlines

                                    Dimension

                                    Label column grid letter and number designations

                        Construct column by depth and width at centerline intersection

                        Assign mark numbers

                        Add schedules

                        Page formatting for border and title blocks

                  Beam Framing Plan

                        Based on column centerline dimensions, determine beam lengths

                        One inch joint gap between abutting beams

                        Dimension for length and location

                        Assign mark numbers

                        Complete schedules

                        Assign designations for connection details

                        Label ‘North’

                  Floor Framing Plan, if applicable

                        Bearing surface edges of beams drawn as hidden lines

                        Calculate required framing from raw data, draw and dimension

                        Establish blockouts, dimension and label

Establish sections using cutting plane lines and designations to clarify internal relationships

Establish mark numbers

Complete schedules, notes, legends, ‘North’, borders, and titleblocks

                  Wall Framing Plan

                        Using the raw data, determine size and type of product

                        Determine total amount, widths, and heights of framing materials

                        Layout wall panel framing

                        Drawings consist of plan and elevation views as seen from the inside of the building

                              Columns and beams are superimposed with phantom lines

                        Locate and size openings for blockout designation

Complete schedules, notes, legends, ‘North’, borders, and titleblocks

Repeat Floor and Wall Framing Plans, as appropriate to the number of floors in the structure

                  Roof Framing Plan

                        Same approach as Floor Framing

                 

Precast Concrete Sections

      Precast Concrete Sections Defined

                  Prepared as single line symbolic representations or scaled duplicates of actual shapes

                  Precast Concrete sections show only structural or load-bearing components

                  Architectural sections show interior/exterior features

            Full Sections

                  Cut through the entire structure

                        Longitudinal Sections across length of structure

                        Cross Sections across width of structure

            Partial Sections

                  Clarify internal relationships

            Offset Sections

                  Use of cutting lane lines that do not run straight

      Section Conventions

            All materials have standard symbols for use in sections

      Drawing Precast Concrete Sections

            Obtain information from framing plans and raw data

                  Determine sectional drawings are needed

                  Should the sectional drawings be full,  partial, or offset

                  What materials are used?

                  How do the components fit together?

                  Important heights and distances are noted

                        Base elevations

                        Top of foundations

                        Floor elevation(s)

                        Roof elevation

                        Column Heights

                        Top of elevations

                  Scaled representations ¾” = 1’-0” or larger

 

Precast Concrete Connection Details

      Precast Concrete Connection Details Defined

            Precast concrete members are fabricated offsite and shipped by truck or train for erection

            Connections achieved by bolting, welding, or a combination

            Connection details are plan views with sections cut to show elevations

      Column Baseplate Connections

            Cast heavy steel baseplate in one end with holes to fit over anchor bolts

                  Plate extends beyond the column with external/exposed anchor bolt connections

                  Plate flush with column sides with pockets to accommodate anchor bolt connections

            Drawing Baseplate Connection Details

                  Select appropriate scale

Construct elevation view showing anchor bolts, footing, leveling nuts, washers and locking nuts

Section horizontally to look down on column and baseplate

Label components

      Bolted Beam to Column Connection Details

                  Connection details drawn for each letter designation called on framing plan

                        The same, similar , or opposite connections noted similar (Sim) opposite hand (Opp Hd)

                  ¾” Neoprene bearing pad between beams to avoid damage

                  Six basic beam to beam connections

                        Single beam bearing fully on column with ½-1” joint between abutting beams

Two rectangular beams bearing on the same column with ½-1” joint between abutting beams

Single L-shaped beam bearing on a column

Two L-shaped beams bearing on the same column with ½-1” joint between abutting beams

Single inverted-Tee bearing fully on a column

Two inverted-Tees bearing fully on a column with ½-1” joint between abutting beams

            Drawing Beam to Column Connection details

Plan and sectioned elevation views showing column, beam(s), blockouts, threaded rod(s), washers/nuts, bearing pads and anything else

      Welded Connections

            The most frequently used connection method is welding due to its versatility

                  Flange connections in double-tee and single-tee

                  Base and top connections for wall panels

                  Connections between beams and floor or roof members

                  Stem connections for double and single tees

            Flange weld plate welded to a reinforcing bar anchor provides smooth surface  for field welds

            Weld Plate-Angle connection versatile adoption to misalignment by shifting the angle

            Weld Plate-Strap uses matched weld plates connected by a single strap welded to both

            Stem Plate-Weld Strip to permanently fasten single and double tee stems  to continuous strip

            Drawing Welded Connections

      Precast Concrete Haunch Connections

            Bearing surface cast onto column or wall in a secondary pour  to support beam or roof member

            Flat support face with tapered back-side

            Double haunch occurs on both sides of column

Column haunch connections usually bolted to embedded threaded rod, wall connections are usually welded

Draw plan and sectioned elevations showing column, beam(s), haunch(s), blockouts, threaded rod(s), washers/nuts, bearing pads and other information

 

Precast Concrete Fabrication Details

      Shop Drawings Defined

Detailed Fabrication Drawings and Bill of Materials used in fabrication of concrete products and connectors they contain

      Fabrication Details Defined

Separate Orthographic Drawings of each beam, column, wall panel, roof/floor member, and metal connectors

      Constructing Fabrication Details

            Column fabrication details

                  Two adjacent orthographic views with overall dimensions

Section(s) showing reinforcing bars or strand patterns , represented by dashed lines, with size, spacing, location dimensions and numeric designations

                  Baseplate configuration diagram with width, length, and thickness dimensions

                  Special view(s) showing size, location, and embedment of threaded rods with dimensions

            Beam Fabrication Details

                  Same content as Column Fabrication detail

                  Additionally requirements

                        Blockout sizes, locations, and designations

                        Metal connectors with size and location

            Floor/Roof Member Fabrication Details

                  Includes Single and Double Tees, Flat or Cored Slabs

                  Similar content as Column and Beam Fabrication Details

                  Prestressed strand run the entire length of the member and are not dimensioned

Wall Panel Fabrication Details

                  Similar to Floor/Roof Fabrication Details

Exaggerated length to width ratio, and repetitive length of Columns, Beams, Floor/Roof members, and Wall Panels, allow lengths to be broken out and removed

Metal Connectors and Miscellaneous Materials

      Multi-view Orthographic views of

            Connector Details and master legend

            Neoprene Bearing Pad Details

            Reinforcing Bar Schedule

                  Letter designation, Bar type, Bending dimension

      When combined with the Engineering Drawings, placed as the first sheet

 

Precast Concrete Bill of Materials

      Definition and Purpose

            List of all materials used in the fabrication and erection of precast concrete products

            Several Procedures

                  One complete Bill of Materials covering all members of the job

                  Individual and independent Bill of Materials for each individual member  in the job

                  One Bill of Material for each separate type of product used on the job

                        The most popular, same purpose as first two, more efficient

            Bill of Materials list the following

                  Type of Product

                  The mark numbers for all members of a product

                  All members contained in the members

                  Quantity of each type of material

                  Totaled by product type

                  Totaled again for entire job

      Constructing Bill of Materials

            Prepared from Fabrication Details

      Counting Material Quantities

            Determined from dimensions for the materials not the pictures of the material