Attachment 4 - ACROW Bridge 700XS Technical Handbook 2015 Metric.pdf

ACROW

700XS

PANEL BRIDGE

TECHNICAL HANDBOOK

FOURTH EDITION 2015 (METRIC)

TYPICAL ACROW BRIDGE

ACROW 700XS TECHNICAL HANDBOOK

COPYRIGHT ACROW ® CORPORATION 2015

BUILDING BRIDGES. CONNECTING PEOPLE.

ACCESS RAMP AT WORLD TRADE CENTER RECOVERY EFFORT, NEW YORK

LIFT BRIDGE AT QUINCY, MASSACHUSETTS

2 COPYRIGHT ACROW ® CORPORATION 2015

ACROW CORPORATION

BUILDING BRIDGES. CONNECTING PEOPLE.

ACROW PANEL BRIDGING TECHNICAL HANDBOOK

700XS MODULAR BRIDGING SYSTEM

FOURTH EDITION 2015

This publication has been rewritten to reflect improvements recently made to the Acrow 700XS Modular Bridging System. It is intended to explain the design characteristics and requirements of ordering and installing an Acrow 700XS Bridge. All dimensions and other design factors are expressed in metric units.

COPYRIGHT ACROW ® CORPORATION 2015 3

COPYRIGHT ACROW ® CORPORATION 2015 4

ACROW PANEL 700XS BRIDGE HANDBOOK

TABLE OF CONTENTS

SECTION 1 INTRODUCTION Page 7

SECTION 2 GENERAL DESCRIPTION AND USE 8

SECTION 3 DESCRIPTION OF MAJOR COMPONENTS

3.1 Bridge Components 11

3.2 Footwalk Components 23

3.3 Launching Components 25

3.4 Construction Tools 27

SECTION 4 BRIDGE DESIGN

4.1 Specification 28

4.2 Site Assessment 29

4.3 Bridge and Truss Selection 29

4.4 Launching Design 30

SECTION 5 BRIDGE CONSTRUCTION

5.1 Introduction 31

5.2 Construction Area 32

5.3 Abutment and Site Layout 34

5.4 Roller and Equipment Layout 34

5.5 Construction of the Launching Nose 36

5.6 Construction of the Main Span 40

5.7 Installing the Bridge 45

5.8 Jacking the Bridge 51

5.9 Construction of Double-Storey Bridges 54

5.10 Construction of Footwalks 55

4 COPYRIGHT ACROW ® CORPORATION 2015

COPYRIGHT ACROW ® CORPORATION 2015 5

SECTION 6 MULTIPLE-SPAN BRIDGES

6.1 General 57

6.2 Discontinuous Bridges 57

6.3 Continuous Bridges 57

6.4 Pier Towers 57

SECTION 7 BRIDGE MAINTENANCE AND INSPECTION

7.1 Storage of Bridging Components 61

7.2 Bridge Inspection 61

SECTION 8 REFERENCE TABLES

8.1 Component Weights 64

8.2 Bridge Dimensions 66

8.3 Bridge Weights 68

8.4 Truss Constructions -

AASHTO (ASD) 69

TABLE OF CONTENTS (Continued)

COPYRIGHT ACROW ® CORPORATION 2015 6

DISCLAIMER

This Handbook is intended to provide only general information concerning the Acrow 700XS Panel Bridge (The “Bridge”). The information included in this Handbook is not intended to be comprehensive, precise, definitive, or authoritative, and should not be relied upon as such for any reason.

Neither Acrow nor any of its affiliates will be liable or in any way responsible for any errors or deficiencies of any kind in the information contained herein.

More specific, definitive, and authoritative information is available from Acrow only by contracting with Acrow specifically for on-site technical assistance. You may contact Acrow for the rates, terms and availability of such technical assistance.

NO PART OF THIS PUBLICATION MAY BE REPRODUCED, STORED IN AN INFORMATION OR

DATA RETRIEVAL SYSTEM OR TRANSMITTED IN ANY FORM OR BY ANY MEANS –

ELECTRONIC, MECHANICAL, PHOTOCOPYING, RECORDING OR OTHERWISE – WITHOUT

THE PRIOR WRITTEN PERMISSION OF ACROW

CORPORATION OF AMERICA.

6 COPYRIGHT ACROW ® CORPORATION 2015

COPYRIGHT ACROW ® CORPORATION 2015 7

SECTION 1 INTRODUCTION

The Acrow 700XS Panel Modular Bridging System is now well established worldwide as a leading bridge product, able to provide solutions to most difficult access situations.

Acrow 700XS Panel is a direct descendant of the military Bailey Bridge through several well-known Acrow developments, and as such, is recognized as an unsurpassed product in its field. It is fully modular and uses many of the same principles incorporated in the Bailey concept, including: easy transportability to remote locations, erection by unskilled crews with or without cranage, low maintenance, and versatility.

The Acrow system has been designed to carry highway and pedestrian loadings as specified by the American AASHTO bridge design code, and complies with most national standards including Euro, British, and Canadian, as well as Military Tri-Lateral specifications. The equipment is fabricated entirely from steel and is provided with a hot dipped galvanized finish to ensure excellent weathering capability. The bridge is assembled using only pins and bolts and requires no site welding. All components are 100% reusable.

Acrow’s 700XS bridging is manufactured in the United States. There is a core group of typical components used in the assembly of a bridge. With these typical components, one can assemble bridges of different widths and of varying weight-carrying capacity from light trucks to the heaviest earthmoving mining trucks. Single spans can range from six to ninety-one meters and, with multiple spans, any length of bridge may be accommodated. Special components may also be designed and produced for non-standard situations.

The standard deck units are orthotropic in design. This is a highly efficient design that will support very heavy loads over decades of use. The panels forming the side trusses are 2.29 meters in height, which provides a tall and efficient structural system.

All components, including the panels, are manufactured to extremely close tolerances, ensuring that all components are always fully interchangeable regardless of their year of manufacture.

COPYRIGHT ACROW ® CORPORATION 2015 8

SECTION 2 GENERAL DESCRIPTION AND USE

The Acrow 700XS Panel Bridge is a fully modular system intended to be used as a permanent or temporary road bridge, or to provide an economical solution to an access problem.

The system is based on steel, structural truss panels, measuring 3.05 x 2.26 meters, which can be combined in a variety of configurations to provide a bridge side truss designed for any specific purpose. Transoms (transverse deck beams) of various standard lengths, link the trusses together and provide support for the deck. With these variations, the Acrow 700XS Bridging system can accommodate a wide range of span, width, and load specifications. A standard truss panel is illustrated in Figure 2.1.

Acrow bridges may be built as either simple span or multispan structures. Multi span bridges may be designed either as continuous structures over intermediate piers or as a series of simple spans linked together. The simple spans can vary in size from a single lane bridge six meters long, to a two, three, or four-lane highway bridge with spans up to ninety-one meters.

The side trusses comprise standard truss panels assembled in a variety of ways to suit any particular design specification. The panels can be accommodated side by side and also stacked. Further versatility and range is given by the use of reinforcing chords attached to the tops and bottoms of the trusses. The various standard truss configurations with their abbreviated names are illustrated in Figure 2.2.

The side trusses are connected by bridge transoms (transverse floor beams) which are placed at 3.048 meter centers and accommodate the deck units spanning longitudinally between them. The transoms are bolted to the panels and are also connected by diagonal rakers.

The deck units are designed as orthotropic structures with longitudinal edge stiffening, and are able to withstand the heaviest wheel loading at any point. The outside deck units can be provided with integral welded curbs. The deck units are 1.83 meters wide so that a single lane bridge has two curb units side by side, providing a deck width of 3.67 meters. A two-lane bridge deck is comprised of two central decks and two outside curb units giving a width of 7.35 meters. The deck units may be provided with a plain galvanized finish suitable for an asphalt surfacing, or with a factory-applied aggregate driving surface that prevents skidding.

8 COPYRIGHT ACROW ® CORPORATION 2015

COPYRIGHT ACROW ® CORPORATION 2015 9

In addition to the single and two-lane bridges detailed above, the following alternatives are available:

Extra Wide: Single lane bridge with a width of 4.2 meters EW18: Single lane bridge, width 5.5 meters 2L30: Two-lane bridge, width 9.15 meters 3L36: Three lane bridge: width 11 meters

Cantilevered foot walks are available as standard equipment and can provide pedestrian access on one or both sides of the bridge. The footwalks are fully separated from vehicular traffic and allow complete pedestrian security. Foot walks are described in Section 3.2.

The most common method of installation for an Acrow bridge is by a “cantilever launch”. The bridge is partially built on rollers on the home bank of the gap and then pushed across to land on the far bank. To prevent overturning, the front of the bridge is extended with a lighter structure known as the “launching nose”. A modified version of this method is the “crane-assisted launch”, which can be carried out with either a much shorter nose or none at all. Both methods are described in Section 5. When cranes of sufficient capacity are available, partially-built bridges may be lifted on to their abutments without launching considerations.

FIGURE 2.1 STANDARD PANEL: AB701

COPYRIGHT ACROW ® CORPORATION 2015 10

FIGURE 2.2 STANDARD TRUSS CONFIGURATIONS

10 COPYRIGHT ACROW ® CORPORATION 2015

COPYRIGHT ACROW ® CORPORATION 2015 11

SECTION 3 DESCRIPTION OF MAJOR COMPONENTS

3.1 BRIDGE COMPONENTS

TRUSS MEMBERS

AB701 PANEL

The truss panel is the basic building block of the Acrow bridging system and provides the structural strength of the bridge side trusses. They may be used singly on each side of the bridge or combined together in various configurations to provide trusses with enormous capacity, capable of carrying up to four lanes of highway traffic over spans in excess of sixty meters. The truss panel is a welded steel fabrication, comprised of top and bottom chords linked by a series of vertical and diagonal bracing members. The chords at one end of the panel terminate in a male jaw, while the other end has a female jaw; both jaws have a transverse pin hole. The panels connect the male to female end, and are secured by inserting an AB051 Panel Pin through the coinciding pin holes; AB052 Safety Clips secure the pin in position at both ends. The AB701 Panel is capable of 267 kN in shear at its end.

The panel dimensions between pin hole centers are 3.05 long by 2.18 meters high.

The panels are fabricated from hot rolled steel sections of specification ASTM A572 Grade 65, also known as AASHTO M223, and are hot dip galvanized to ASTM A123, as are all components.

AB702 SHEAR PANELS

A bridge truss will be comprised mostly of AB701 Panels. However, to generate capacity at the bearings without the need to provide end posts, it is necessary to include shear panels in the end bays of bridge. The AB702 Shear Panel has the same overall dimensions as those of the AB701, but incorporates heavier bracing members, thus enabling the traffic loads to be transferred to the bridge bearings.

NOTE: Because the correct positioning of different panels within a truss is essential to the structural capability of the bridge, it is extremely important to correctly identify them prior to commencing the build. The main distinguishing feature of the AB702 Shear Panel is the use of solid rectangular sections as the end verticals and rectangular tubes as diagonals. The AB701 is fabricated entirely from channel sections.

AB708 HIGH SHEAR PANEL

The AB708 High Shear Panel is dimensionally similar, but has a greater load capacity which will be required in some very large bridges. They are always used with

COPYRIGHT ACROW ® CORPORATION 2015 12

AB702 Panels in the adjacent bays. They differ from the AB702 Panels by the use of solid rectangular sections for the diagonal members.

AB051 PANEL PIN

The standard panel pins are manufactured in compliance with 4140, Grade B7/ASTM A193. They are 206mm long by 47mm in diameter and can carry a safe working load of 650 KN in double shear. They are tapered at each end and can be safely hammered home into the panel jaws using a 4kg hammer without damage. In use, the pins are secured at each end with an AB052 Safety Circlip.

AB620, AB621 REINFORCING CHORDS

Reinforcing chords are double channel fabrications similar to the top/bottom chord of the AB701 Truss Panels. The AB620 is 3.28 meters in length; i.e., one bay in length, and the AB621 is two bays long. The chords are used to increase the moment capacity of the trusses, but do not add to the shear capacity. Reinforcing chords are bolted to the top and bottom chords of the panels using eight AB584 Chord Bolts per AB621 Reinforcing Chord and four AB584 Chord Bolts per AB620 Reinforcing Chord.

The chords are joined end to end with AB051 Panel Pins. In a reinforced bridge the chords are typically used in all bays except the end bays which are un-reinforced.

Double and triple trusses may be partially reinforced to produce DSR1 and TSR2 trusses.

12 COPYRIGHT ACROW ® CORPORATION 2015

FIGURE 3.1 PANEL PIN : AB051 & AB052 CIRCLIP

COPYRIGHT ACROW ® CORPORATION 2015 13

AB622, AB623 HEAVY REINFORCING CHORDS

Fabricated from heavier channel sections, the heavy chords are used in a similar manner to the AB620 & AB621 chords, but where greater moment capacity is required.

The AB622 Heavy Reinforcing Chord is one bay long and the AB623 is two bays long.

The heavy chords have a larger pinholes and are connected end to end with the AB079 Heavy Panel Pin.

AB079 HEAVY PANEL PIN

Similar to AB051 Pins but with a diameter of 56mm for use with heavy reinforcing chords. They are secured at each end with a heavy safety ring, AB079A.

FIGURE 3.2 REINFORCING CHORDS : AB620 AND AB621

COPYRIGHT ACROW ® CORPORATION 2015 14

BRACING MEMBERS

AB703 RAKER

Connects the panels to the transoms and provides vertical truss bracing. The bottom of the raker is bolted to the web of the transom using a single AB547A Transom Bolt which also passes through the end vertical of the outer panel of multiple panel trusses.

At the end bays where an AB702 or AB708 is used, the longer AB547AS Transom Bolt is required. The upper end of the raker is bolted to the end vertical of the inner panel.

With multiple panel trusses, the same bolt also connects to the AB513 Raker Brace.

AB513 RAKER BRACE

The raker brace is bolted horizontally to the other panels in the truss assembly using an AB549A Short Brace Bolt at each panel, or in shear panels with an AB548A Raker Bolt.

It should be noted that all bolts passing through the panel end verticals should be inserted from the panel side, and the securing nut placed in the gap between the panels with the washer being placed at the head side of the bolt.

The raker brace is provided with an extra bolt hole to be positioned at the transom for an AB547 bolt, only in a single truss configuration.

14 COPYRIGHT ACROW ® CORPORATION 2015

FIGURE 3.3 RAKER : AB703 AND RAKER BRACE : AB513

COPYRIGHT ACROW ® CORPORATION 2015 15

AB514 CHORD BRACE and AB522 DIAGONAL BRACE

The AB514 Chord Brace is very similar to the AB513 Raker Brace described earlier. It differs only in that it has no spacer plate welded to the bolt hole at one end. The AB514 Chord Brace and the AB522 Diagonal Brace are connected with AB549A bolts to the underside of the top chords of all trusses to form a continuous "Z" brace for the whole length of the truss. However the starting and ending transverse members are AB513 Raker Braces instead of AB514 Chord Braces. The spacer makes up for the lack of a diagonal brace on one side.

The AB522 Diagonal Brace is the primary horizontal bracing system for multiple-truss configurations.

FIGURE 3.4 CHORD BRACE: AB514 AND DIAGONAL BRACE : AB522

COPYRIGHT ACROW ® CORPORATION 2015 16

SWAYBRACES

Swaybraces form the main horizontal bracing system which ensures the bridge will be built squarely and resists transverse forces on the bridge (wind, etc.). There are four standard Swaybraces in use: AB590 Swaybrace used with the single lane and two-lane bridges, and the AB591 Swaybrace EW used for Extra Wide bridges. There are also the AB515 Swaybrace Heavy and AB516 Swaybrace Heavy EW which are heavy duty braces used in two storey and long span bridges.

All swaybraces are fabricated from steel channel sections and are provided with a clevis at each end. This fits over a cleat welded to the web of the transoms, and is secured by a single AB536A Brace Bolt. In each bay of bridge there are two swaybraces which, in single lane constructions, cross and are bolted together at the center using a single AB549A Short Brace Bolt. In two-lane bridges, the swaybraces form a “V” in each bay and must follow the bracing pattern to be effective.

FIGURE 3.5 EXTRA WIDE SWAYBRACE : AB591

AB518 & AB519 TRANSOM BRACE

Every transom must be braced vertically. This is accomplished by the use of transom braces consisting of 76mm channels or angles in alternate bays. The braces are placed in pairs in two parallel lines close to the trusses, and take the form of a simple “X” brace bolted to the transoms and to each other where they cross, with AB549A bolts. The AB518 Transom Brace Standard is used with all single lane bridges, and the AB519 Transom Brace Two Lane with all two or three lane structures.

16 COPYRIGHT ACROW ® CORPORATION 2015

COPYRIGHT ACROW ® CORPORATION 2015 17

FIGURE 3.6 TRANSOM BRACE: AB518

TRANSOM BEAMS

Transoms are the main floor beams which determine the width of the bridge. They are available in the following typical lengths: Standard Carriageway (SCW), Extra Wide (EW), Extra Wide 18 (EW 18), Two Lane (TL24), Two Lane (2L30) and Three Lane (3L36). Other roadway widths can also be accommodated. The transoms are located at the end of each bay over the panel pin position, and at each end of the bridge.

They are provided with special channels (Halfen Channels), welded to their tops into which the deck units are located and secured with deck bolts. The transoms are fabricated from standard hot-rolled beams.

AB511 SCW TRANSOM

The standard single lane transom which provides a deck width of 3.67 meters.

AB507 EW TRANSOM

A single-lane transom giving a deck width of 4.2 meters.

COPYRIGHT ACROW ® CORPORATION 2015 18

FIGURE 3.7 EXTRA WIDE TRANSOM: AB507

AB690 EW18 TRANSOM

A single-lane transom with a deck width of 5.5 meters for wider loads. All single lane transoms are fabricated from steel beams having a 410 mm depth.

AB585 TL24 TRANSOM

The standard two-lane transom fabricated from a beam of 608 mm depth. The deck width provided is 7.35 meters.

AB510 TL24 TRANSOM HEAVY

Heavy duty, two-lane transom with deck width of 7.35 meters, and a beam depth of 618mm.

AB890 3L36 TRANSOM

The standard three-lane transom fabricated from a beam 780 mm deep. The deck width provided is 11 meters.

18 COPYRIGHT ACROW ® CORPORATION 2015

COPYRIGHT ACROW ® CORPORATION 2015 19

DECK UNITS

AB601 DECK UNIT AND AB602 CURB UNIT

Deck units are constructed with a plain steel running surface having a cross sectional depth of 137 mm. ( See Figure 3.8.) The deck units are fabricated as true orthotropic structures with longitudinal edge stiffening and lateral tubes for distributing wheel loads.

The curb units are provided with integrally welded curbs.

Each deck unit provides an effective deck width of 1.80 m so that two curbs on a single lane bridge gives a lane width of 3.67 meters and two curbs plus two decks give a running width of 7.35 meters.

Deck units are bolted to the transoms using a special AB546 “T” Bolt which locates into the special channel welded to the transom. Four bolts are used per deck unit, and all bolting is carried out from the top of the deck. (See Figure 3.9)

The deck units are provided with end plates which are designed to allow all vertical loads to be transferred from the deck to the transom close to the center of the beam and thus directly into the web. This load pattern prevents any torsional loads being imposed on the transom. Eliminating torsional loads results in a longer life for a transom.

If required, the decks can be given an asphalt surface overlay on site. Alternatively, the deck units may be provided with a factory applied, anti-skid epoxy and aggregate driving surface.

AB604 EW INFILL DECK UNIT

In order to provide the wider lane of the Extra Wide bridge, the AB604 EW Infill Deck is used between the two curb units to give a deck width of 4.2 meters. Each infill panel/unit is bolted to the transom with four deck bolts.

FIGURE 3.8 DECK UNIT: AB601

COPYRIGHT ACROW ® CORPORATION 2015 20

AB720 & AB721 EOB INFILL UNITS

Because the deck units locate to the center of the transoms, there will be a gap at each end of the bridge between the last deck unit and the abutment of approximately 140mm. The EOB (End of Bridge) infill units fill this gap with an AB720 EOB Infill used adjacent to each end deck or curb unit, and the AB721 EOB Extra Wide Infill where the AB604 EW Infill Deck has been used. Each EOB Infill is bolted down with two AB546 Deck Bolts.

BEARINGS

AB503/AB504 BEARING BLOCKS

The bearing block is pinned to the bottom of the AB702 Shear Panel or AB708 Heavy Shear Panel at the end of the bridge. The bridge loads are transferred to the bearings through AB503 Male Bearing Block or AB504 Female Bearing Block seated on an AB587 Bearing. (See Figure 3.10)

FIGURE 3.9 DECK HOLD DOWN SYSTEM

20 COPYRIGHT ACROW ® CORPORATION 2015

COPYRIGHT ACROW ® CORPORATION 2015 21

AB587 BEARING

Located on the abutment beneath the AB503 Male or the AB504 Female Bearing Block. It is effectively a rocker bearing that can be bolted down or restrained to an abutment or pier for a fixed bearing, or it can sit on top of the AB587U & AB587L for a sliding bearing condition. The bearing capacity is 588 kN. (See Figure 3.11)

AB587U & AB587L UPPER & LOWER BEARING ELEMENT

For the expansion bearings of a bridge, a sliding bearing elements are provided, and are located beneath the AB587 Bearings at the free end of the bridge. The AB587L Lower Bearing Element consists of a 178mm x 127mm x 3mm steel plate with a 152mm x 102mm x 3mm Teflon pad bonded to it. It is placed on the abutment or pier

FIGURE 3.11 BEARING: AB587

FIGURE 3.10 BEARING BLOCKS: AB503 AND AB504

COPYRIGHT ACROW ® CORPORATION 2015 22

with the Teflon pad facing up, and secured with epoxy adhesive selected for the application. The AB587U Upper Bearing Element is a 292mm x 216mm x 3mm stainless steel plate, which is placed on top of the Teflon. The AB587 Bearing is then placed on top of both plates. (See Figure 3.12)

BOLTS

All bolts used in the bridge are grade A325 and have a galvanized finish. They are all provided with a galvanized washer and nut. The typical location for each bolt type is described below. However, Acrow bridge plans provide explicit, detailed locations and bolt designations for the entire bridge assembly. All connection bolts in the bridge are to be properly tightened during the assembly process.

AB536A BRACING BOLT LONG

25.4mm diameter by 89mm long. It is used for bolting the swaybracing to the transoms. Also used as the bottom raker bolt for single truss constructions and for connecting the AB517 EOB Strut.

AB546 DECK BOLT

19mm diameter and 102mm long. It is provided with a “T” head which fits into the special channel on the transom and bolts the deck units down. This bolt comes as an assembly incorporating a square washer plus the round washer and two nuts. (See Figure 3.9)

AB547A TRANSOM BOLT

25.4mm diameter by 108mm long. It is used to secure the transoms to the AB701 Panels.

AB547AS TRANSOM BOLT SHEAR

25.4mm diameter by 140mm long. This bolt is used to bolt the transoms to the end verticals of the AB702 or AB708 Shear Panels.

22 COPYRIGHT ACROW ® CORPORATION 2015

FIGURE 3.12 UPPER AND LOWER BEARING

ELEMENTS: AB587U AND AB587L

COPYRIGHT ACROW ® CORPORATION 2015 23

AB548A RAKER BOLT

25.4mm in diameter and 64mm long. This bolt is used to secure the AB703 Raker to the end vertical of either the AB702 Shear Panel or the AB708 Heavy Shear Panel.

AB584 CHORD BOLT

32mm in diameter and 88mm long. This bolt is used to secure reinforcing chords to the truss panels (see Figure 5.7 for orientation)

3.2 FOOTWALK COMPONENTS

A cantilevered footwalk system can be attached to the transoms at either or both sides of the bridge. The standard walk surface is 5’ wide. However, other widths are also available to suit the site requirements.

AB480 FOOTWALK BEARER

Bolted to the top of the transom with AB053 Bearer Bolts. The footwalk bearer consists of double channels which will support the footwalk deck units. Tubes welded to the top of the bearer receive the footwalk railing posts.

AB481 FOOTWALK POST

A square tube which fits into the post receptacles on the footwalk bearer and are secured with AB487 Post Bolts. Plates welded to the sides of the post accommodate the AB482 Footwalk Handrail.

AB482 FOOTWALK HANDRAIL

Consists of a 76mm wide channel which is secured to the AB481 Footwalk Post, with AB485 Footwalk Rail Bolts.

AB483 FOOTWALK DECK

The Footwalk Deck unit measures 3.04 meters by 1.5 meters, and is provided with small curbs to prevent debris falling from the footwalk and to satisfy toe plate requirements. The deck units are secured to the AB480 Footwalk Bearer with AB486 Footwalk Deck Bolts. A deck unit can be supplied with the epoxy-aggregate, anti-skid surface, or a galvanized, checker plate surface.

AB484 FOOTWALK BEARER STRUT

Consists of a steel angle which bolts to the transom and supports the end of the AB480 Footwalk Bearer as a diagonal strut. The connection to the transom is with an AB549 Bracing Bolt Short.

AB053 BEARER BOLT ASSEMBLY

19mm diameter by 89mm. Connects the AB480 Footwalk Bearer to the transom. This comes as an assembly including a bevelled washer to compensate for the bevelled flange of the bearer channel. (See Figure 3.18)

COPYRIGHT ACROW ® CORPORATION 2015 24

FIGURE 3.13 FOOTWALK BEARER: AB480 FIGURE 3.14 FOOTWALK POST: AB481

FIGURE 3.15FOOTWALK HANDRAIL: AB482

FIGURE 3.16 FOOTWALK DECK: AB483

FIGURE 3.17 FOOTWALK BEARER STRUT: AB484 FIGURE 3.18 FOOTWALK BEARER BOLT: AB053

24 COPYRIGHT ACROW ® CORPORATION 2015

COPYRIGHT ACROW ® CORPORATION 2015 25

AB485 FOOTWALK RAIL BOLT

13mm diameter by 38mm; it is used to secure the AB482 Footwalk Handrail to the AB481 Footwalk Post.

AB486 FOOTWALK DECK BOLT

13mm diameter by 50mm; it is used to secure the AB483 Footwalk Deck to the AB480 Footwalk Bearer.

AB487 FOOTWALK POST BOLT

13mm diameter by 102mm. This bolt is used to secure the AB481 Footwalk Post to the AB480 Footwalk Bearer receptacle.

3.3 LAUNCHING COMPONENTS

AB043 ROCKING ROLLER

These rollers are used at the abutments as both the launching and receiving rollers during a launch. Each roller is located on a AB587 Bearing and has the ability to articulate so that it is able to receive the launching nose in the correct alignment, and also to allow the taper chords to pass over easily. The unit contains two built-in horizontal rollers, and the bridge alignment is maintained by two vertical guide rollers.

The total safe working load is 25 tonnes. (See Figure 3.19)

FIGURE 3.19 ROCKING ROLLER: AB043

COPYRIGHT ACROW ® CORPORATION 2015 26

AB042 PLAIN ROLLER

The launching nose and bridge are built on the plain rollers which are typically placed at

7.5 meter centers behind the rocking rollers. The number of stations of plain rollers depends on the available length of build area and on the bridge length. One side of the roller has a vertical side plate which acts as a guide to the bridge as it is pushed forward. The side plate side is usually orientated to the outside of the truss. The Plain Roller has a working capacity of 15 tonnes. (See Figure 3.20)

AB654 LAUNCHING LINK

This link is pinned between two adjacent panels in the launching nose. It lengthens the bottom chord and elevates the nose sufficiently to overcome deflection during launch.

(See Figure 3.21).

AB660 TAPER CHORD MALE

These units are typically required when launching a reinforced bridge to enable the reinforcing to pass easily over the rocking rollers. Bridges are normally built female end forward and the AB660 Taper Chord Male is pinned to the front female end of the bottom reinforcing and typically bolted to the underside of the front AB702 Shear Panel with a single AB584 Chord Bolt. (See Figure 3.22)

FIGURE 3.20 PLAIN ROLLER: AB042 FIGURE 3.21 LAUNCHING LINK: AB654

FIGURE 3.22 TAPER CHORD MALE: AB660

26 COPYRIGHT ACROW ® CORPORATION 2015

COPYRIGHT ACROW ® CORPORATION 2015 27

AB661 TAPER CHORD FEMALE

Similar to the AB660 but used at the rear of the bridge, and is pinned to the end of the reinforcing chords. This allows the reinforcing chord to pass over the rocking rollers.

(See Figure 3.23)

AB662 TAPER CHORD MALE HEAVY & AB663 TAPER CHORD FEMALE HEAVY

The components have the same functions as the AB660 and AB661, but are used when a heavy reinforced bridge is launched. They are pinned to the reinforcing chords using an AB079 Panel Pin Heavy.

3.4 CONSTRUCTION TOOLS:

AB205 SNAP RING PLIERS

Used to place the AB052 Safety Circlips on the Panel Pins.

AB207 HYDRAULIC JACK

Used to lift the bridge from the rollers and lower it on to the bearings, with a maximum 27 tonne capacity.

Other construction tools required for bridge assembly generally consist of standard ironworker’s tools including ratchet wrenches, 4kg and 1kg hammers, come-alongs and pry bars. Thin wall sockets required are: 27mm, 41mm and 51mm plus a 200mm extension and universal. String lines and measuring tapes are also suggested. These tools are typically provided by the erector, but can be provided by Acrow for additional cost.

FIGURE 3.23 TAPER CHORD FEMALE: AB661

COPYRIGHT ACROW ® CORPORATION 2015 28

SECTION 4 BRIDGE DESIGN

4.1 SPECIFICATION

A bridge will be specified by a number of parameters, some of which are as follows:

Bridge width required Required span Loads to be carried Need for Pedestrian Footwalks Single or Multispan Simple spans or continuous spans

Having determined the basic requirements, a bridge can be selected from the design tables in Section 8. These will provide the recommended truss configuration based on deck width, and enable the weight of the structure to be calculated.

It should be noted however, that while the size and weight of a bridge may be determined from the tables for purposes of estimating and construction planning, Acrow Corporation will always provide their clients with a full engineering service.

This service will include all design calculations and construction drawings ready for submission to interested authorities. Within these calculations will be a bearing reaction table, which will be transmitted to the bearings thus enabling the foundations to be designed.

For a nominal fee, Acrow Corporation will provide on-site technical personnel to oversee the construction of the bridge, which is strongly recommended to assure proper assembly.

Once the size and weight of the bridge have been determined, the method of construction can be decided upon. The common method of construction is by cantilever launch. However, there may be circumstances which can make this either difficult or impossible, and other solutions must be considered. For a launch it is necessary to construct most of the bridge plus a launching nose on rollers behind the home abutment. A site survey is required to determine if an area of sufficient size is available, since the entire launch procedure and details are dependent on the available build area behind the home rollers.

If cranes of sufficient size are available, a bridge may be also lifted into position.

Specific rigging details would be developed with the erector to assure a safe lift plan and avoid damage to the bridge.

28 COPYRIGHT ACROW ® CORPORATION 2015

COPYRIGHT ACROW ® CORPORATION 2015 29

4.2 SITE ASSESSMENT

If an Acrow Bridge is being built to replace a damaged structure as an emergency structure, or is being used as a temporary bypass to a permanent bridge under reconstruction, there may be some flexibility as to its exact location. In this case it is important to assess the approaches to the bridge and access for vehicles delivering the components in order to determine the optimum bridge location. If the location is pre-determined, the site should be assessed as to the suitability of the available working area behind the abutments, and to decide from which end the bridge should be launched.

If possible, the home and far bank bearing elevation should be the same.

However, if a longitudinal slope greater than 2% (1 in 50) is inevitable, special precautions may be necessary and Acrow should be consulted on the design.

Transverse cross-slopes are to be avoided. The build area for the structure should be straight and in line with the center line of the bridge. It should preferably be at least equal to the span length and have a working width three meters wider than the transom length. If the build and launch area is less than that suggested, the result may be a more difficult, restricted build, necessitating extra counterweights and extra steps during the launch.

The build area and launch plane must be level laterally and, if possible, longitudinally.

If there is a longitudinal slope, it is most important that the top of the rollers lies in a single continuous plane. The soil surface should be compacted enough to accommodate the reactions to be imposed by each roller station.

The landing area on the far side of the gap should be sufficient for at least two bays of bridge to pass beyond the landing rollers. Ideally it should be possible for the complete nose to pass the abutment to avoid unnecessary pauses during the launch.

The bridge/nose reactions at the landing rollers must also be considered in developing the launch plan to avoid overloading the rollers or the truss members.

4.3 BRIDGE AND TRUSS SELECTION

From the specification parameters listed in 4.1 above, the span and required width will be determined together with the load to be carried. For AASHTO loadings, the truss size can be selected from Table 8.4 which gives the recommended truss configuration for single span bridges with various deck widths.

If the bridge requires footwalks or is a multispan structure, then further design work must be carried out by Acrow’s engineers. If only one footwalk is required, it is possible for the side truss carrying it to be of stronger configuration than the truss with no footwalk.

The Tables in Section 8 are to be used only for estimating purposes and to assess the bridge dead loads imposed on the abutments. All design loads will be confirmed by Acrow, although it should be noted that Acrow does not design sub-structures.

COPYRIGHT ACROW ® CORPORATION 2015 30

4.4 LAUNCHING DESIGN

It is not within the scope of this book to give a full description of the launch design pro-cedure. Launching a bridge is potentially hazardous and the design of the launching nose and launching procedure, i.e. length, truss size, position of the launching link, required counterweights, etc., is technically complex.

1. In general terms the length of a launching nose is commonly half the bridge span plus one bay.

2. A bridge is usually launched with some counterweight in the rear bays of the bridge.

3. The bridge can also be launched with the rear half of the bridge deck in place, providing additional counterweight for the launch.

4. The object of the design and launch procedure is to always know the position of the center of gravity of the structure as built, and to ensure that the C.G. always re-mains behind the launching rollers with a degree of safety.

Acrow Corporation can always provide the full launching design including drawings and project specific procedures. A launch procedure should only be carried out under the supervision of an Acrow-appointed engineer or Field Representative.

30 COPYRIGHT ACROW ® CORPORATION 2015

COPYRIGHT ACROW ® CORPORATION 2015 31

SECTION 5 BRIDGE CONSTRUCTION

5.1 INTRODUCTION

Acrow bridges may be built and installed by several methods, the most common one being a full cantilever launch from the home bank to the far bank. This method requires the construction of a launching nose at the front of the bridge. The nose is built on rollers and is comprised of standard panels braced to transoms to form a light-weight structure which lengthens the bridge and enables the whole structure, nose plus bridge, to be pushed out over the gap. By adding counterweight to the rear of the structure, it is possible to ensure that the center of gravity of the build always remains behind the launching rollers located on the home abutment, until the nose reaches the receiving rollers on the far abutment.

If a crane with sufficient capacity is available, a crane-assisted launch can also be used. This method requires either a very short nose or none at all, and utilizes the crane located on the far bank and hooked to the front of the bridge. The crane provides the increasing lift of the tip to prevent overturning as the bridge nears the far bank. This method requires great care and skill by the crane operator, and should only be undertaken with Acrow if all those concerned are confident of success, given the circumstances.

If sufficiently large cranes are available, bridges may be also lifted into place either complete or without the deck. The lifting points should always be at transom level and incorporate straps or wire rope, of adequate capacity, around the lower truss chords with adequate blocking to prevent damage of the bridge. Any construction method should be engineered by Acrow engineers and supervised by a qualified Acrow Representative.

COPYRIGHT ACROW ® CORPORATION 2015 32

F

IG

U R

E

.1 T

Y P

IC

A

L B

U

IL

D A

R E

A L

A Y

O U

T

E W

B R

ID

G

E

5.2 CONSTRUCTION AREA

BUILDING AREA

For a conventional launch, it is preferable to have an area behind the launching rollers equal in length to the span. The area should be approximately 3m wider than the transoms in use and have room to stack components within easy reach of the as-sembly equipment. A typical arrangement is shown in Figure 5.1.

32 COPYRIGHT ACROW ® CORPORATION 2015

COPYRIGHT ACROW ® CORPORATION 2015 33

The working area should be such that the plain and rocking rollers can be placed level transversely and in a common plane longitudinally. If the launch is on a gradient, either positive or negative, the slope should not exceed 2 percent. Bridges launched on a slope must be fully secured at all times during launch and assembly, by being tied to the launch vehicle or an external restraint, in order to prevent accidental movement during construction. In all cases it is imperative the rollers be level or at a constant gradient and level transversely.

The careful positioning and levelling of rollers prior to the build will often be a time consuming operation, but is essential in order to ensure that the first bays of bridge are built square, and allowing the easy insertion of all the bracing bolts. Time spent on accurately placing and levelling rollers will be repaid with dividends during construction and launching. Setting the rollers to an accuracy within 5 mm vertically is recommended. Care must be taken to ensure that the support grillage for rollers is able to take the loads without sinking or failing. Timber grillages are usually used to support the plain rollers, but if the soil conditions do not permit the use of timbers, concrete pads may be used. If concrete is used, the minimum size is 1500mm by 1500mm by 300mm thick with re-bar for structural integrity. It is critical to note that all rollers and cribbing/grillages must be restrained to resist the longitudinal thrusts inherent with any launch procedure.

If the available construction area is less than the ideal, it may be necessary to construct the bridge ‘restrictively’ or in stages. Counterweights will be required at the rear of the bridge as constructed during any launch procedure to ensure that the center of gravity remains behind the launching rollers at all times. When short interim launch pushes are required in a restrictive build, it will be necessary to place counterweights for the push and then to remove them following further construction. Inevitably this will involve double handling of counterweight material and increase the time required for the build.

A longer nose can sometimes be usefully employed in a restrictive build. Deck units are ideal for use as counterweights, as they may be readily stacked on the transoms in the rear bays.

LANDING AREA

A sufficiently clear space is required on the far bank to allow at least two bays of nose to pass beyond the landing rollers. Ideally, it should be possible for the complete launching nose to pass the rollers so that unnecessary interruptions of the launch may be avoided. It is also necessary to be aware of the structural integrity of the nose plus bridge before removing any nose as partial removal may compromise the structure.

During construction of the bridge, the engineer must always be cognizant of weather conditions. Wind gusts can add unwanted weight to the bridge and apply lateral forces that may affect the alignment of the bridge during a launch. Therefore, it is not recommended to launch a bridge with sustained winds of 40 km/h or gusts of 55 km/h or greater.

COPYRIGHT ACROW ® CORPORATION 2015 34

5.3 ABUTMENT AND SITE LAYOUT

The home and far bank construction areas should be cleared, graded and compacted if necessary, so that roller foundations can be placed, components stored, and construction traffic can operate upon it without uneven or undue subsidence.

Acrow does not design foundations, although we will provide typical drawings showing the dimensional requirements. The abutments must be designed to accommodate Acrow’s design loads considering the underlying ground conditions. Except for emer-gency situations, the abutments are usually formed in reinforced concrete as spread foundations, or by constructing a pile cap on bearing piles. Alternatively, the bridge bearings can be located on steel beams which themselves will be located on bearing piles.

If the abutments are concrete, the launching and landing rollers should be set out on the bearing shelf, usually in front of the bearing positions to avoid the need for a tail during the launch. It is always recommended that the rear retaining walls of the abut-ment (the end dam walls), be left off until the bridge is in place on its bearings. Also that the grading behind the abutments is left low enough to accommodate the plain roller and pads. If this is not done, the rollers have to be located at a higher elevation requiring temporary blocking, and work involved in subsequent jacking down is consid-erably increased. If the bridge is on steel foundations, provisions must be made to ac-commodate the home roller positions, and the end retaining wall may be formed by sheet piling or possibly stone Gabions.

5.4 ROLLER AND EQUIPMENT LAYOUT

Set out the centerline of the bridge by sighting a line from the far bank abutment across the gap and back into the construction area. The line from the home abutment can be marked with a string line, against which can be marked the centerline positions of the construction rollers. The ideal positions of the launching and landing rollers are marked on the bearing shelf 750mm in front of (i.e. toward the gap) the bearing posi-tions. If the rollers can be placed in these positions, it will shorten the effective span by

1.5 meters and also simplify the eventual jacking down procedures.

Plain rollers are typically placed at 7.62m centers behind the launching rollers on lines at right angles to the centerline. The rollers are set in pairs located under the inner and outer panel lines of each truss. (See Figure 5.1) Other configurations may also be re-quired as dictated by the site-specific launch procedures generated by Acrow engi-neers.

34 COPYRIGHT ACROW ® CORPORATION 2015

COPYRIGHT ACROW ® CORPORATION 2015 35

The distance at which the rollers should be set from the centerline of the bridge is as follows:

CENTERLINE OF BRIDGE TO CENTER OF INNER ROLLERS OUTER ROLLERS

Standard Wide (SCW) 2.019m 2.705m

Extra Wide (EW) 2.477m 3.162m

Extra Wide 18 (EW18) 2.896m 3.581m

Two Lane (TL24) 3.848m 4.534m

Two Lane (TL30) 4.859m 5.544m

Three Lane 36 (3L36) 5.690m 6.375m

When laying out the construction equipment, plan to place the components for the launching nose and fifty percent of the bridge trusses at the midway point of the storage area and the remaining fifty percent plus deck, at the rear of the storage area. Storage of the components should be to the side of the build area but within reach of the assembly crane.

Many project sites will not meet the ideal layout as shown in Figure 5.1, and the area must then be adapted to suit the conditions. Bear in mind the general principle that the material stockpiles should be placed as near as possible to the positions in the bridge where they will be used during assembly.

FIGURE 5.2 CANTILEVER LAUNCH OF ACROW BRIDGE

COPYRIGHT ACROW ® CORPORATION 2015 35

COPYRIGHT ACROW ® CORPORATION 2015 36

5.5 CONSTRUCTION OF THE LAUNCHING NOSE

INTRODUCTION

This description of a typical launching nose build is for use with an Extra Wide bridge and a 17-Bay (51.82m) span. The truss construction of the bridge will be Double Single Reinforced Two (DSR2) and the nose will be 27.43 meters (9 Bays) in length, and its truss construction will be 7 bays of Single Single (SS) plus two bays of Double Single (DS) construction.

The bays of the structure (each 3.048 meters long), are numbered from the front of the nose through to the rear of the bridge. Therefore Bays 1 to 7 (nose) are Single Single construction, Bays 8 & 9 (nose) are Double Single, and Bays 10 to 26 are the bridge itself using Double Single Reinforced Two construction.

CONSTRUCTION OF BAYS 1 TO 3 OF NOSE

The first Bay of the launching nose consists only of two AB 701 Panels without a forward transom. For this reason the building commences with Bay 2. For ease of construction, bridges are usually built with the female jaws of the panels towards the gap (Female Forward).

With the rollers laid out as described in Section 5.4, the first AB507 Transom is placed on blocking about 5 meters ahead of the first pair of plain rollers, at right angles to the alignment of the bridge. The position of this transom must be such that the inner panel connection holes are in line with the rollers. This first transom is placed with the “cut-outs” in the top flange facing away from the gap. (see Figure 5.3). The transom must be located on packing so that its underside is at least 100mm above the tops of the rollers. (see Figure 5.4A)

An AB701 Panel is now brought up to the transom with female jaws forward, and bolted to it at the inner position using AB547A Transom Bolts. The rear end of the panel is supported on blocking placed approximately 500mm from the rear jaw for stability of the panels (see Figure 5.4.A). An AB703 Raker is now bolted to the transom at the outer panel position and to the panel at the bolt hole near the top of the end vertical member.

The connection to the transom uses an AB536A Bracing Bolt Long and the connection to the panel is made with an AB549A Bracing Bolt. The procedure above is then repeated for the panel on the other side of the bridge.

The rear transom of Bay 3 may now be placed in position, located on the male jaws at the rear of the panels. The “cut-outs” for this transom will be facing towards the gap, and it should now be bolted to the trusses as above, and the rakers installed. All the remaining transoms in the nose will be placed with “cut-outs” facing towards the gap, except for the one between bays 7 & 8, which is the start of the Double Single construction. (see Figure 5.3).

36 COPYRIGHT ACROW ® CORPORATION 2015

COPYRIGHT ACROW ® CORPORATION 2015 37

FIGURE 5.3 LAYOUT OF TRANSOMS AT LAUNCHING NOSE

COPYRIGHT ACROW ® CORPORATION 2015 38

Every bay of bridge or nose contains a pair of AB519 Swaybraces. These braces, which are placed as a cross brace, ensure that the bridge bays are accurately squared and also function as the plan braces resisting lateral forces in the bridge. The swaybraces are placed by hand, the lower one first, located with its channel flanges pointing downwards and connected to the transom using the boltholes located in the lower flange near the truss panel position. The second, upper swaybrace is located with its flanges pointing up.

The bolts used at the transoms are AB536A Bracing Bolt Long. Where the swaybraces cross at their centers, they are bolted together using an AB549A Bracing Bolt Short. At this stage, bolts should be only hand tightened.

If the initial transom was situated correctly, the panels of Bay 3 should now be located directly over the first pair of plain rollers. If they are slightly out of position or out of line, this is the time to make corrections as the whole construction can be easily lifted and moved by the crane to achieve the correct alignment.

Bay 3 may now be constructed in a similar sequence behind Bay 2, and supported on packing.

Bay 1 may now be constructed by adding two panels to the front of Bay 2. Bay 1 does not have either a front transom or swaybracing. With a nose of 9 bays, the AB654 Launching Links would be installed between Bays 2 & 3, connected to the bottom jaws of the truss panels. Once the first three bays are complete the structure can be lifted off the front packing and lowered on to the plain rollers.

CONSTRUCTION OF BAYS 4 TO 9 OF NOSE

Bays 4, 5 and 6 may now be added to the rear and once these are built, Bays 1 to 3 may be fully tightened with wrenches. This procedure of tightening three bays ahead of construction should be followed throughout the nose and bridge build in order to allow flexibility of the assembly for component installation.

The rear packing may now be removed and the remainder of the nose built on the rollers. Restraints should be attached to the structure to prevent any movement during the remaining build. Bay 7 may now be added and as this is the last SS bay before the start of the DS Bay 8, the transom at the rear should be placed so that the top flange cut outs are facing away from the gap. This enables the outer panels of Bay 8 to be bolted to that transom.

The transom should be temporarily bolted to the Bay 7 trusses with AB547A Transom Bolts or tied to the panels to prevent it from falling. The swaybraces are then installed at which point the temporary restraints can be removed.