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

Page 6-156

Steel Structures

The Contractor shall submit Type 1 Working Drawings providing documentation of the
bolt tension calibrator, including brand, capacity, model, date of last calibration, and
manufacturer’s instructions for use. The Contractor shall supply the bolt tension calibrator
and all accompanying hardware and calibrated torque wrenches to conduct all testing
and inspections described herein. Use of the bolt tension calibrator shall comply with
manufacturer’s recommendations.

Fastener components shall be protected from dirt and moisture in closed containers at the
site of installation. Only as many fastener components as are anticipated to be installed
during the Work shift shall be taken from protected storage. Fastener components
that are not incorporated into the Work shall be returned to protected storage at the
end of the Work shift. Fastener components shall not be cleaned or modified from the
as-delivered condition. Fastener components that accumulate rust or dirt shall not be
incorporated into the Work. Tension control bolt assemblies shall not be relubricated,
except by the manufacturer.

All bolted connections are slip critical. Painted structures require either Type 1 or Type 3
bolts. Bolts shall not be galvanized unless specified in the Contract documents. When
galvanized bolts are specified, tension-control galvanized bolts are not permitted.
Unpainted structures require Type 3 bolts. ASTM F3125 Grade A490 bolts shall not be
galvanized and shall not be used in contact with galvanized metal.

Washers are required under turned elements for bolted connections and as required
in the following:
1. Washers shall be used under both the head and the nut when ASTM F3125

Grade A490 bolts are to be installed in structural carbon steel, as specified in

Section 9-06.1

2. Where the outer face of the bolted parts has a slope greater than 1:20 with respect

to a plane normal to the bolt axis, a beveled washer shall be used.

3. Washers shall not be stacked unless otherwise specified by the Engineer.
4. It is acceptable to place a washer under the unturned element.

All galvanized nuts shall be lubricated by the manufacturer with a lubricant containing
a visible dye so a visual check for the lubricant can be made at the time of field
installation. Black bolts shall be lubricated by the manufacturer and shall be “oily” to the
touch when installed.

After assembly, bolted parts shall fit solidly together. They shall not be separated by
washers, gaskets, or any other material. Assembled joint surfaces, including those next
to bolt heads, nuts, and washers, shall be free of loose mill scale, burrs, dirt, and other
foreign material that would prevent solid seating.

Steel Structures

6-03

When all bolts in a joint are tight, each bolt shall carry at least the proof load shown in

Table 1

below:

Table 1

Minimum Bolt Tension

Bolt Size (inches)

ASTM F3125 Grade A325

and Grade F1852 (pounds)

ASTM F3125

Grade A490 (pounds)

12,050

14,900

⅝

19,200

23,700

28,400

35,100

⅞

39,250

48,500

51,500

63,600

1⅛

56,450

80,100

1¼

71,700

101,800

1⅜

85,450

121,300

1½

104,000

147,500

Prior to final tightening of any bolts in a bolted connection, the connection shall
be compacted to a snug tight condition. Snug tight shall include bringing all plies
of the connection into firm contact and snug tightening all bolts in accordance with

Section 6-03.3(32)

Final tightening may be done by the Turn-of-Nut Method, the direct-tension indicator
method, or the twist off-type tension control structural bolt/nut/washer assembly
method. Preferably, the nut shall be turned tight while the bolt is prevented from rotating.
However, if required by either turn-of-nut or direct-tension-indicator methods because
of bolt entering and/or wrench operational clearances, tightening may be done by turning
the bolt while the nut is prevented from rotating.
1. Turn-of-Nut Method – After all specified bolting conditions are satisfied, and before

final tightening, the Contractor shall match-mark with crayon or paint the outer face
of each nut and the protruding part of the bolt. Each bolt shall be final tightened to
the specified minimum tension by rotating the amount specified in

Table 2

. To ensure

this tightening method is followed, the Engineer will (1) observe as the Contractor
installs, snug tightens, and final tightens all bolts and (2) inspect each match-mark.

Table 2

Turn-of-Nut Tightening Method Nut Rotational From Snug Tight

Condition

Bolt Length

Disposition of Outer Faces of Bolted Parts

Condition 1

Condition 2

Condition 3

L <= 4D

⅓-turn

½-turn

⅔-turn

4D < L<= 8D

½-turn

⅔-turn

5⁄6

-turn

8D < L<= 12D

⅔-turn

5⁄6

-turn

1-turn

Bolt length measured from underside of head to top of nut.

Condition 1 – Both faces at right angles to bolt axis.

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Steel Structures

Condition 2 – One face at right angle to bolt axis, one face sloped no more than
1:20, without bevel washer.

Condition 3 – Both faces sloped no more than 1:20 from right angle to bolt axis,
without bevel washer.

Nut rotation is relative to the bolt regardless of which element (nut or bolt) is being

turned. Tolerances permitted plus or minus 30 degrees (1/12-turn) for final turns of
½-turn or less; plus or minus 45 degrees (⅛-turn) for final turns of ⅔-turn or more.

D = nominal bolt diameter of bolt being tightened.

When bolt length exceeds 12D, the rotation shall be determined by actual tests in
which a suitable tension device simulates actual conditions.

2. Direct Tension Indicator Method (DTIs) – Shall not be used under the turned

element. DTIs shall be placed under the bolt head with the protrusions facing the
bolt head when the nut is turned. DTIs shall be placed under the nut with the
protrusions facing the nut when the bolt is turned.

Gap refusal shall be measured with a 0.005 inch tapered feeler gage. After all
specified bolting conditions are satisfied, the snug tightened gaps shall meet

Table 3

snug tight limits.

Each bolt shall be final-tightened to meet

Table 3

final-tighten limits. If the bolt

is tensioned so that no visible gap in any space remains, the bolt and DTI shall be
removed and replaced by a new properly tensioned bolt and DTI.

The Contractor shall tension all bolts, inspecting all DTIs with a feeler gage, in the
presence of the Engineer. DTIs shall be installed by two-person (or more) crews, with
one individual (1) preventing the element at the DTI from turning and (2) measuring
the gap of the DTI to determine the proper tension of the bolt.

If a bolt, that has had its DTI brought to full load, loosens during the course of
bolting the connection, it shall be rejected. Reuse of the bolt and nut are subject
to the provisions of this section. The used DTI shall not be reinstalled.

Table 3

Direct Tension Indicator Requirements

Bolt Size

(inches)

DTI Spaces

Maximum Snug Tight

Refusals

Minimum Final

Tighten Refusals

ASTM F3125

Grade A 325

ASTM F3125

Grade A490

ASTM F3125

Grade A 325

ASTM F3125

Grade A490

ASTM F3125

Grade A 325

ASTM F3125

Grade A490

⅝

⅞

1⅛

1¼

1⅜

1½

Steel Structures

6-03

3. Twist Off-Type Tension Control Structural Bolt/Nut/Washer Assembly Method

(Tension Control Bolt Assembly) – Tension control bolt assemblies shall include the
bolt, nut, and washer(s) packaged and shipped as a single assembly. Unless otherwise
accepted by the Engineer, tension control bolt assembly components shall not be
interchanged for testing or installation and shall comply with all provisions of ASTM
F3125 Grade F1852. If accepted by the Engineer, the tension control bolt assembly
components may be interchanged within the same component lot for girder web
slices or other locations where access to both sides of the connection is restricted.

The tension control bolts shall incorporate a design feature intended to either
indirectly indicate, or to automatically provide, the minimum tension specified in

Table 1

The Contractor shall submit Type 1 Working Drawings of the tension control bolt
assembly, including bolt capacities; type of bolt, nut, and washer lubricant; method
of packaging and protection of the lubricated bolt; installation equipment; calibration
equipment; and installation procedures.

The tension control bolt manufacturer’s installation procedure shall be followed for
installation of bolts in the verification testing device, in all calibration devices, and in
all structure connections.

In some cases, proper tensioning of the bolts may require more than one cycle of
systematic partial tightening prior to final yield or fracture of the tension control
element of each bolt. If yield or fracture of the tension control element of a bolt
occurs prior to the final tightening cycle, that bolt shall be replaced with a new one.

Additional field verification testing shall be performed as requested by the Engineer.

All bolts and connecting hardware shall be stored and handled in a manner to
prevent corrosion and loss of lubricant. Bolts that are installed without the same
lubricant coating as tested under the verification test will be rejected, and they shall
be removed from the joint and be replaced with new lubricated bolts at no additional
cost to the Contracting Agency.

ASTM F3125 Grade A490 bolts, galvanized ASTM F3125 Grade A325 bolts, and ASTM
F3125 Grade F1852 tension control bolt assemblies shall not be reused. Black ASTM
F3125 Grade A325 bolts may be reused once if accepted by the Engineer. All bolts to be
reused shall have their threads inspected for distortion by reinstalling the used nut on the
bolt and turning the nut for the full length of the bolt threads by hand. Bolts to be reused
shall be relubricated in accordance with the manufacturer’s recommendation. Used bolts
shall be subject to a rotational capacity test as specified in

Section 6-03.3(33)A

Pre-

Erection Testing. Touching up or retightening bolts previously tightened by the Turn-of-
Nut Method, which may have been loosened by the tightening of adjacent bolts shall not
be considered as reuse, provided the snugging up continues from the initial position and
does not require greater rotation, including the tolerance, than that required by

Table 2

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Steel Structures

6-03.3(33)A

Pre-Erection Testing

High-strength bolt assemblies (bolt, nut, direct tension indicator, and washer), both
black and galvanized, shall be subjected to a field rotational capacity test, as outlined
below, prior to any permanent fastener installation. For field installations, the rotational
capacity test shall be conducted at the jobsite. Each combination of bolt production lot,
nut production lot, washer production lot, and direct tension indicator production lot
shall be tested as an assembly, except tension control bolt assemblies, which shall be
tested as supplied by the manufacturer. Each rotational capacity test shall include three
assemblies. Once an assembly passes the rotational capacity test, it is accepted for use
for the remainder of the project unless the Engineer deems further testing is necessary.
All tests shall be performed in a bolt tension calibrator by the Contractor in the presence
of the Engineer. High-strength bolt assemblies used in this test shall not be reused.
The bolt assemblies shall meet the following requirements after being pretensioned to
15 percent of the minimum bolt tension in

Table 1

. The assembly shall be considered

as nonconforming if the assembly fails to pass any one of the following specified
requirements:
1. The measured torque to produce the minimum bolt tension shall not exceed the

maximum allowed torque value obtained by the following equation:

Torque = 0.25 PD
Where:

Torque

= Calculated Torque (foot-pounds)

= Measured Bolt Tension (pounds)

= Normal Bolt Diameter (feet)

2. After placing the assembly through two cycles of the required number of turns,

where turns are measured from the 15 percent pretension condition, as indicated in

Table 2

a. The maximum recorded tension after the two turns shall be equal to or greater

than 1.15 times the minimum bolt tension listed in

Table 1

b. Each assembly shall be successfully installed to the specified number of turns.
c. The fastener components in the assembly shall not exhibit shear failure or

stripping of the threads as determined by visual examination of bolt and nut
threads following removal.

d. The bolts in the assembly shall not exhibit torsional or torsional/tension failure.

3. If any specimen fails, the assembly will be rejected. Elongation of the bolt between

the bolt head and the nut is not considered to be a failure.

Bolts that are too short to test in the bolt tension calibrator shall be tested in a steel
joint. The Contractor shall (1) install the high-strength bolt assemblies (bolt, nut, direct
tension indicator, and washer) in a steel joint of the proper thickness; (2) tighten to the
snug tight condition; (3) match-mark the outer face of each nut and the protruding part
of the bolt with crayon or paint; (4) rotate to the requirements of

Table 2

; and (5) record

the torque that is required to achieve the required amount of rotation. The assembly shall
be considered as nonconforming if the assembly fails to pass any one of the following
specified requirements:

Steel Structures

6-03

1. The recorded torque to produce the minimum rotation shall not exceed the

maximum allowed torque value obtained by the following equation:

Torque = 0.25 PD
Where:

Torque

= Calculated Maximum Allowed Torque (foot-pounds)

= Specified Bolt Tension per

Table 1

, multiplied by a factor of 1.15 (pounds)

= Normal Bolt Diameter (feet)

2. After placing the assembly through two cycles of the required number of

turns, where turns are measured from the snug tight condition specified in

Section 6-03.3(32)

a. Each assembly shall be successfully installed to the specified number of turns.
b. The fastener components in the assembly shall not exhibit shear failure or

stripping of the threads as determined by visual examination of bolt and nut
threads following removal.

c. The bolts in the assembly shall not exhibit torsional or torsional/tension failure.

3. If any specimen fails, the assembly will be rejected. Elongation of the bolt between

the bolt head and the nut is not considered to be a failure.

The Contractor shall submit Type 1 Working Drawings consisting of the manufacturer’s
detailed procedure for pre-erection (rotational capacity) testing of tension control bolt
assemblies.

Three DTIs, per lot, shall be tested in a bolt tension calibrator. The bolts shall be
tensioned to 105 percent of the tension shown in

Table 1

. If all of the DTI protrusions are

completely crushed (all five openings with zero gap), this lot of DTIs is rejected.

Three twist off-type tension controlled bolt assemblies, per assembly lot, shall be tested
in a bolt tension calibrator. The bolts shall first be tensioned to a snug tight condition.
Tensioning shall then be completed by tightening the assembly nut in a continuous
operation using a spline drive installation tool until the spline shears from the bolt. The
bolt assembly tension shall meet the requirements of

Table 1

. If any specimen fails, the

assembly lot is rejected.

6-03.3(33)B

Bolting Inspection

The Contractor, in the presence of the Engineer, shall inspect the tightened bolt using a
calibrated inspection torque wrench, regardless of bolting method. The Contractor shall
supply the inspection torque wrench. Inspection shall be performed within seven calendar
days from the completion of each bolted connection or as specified by the Engineer.

If the bolts to be installed are not long enough to fit in the bolt tension calibrator, five
bolts of the same grade, size, and condition as those under inspection shall be tested
using Direct-Tension-Indicators (DTIs) to measure bolt tension. This tension measurement
test shall be done at least once each inspection day. The Contractor shall supply the
necessary DTIs. The DTI shall be placed under the bolt head. A washer shall be placed
under the nut, which shall be the element turned during the performance of this

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Steel Structures

tension measurement test. Each bolt shall be tightened by any convenient means to the
specified minimum tension as indicated by the DTI. The inspecting wrench shall then be
applied to the tightened bolt to determine the torque required to turn the nut 5 degrees
(approximately 1 inch at a 12-inch radius) in the tightening direction. The job inspection
torque shall be taken as the average of three values thus determined after rejecting the
high and low values.

Five representative bolts/nuts/washers and DTIs if used (provided by the Contractor) of
the same grade, size, and condition as those under inspection shall be placed individually
in a bolt tension calibrator to measure bolt tension. This calibration operation shall be
done at least once each inspection day. There shall be a washer under the part turned in
tightening each bolt if washers are used on the Structure. In the bolt tension calibrator,
each bolt shall be tightened by any convenient means to the specified tension. The
inspection torque wrench shall then be applied to the tightened bolt to determine the
torque required to turn the nut or head 5 degrees (approximately 1 inch at a 12-inch
radius) in the tightening direction. The job-inspection torque shall be taken as the average
of three values thus determined after rejecting the high and low values.

Ten percent (at least two), or as specified by the Engineer, of the tightened bolts on the
Structure represented by the test bolts shall be selected at random in each connection.
The job-inspection torque shall then be applied to each with the inspecting wrench
turned in the tightening direction, with no restraint applied to the opposite end of the
bolt. If this torque turns no bolt head or nut, the Contracting Agency will accept the
connection as being properly tightened. If the torque turns one or more bolt heads or
nuts, the job-inspection torque shall then be applied to all bolts in the connection. Except
for tension control bolt assemblies and DTIs with zero gap at all protrusion spaces,
any bolt whose head or nut turns at this stage shall be tightened and reinspected. Any
tension control bolt assemblies or DTIs that have zero gap at all protrusion spaces shall be
replaced if the head or nut turns at this stage.

The Contractor shall submit Type 1 Working Drawings consisting of the manufacturer’s
detailed procedure for routine observation to ensure proper use of the tension control
bolt assemblies.

6-03.3(34) Adjusting Pin Nuts

All pin nuts shall be tightened thoroughly. The pins shall be placed so that members bear
fully and evenly on the nuts. The pins shall have enough thread to allow burring after the
nuts are tightened.

6-03.3(35) Setting Anchor Bolts

Anchor bolts shall be set in masonry as required in

Section 6-02.3(18)

. Anchor bolts

shall be grouted in after the shoes, masonry plates, and keeper plates have been set
and the span or series of continuous spans are completely erected and adjusted to line
and camber.

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6-03

6-03.3(36) Setting and Grouting Masonry Plates

The following procedure applies to masonry plates for all steel spans, including shoes,
keeper plates, and turning racks on movable bridges.

To set masonry plates, the Contractor shall:
1. Set masonry plates on the anchor bolts;
2. Place steel shims under the masonry plates to position pin centers or bearings to

line and grade and in relationship to each other. Steel shims shall be the size and be
placed at the locations shown in the Plans;

3.  Level the bases of all masonry plates;
4.  Draw anchor bolt nuts down tight;
5.  Recheck pin centers or bearings for alignment; and
6.  Leave at least ¾ inch of space under each masonry plate for grout.

After the masonry plates have been set and the span or series of continuous spans are
completely erected and swung free, the space between the top of the masonry and
the top of the concrete bearing seat shall be filled with grout. Main masonry plates for
cantilever spans shall be set and grouted in before any steel Work is erected.

Grout shall conform to

Section 9-20.3(2)

and placement shall be as required in

Section 6-02.3(20)

6-03.3(37) Setting Steel Bridge Bearings

Masonry plates, shoes, and keeper plates of expansion bearings shall be set and adjusted
to center at a normal temperature of 64ºF. Adjustment for an inaccuracy in fabricated
length shall be made after dead-load camber is out.

6-03.3(38) Placing Superstructure

The concrete in piers and crossbeams shall reach at least 80 percent of design strength
before girders are placed on them.

6-03.3(39) Swinging the Span

Forms weighing less than 5 pounds per square foot of bridge deck area and uniformly
distributed along the steel spans may be placed before the spans swing free on their
supports. Steel reinforcing bars or concrete bridge deck shall not be placed on steel spans
until the spans swing free on their supports and elevations are recorded. No simple span
or any series of continuous spans will be considered as swinging free until all temporary
supports have been released. Reinforcing steel or concrete bridge decks shall not be
placed on any simple or continuous span steel girder bridge until all its spans are adjusted
and its masonry plates, shoes, and keeper plates grouted. For this specification, the
structure shall be considered as continuous across hinged joints.

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Steel Structures

After the falsework is released (spans swung free), the masonry plates, shoes, and keeper
plates are grouted, and before any load is applied, the Contractor (or the Engineer if the
Contracting Agency is responsible for surveying) shall survey elevations at the tenth
points along the centerline on top of all girders and floorbeams. The Contractor shall
calculate the theoretical top of girder or floorbeam flange elevations and compare
the calculated elevations to the surveyed elevations. The theoretical pad or haunch
depth shown in the Plans shall be increased or decreased by the difference between
the theoretical and surveyed top of girder or floorbeam elevations. The soffit (deck
formwork) shall be set based on the Plan bridge deck thickness and the adjusted pad or
haunch depth.

The Contractor shall submit all survey data and calculations to the Engineer for review ten
working days prior to placing any load, beyond the maximum five pounds per square foot
of form weight allowed, on the Structure.

6-03.3(40) Draining Pockets

The Contractor shall provide enough holes to drain all water from pockets in trusses,
girders, and other members. Unless shown on approved shop plans, drain holes shall not
be drilled without the written approval of the Engineer.

All costs related to providing drain holes shall be included in the unit Contract prices for
structural or cast steel.

6-03.3(41) Vacant

6-03.3(42) Surface Condition

As the Structure is erected, the Contractor shall keep all steel surfaces clean and free
from dirt, concrete, mortar, oil, paint, grease, and other stain-producing foreign matter.
Any surfaces that become stained shall be cleaned as follows:

Painted steel surfaces shall be cleaned by methods required for the type of staining.
The Contract shall submit a Type 1 Working Drawing of the cleaning method.
Unpainted steel surfaces shall be cleaned by sandblasting. Sandblasting to remove
stains on publicly visible surfaces shall be done to the extent that, in the Engineers
opinion, the uniform weathering characteristics of the Structure are preserved.

6-03.3(43) Castings, Steel Forgings, and Miscellaneous Metals

Castings, steel forgings, and miscellaneous metals shall be built to comply with

Section 9-06

6-03.3(43)A

Shop Construction, Castings, Steel Forgings, and Miscellaneous

Metals

This section’s requirements for structural steel (including painting requirements) shall also
apply to castings, steel forgings, and miscellaneous metals.

Steel Structures

6-03

Castings shall be:
1. True to pattern in form and dimensions;
2. Free from pouring faults, sponginess, cracks, blow holes, and other defects in places

that would affect strength, appearance, or value;

3.  Clean and uniform in appearance;
4.  Filleted boldly at angles; and
5.  Formed with sharp and perfect arises.

Iron and steel castings and forgings shall be annealed before any machining, unless the
Plans state otherwise.

6-03.4 Measurement

Cast or forged metal (kind) shown in the Plans will be measured by the pound or will be
paid for on a lump sum basis, whichever is shown on the Proposal.

6-03.5 Payment

Payment will be made for each of the following Bid items that are included in the
Proposal:

“Structural Carbon Steel”, lump sum.
The lump sum Contract price for “Structural Carbon Steel” shall be full pay for
all costs in connection with furnishing all materials, labor, tools, and equipment
necessary for the manufacture, fabrication, transportation, erection, and painting of
all structural carbon steel used in the completed Structure, including the providing
of such other protective coatings or treatment as may be shown in the Plans
or specified in the Special Provisions.
For steel Structures, the estimated weight of the structural carbon steel in the
project will be shown in the Plans or in the Special Provisions. In the event any
change in the Plans is made which will affect the weight of materials to be furnished,
payment for the additional structural carbon steel required as a result of the
change in the Plans will be made at a unit price per pound obtained by dividing the
Contractor’s lump sum Bid for structural carbon steel by the total estimated weight
of structural carbon steel shown in the Plans or in the Special Provisions.
Reductions in weight due to a change in the Plans will be made at the same rate as
determined above and will be deducted from payments due the Contractor.
Prospective Bidders shall verify the estimated weight of structural carbon steel
before submitting a Bid. No adjustment other than for approved changes shall be
made in the lump sum Bid even though the actual weight may deviate from the
stated estimated weight.

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Steel Structures

For concrete and timber Structures, where the structural carbon steel is a minor
item, no estimated weight will be given for the structural carbon steel. In the event
any change in the Plans is necessary which will affect the weight of material to be
furnished for this type of Structure, the payment or reduction for the revision in
quantity will be made at a unit price per pound obtained by dividing the Contractor’s
lump sum Bid for the structural carbon steel by the calculated weight of the original
material. The calculated weight will be established by the Engineer and will be based
on an estimated weight of 490 pounds per cubic foot for steel.
Any change in the Plans which affects the weight of material to be furnished as
provided herein will be subject to the provisions of

Section 1-04.4

“Structural Low Alloy Steel”, lump sum.
“Structural High Strength Steel”, lump sum.
Payment for “Structural Low Alloy Steel” and “Structural High Strength Steel” shall be
made on the same lump sum basis as specified for structural carbon steel.
“(Cast or Forged) Steel”, lump sum or per pound.
“(Cast, Malleable, or Ductile) Iron”, lump sum or per pound.
“Cast Bronze”, lump sum or per pound.
Payment for “(Cast or Forged) Steel”, “(Cast, Malleable or Ductile) Iron”, and “Cast
Bronze” will be made at the lump sum or per pound Contract prices as included in
the Proposal.
For the purpose of payment, such minor items as bearing plates, pedestals, forged
steel pins, anchor bolts, field bolts, shear connectors, etc., unless otherwise provided,
shall be considered as structural carbon steel even though made of other materials.
When no Bid item is included in the Proposal and payment is not otherwise
provided, the castings, forgings, miscellaneous metal, and painting shall be
considered as incidental to the construction, and all costs therefore shall be included
in the unit Contract prices for the payment items involved and shown.

Timber Structures

6-04

Timber Structures

6-04.1 Description

This Work is the building of any Structure or parts of Structures (except piling) made of
treated timber, untreated timber, or both. The Contractor shall erect timber Structures on
prepared foundations. The Structures shall conform to the dimensions, lines, and grades
required by the Plans, the Engineer, and these Specifications.

Any part of a timber Structure made of nontimber materials shall comply with the sections
of these Specifications that govern those materials.

6-04.2 Materials

Materials shall meet the requirements of the following sections:

Structural Steel and Related Material

9-06

Bolts, Washers, Other Hardware

9-06.22

Paints

9-08

Timber and Lumber

9-09

6-04.3

Construction Requirements

6-04.3(1) Storing and Handling Material

At the Work site, the Contractor shall store all timber and lumber in piles. Weeds and
rubbish under and around these piles shall have been removed before the lumber is
stacked.

Untreated lumber shall be open stacked at least 12 inches above the ground. It shall be
piled to shed water and prevent warping.

Treated timber shall be:
1.  Cut, framed, and bored (whenever possible) before treatment;
2.  Close stacked and piled to prevent warping;
3.  Covered against the weather if the Engineer requires it;
4.  Handled carefully to avoid sudden drops, broken outer fibers, and surface

penetration or bruising with tools; and

5. Lifted and moved with rope or chain slings (without use of cant dogs, peaveys,

hooks, or pike poles).

6-04.3(2) Workmanship

The Contractor shall employ only competent bridge carpenters. All their Work shall be
true and exact. Nails and spikes shall be driven with just enough force to leave heads
flush with wood surfaces. The Contractor shall discharge any worker who displays poor
workmanship by leaving deep hammer marks in wood surfaces. Workmanship on metal
parts shall comply with requirements for steel Structures.

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Timber Structures

6-04.3(3) Shop Details

The Contractor shall submit Type 2 Working Drawings consisting of shop detail plans for
all treated timber. These plans shall show dimensions for all cut, framed, or bored timbers.

6-04.3(4) Field Treatment of Cut Surfaces, Bolt Holes, and Contact Surfaces

All cut surfaces, bolt holes, and contact surfaces shall be treated in accordance with

Section 9-09.3

for all timber and lumber requiring preservative treatment.

All cuts and abrasions in treated piles or timbers shall be trimmed carefully and treated in
accordance with

Section 9-09.3

6-04.3(5) Holes for Bolts, Dowels, Rods, and Lag Screws

Holes shall be bored:

1. For drift pins and dowels – with a bit 1/16 inch smaller in diameter than the pins

and dowels.

2. For truss rods or bolts – with a bit the same diameter as the rods or bolts.
3. For lag screws – in two parts: (a) with the shank lead hole the same diameter as the

shank and as deep as the unthreaded shank is long; and (b) with the lead hole for the

threaded part approximately ⅔ of the shank diameter.

6-04.3(6) Bolts, Washers, and Other Hardware

Bolts, dowels, washers, and other hardware, including nails, shall be black or galvanized
as specified in the Plans, but if not so specified shall be galvanized when used in treated
timber Structures.

Washers of the size and type specified shall be used under all bolt heads and nuts that
would otherwise contact wood.

All bolts shall be checked by burring the threads after the nuts have been finally
tightened. Vertical bolts shall have nuts on the lower ends.

Wherever bolts fasten timber to timber, to concrete, or to steel, the members shall be
bolted tightly together at installation and retightened just before the Contracting Agency

accepts the Work. These bolts shall have surplus threading of at least ⅜ inch per foot of

timber thickness to permit future tightening.

6-04.3(7) Countersinking

Countersinking shall be done wherever smooth faces are required. Each recess shall be
treated in accordance with

Section 9-09.3

Timber Structures

6-04

6-04.3(8) Framing

The Contractor shall cut and frame lumber and timber to produce close-fitting, full-
contact joints. Each mortise shall be true to size for its full depth, and its tenon shall fit it
snugly. Neither shimmed nor open joints are permitted.

6-04.3(9) Framed Bents

Mudsills shall be of pressure-treated timber, firmly and evenly bedded to solid bearing,
and tamped in place.

Concrete pedestals that support framed bents shall be finished so that sills will bear
evenly on them. To anchor the sills, the Contractor shall set dowels in the pedestals
when they are cast. The dowels shall be at least ¾ inch in diameter and protrude at least
6 inches above the pedestal tops. Pedestal concrete shall comply with

Section 6-02

Each sill shall rest squarely on mudsills, piles, or pedestals. It shall be drift-bolted to
mudsills or piles with ¾-inch diameter or larger bolts that extend at least 6 inches into
them. When possible, the Contractor shall remove any earth touching the sills to permit
free air circulation around them.

Each post shall be fastened to sills with ¾-inch diameter or larger dowels that extend at
least 6 inches into the post.

6-04.3(10) Caps

Timber caps shall rest uniformly across the tops of posts or piles and cap ends shall be
aligned evenly. Each cap shall be fastened with a drift bolt ¾ inch in diameter or larger
that penetrates the post or pile at least 9 inches. The bolt shall be approximately in the
center of the pile or post.

If the Roadway grade exceeds 2 percent, each cap shall be beveled to match the grade.

6-04.3(11) Bracing

When pile bents are taller than 10 feet, each shall be braced transversely and every other
pair shall be braced longitudinally. No single cross-bracing shall brace more than 20 feet
of vertical distance on the piles. If the vertical distance exceeds 20 feet, more than one
cross-bracing shall be used. Each brace end shall be bolted through the pile, post, or cap
with a bolt ¾ inch in diameter or larger. Other brace/pile intersections shall be bolted or
boat-spiked as the Plans require. Cross-bracing shall lap both upper or lower caps and
shall be bolted to the caps or sills at each end.

6-04.3(12) Stringers

All stringers that carry laminated decking or vary more than ⅛ inch in depth shall be

sized to an even depth at bearing points. Outside stringers shall be butt jointed and
spliced. Interior stringers shall be lapped so that each rests over the full width of the
cap or floorbeam at each end. Except on sharp horizontal and vertical curves, stringers
may cover two spans. In this case, joints shall be staggered and the stringers either

Page 6-170

Timber Structures

toenailed or drift bolted as the Plans require. To permit air circulation on untreated timber
Structures, the ends of lapped stringers shall be separated. This separation shall be done
by fastening across the lapping face a 1 by 3-inch wood strip cut 2 inches shorter than the
depth of the stringer.

Any cross-bridging or solid bridging shall be neatly and accurately framed, then securely
toenailed at each end (with two nails for cross-bridging and four nails for solid bridging).
The Plans show bridging size and spacing.

6-04.3(13) Wheel Guards and Railings

Wheel guards and railings shall be built as

Section 6-06.3(1)

requires.

6-04.3(14) Single-Plank Floors

Single-plank floors shall be made of a single thickness of plank on stringers or joists.
Unless the Engineer directs otherwise, the planks shall be:
1. Laid heart side down with tight joints,
2. Spiked to each joist or nailing strip with at least two spikes that are at least 4 inches

longer than the plank thickness,

3. Spiked at least 2½ inches from the edges,
4. Cut off on a straight line parallel to the centerline of the Roadway,

5. Arranged so that no adjacent planks vary in thickness by no more than 1/16 inch, and

6. Surfaced on one side and one edge (S1S1E) unless otherwise specified.

6-04.3(15) Laminated Floors

The strips shall be placed on edge and shall be drawn down tightly against the stringer or
nailing strip and the adjacent strip and, while held in place, shall be spiked. Each strip shall
extend the full width of the deck, unless some other arrangement is shown in the Plans or
permitted by the Engineer.

Each strip shall be spiked to the adjacent strip at intervals of not more than 2 feet, the
spikes being staggered 8 inches in adjacent strips. The spikes shall be of sufficient length
to pass through two strips and at least halfway through the third. In addition, unless
bolting is specified in the Plans, each strip shall be toenailed to alternate stringers with
40d common nails and adjacent strips shall be nailed to every alternate stringer. The
ends of all pieces shall be toenailed to the outside stringer. The ends of the strips shall
be cut off on a true line parallel to the centerline of the Roadway. When bolts are used
to fasten laminated floors to stringers, the bolts shall be placed at the spacing shown in
the Plans, and the pieces shall be drawn down tightly to the bolting strips. The bolt heads
shall be driven flush with the surface of the deck. Double nuts or single nuts and lock
nuts shall be used on all bolts. The strips shall be spiked together in the same manner as
specified above.

Timber Structures

6-04

6-04.3(16) Plank Subfloors for Concrete Decks

Any plank subfloor shall be laid surfaced side down with close joints at right angles
to the centerline of the Roadway. Planks shall be spiked in place as required in

Section 6-04.3(14)

Floor planks shall be treated in accordance with

Section 9-09.3

6-04.3(17) Trusses

Completed trusses shall show no irregularities of line. From end to end, chords shall be
straight and true in horizontal projection. In vertical projection they shall show a smooth
curve through panel points that conforms to the correct camber. The Engineer will reject
any pieces cut unevenly or roughly at bearing points. Before placement of the hand
railing, the Contractor shall complete all trusses, swing them free of their falsework, and
adjust them for line and camber (unless the Engineer directs otherwise).

6-04.3(18) Painting

Section 6-07.3(13)

governs painting of timber Structures.

6-04.4 Measurement

The criteria in

Section 6-03.4

will be used to determine the weight of structural metal

other than hardware.

Timber and lumber (treated or untreated) will be measured by the 1,000-board feet
(MBM), using nominal thicknesses and widths. Lengths will be actual lengths of individual
pieces in the finished Structure with no deduction for daps, cuts, or splices. To measure
laminated timber decking, the Contracting Agency will use the number and after-dressing
sizes of pieces required in the Plans. The length of each lamination shall be the length
remaining in the finished Structure.

6-04.5 Payment

Payment will be made for each of the following Bid items that are included in the
Proposal:
1. “Timber and Lumber (untreated or name treatment)”, per MBM.
2. “Structural Metal”, lump sum.

Where no item for structural metal is included in the Proposal, full pay for furnishing
and placing metal parts shall be included in the unit Contract price per MBM for
“Timber and Lumber”.

When no Bid item is included in the Proposal and is not otherwise provided, painting shall
be considered as incidental to the construction, and all costs therefore shall be included in
the unit Contract prices for the payment items involved and shown.

Standard Specifications for Road, Bridge, and Municipal Construction 2020 (M 41-10) - page 67