WELCOME

CONSTRUCTION SUPERVISION CONSULTANT, PMBPBANGLADESH ARMY

BRIDGE EXPANSION JOINT

INTRODUCTION

INTRODUCTION

Generally Expansion Joints of Bridges are designed to provide continuity betweentwo parts of the structures which are in relative movements because of thermaldeformation, creep, shrinkage and displacement/deflection of the structuresunder traffic load. Expansion Joints should be capable of accommodating allmovements of the deck slab.

TYPE OF EXPANSION JOINT BASED ON MOVEMENT

Small Movement Joints: capable of accommodating total motion up to45 mm.

Medium Movement Joints: capable of accommodating total motion 45mm to 130 mm.

Large Movement Joints: capable of accommodating total motion excessof 130 mm.

TYPE OF SMALL MOVEMENT JOINT (Based On Construction)

Sliding Plate joints

Compression Seal Joints

Asphaltic Plug Joints

Poured Sealant Joints

SLIDING PLATE JOINT

Advantages:

1. Sliding Plate Joints are used for short andmedium span bridges.

2. These Joints are structurally simple, reasonablein cost.

Disadvantages:

1. These are limited to horizontal movement andthere would be no differential verticalmovement.

2. Plates need to be adjusted periodically to reducenoise level.

3. The corrosion of plates and debris collected mayresult in jamming of the joint preventing the freemovement of superstructure.

COMPRESSION SEAL JOINT

Advantages: These seals are versatile, relativelyinexpensive and easy to replace.

Disadvantages:

1. For wider joints, adherence of the seal to thesides of the joint throughout the length is difficult.

2. Not suitable for deck slab with a large skew andcurvature.

ASPHALTIC PLUG JOINT

Advantages:1. They provide smooth roadway surface for traffic.2. They are water tight and snow proof.3. There is no debris collection at the top of the joint.

Disadvantages:1. Not suitable in cold areas where lowest temperature

is below Transition temperature of APJ material.2. Generally limited to the skew angle below 30

degrees.3. Can not accommodate differential vertical

displacement.

POURED SEALANT JOINT

Advantages:1. Easy to use and self leveling.

2. Can be placed in a short time so suitable forrehabilitation/repair project.

3. Exhibit good elastic properties over a wide range oftemperature variation.

Disadvantages:1. It’s a temporary type of joint system(8-10 years) and

mainly used for bridge rehabilitation projects where itis difficult to replace existing seals.

2. Very sensitive to field installation conditions, such asworkmanship.

TYPE OF MEDIUM MOVEMENT JOINT (Based On Construction)

Strip Seal joints

Finger Plate Joints

STRIP SEAL JOINT

Advantages:

1. Properly installed strip seals have demonstratedrelatively good performance.

2. Damage seals can be replaced with minimumtraffic disruptions.

Disadvantages:

1. Accumulates debris which can resist jointmovement and result in a premature seal failure.

2. Faulty installations or unclean locking devicescause seal pullout from metallic rail edges.

FINGER PLATE JOINTAdvantages:

1. It can accommodate all movements of the structureboth horizontal and vertical.

2. Successfully used in medium and long span bridges.3. It has a good riding quality without causing any

hazards to any class of road users.4. Silent and skid & vibration free in operation.5. It allows easy inspection, maintenance, repair or

replacement.

Disadvantages: Finger Plate joints allow water and de-icing chemical to pass through them. Elastomeric ormetallic seal must be placed beneath them to interceptthe deck water and debris way from the substructuremember.

TYPE OF LARGE MOVEMENT JOINT (Based On Construction)

Bolt-Down Panel Joints

Modular Elastomeric Seal Joints

BOLT-DOWN JOINT

Advantages: Bolt-down panels can be fabricatedin varying widths proportional to the total allowablemovement range.

Disadvantages: Bolts and nuts connecting panelto bridge decks are prone to loosening and breakingunder high speed traffic. The loose panels andhardware in the roadway present hazards tovehicular traffic, particularly to motorcycles.

Elastomeric dam

MODULAR ELASTOMERIC SEAL JOINT

Advantages: These joints provide watertightand vehicular load transfer across a wideexpansion joint openings and performance ofthese joints at many locations have been foundsatisfactory.

Disadvantages: These devices are structurallycomplex and very expensive.

INSTALLATION OF FINGER TYPE EXPANSION JOINT IN APPROACH ROAD BRIDGES OF PMBP

TERMINOLOGY

Fine Steel Finger Plate

It is made of high-grade steel plates ofidentical thickness according the requiredcontractility. It is subjected to special anti-rusty treatment.

Steel Profile Sealer Strip

It uses mature profile steel to make sealingset with good water protection. It isdesigned to connect finger plate, easyinstalling and reliable.

Rubber Seal

It is a made of age enduring rubber.

HT Bolt

It is used as anchorage to fix the Finger Plate with profile sealer strip andconcrete. Dimension and quantity to be specified according to expansionvalue.

DESIGN OF FINGER TYPE EXPANSION JOINT

INSTALLATION STEPS WITH PICTORAL VEIW

Prepare the Block-out area Reference Beam Installation

Reference Beam Reference Beam

Block-out area after deck slabs concreting

Placing Steel Profile Sealer Strip Placing Cross Beam for level adjustment of Steel Profile

Level adjustment Center line checking Level checking

Final Level checking by Level Machine

After installation Anchor BoltInstalling of Anchor Bolt

Welding of rectangular anchor bar with Steel Profile

After installation and welding of anchor bar

Welding Anchor Bolt with anchor Rebar Welding extra cut piece rebar with Anchor Bolt & anchor Rebar

Cleaning by Air Compressor Formwork placing for Expansion Gap Cleaning by Water

Rubber Seal placing on Steel Profile Rubber Seal installation by hand

Rubber Seal installation by Crowbar After installation Rubber Seal

Concreting up to the level of Steel Profile Concreting in Block-out area (Concrete Class C-50)

Tightening Anchor Bolt by Hand Wrench

Tightening Anchor Bolt by Electric Wrench

Placing Finger Plate

Concreting up to the level of Finger Plate

Curing

After complete Installation

SEALING OF ANCHOR BOLT HOLES WITH EPOXY RESIN

MAINTENANCE OF FINGER TYPE EXPENSION JOINT

During regular maintenance work of the bridge, frequently removeaccumulated dust and gravels to avoid effects on free expansion anddamage to finger plate or seal leakage.

Regularly inspect the anchor bolts for damage and look for cracks orleakage at the joint between the finger plate and the deck concrete. If itoccurs, it is required to carry out timely repairs.

Take regular anti-rust measures to assure the expansion joints are in normalworking condition.

CONTRACTION JOINT

WHY USED?

Contraction Joint is used to reduced the number of expansion joint,thereby reducing cost and increasing driving comfort .

It allows only contraction of deck slab while the expansion joint allowsboth expansion and contraction.

DESIGN OF CONTRACTION JOINT

Debonding coat will be provided at dowel bars before concreting adjacent deck slab

Contraction Joint after concreting deck slab(one side)

Dowel Bars

Sealing compound will be provided in this gap (10x20 mm)

OPEN FORUM

CONCLUSION