221 ALASKA 2020 SECTION 505
505-1.01 DESCRIPTION . Furnish and drive piles, and assist in high str ain dynamic pile testing.
505-1.02 Definitions .
CUT-OFF. The cut off end of a pile, or cutting a pile end at the finish elevation. DIFFICULT DRIVING. Difficult driving occurs when the approved hammer exceeds 120 blows per foot, while operating at the corresponding stroke indicated in the approved wave equation analysis used to assess pile stresses. DRIVECAP. A pile driver component that is used to transmit impact forces from the hammer ram to the pile top. The drivecap includes the anvil or striker plate, hammer cushion (capblock), helmet, and pile cushion, if used. (Also termed the driving head). DRIVING RESISTANCE. The required axial resistance, in units of force, to be demonstrated during pile installation. ESTIMATED PILE TIP ELEVATION. The pile tip elev ation that was assumed in order to estimate the pile quantities shown on the bid schedule. FRESH HEADING. Cutting the end of a pile perpendicular to the long axis to remove damage, and to obtain a proper driving or splicing surface. FOLLOWER. A pile driv ing aid placed between the helmet and the pile top when the pile head is below the reach of the hammer. HAMMER CUSHION. A disk of material placed on top of the helmet but below the anvil or striker plate to relieve impact shock and provide protection for t he hammer and pile. HAMMER ENERGY: Maximum Rated Hammer Energy . The theoretical maximum amount of gross energy that a pile driving hammer can generate. Transferred Hammer Energy. The amount of energy transferred to the pile for a given blow accounting for friction energy during the ram down stroke, energy retained in the ram and drivecap during rebound, and other impact losses as measured by high strain dynamic testing. HELMET. A pile driver component that fits closely on top of the pile to ensure the impac t force is transmitted uniformly across the top of the pile and concentric with the axis of the pile. LEADS. Pile driver components used to maintain pile and hammer alignment during driving, and on which the pile hammer may travel. Types of leads include: Fixed Leads . Pile driving leads that are attached at the top of the boom by a pivot and to the crane at the bottom with a brace. The pile is held at the top by the helmet and is guided at the bottom by the pile gate. Semi -Fixed Leads . Pile driving leads t hat are attached at the top of the boom by a pivot and supported by the lead line. The lead can slide axially along the pivoted boom point and may be fitted with an extendable brace at the bottom of the leads. Swinging Leads . Pile driving leads that are suspended from the boom by the cable and are not attached to the crane at the bottom with a brace. (Also known as offshore leads) 222 ALASKA 2020 MINIMUM PENETRATION . The minimum length of pile below the footing or finished ground elevation to which the pile must be driven. OBSTRUCTION. An unanticipated object projecting within the path of the pile that causes pile refusal or impedes the pile's advance within required tolerances. PILE GATE. A device at the base of the leads that is closed around the pile to maintain alignment. REFUSAL. Refusal occurs when the approved hammer requires 15 or more blows to move the pile one inch or less while the hammer is operating at the hammer’s rated stroke or higher, or, when the pile yield stress is measured or estimated to be equal to or greater than 90 percent of the specified pile yield stress. SUBSTRUCTURE UNIT . A unit of the substructure such as an abutment or pier that transmits loads directly from the superstructure to the ground. TEST PILE. A pile that has a high- strain dynamic test performed on it. TEMPLATE . A structure affixed to the ground used to maintain proper pile alignment during driving. WAVE EQUATION ANALYS IS. A numerical method of analysis for the behavior of driven piles that predicts the pile capacity versus blow count r elationship (bearing graph) and pile driving stress. Wave equation analysis is performed using a commercially available wave equation analysis program (WEAP) with a version dated 2010 or later.
505-2.01 MATERIALS . Use materials that conform to the following:
Structural Steel Piles Section 715 Sand Subsection 703- 2.12
505-2.02 PILES . Furnish piles sufficient in length to extend to the Estimated Pile Tip Elevation
specified in the Contract documents. Furnish full -length piles where practical. Where splices are required, follow the provisions of Subsection 505- 3.04. Furnish additional pile length to provide for fresh heading and to suit the method of installation. Use metal shoes or reinforced tips as required. Store and handle piles in a manner that protects them from damage.
1.Steel Piles . Furnish H -pile sections, pipe piles, sheet piles or other structural steel sections described in the Contract. The Engineer will reject steel piles that exceed the camber and sweep permitted by allowable mill tolerance. Hot-dip galvanize steel piles a minimum thickness of 4 mils from the top to a distance not less than 10 feet below the finished ground line according to Subsection 716- 2.07. Steel piles and pile shells that do not protrude above the final ground line do not r equire galvanizing. CONSTRUCTION REQUIREMENTS
505-3.01 Pile Drivin G Equipment.
1.Pile Driving System . Use impact hammers to drive piles and to determine resistance during pile driving. Vibratory hammers may be used only for initial placement up to a penetr ation of 15 feet unless approved by the Engineer. Use pile driver leads that allow the hammer to move freely. Do not use followers to drive piles. 223 ALASKA 2020 Fit the pile driving hammer with a cast -steel driving head (or similar device) that is recommended in the hammer manufacturer’s guidelines, is compatible with the pile, and aligns concentrically and fits closely with the top of the pile. If the pile driving hammer is fitted with a hammer cushion, use a cushion that satisfies the recommendation in the hammer manufacturer’s guidelines, is appropriate to prevent damage to the hammer or pile, and ensures uniform driving performance. If not new, ensure the hammer cushion is at least 75 percent of the manufactured thickness. Replace driving hammer cushions with a reduction in cushion thickness exceeding 25 percent of the manufactured thickness. Do not use wood, wire rope, or asbestos hammer cushions. Use only equipment included in the approved pile driving plan. The Engineer may inspect the pile driving equipment for conformance with the approved pile driving plan after it has been mobilized to the site and prior to beginning pile driving operations. Remove and replace pile driving equipment the Engineer determines does not conform with the approved pile driving plan, at no extra cost to the Department and with no adjustment to contract time.
2.Pile Driving Plan . No less than 30 days prior to the anticipated start of pile driving, submit for approval the details of each proposed pile driving system. Include in the pile dr iving plan:
a.A completed Pile Driving Equipment Data form (Form 25D -098) for all hammer/pile configurations proposed for use on the project.
b.Manufacturer’s catalog cuts, specifications, manuals, guidelines, and technical bulletins for all pile driving equipment to be used.
c.A description of the techniques to be used for ensuring proper placement and alignment of the piles, and advancing the piles to the Minimum Penetration and Driving Resistance as provided on the plans. Include proposed pile section lengths , estimated pile cutoff lengths, number of splices expected for each pile, and where galvanized pile will be used, if applicable.
d.Alternate methods of pile installation in the event obstructions are encountered.
e.A wave equation analysis for each pile driv ing system (see 505- 3.01- 3). The Engineer will base approval of the pile driving hammer on the wave equation analysis submitted by the Contractor and the requirements in this Subsection. The Department will verify the wave equation analysis using the computer program “GRLWEAP” and GRLWEAP industry standard hammer input data. The Engineer’s approval of the pile driving plan will not relieve the Contractor of responsibility for:
f.removing and replacing piles damaged during pile driving operations,
g.obtaining t he Driving Resistance specified in the Contract, or
h.meeting Minimum Penetration specified in the Contract documents. Do not mobilize pile driving equipment to the site without an approved pile driving plan. Submit all revisions to the approved pile drivin g plan to the Engineer for approval. For all pile driving equipment not previously identified in the pile driving plan, include in the submittal all of the information required above for the pile driving plan. Explain to the Engineer, in writing, which por tions of the approved pile driving plan will be superseded by the revision and which portions remain unchanged. Allow at least 5 days for the Engineer’s approval of pile driving plan revisions. 224 ALASKA 2020 3. Wave Equation Analysis . Submit a wave equation analysis sealed by a registered professional civil engineer licensed in the State of Alaska for all pile impact driving systems used to install piling according to the requirements of this subsection and the user’s manual for the program. Verify that the pile driving sy stem proposed does not produce pile stresses greater than 90- percent of the yield stress at the Driving Resistance specified in the plans. The rate of pile penetration must be between 30 and 100- blows per foot at the Driving Resistance specified in the pla ns, unless approved by the Engineer. Unless otherwise specified in the Contract or directed by the Engineer, use the presumptive quake and damping values presented in the program user’s manual for the pile and soil conditions. Use of residual stress option is not allowed for prediction of blow counts. TABLE 505 -1 HAMMER EFFICIENCIES USED IN HAMMER APPROVAL
505-3.02 PILE TESTIN G AND PILE DRIVING CRITERIA . The Engineer will use high- strain
dynamic testing to monitor pile driving performance and to evaluate the resistance of the pile during driving. The pile driving acceptance criteria will be developed using the results of the dynamic testing. The Engineer may also perform pile testing to confirm hammer -system efficiency; pile driving stresses, and pile integrity. Attend a meeting with the Engineer at least 14 days prior to the beginning of pile driving operations to evaluate and discuss the test pile program. Give the Engineer 7 days advance notice before driving each test pile. The Engineer will perform the high- strain dynamic testing in accordance with ASTM D4945. Piles tested using high- strain dynamic testing may be incorporated into the work. Dynamic pile testing will include gathering dynamic data for at least 25 feet of the final pile drive as well as a restrike up to 30 hours after end of initial drive. The restrike may be waived at the direction of the Engineer. The Engineer will test the first pile driven at each substructure. Do not install any production piles at the substructure unit until the test pile has been driven to the Driving Resistance and Minimum Penetration specified in the Contract documents unless directed in writing by the Engineer. The Engineer will require 4 hours at each test pile to set up and install the test equipment. The Engineer will attach testing instruments near the top of the test pile through drilled and threaded holes. When the pile is driven t o the point where the testing instruments need to be removed from the lower pile section, they will be reattached to the top of the newly spliced section. The Department will furnish the testing equipment and labor necessary to mount the testing instrument s to the pile. Provide a reasonable and safe means of access to the top of the test pile after the pile is placed in the leads. Furnish electrical power (a 115 volt, 55- 60 cycle AC outlet, 10 amp minimum) for the Engineer’s use during the installation and operation of the testing instruments. Drive each test pile to the Driving Resistance and Minimum Penetration specified in the Contract documents as indicated by the driving criteria provided by the Engineer. The Engineer will record Hammer Type For Analysis of Driving Rate For Analysis of Driving Stresses Single acting diesel hammers 0.72 0.84 Closed -ended diesel hammers 0.72 0.84 Single acting air/steam hammers 0.60 0.70 Double acting air/steam hammers 0.45 0.53 Hydraulic hammers or other external combustion hammers having ram velocity monitors that may be used to assign an equivalent stroke. 0.85 1.00 225 ALASKA 2020 driving data for the test pile. If an obstruction is encountered during driving of the test pile, testing will stop on that pile and the next pile driven at the substructure unit will be designated as a test pile. If a pile is driven to Estimated Pile Tip Elevation and the high- strain dynamic test results do not support the conclusion that the Driving Resistance has been obtained, the Engineer may direct testing of additional piles and or suspension of pile driving operations and require the Contractor to restrike the pile up to 30 hours later with the Engineer present to record driving data. Perform the restrike with a warmed- up hammer with the energy or fuel setting adjusted to the position indicated in the approved pile driving plan. Strike the test pile with 60 consecutive blo ws or until the pile penetrates an additional 3 inches, whichever comes first. The Engineer may terminate the re-strike at any point during the testing. If the results from the high- strain dynamic testing are acceptable to the Engineer, drive the remaining piles at the substructure unit using the driving criteria developed from the high- strain dynamic testing. The Engineer will provide the driving criteria within 1 day of the completion of high-strain dynamic testing. If the results from high- strain dynamic testing are not acceptable to the Engineer, proceed as per the written direction of the Engineer. Account for the entire allotted equipment installation time required by the Engineer in the progress schedule submitted under Subsection 108- 1.03 or Section 646, as applicable. Suspension of pile driving operations at a testing location to allow for testing instrument installation or a re -strike of a test pile is not a suspension of work per Subsection 108- 1.06 and additional contract time will not be allowed.
505-3.03 DRIVING PIL ES. Drive all piles to the Driving Resistance and Minimum Penetration
specified in the Contract documents using the pile driving criteria provided by the Engineer. Use the same pile driving system used to set pile driving criteria to drive all piles. Install piles in groups starting from the center of the group and proceed outward in either direction. If the pile is driven to the Estimated Pile Tip Elevation and does not meet the acceptance criteria, continue driving only at the written direction of the Engineer.
1.Placement and Alignment . Ensure proper placement and alignment of the piles. The Engineer will reject piles that are bent or otherwise damaged by forcing the pile into the leads or template. Drive piles within an allowed vari ation as to direction of pile of not more than 1/4 inch per foot. Limit the rotation of steel piles about their longitudinal axis to 15 degrees from the plan position. In addition, position piles to the following tolerances:
a.Abutments . Position the piles at the bottom of an abutment within 3 inches of the position specified in the Contract documents. Do not vary the distance between any two piles more than 3 inches from that specified in the Contract documents, and keep the clear distance from the edge of p ile to the edge of footing to at least 9 inches.
b.Pier Footings . Position the piles at the bottom of a footing within 6 inches of the position specified in the Contract documents. Do not vary the distance between any 2 piles more than 6 inches from that specified in the Contract documents, and keep the clear distance from the edge of pile to the edge of footing to at least 9 inches.
c.Exposed Pile Piers . Position the piles within 2 inches of the position specified in the Contract documents at cut -off elevatio n and within 3 inches of the position specified in the Contract documents at the original ground line elevation. 226 ALASKA 2020 2. Protection of New Concrete. When driving a pile near concrete placed within 28 days, ensure the distance between the pile being driven and the nearest edge of concrete is not less than the distance determined by the following formula: ECD= Where: D = Distance in feet E = Maximum rated hammer energy in foot -pounds C = Vibration coefficient shown in Table 505- 2 based on the num ber of calendar days after concrete placement TABLE 505 -2 VIBRATION COEFFICIEN T Concrete Age (days) Coefficient 1 0.34 2 0.23 3 0.18 4 0.15 5 0.13 6 0.12
7-9 0.11
10-13 0.10
14-20 0.09
21-28 0.08
3.Obstructions . Use alternate methods to drive thro ugh or remove obstructions. Obtain written approval from the Engineer before employing any alternative methods of pile advancement. After exhausting all practicable means to obtain the minimum penetration, but without success, the Engineer will evaluate t he structural adequacy of the bridge at a lesser penetration. This review will be based on the resistance of the pile during driving. If the Engineer finds the structure to be adequate, the pile will be accepted at the lesser pile penetration.
4.Concrete Fil led Pipe Piles . After driving pile, clean out the pile to the bottom of concrete elevation specified in the Contract documents. If there is a delay between cleanout and placing concrete, verify that the soil level in the pile has not rebounded before placi ng concrete.
505-3.04 SPLICES, EXTENSIONS AND BUILD- UPS. If the length of a steel pile is not sufficient
to obtain the Minimum Penetration and Driving Resistance specified in the Contract documents, the pile may be spliced in order to obtain the length required to reach the Minimum Penetration and Driving Resistance. Use pile additions with cross sections identical to the pile cross sections. Make splices with complete joint penetration welds over the entire cross section. If approved, piles may be spliced using pile cut -offs and short pieces if no piece used is less than 10 feet long. Meet the welding requirements of Section 504. Align the piles at a splice to meet the dimensional tolerances for the allowable variation in straightness of welded columns in AWS D1.1. 227 ALASKA 2020 505-3.05 DEFECTIVE PILES. Use a pile driving method which does not damage the pile. Do not manipulate the piles to force them into proper position. Correct damaged or improperly driven piles using a method approved by the Engineer. Drive down all piles pushed up by driving adjacent piles or by any other cause. Approved methods may include one of the following:
1.Withdraw and replace the pile with a new and, when necessary, longer pile.
2.Drive a second pile adjacent to the defective pile.
3.Splice or bu ild up the pile.
4.Extend a sufficient portion of the footing to properly imbed the pile.
505-3.06 CUTTING OFF PILES. Cut off the piles at the elevations indicated on the Plans. Ensure
that all injured material is removed. When steel piles are shown embedded in concrete footings or pile caps, cut off piles within -1/2 inch to +3 inches of the plan embedment, but do not interfere with reinforcing steel or other items embedded in concrete. When steel pipe piles are shown cutoff below concrete footings or pile caps, cut off piles within -1/2 inch to +1/2 inch of the plan elevation. In pile bents with steel cap beams, make accurate cut -offs to ensure full bearing between the caps and piles.
505-4.01 METHOD OF M EASUREMENT . See Section 109 and as follows:
Furnish Pi les. The sum of the lengths of the piles in place in the completed structure, measured from the tip of pile to the cut -off elevation. Drive Piles . The number of piles driven which are incorporated into the completed structure. Sheet Piles . The projected ar ea of furnished and driven sheet piles remaining in place in the permanent structure as called for on the Plans, measured in final position.
505-5.01 Basis of Pa Yment .
Furnish Piles . The contract price includes pile materials delivered to the site, pile s hoes, reinforced tips and casing. Unused pile lengths removed by cut -offs and fresh heading are subsidiary. The payment amount will be calculated using the quantity of pile indicated on the bid schedule, or the measured quantity of installed piles, whichev er is greater. Drive Piles . The contract price includes:
1.All related work required to drive the piles to the Minimum Penetration and Driving Resistance, including: pile crew time (including payroll and administrative additives), equipment costs, and other fixed or variable items incurred during pile driving, the construction of temporary work platforms, fresh heading, splicing, restrike, pile cleanout and cutting off.
2.All related work required to construct preformed pile holes in locations identified in the Contract and sand backfill material.
3.All related work required to assist the Engineer in performing High Strain Dynamic Testing is subsidiary. Sheet Piles . Sheet piles used as temporary shoring for excavation, whether removed or left in place at your opti on with permission of the Engineer, are subsidiary. 228 ALASKA 2020 Obstruction Removal . Alternate methods of pile advancement through obstructions or difficult driving will be performed at the direction of the Engineer and will be paid in accordance with section 109- 1.05 under item 505.0014.____ Special Pile Excavation. Payment will be made under: PAY ITEM Item Number Item Description Unit 505.0005.____ Furnish Structural Steel Piles, ______ LF 505.0006.____ Drive Structural Steel Piles,______ EACH 505.0009.____ Structural Steel Sheet Piles SF 505.0014.____ Special Pile Excavation CS 229 ALASKA 2020 SECTION 506 TIMBER STRUCTURES
506-1.01 DESCRIPTION . Construct timber structures and the timber portions of composite
structures. Furnish, prepare, fabricate, erect, treat and/or paint timber and hardware, as specified.
506-2.01 MATERIALS. Use materials that conform to the following:
Timber Section 713 Preservatives for Timber Section 714 Structural Shapes, Rods, and Plates Section 716 Glued- Laminated Timber Members . Construct of Dougl as Fir produced and inspected in conformance with the requirements of ANSI/AITC A 190.1. Use laminating adhesives for timber to be used in wet conditions. Use Industrial -Grade glued -laminated members that have been treated with pressure preservative. Bolts , Screws and Drive Spikes . Conform to ASTM A307 (ANSI/ASME B 18.2.1). Galvanize meeting AASHTO M 232. Use standard timber fasteners manufactured with economy heads and spiral threads as drive spikes for fastening glued- laminated deck panels. Preservatives . Use pressure treatment preservatives for timber bridges as specified. Mastic Sealer . Use Seal Tight 158 Rubber Asphalt Sealer, or approved equal. Steel Dowels . Use uncoated steel dowels with a minimum yield strength of 36,000 psi on glued- laminated deck panels. Timber Connectors . Conform to the requirements of the AASHTO Standard Specifications for Highway Bridges , Division II, Section 16.2.6, Timber Connectors. CONSTRUCTION REQUIREMENTS
506-3.01 GENERAL. Employ competent bridge carpenters. Framing must be true and exact. Set
the heads of nails and spikes flush with the wood surface. Workmanship on all metal parts must conform to specified requirements. Stack all lumber and timber at the worksite to prevent warping. Open- stack untreated material at least 12 inches above the ground surface so that the pile will shed water. When required, cover untreated timber to protect it from the weather. Close -stack treated timber above the ground on blocks or lagging. Clear weeds and rubbish underneath and around all st acks. Locate all non- removable erection marks on fabricated timber so they are hidden from view in the completed work. Do not drag or drop timber members. Use web- belting slings and chokers to handle timber members. Protect corners with protection angles or blocking at pickup points. The estimated quantity of treated timber shown on the Plans is approximate only and no guarantee is made that it is the exact quantity to be furnished. Glued- laminated timber quantities shown on the Plans indicate gross quantit ies of timber, based on nominal dimensions and actual lengths before final planing of the laminated member.
506-3.02 TREATED TIM BER. Fabricate timber (including all cutting, shaping, and boring) before
treatment. Handle timber carefully without dropping, breaking the outer fibers, or bruising or penetrating the surface with tools. In coastal waters, avoid cutting and boring below the high- water mark. Carefully trim all abrasions and treat all cuts in treated piles according to AWPA standard M 4.
Source: Alaska Standard Specifications for Highway Construction, 2020 Edition. Pages 249–256 of 584.