Standard Specifications for Road, Bridge, and Municipal Construction 2020 (M 41-10)

Page 6-72

Concrete Structures

in this section, the Contractor shall submit Type 2 Working Drawings consisting of the
certified test reports.

The safe working load for shop manufactured devices named in this section shall be
derived by dividing the ultimate strength by a safety factor of 2.0. The safe working load
for field fabricated or field modified devices (including the use of timber blocks or wedges
with the device) shall be determined by dividing the ultimate strength by a safety factor of
3.0. Working load shall include masses of all successive concrete placements, falsework,
forms, all load transfer that takes place during post-tensioning, and any live loads; such
as workers, Roadway finishing machines, and concrete delivery systems. The maximum
allowable free end deflection of deck overhang brackets with combined dead and live

working loads applied shall be 3/16 inch even though deflection may be compensated for

by pre-cambering or setting the elevations high. The Contractor shall comply with all
manufacturer’s Specifications; including those relating to bolt torque, cleaning and oiling
of parts, and the reuse of material. Devices which are deteriorated, bent, warped or have
poorly fitted connections or welds, shall not be installed.

6-02.3(17)H Formwork Accessories

Formwork accessories such as form ties, form anchors, form hangers, anchoring inserts,
and similar hardware shall be specifically identified in the formwork plans including the
name and size of the hardware, manufacturer, safe working load, and factor of safety. The
grade of steel shall also be indicated for threaded rods, coil rods, and similar hardware.
Wire form ties shall not be used. Welding or clamping formwork accessories to Contract
Plan reinforcing steel will not be allowed. Driven types of anchorages for fastening forms
or form supports to concrete, and Contractor fabricated “J” hooks shall not be used. Field
drilling of holes in prestressed girders is not allowed.

Taper ties may be used provided the following conditions are met:
1. The structure is not designed to resist water pressure (pontoons, floating dolphins,

detention vaults, etc.).

2. After the taper tie is removed, plugs designed and intended for plugging taper

tie holes shall be installed at each face of concrete. The plug shall be installed a
minimum of 1½ inches clear from the face of concrete.

3. After the plug is installed, the hole shall be cleaned of all grease, contamination and

foreign matter.

4. Holes on the exposed faces of concrete shall be patched and finished to match the

surrounding concrete.

The following table from ACI 347R-88 provides minimum safety factors for formwork
accessories. The hardware proposed shall meet these minimum ultimate strength
requirements or the manufacturer’s minimum requirements, whichever provides the
greater factor of safety. The Contractor shall attach copies of the manufacturer’s catalog
cuts and/or test data of hardware proposed, to the formwork plans and submit the
falsework and formwork Working Drawings with supporting calculations in accordance

Concrete Structures

6-02

with

Section 6-02.3(16)

. In situations where catalog cuts and/or test data are not

available, testing shall be performed in accordance with

Section 6-02.3(17)G

Minimum Safety Factors of Formwork Accessories*

Accessory

Safety

Factor

Type of Construction

Form Tie

2.0

All applications.

Form Anchor

2.0

Formwork supporting form mass and concrete pressures only.

Form Anchor

3.0

Formwork supporting masses of forms, concrete, construction live

loads, and impact.

Form Hangers

2.0

All applications.

Anchoring

Inserts

2.0

Placed in previous opposing concrete placement to act as an

anchor for form tie.

*Safety factors are based on ultimate strength of the formwork accessory.

The bearing area of external holding devices shall be adequate to prevent excessive
bearing stress on form lumber. Form ties and form hangers shall be arranged
symmetrically on the supporting members to minimize twisting or rotation of the
members. Form tie elongation shall not exceed the allowable deflection of the wale or
member that it supports. Inserts, bolts, coil rods, and other fasteners shall be analyzed
and designed for appropriately combined bending, shear, torsion, and tension stresses.
The formwork shall not be attached to Contract Plan rebar or rebar cages. However, the
Contractor may install additional reinforcing steel for formwork anchorage.

Frictional resistance shall not be considered as contributing to the stability of any
connection or connecting device, except those designed as friction connectors such as
U-bolt friction-type connectors.

Form anchors and anchoring inserts shall be designed considering concrete strength at
time of loading, available embedment, location in the member, and any other factors
affecting their working strength, and shall be installed in concrete in accordance with the
manufacturer’s published requirements. Form anchors and anchoring inserts embedded
in previous concrete placements shall not be loaded until the concrete has reached the
required design strength. The required design strength of concrete for loading of an
anchor shall be shown in the formwork drawing if it is assumed that the anchor will be
loaded before the concrete has reached its 28-day strength.

Installation of permanent concrete inserts, such as form ties hangers, or embedded
anchor assemblies, shall permit removal of all metal to at least ½ inch below the concrete
surface. Holes shall be patched in accordance with

Section 6-02.3(14)

. During removal

of the outer unit, the bond between the concrete and the inner unit or rod shall not
be broken.

Page 6-74

Concrete Structures

6-02.3(17)I

Timber Connections

Timber connections shall be designed in accordance with the methods, stresses, and
loads allowed in the Timber Construction Manual, Third Edition by the American Institute
of Timber Construction (AITC). Timber falsework and formwork connections shall be
designed using wet condition stresses for all installations West of the Cascade Range
crest line and by criteria provided in the following sections. Frictional resistance shall not
be considered as contributing to the stability of any timber connection.

6-02.3(17)I1 Bolted Connections

Tabulated values in the AITC Timber Construction Manual, Current Edition are based on
square posts. For a round post or pile, the main member thickness shall be the side of a
square post having the same cross-sectional area as the round post used.

The AITC Table 6.20 for Douglas Fir-Larch bolt Group 3 and for Hem-Fir bolt Group
8 show design values for bolts to be used when the load is applied either parallel or
perpendicular to the direction of the wood grain. When the load is applied at an angle
to the grain, as is the case with falsework bracing, the design value for the main member
shall be obtained from the Hankinson formula shown in the AITC manual.

Design values in the AITC Table 6.20 apply only to three-member joints (bolt in double-
shear) in which the side members are each ½ the thickness of the main member. This joint
configuration is not typical of bridge falsework where side members are usually much
smaller than main members. For two-member joints (single shear bolt condition), the AITC
Table 6.20 values shall be adjusted by a single shear load factor as follows:
1. 0.75 for installations East of the Cascade Range crest line, except as shown in item 3

below;

2. 0.50 for installations West of the Cascade Range crest line; and
3. 0.50 for load acting at an angle to the bolt axis, as is the case with longitudinal

bracing when falsework bents are skewed.

Except for connections in falsework adjacent to or over railroads or Roadways, threaded
rods and coil rods may be used in place of bolts of the same diameter with no reduction
in the tabulated values. At openings for Roadways and railroads, all connections shall be

bolted using ⅝-inch diameter or larger through bolts.

Bolt holes shall be a minimum 1/32 inch to a maximum ⅛ inch larger than the bolt diameter.

A washer not less than a standard cut washer shall be installed between the wood and the
bolt head and between the wood and the nut to distribute the bearing stress under the
bolt head and nut and to avoid crushing the fibers. In lieu of standard cut washers, metal
plates or straps with dimensions at least equal to that of a standard cut washer may be
substituted.

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6-02

When steel bars or shapes are used as diagonal bracing, the tabulated design values
shown in AITC Table 6.20 for the main members loaded parallel to grain (P value) are
increased 75 percent for joints made with bolts ½ inch or less in diameter, 25 percent for
joints made with bolts 1½ inch in diameter, and proportionally for intermediate diameters.
No increase in the tabulated values is allowed for perpendicular-to-grain loading (Q value).

Clearance requirements for end, edge, and bolt spacing distance shall be as shown below.
All distances are measured from the end or side of the wood member to the center of the
bolt hole. For members which are subject to load reversals the larger controlling distances
shall be used for design. For parallel-to-grain loading, the minimum distances for full
design load:
1.  In tension, minimum end distance shall be seven times the bolt diameter;
2.  In compression, minimum end distance shall be four times the bolt diameter; and
3.  In tension or compression, the minimum edge distance shall be one and one-half

times the bolt diameter.

For perpendicular-to-grain loading, the minimum distance for full design load:
1. Minimum end distance shall be four times the bolt diameter;
2. Edge distance toward which the load is acting shall be at least four times the bolt

diameter; and

3. Distance on the opposite edge shall be at least 1½-bolt diameters.

Minimum clearance (spacing) between adjacent bolts in a row shall be four times the bolt
diameter, measured center-to-center of the bolt holes.

When more than two bolts are used in a line parallel to the axis of the side member,
additional requirements shall be followed as shown in the AITC manual.

6-02.3(17)I2 Lag Screw Connections

Design values for lag screws subject to withdrawal loading are found in AITC Table
6.27. Values for wood having a specific gravity of 0.51 for Douglas Fir-Larch or 0.42 for
Hem-Fir shall be assumed when using the table. The withdrawal values are in pounds
per inch of penetration of the threaded part of the lag screw into the side grain of the
member holding the point, with the axis of the screw perpendicular to that member. The
maximum load on a given screw shall not exceed the allowable tensile strength of the
screw at the root section.

AITC recommends against subjecting lag screws to end-grain withdrawal loading.
However, if this condition cannot be avoided, the design value shall be 75 percent of the
corresponding value for withdrawal from the side grain.

Values in the Group II wood species column shall be used for Douglas Fir-Larch and the
Group III wood species column shall be used for Hem-Fir. When the load is applied at an
angle to the grain, as is the case with falsework bracing, the design value shall be obtained
from the Hankinson formula shown in the AITC manual.

Page 6-76

Concrete Structures

When lag screws are subjected to a combined lateral and withdrawal loading, as would be
the case with longitudinal bracing when the falsework bents are skewed, the effect of the
lateral and withdrawal forces shall be determined separately. The withdrawal component
of the applied load shall not exceed the allowable value in withdrawal. The lateral
component of the applied load shall not exceed the allowable lateral load value.

Lag screws shall be inserted in lead holes as follows:
1. The clearance hole for the shank shall have the same diameter as the shank, and the

same depth of penetration as the length of unthreaded shank;

2. The lead hole for the threaded portion shall have a diameter equal to 60 to

75 percent of the shank diameter and a length equal to at least the length of the
threaded portion. The larger percentile figure in each range shall apply to screws of
the greater diameters used in Group II wood species;

3. The threaded portion of the screw shall be inserted in its lead hole by turning with a

wrench, not by driving with a hammer; and

4. To facilitate insertion, soap or other lubricant shall be used on the screws or in the

lead hole.

6-02.3(17)I3 Drift Pin and Drift Bolt Connections

When drift pins or drift bolts are used, the required length and penetration shall be
determined using the following criteria. The lateral load-carrying capacity of drift pins
and drift bolts driven into the side grain of a wood member shall be limited to 75 percent
of the design values for a common bolt of the same diameter and length in the main
member. For drift pin connections, the pin penetration into the connected members shall
be increased to compensate for the absence of a bolt head and nut. For drift bolts or pins
driven into the end grain of a member, the lateral load-carrying capacity shall be limited
to 60 percent of the allowable side grain load (perpendicular to grain value) for an equal
diameter bolt with nut. To develop this allowable load the drift bolt or pin shall penetrate
at least 12 diameters into the end grain. To fully develop the allowable load of the drift

bolts or pins, they shall be driven into predrilled holes, 1/16 inch less in diameter than the

drift pin or bolt diameter.

The criteria shown in the AITC Timber Construction Manual, Current Edition shall apply to
drift bolt or pin connection allowable loads for the following conditions:
1. Withdrawal resistance; and
2. When there are more than two drift bolts or pins in a joint, allowable loads shall

be further reduced by applying applicable modification factors shown in the AITC
Table 6.3.

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6-02

6-02.3(17)I4 Nailed and Spiked Joints

Joints using nails or spikes shall conform to the provisions of AITC. For side grain
withdrawal, the values in AITC Table 6.35 for wood having a specific gravity of 0.51 for
Douglas Fir-Larch and a specific gravity of 0.42 for Hem-Fir shall be used. End grain
withdrawal shall not be used. For lateral loading, the values in AITC Table 6.36 for wood
species Group II for Douglas Fir-Larch and wood species Group III for Hem-Fir shall be
used. Diameters listed in the tables apply to fasteners before application of any protective
coating.

When more than one nail or spike is used in a joint, the total design value for the joint in
withdrawal or lateral resistance shall be the sum of the design values for the individual
nails or spikes.

The tabulated design values for lateral loads are valid only when the nail penetrates into
the main member at least 11 diameters for Douglas Fir-Larch and 13 diameters for Hem-
Fir. Note that the values are maximum values for the type and size of fastener shown. The
tabulated values shall not be increased even if the actual penetration is exceeded.

When main member penetration is less than 11 diameters for Douglas Fir-Larch
and 13 diameters for Hem-Fir, the design value shall be determined by straight-line
interpolation between zero and the tabulated load, except that penetration shall not be

less than ⅓ of that specified.

Double-headed or duplex nails used in falsework and formwork construction are
shorter than common wire nails or box nails of the same size designation. They have less
penetration into the main member and therefore their load-carrying capacity shall be
adjusted accordingly.

Nail and spike minimum spacing in timber connections shall be as follows:
1. The average center-to-center distance between adjacent nails, measured in any

direction, shall not be less than the required penetration into the main member for
the size of nail being used; and

2. The minimum end distance in the side member, and the minimum edge distance in

both the side member and the main member, shall not be less than ½ of the required
penetration.

Allowable values for withdrawal and lateral load resistance are reduced when toe nails are
used in accordance with the following:

1. For withdrawal loading, the design load shall not exceed ⅔ of the value shown in the

applicable design table; and

2. For lateral loading, the design load shall not exceed

5⁄6

of the value shown in the

applicable design table.

Toe nails are recommended to be driven at an approximate angle of 30 degrees with

the piece and started approximately ⅓ of the length of the nail from the end or side of

the piece.

Page 6-78

Concrete Structures

6-02.3(17)I5 Timber Connection Adjustment for Duration of Load

Tabulated values for timber fasteners are for normal duration of load and may be
increased for short duration loading, except for connections used in falsework and
formwork for post tensioned Structures and staged construction sequences. Duration
of load adjustment for timber connections shall not be allowed for all post tensioned
Structures and for staged construction sequences where delayed and/or staged loading
occurs for any type of concrete Structure. The adjustment for duration of load as
described in this section applies only to design values for timber connectors, such as nails,
bolts, and lag screws. Allowable stresses for timber and structural steel components used
in the connection, as described in

Section 6-02.3(17)B

, are maximums and thus shall not

be increased.

Tabulated values for nails, bolts, and lag screws may be adjusted by the following
duration-of-load factors:
1. 1.25 for falsework design governed by the minimum design horizontal load or

greater (3 percent or greater of the dead load),

2. 1.33 for falsework design governed by wind load, and
3. 2.00 for falsework design governed by impact loading.

6-02.3(17)J

Face Lumber, Studs, Wales, and Metal Forms

Elements of this section shall be designed for the loads, allowable stresses, deflections,
and conditions which pertain from other Subsections of

Section 6-02.3(17)

Forms battered or inclined above the concrete will tend to lift up as concrete is placed
and shall have positive anchorage or counterweights designed to resist uplift and shall
be shown in the formwork plans. Where the concrete pouring sequence causes fresh
concrete to be significantly higher along one side of tied forms than the opposite side, a
positive form anchorage system shall be designed capable of resisting the imbalance of
horizontal thrust, and prevent the dislocation and sliding of the entire form unit.

Wooden forms shall be faced with smooth sanded, exterior plywood. This plywood shall
meet the requirements of the National Bureau of Standards, U.S. Product Standard PS 1,
and the Design Specification of the American Plywood Association (APA). Each full sheet
shall bear the APA stamp. The Contractor shall list in the form plans the grade and class of
plywood. If the Engineer accepts the manufacturer’s certification of structural properties,
the Contractor may use plywood that does not carry the APA stamp. Plywood panels
stamped “shop” or “shop cutting”, shall not be used.

Plyform is an APA plywood specifically designed and manufactured for concrete forming.
Plyform differs from conventional exterior plywood grades in strength and the exterior
face panels are sanded smooth and factory oiled. Likewise, there is a significant difference
between grades designated Class 1, Class 2, and Structural I Plyform.

Concrete Structures

6-02

The grades of plywood for various form applications shall be as follows:
1. Traffic and Pedestrian Barriers (except those that will receive an architectural

surface treatment) – Plywood used for these surfaces shall be APA grade High-
Density Overlaid (HDO) Plyform Class I. But if the Contractor coats the form to
prevent it from leaving joint and grain marks on the surface, plywood that meets
or exceeds APA grades B-B Plyform Class I or B-C (Group I species) may be used.
Under this option, the Contractor shall provide for the Engineer’s acceptance
a 4-foot-square, test panel of concrete formed with the same plywood and
coating as proposed in the form plans. This panel shall include one form joint
along its centerline. The Contractor shall apply coating material, according to the
manufacturer’s instructions, before applying chemical release agents.

2. Other Exposed Surfaces (all but those on traffic and pedestrian barriers) – Plywood

used to form these surfaces shall meet or exceed the requirements of APA grades
B-B Plyform Class I or B-C (Group I series). If one face is less than B quality, the B (or
better) face shall contact the concrete.

3. Unexposed Surfaces (such as the underside of the bridge deck between girders,

the interiors of box girders, etc., and traffic and pedestrian barriers where surfaces
will receive an architectural treatment) – Plywood used to form these surfaces may
be APA grade CDX, provided the Contractor complies with stress and deflection
requirements stated elsewhere in these Specifications.

Form joints on an exposed surface shall be in a horizontal or vertical plane. But in
wingwalls and box girders, side form joints shall be placed at right angles and parallel to
the Roadway grade. Joints parallel to studs or joists shall be backed by a stud or joist.
Joints at right angles to studs and joists shall be backed by a stud or other backing the
Engineer accepts. Perpendicular backing is not required if studs or joists are spaced:
1. Nine inches or less on center and covered with ½-inch plywood, or
2. Twelve inches or less on center and covered with ¾-inch plywood.

The face grain of plywood shall run perpendicular to studs or joists unless shown
otherwise on the Contractor’s formwork Working Drawings. Proposals to deviate from
the perpendicular orientation shall be accompanied by supporting calculations of the
stresses and deflections.

Forming for all exposed curved surfaces shall follow the shape of the curve shown in the
Contract Plans and shall not be chorded except as follows. On any retaining wall that
follows a horizontal circular curve, the wall stems may be a series of short chords if:
1. The chords within the panel are the same length, unless otherwise allowed by the

Engineer;

2. The chords do not vary from a true curve by more than ½ inch at any point; and
3. All panel points are on the true curve.

Where architectural treatment is required, the angle point for chords in wall stems shall
fall at vertical rustication joints.

Page 6-80

Concrete Structures

For exposed surfaces of abutments, wingwalls, piers, retaining walls, and columns, the
Contractor shall build forms of plywood at least ¾ inch thick with studs no more than
12 inches on center. The Engineer may allow exceptions, but deflection of the plywood,
studs, or wales shall never exceed

1⁄360

of the span (or

1⁄270

of the span for unexposed

surfaces, including the bottom of the deck slab between girders).

All form plywood shall be at least ½ inch thick except on sharply curved surfaces. There,
the Contractor may use ¼-inch plywood if it is backed firmly with heavier material.

Round columns or rounded pier shafts shall be formed with a self-supporting metal
shell form or form tube that leaves a smooth, nonspiralling surface. Wood forms are not
permitted.

Metal forms shall not be used elsewhere unless the Engineer is satisfied with the surface
and allows use in writing. The Engineer may withdraw allowing use of metal forms at
any time. If permitted to use a combination of wood and metal in forms, the Contractor
shall coat the forms so that the texture produced by the wood matches that of the metal.
Aluminum shall not be used for metal forms.

For design purposes, the Contractor shall assume that on vertical surfaces concrete exerts
150 pounds per square foot per foot of depth. However, when the depth is reached
where the rate of placement controls the pressure, the following table applies:

Rate of Placing

Feet per Hour

Pressure, Pounds per Square Foot for Temperature of

Concrete as Shown

60°F

70°F and Above

470

375

640

565

725

625

815

690

900

750

990

815

1,075

875

1,165

935

1,250

1,000

1,670

1,300

The pressures in the above table have been increased to provide an allowance for the
vibration and impact.

All corners shall be beveled ¾ inch. However, footings, footing pedestals, and seals need
not be beveled unless required in the Plans.

All forms shall be as mortar-tight as possible with no water standing in them as the
concrete is placed.

Concrete Structures

6-02

The Contractor shall apply a parting compound on forms for exposed concrete surfaces.
This compound shall be a chemical release agent that permits the forms to separate
cleanly from the concrete. The compound shall not penetrate or stain the surface and
shall not attract dirt or other foreign matter. After the forms are removed, the concrete
surface shall be dust-free and have a uniform appearance. The Contractor shall apply the
compound at the manufacturer’s recommended rate to produce a surface free of dusting
action and yet provide easy removal of the forms.

The Engineer may reject any forms that will not produce a satisfactory surface.

6-02.3(17)K

Concrete Forms on Steel Spans

Concrete forms on all steel Structures shall be removable and shall not remain in place.
Where needed, the forms shall have openings for truss or girder members. Each opening
shall be large enough to leave at least 1½ inches between the concrete and steel on all
sides of the steel member after the forms have been removed. Unit Contract prices cover
all costs related to these openings.

The Contractor shall not weld any part of the form to any steel member.

The compression member or bottom connection of cantilever formwork support brackets
shall bear either within 6 inches maximum vertically of the bottom flange or within
6 inches maximum horizontally of a vertical web stiffener. The Contractor’s bridge deck
form system shall be designed to prevent rotation of the steel girder. This can be achieved
by temporary struts and ties or other methods the Contractor shows to be effective.
Partial depth cantilever formwork support brackets that do not conform to the above
requirements shall not be used unless the Contractor submits Type 2E Working Drawings
consisting of details showing the additional formwork struts and ties used to brace the
steel girder against web distortion caused by the partial depth bracket.

If the Engineer permits bolt holes in the web to support form brackets, the holes shall be
shop drilled unless otherwise allowed by the Engineer. The Contractor shall fill the holes
with fully torqued ASTM F3125 Grade A325 bolts in accordance with

Section 6-03.3(33)

Each bolt head shall be placed on the exterior side of the web. There shall be no holes
made in the flanges.

6-02.3(17)L

Finishing Machine Support System

Before using any finishing machine, the Contractor shall submit a Type 2 Working
Drawing consisting of detailed drawings that show the system proposed to support it. The
Contractor shall not attach this (or any other) equipment support system to the sides or
suspend it from any girder unless the Engineer permits. The Engineer will not permit such
a method if it will unduly alter stress patterns or create too much stress in the girder.

6-02.3(17)M Restricted Overhead Clearance Sign

The Contractor shall notify the Engineer not less than 15 working days before the
anticipated start of each falsework and girder erection operation whenever such
falsework or girders will reduce clearances available to the public traffic. Falsework
openings shall not be more restrictive to traffic than shown in the Contract Plans.

Page 6-82

Concrete Structures

Where the height of vehicular openings through falsework is less than 15 feet, a W
12-2 “Low Clearance Symbol Sign” shall be erected on the Shoulder in advance of the
falsework and two or more W 12-301 and/or W 12-302 signs shall be attached to the
falsework to provide accurate usable clearance information over the entire falsework
opening. The posted low clearance shall include an allowance for anticipated falsework
girder deflection (rounded-up to the next whole inch) due to design dead load, including
all successive concrete pours. W 12-302 signs shall be used to designate prominent
clearance restrictions and limits of usable clearance. In addition, where the clearance
is less than the legal height limit (14 feet), a W 12-2 sign shall be erected in advance of
the nearest intersecting road or wide point in the road at which a vehicle can detour
or turn around. A W 13-501 sign indicating the distance to the low clearance shall be
installed below the advance sign. The Engineer will furnish the above noted signs and the
Contractor shall erect and maintain them, all in accordance with

Section 1-10.3(3)

When erecting falsework that restricts overhead clearance above a railroad track, the
Contractor shall immediately (as soon as the restriction occurs) place restricted overhead
clearance signs. Sign details are shown in the

Standard Plans

. Unit Contract prices cover all

costs relating to these signs.

6-02.3(17)N Removal of Falsework and Forms

If the Engineer does not specify otherwise, the Contractor may request to remove forms
based on the criteria in the table below. Both compressive strength and minimum time
criteria shall be met if both are listed in the applicable row. The minimum time shall be
from the time of the last concrete placement in the forms. In no case shall the Contractor
remove forms or falsework without the Engineer’s concurrence.

Concrete Placed In

Percent of

Specified

Minimum

Compressive

Strength

Minimum

Compressive

Strength

Minimum

Time

Side forms not supporting the concrete weight,

including columns, walls, crossbeams, nonsloping box

girder webs, abutments, and traffic and pedestrian

barriers.

3 days

1,400 psi

18 hours

Side forms of footings, pile caps, and shaft caps.

18 hours

Crossbeams, sloping box girder webs, struts, inclined

columns, inclined walls, and other forms that support

the concrete weight.

5 days

Bridge decks supported on stringers, beam, or girders.

10 days

Box girders, T-beam girders, and flat-slab

Superstructure.

14 days

Arches

21 days

Strength shall be proved by test cylinders made from the last concrete placed into the form. The cylinders

shall be cured according to FOP for AASHTO T 23.

Curing compound shall be immediately applied to the sides when forms are removed.

Where continuous spans or segments are involved, the time for all spans will be determined by the last

concrete placed affecting any span.

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6-02

Before releasing supports from beneath beams and girders, the Contractor shall remove
forms from columns to enable the Engineer to inspect the column concrete.

Curing shall comply with the requirements of

Section 6-02.3(11)

. The concrete surface

shall not become dry during form removal if removed during the cure period.

Before placing forms for traffic and pedestrian barriers, the Contractor shall completely
release all falsework under spans.

The Engineer may allow leaving in place forms for footings in cofferdams or cribs. This
decision will be based on whether removing them would harm the cofferdam or crib and
whether the forms will show in the finished Structure.

All cells of a box girder Structure which have permanent access shall have all forms
completely removed, including the bridge deck forms. All debris and all projections into
the cells shall be removed. Unless otherwise shown in the Plans, the bridge deck interior
forms in all other cells where no permanent access is available, may be left in place.

Falsework and forms supporting sloping exterior webs shall not be released until the
bridge deck and deck overhang concrete has obtained its removal strength and number of
days criteria listed in the table above. Stem reshoring shall not be used.

Open joints shown in the Plans shall have all forms completely removed, including
Styrofoam products and form anchors, allowing the completed Structure to move freely.

If the Contractor intends to support or suspend falsework and formwork from the bridge
Structure while the falsework and formwork is being removed, the Contractor shall
submit a Type 2 Working Drawing consisting of the falsework and formwork removal plan
and calculations. The falsework and formwork removal plan shall include the following:
1. The location and size of any cast-in-place falsework lowering holes and how the

holes are to be filled;

2. The location, capacity, and size of any attachments, beams, cables, and other

hardware used to attach to the Structure or support the falsework and formwork;

3. The type, capacity and factor of safety, weight, and spacing of points of reaction of

lowering equipment; and

4. The weight at each support point of the falsework and formwork being lowered.

All other forms shall be removed whether above or below the level of the ground or
water. Sections

6-02.3(7)

and

6-02.3(8)

govern form removal for concrete exposed to sea

water or to alkaline water or soil. The forms inside of hollow piers, girders, abutments,
etc., shall be removed through openings shown in the Plans or as allowed by the Engineer.

6-02.3(17)O Early Concrete Test Cylinder Breaks

The fabrication, curing, and testing of the early cylinders shall be the responsibility of the
Contractor. Early cylinders are defined as all cylinders tested in advance of the design age
of 28 days whose purpose is to determine the in-place strength of concrete in a Structure
prior to applying loads or stresses. The Contractor shall retain a testing Laboratory to

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perform this Work. Testing Laboratories’ equipment shall be calibrated within 1 year prior
to testing and testers shall be either ACI certified or qualified in accordance with AASHTO
R 18.

The concrete cylinders shall be molded in accordance with FOP for AASHTO T 23 from
concrete last placed in the forms and representative of the quality of concrete placed in
that pour.

The cylinders shall be cured in the field in accordance with FOP for AASHTO T 23 Section
10.2 Field Curing.

The concrete cylinders shall be tested for compressive strength in accordance with
AASHTO T 22. The number of early cylinder breaks shall be in accordance with the
Contractor’s need and as allowed by the Engineer.

The Contractor shall submit a Type 2 Working Drawing consisting of all test results, proof
of equipment calibration, and tester’s certification. The Contractor shall not remove forms
without the concurrence of the Engineer.

All costs in connection with furnishing cylinder molds, fabrication, curing, and testing of
early cylinders shall be included in the unit Contract prices for the various Bid items of
Work involved.

6-02.3(18) Placing Anchor Bolts

The Contractor shall comply with the following requirements in setting anchor bolts in
piers, abutments, or pedestals:
1. If set in the wet concrete, the bolts shall be accurately placed before the concrete is

placed.

2. If the bolts are set in drilled holes, hole diameter shall exceed bolt diameter by at

least 1 inch. Grouting shall comply with

Section 6-02.3(20)

3. If the bolts are set in pipe, grouting shall comply with

Section 6-02.3(20)

4. If freezing weather occurs before bolts can be grouted into sleeves or holes, they

shall be filled with an accepted antifreeze solution (non-evaporating).

6-02.3(19) Bridge Bearings

6-02.3(19)A

Submittals of Acceptance Test Reports and Certificates

The Contractor shall submit the following production samples and test reports and
certificates for fabricated bridge bearing assemblies as applicable:

1. A Type 2 Working Drawing consisting of a six-inch square by 1/8-inch thick sample of

PTFE taken from the lot of production material.

2. A Type 2 Working Drawing consisting of a six-inch square by 1-inch thick sample of

pre-formed fabric pad taken from the lot of production material.

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3. Type 1 Working Drawings consisting of Manufacturers’ Certificates of Compliance

for the PTFE, polyether urethane, pre-formed fabric pad duck, silicone grease, epoxy
gel, and resin filler.

4. Type 1 Working Drawings consisting of certified mill test reports for all steel and

stainless steel in the bearing assemblies.

5. Type 1 Working Drawings consisting of certified test reports confirming that the pre-

formed fabric pads meet the specific requirements of proof load.

6-02.3(19)B

Bridge Bearing Assemblies

For all fixed, sliding, or rolling bearings, the Contractor shall:
1. Machine all sliding and rolling surfaces true, smooth, and parallel to the movement of

the bearing;

2.  Polish all sliding surfaces;
3.  Anchor expansion bearings securely, setting them true to line and grade;
4.  Avoid placing concrete in such a way that it might interfere with the free action of

any sliding or rolling surface.

Grout placement under steel bearings shall comply with

Section 6-02.3(20)

6-02.3(20) Grout for Anchor Bolts and Bridge Bearings

Grout shall conform to

Section 9-20.3(2)

for anchor bolts and for bearing assemblies with

bearing plates. Grout shall conform to

Section 9-20.3(3)

for elastomeric bearing pads and

fabric pad bearings without bearing plates.

Grout shall be a workable mix with a viscosity that is suitable for the intended application.
Grout shall not be placed outside of the manufacturer recommended range of thickness.
The Contractor shall receive concurrence from the Engineer before using the grout.

Field grout cubes and cylinders shall be fabricated and tested in accordance with Section
9-20.3 when requested by the Engineer, but not less than one per bridge pier or once
per day.

Before placing grout, the substrate on which it is to be placed shall be prepared as
recommended by the manufacturer to ensure proper bonding. The grout shall be cured
as recommended by the manufacturer. The grout may be loaded when a minimum of
4,000 psi compressive strength is attained.

To grout bridge bearing masonry plates, the Contractor shall:
1. Build a form approximately 4 inches high with sides 4 inches outside the base of

each masonry plate,

2.  Fill each form to the top with grout,
3.  Work grout under all parts of each masonry plate,
4.  Remove each form after the grout has hardened,

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5.  Remove the grout outside each masonry plate to the base of the masonry plate,
6.  Bevel off the grout neatly to the top of the masonry, and
7.  Place no additional load on the masonry plate until the grout has set at least

72 hours.

After all grout under the masonry plate and in the anchor bolt cavities has attained a
minimum strength of 4,000 psi, the anchor bolt nuts shall be tightened to snug tight.
“Snug tight” means either the tightness reached by (1) a few blows from an impact
wrench, or (2) the full effort of a person using a spud wrench. Once the nut is snug tight,
the anchor bolt threads shall be burred just enough to prevent loosening of the nut.

6-02.3(21) Drainage of Box Girder Cells

To drain box girder cells, the Contractor shall provide and install, according to details in
the Plans, short lengths of nonmetallic pipe in the bottom slab at the low point of each
cell. The pipe shall have a minimum inside diameter of 4 inches. If the difference in Plan
elevation is 2 inches or less, the Contractor shall install pipe in each end of the box girder
cell. All drainage holes shall be screened in accordance with the Plan details.

6-02.3(22) Drainage of Substructure

The Contractor shall use weep holes and gravel backfill that complies with

Section

9-03.12(2)

to drain fill material behind retaining walls, abutments, tunnels, and wingwalls.

To maintain thorough drainage, weep holes shall be placed as low as possible. Weep holes
shall be covered with geotextile meeting the requirements of

Section 9-33.2

, Table 2

Class C before backfilling. Geotextile screening shall be bonded to the concrete with an
accepted adhesive. Gravel backfill shall be placed and compacted as required in

Section

2-09.3(1)E

. In addition, if the Plans require, tiling, French or rock drains, or other drainage

devices shall be installed.

If underdrains are not installed behind the wall or abutment, all backfill within 18 inches
of weep holes shall comply with

Section 9-03.12(4)

. Unless the Plans require otherwise,

all other backfill behind the wall or abutment shall be gravel backfill for walls.

6-02.3(23) Opening to Traffic

Bridges with a bridge deck made of concrete shall remain closed to all traffic, including
construction equipment, until the concrete has reached the 28-day specified compressive
strength. This strength shall be determined with cylinders made of the same concrete as
the bridge deck and cured under the same conditions. A concrete deck bridge shall never
be opened to traffic earlier than 10 days after the deck concrete was placed and never
before the Engineer allows.

For load restrictions on bridges under construction, refer to

Section 6-01.6

After curing bridge approach slabs in accordance with Section 6-02.3(11), the bridge
approach slabs may be opened to traffic when a minimum compressive strength of
2,500 psi is achieved.

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6-02.3(24) Reinforcement

Although a bar list is normally included in the Plans, the Contracting Agency does not
guarantee its accuracy and it shall be used at the Contractor’s risk. Reinforcement
fabrication details shall be determined from the information provided in the Plans.

Before delivery of the reinforcing bars, the Contractor shall submit Type 1 Working
Drawings consisting of two informational copies of the supplemental bending diagrams.

6-02.3(24)A

Field Bending

Field bending of AASHTO M31 Grade 60 and ASTM A706 Grade 60 reinforcement shall
be done in accordance with the requirements of this section. Field bending of all other
reinforcement shall require a Type 2 Working Drawing showing the bend radii, bending
and heating procedures, and any inspection or testing requirements.

Field bending shall not be done on reinforcement within the top or bottom third of
column lengths or within plastic hinge regions identified in the Plans. Field bending shall
not be done on bar sizes No. 14 or No. 18.

In field-bending steel reinforcing bars, the Contractor shall:
1. Make the bend gradually using a bending tool equipped with a bending diameter

as listed in Table 1. Bending shall not be done by means of hammer blows and
pipe sleeves. When bending to straighten a previously bent bar, move a hickey bar
progressively around the bend.

2. Apply heat as described below for bending bar sizes No. 6 through No. 11 and

for bending bar sizes No. 5 and smaller when the bars have been previously bent.
Previously unbent bars of sizes No. 5 and smaller may be bent without heating when
the bar temperature is 40°F or higher. When previously unbent bars of sizes No. 5
and smaller have a bar temperature lower than 40°F, they shall be heated to within
the range of 100°F to 150°F prior to bending. In applying heat for field-bending steel
reinforcing bars, the Contractor shall:
a. Avoid damage to the concrete by insulating any concrete within 6 inches of the

heated bar area;

b. Apply two heat tips simultaneously at opposite sides of bar sizes No. 7 or larger;
c. Heat the bar to within the required temperature range shown in Table 2 as

verified by using temperature-indicating crayons or other suitable means;

d. Heat a minimum bar length as shown in Table 3. Locate the heated section of

the bar to include the entire bending length;

e. Bend immediately after the required temperature range has been achieved.

Maintain the bar within the required temperature range during the entire
bending process;

Do not cool bars artificially with water, forced air, or other means.

3. Limit any bend or straightening to these maximum angles: 135 degrees for bar sizes

No. 8 or smaller, and 90 degrees for bar sizes No. 9 through No. 11.

Standard Specifications for Road, Bridge, and Municipal Construction 2020 (M 41-10) - page 33